Articles | Volume 8, issue 10
https://doi.org/10.5194/amt-8-4281-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/amt-8-4281-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
14 Oct 2015
Research article |
| 14 Oct 2015
A perspective on the fundamental quality of GPS radio occultation data
T.-K. Wee
CORRESPONDING AUTHOR
University Corporation for Atmospheric Research, Boulder, Colorado, USA
Y.-H. Kuo
University Corporation for Atmospheric Research, Boulder, Colorado, USA
Related authors
Tae-Kwon Wee
Atmos. Meas. Tech., 11, 1947–1969, https://doi.org/10.5194/amt-11-1947-2018, https://doi.org/10.5194/amt-11-1947-2018, 2018
Short summary
Short summary
The refractivity in the radio occultation (RO) is generally obtained from the inverse Abel transform (AI) of measured bending angle. While concise and mathematically exact, AI is susceptible to the error present in the measurement. Aiming to reduce the adverse effects of the measurement error, this study proposes a new method for determining the refractivity through a variational regularization (VR). Verification shows that VR offers a definite advantage over AI in the quality of refractivity.
Ming Shangguan, Katja Matthes, Wuke Wang, and Tae-Kwon Wee
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2016-248, https://doi.org/10.5194/amt-2016-248, 2016
Revised manuscript has not been submitted
Short summary
Short summary
A first validation of the COSMIC Radio Occultation (RO) water vapor data in the upper troposphere and lower stratosphere (UTLS) are presented in this paper. The COSMIC water vapor shows a good agreement with the Microwave limb Sounder (MLS) in both the spatial distribution and the seasonal to interannual variations. It is very valuable for studying the water vapor in the UTLS, thanks to its global coverage, all- weather aptitude and high vertical resolution.
Shu-Ya Chen, Ying-Hwa Kuo, Hsiu-Wen Li, Ramon Padullés, Estel Cardellach, and F. Joseph Turk
EGUsphere, https://doi.org/10.5194/egusphere-2024-3708, https://doi.org/10.5194/egusphere-2024-3708, 2025
This preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).
Short summary
Short summary
This study used Polarimetric radio occultation (PRO) observations to evaluate simulations of cloud hydrometeors with five microphysics schemes for three typhoons from 2019 and 2021. The simulated cloud hydrometeors distributions varied significantly depending on model initial conditions, typhoon structures, and microphysics schemes. Results in this study demonstrate the potential for using PRO observation to evaluate the performance of different microphysics schemes in numerical models.
Tae-Kwon Wee
Atmos. Meas. Tech., 11, 1947–1969, https://doi.org/10.5194/amt-11-1947-2018, https://doi.org/10.5194/amt-11-1947-2018, 2018
Short summary
Short summary
The refractivity in the radio occultation (RO) is generally obtained from the inverse Abel transform (AI) of measured bending angle. While concise and mathematically exact, AI is susceptible to the error present in the measurement. Aiming to reduce the adverse effects of the measurement error, this study proposes a new method for determining the refractivity through a variational regularization (VR). Verification shows that VR offers a definite advantage over AI in the quality of refractivity.
Ming Shangguan, Katja Matthes, Wuke Wang, and Tae-Kwon Wee
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2016-248, https://doi.org/10.5194/amt-2016-248, 2016
Revised manuscript has not been submitted
Short summary
Short summary
A first validation of the COSMIC Radio Occultation (RO) water vapor data in the upper troposphere and lower stratosphere (UTLS) are presented in this paper. The COSMIC water vapor shows a good agreement with the Microwave limb Sounder (MLS) in both the spatial distribution and the seasonal to interannual variations. It is very valuable for studying the water vapor in the UTLS, thanks to its global coverage, all- weather aptitude and high vertical resolution.
Z. Zeng, S. Sokolovskiy, W. Schreiner, D. Hunt, J. Lin, and Y.-H. Kuo
Atmos. Meas. Tech., 9, 335–346, https://doi.org/10.5194/amt-9-335-2016, https://doi.org/10.5194/amt-9-335-2016, 2016
Short summary
Short summary
This study discusses the ionospheric correction problem of RO data in the troposphere and investigates an optimal transition height (OTH) for replacing the standard linear combination method by the L1–L2 bending angle extrapolated from above. By comparing the RO ionosphere-free bending angles with the ECMWF global forecast ones, the OTH is found when it gives the minimal standard deviations. The results show the OTH depends mainly on the L2 signal and is ~20 km for COSMIC L2P and ~10 km for L2C.
Y.-C. Chen, M.-E. Hsieh, L.-F. Hsiao, Y.-H. Kuo, M.-J. Yang, C.-Y. Huang, and C.-S. Lee
Atmos. Meas. Tech., 8, 2531–2542, https://doi.org/10.5194/amt-8-2531-2015, https://doi.org/10.5194/amt-8-2531-2015, 2015
Short summary
Short summary
We systematically evaluated the impact of GPSRO data on typhoon track prediction over the Northwestern Pacific during 2008 to 2010. Specifically, we perform data assimilation and forecast experiments using the TWRF system at 45km resolution on 11 typhoons, with or without the use of GPSRO refractivity. The results indicate that the assimilation of GPSRO reduces the 72-hour track forecast errors by ~12km (5 %). Although this is only a modest improvement, it is statistically significant.
X. Yue, W. S. Schreiner, Z. Zeng, Y.-H. Kuo, and X. Xue
Atmos. Meas. Tech., 8, 225–236, https://doi.org/10.5194/amt-8-225-2015, https://doi.org/10.5194/amt-8-225-2015, 2015
Short summary
Short summary
The occurrence of sporadic E (Es) layers has been a hot scientific topic for a long time. GNSS (global navigation satellite system)-based radio occultation (RO) has proven to be a powerful technique for detecting the global Es layers. In this paper, we show some examples of multiple Es layers occurring in one RO event and the occurrence of Es in a broad region during a certain time interval. The results are then evaluated by independent observations such as lidar and ionosondes.
A. K. Steiner, D. Hunt, S.-P. Ho, G. Kirchengast, A. J. Mannucci, B. Scherllin-Pirscher, H. Gleisner, A. von Engeln, T. Schmidt, C. Ao, S. S. Leroy, E. R. Kursinski, U. Foelsche, M. Gorbunov, S. Heise, Y.-H. Kuo, K. B. Lauritsen, C. Marquardt, C. Rocken, W. Schreiner, S. Sokolovskiy, S. Syndergaard, and J. Wickert
Atmos. Chem. Phys., 13, 1469–1484, https://doi.org/10.5194/acp-13-1469-2013, https://doi.org/10.5194/acp-13-1469-2013, 2013
Related subject area
Subject: Others (Wind, Precipitation, Temperature, etc.) | Technique: Remote Sensing | Topic: Validation and Intercomparisons
Solar background radiation temperature calibration of a pure rotational Raman lidar
Exploring commercial Global Navigation Satellite System (GNSS) radio occultation (RO) products for planetary boundary layer studies in the Arctic
Research on atmospheric temperature fine measurements from the near surface to 60 km altitude based on an integrated lidar system
Testing ground-based observations of wave activity in the (lower and upper) atmosphere as possible (complementary) indicators of streamer events
Quality assessment of YUNYAO radio occultation data in the neutral atmosphere
Turbulence kinetic energy dissipation rate estimated from a WindCube Doppler lidar and the LQ7 1.3 GHz radar wind profiler in the convective boundary layer
Comparison of temperature and wind profiles between ground-based remote sensing observations and numerical weather prediction model in complex Alpine topography: the Meiringen campaign
Cluster analysis of vertical polarimetric radio occultation profiles and corresponding liquid and ice water paths from Global Precipitation Measurement (GPM) microwave data
Enhanced quantitative precipitation estimation through the opportunistic use of Ku TV-SAT links via a dual-channel procedure
The added value and potential of long-term radio occultation data for climatological wind field monitoring
Exploring dual-lidar mean and turbulence measurements over Perdigão's complex terrain
Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-Train
Atmospheric stability from microwave radiometer observations for on/offshore wind energy applications
Improving the estimate of higher-order moments from lidar observations near the top of the convective boundary layer
Closing the gap in the tropics: the added value of radio-occultation data for wind field monitoring across the Equator
Verification of weather-radar-based hail metrics with crowdsourced observations from Switzerland
Observing atmospheric rivers using GNSS radio occultation data
Atmospheric motion vector (AMV) error characterization and bias correction by leveraging independent lidar data: a simulation using an observing system simulation experiment (OSSE) and optical flow AMVs
Rotary-wing drone-induced flow – comparison of simulations with lidar measurements
Application of Doppler sodar in short-term forecasting of PM10 concentration in the air in Krakow (Poland)
Radiative closure tests of collocated hyperspectral microwave and infrared radiometers
Effects of clouds and aerosols on downwelling surface solar irradiance nowcasting and short-term forecasting
Verification of parameterizations for clear sky downwelling longwave irradiance in the Arctic
Global evaluation of fast radiative transfer model coefficients for early meteorological satellite sensors
GPROF V7 and beyond: assessment of current and potential future versions of the GPROF passive microwave precipitation retrievals against ground radar measurements over the continental US and the Pacific Ocean
Assessing sampling and retrieval errors of GPROF precipitation estimates over the Netherlands
Comparisons and quality control of wind observations in a mountainous city using wind profile radar and the Aeolus satellite
On the use of routine airborne observations for evaluation and monitoring of satellite observations of thermodynamic profiles
Daily satellite-based sunshine duration estimates over Brazil: validation and intercomparison
Statistical assessment of a Doppler radar model of TKE dissipation rate for low Richardson numbers
Extended validation of Aeolus winds with wind-profiling radars in Antarctica and Arctic Sweden
The impact of Aeolus winds on near-surface wind forecasts over tropical ocean and high-latitude regions
Long-term validation of Aeolus L2B wind products at Punta Arenas, Chile, and Leipzig, Germany
Turbulence kinetic energy dissipation rate: assessment of radar models from comparisons between 1.3 GHz wind profiler radar (WPR) and DataHawk UAV measurements
The impacts of assimilating Aeolus horizontal line-of-sight winds on numerical predictions of Hurricane Ida (2021) and a mesoscale convective system over the Atlantic Ocean
Evaluation of tropospheric water vapour and temperature profiles retrieved from MetOp-A by the Infrared and Microwave Sounding scheme
Validation of the Aeolus L2B wind product with airborne wind lidar measurements in the polar North Atlantic region and in the tropics
An improved vertical correction method for the inter-comparison and inter-validation of integrated water vapour measurements
An assessment of reprocessed GPS/MET observations spanning 1995–1997
Turbulence parameters measured by the Beijing mesosphere–stratosphere–troposphere radar in the troposphere and lower stratosphere with three models: comparison and analyses
Comparison of planetary boundary layer height from ceilometer with ARM radiosonde data
Behavior and mechanisms of Doppler wind lidar error in varying stability regimes
Inter-comparison of atmospheric boundary layer (ABL) height estimates from different profiling sensors and models in the framework of HyMeX-SOP1
Evaluation of Aeolus L2B wind product with wind profiling radar measurements and numerical weather prediction model equivalents over Australia
Comparison of global UV spectral irradiance measurements between a BTS CCD-array and a Brewer spectroradiometer
Scan strategies for wind profiling with Doppler lidar – an large-eddy simulation (LES)-based evaluation
Exploiting Aeolus level-2b winds to better characterize atmospheric motion vector bias and uncertainty
Modelling the spectral shape of continuous-wave lidar measurements in a turbulent wind tunnel
Three-way calibration checks using ground-based, ship-based, and spaceborne radars
Rainfall retrieval algorithm for commercial microwave links: stochastic calibration
Vasura Jayaweera, Robert J. Sica, Giovanni Martucci, and Alexander Haefele
Atmos. Meas. Tech., 18, 1461–1469, https://doi.org/10.5194/amt-18-1461-2025, https://doi.org/10.5194/amt-18-1461-2025, 2025
Short summary
Short summary
Our study presents a new method, the solar background calibration method, which improves temperature determinations in rotational Raman lidar systems. By utilizing background solar radiation, this technique offers more continuous and reliable temperatures independent of external measuring instruments. This new method enhances our ability to monitor and understand atmospheric trends and their association with climate change with greater accuracy.
Manisha Ganeshan, Dong L. Wu, Joseph A. Santanello, Jie Gong, Chi Ao, Panagiotis Vergados, and Kevin J. Nelson
Atmos. Meas. Tech., 18, 1389–1403, https://doi.org/10.5194/amt-18-1389-2025, https://doi.org/10.5194/amt-18-1389-2025, 2025
Short summary
Short summary
This study explores the potential of two newly launched commercial Global Navigation Satellite System (GNSS) radio occultation (RO) satellite missions for advancing Arctic lower-atmospheric studies. The products have a good sampling of the lower Arctic atmosphere and are useful to derive the planetary boundary layer (PBL) height during winter months. This research is a step towards closing the observation gap in polar regions due to the decomissioning of Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC-1) GNSS RO mission and the lack of high-latitude coverage by its successor (COSMIC-2).
Zhangjun Wang, Tiantian Guo, Xianxin Li, Chao Chen, Dong Liu, Luoyuan Qu, Hui Li, and Xiufen Wang
Atmos. Meas. Tech., 18, 1405–1414, https://doi.org/10.5194/amt-18-1405-2025, https://doi.org/10.5194/amt-18-1405-2025, 2025
Short summary
Short summary
A dual-field, integrated lidar system has been developed to detect atmospheric temperatures from the near surface to 60 km over Qingdao, China. Temperature profiles from the near surface to 60 km are derived by pure rotational Raman and Rayleigh scattering techniques using a single integrated lidar system. The results prove the system can make fine measurements of the atmospheric temperature profiles from the near surface to 60 km.
Michal Kozubek, Lisa Kuchelbacher, Jaroslav Chum, Tereza Sindelarova, Franziska Trinkl, and Katerina Podolska
Atmos. Meas. Tech., 18, 1373–1388, https://doi.org/10.5194/amt-18-1373-2025, https://doi.org/10.5194/amt-18-1373-2025, 2025
Short summary
Short summary
Waves are important as main drivers of different stratispheric patterns (streamers). We analyse changes in waves and infrasound characteristics related to streamers using continuous Doppler soundings and arrays of microbarometers in Czechia. Ground measurements using infrasound arrays showed that gravity wave propagation azimuths were more random during streamers than during calm conditions. Measurements in the ionosphere during streamers did not differ from those expected for the given time.
Xiaoze Xu, Wei Han, Jincheng Wang, Zhiqiu Gao, Fenghui Li, Yan Cheng, and Naifeng Fu
Atmos. Meas. Tech., 18, 1339–1353, https://doi.org/10.5194/amt-18-1339-2025, https://doi.org/10.5194/amt-18-1339-2025, 2025
Short summary
Short summary
Commercial Global Navigation Satellite System (GNSS) radio occultation (RO) satellites are generally cheap and can generate a large volume of globally distributed observations in a short period of time. To evaluate the practical application value of these data, we must assess their quality. We evaluate the quality of YUNYAO RO data. By using the “three-cornered hat” method and comparing with data from Metop-C and COSMIC-2, it was found that the YUNYAO GNSS-RO data are of high quality.
Hubert Luce and Masanori Yabuki
Atmos. Meas. Tech., 18, 1193–1208, https://doi.org/10.5194/amt-18-1193-2025, https://doi.org/10.5194/amt-18-1193-2025, 2025
Short summary
Short summary
Over a 3-week period, simultaneous measurements were conducted using a Doppler lidar and a 1.3 GHz radar wind profiler in Japan. Although the instruments had no range overlap, turbulence kinetic energy dissipation rates were estimated through various methods in convective boundary layers. Hourly averaged estimates showed good agreement, within a factor of approximately 2, suggesting that both instruments and methods provide consistent dissipation rate values.
Alexandre Bugnard, Martine Collaud Coen, Maxime Hervo, Daniel Leuenberger, Marco Arpagaus, and Samuel Monhart
Atmos. Meas. Tech., 18, 1039–1061, https://doi.org/10.5194/amt-18-1039-2025, https://doi.org/10.5194/amt-18-1039-2025, 2025
Short summary
Short summary
Temperature (T) and wind profiles were measured by a Doppler wind lidar and a microwave radiometer in Meiringen in a medium-sized Alpine valley. Ground-based T inversions and thermal winds were studied during the 10 months of the campaign. The comparison between the observations and the COSMO-1E model provides good model performance for monthly climatologies. T inversions are however frequently missed, and important differences for particular cases are found, especially for foehn events.
Jonas E. Katona, Manuel de la Torre Juárez, Terence L. Kubar, F. Joseph Turk, Kuo-Nung Wang, and Ramon Padullés
Atmos. Meas. Tech., 18, 953–970, https://doi.org/10.5194/amt-18-953-2025, https://doi.org/10.5194/amt-18-953-2025, 2025
Short summary
Short summary
Polarimetric radio occultations (PROs) use polarized radio signals from satellites to detect moisture and precipitation in Earth's atmosphere. By applying nonlinear regression and k-means cluster analysis to over 2 years of PRO and non-PRO data, this study shows how deviations from a refractivity model relate to vertical profiles of water vapor pressure (moisture) and that differences between components of PRO signals correlate directly with vertical profiles of water path (precipitation).
Louise Gelbart, Laurent Barthès, François Mercier-Tigrine, Aymeric Chazottes, and Cécile Mallet
Atmos. Meas. Tech., 18, 351–370, https://doi.org/10.5194/amt-18-351-2025, https://doi.org/10.5194/amt-18-351-2025, 2025
Short summary
Short summary
In this paper, we present and evaluate a new method for the quantitative estimation of precipitation from a low-cost sensor. Based on previous work measuring the attenuation of an electromagnetic signal from a broadcast television satellite, we make this approach more accurate so it can be easily deployed and used operationally in areas where rainfall measurements are critical for applications like flood monitoring. In this article, the method is validated in France and applied in Côte d'Ivoire.
Irena Nimac, Julia Danzer, and Gottfried Kirchengast
Atmos. Meas. Tech., 18, 265–286, https://doi.org/10.5194/amt-18-265-2025, https://doi.org/10.5194/amt-18-265-2025, 2025
Short summary
Short summary
Due to the shortcomings of available observations, having accurate global 3D wind fields remains a challenge. A promising option is radio occultation (RO) satellite data, which enable the derivation of winds based on wind approximations. We test how well RO winds describe the ERA5 winds. We separate the total wind difference into the approximation bias and the systematic difference between the two datasets. The results show the utility of RO winds for climate monitoring and analyses.
Isadora L. Coimbra, Jakob Mann, José M. L. M. Palma, and Vasco T. P. Batista
Atmos. Meas. Tech., 18, 287–303, https://doi.org/10.5194/amt-18-287-2025, https://doi.org/10.5194/amt-18-287-2025, 2025
Short summary
Short summary
Dual-lidar measurements are explored here as a cost-effective alternative for measuring the wind at great heights. From measurements at a mountainous site, we showed that this methodology can accurately capture mean wind speeds and turbulence under different flow conditions, and we recommended optimal lidar placement and sampling rates. This methodology allows the construction of vertical wind profiles up to 430 m, surpassing traditional meteorological mast heights and single-lidar capabilities.
Akira Yamauchi, Kentaroh Suzuki, Eiji Oikawa, Miho Sekiguchi, Takashi M. Nagao, and Haruma Ishida
Atmos. Meas. Tech., 17, 6751–6767, https://doi.org/10.5194/amt-17-6751-2024, https://doi.org/10.5194/amt-17-6751-2024, 2024
Short summary
Short summary
A Japanese team developed the Level 2 atmospheric radiation flux and heating rate product for EarthCARE, which offers vertical profiles of longwave and shortwave radiative fluxes and heating rates. This study outlines the algorithm for the radiative product and its comparative validation against satellite and ground-based observations. It also analyzes errors in radiative fluxes at various scales and their dependence on cloud type, with ice-containing clouds identified as a primary error source.
Domenico Cimini, Rémi Gandoin, Stephanie Fiedler, Claudia Acquistapace, Andrea Balotti, Sabrina Gentile, Edoardo Geraldi, Christine Knist, Pauline Martinet, Saverio T. Nilo, Giandomenico Pace, Bernhard Pospichal, and Filomena Romano
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-186, https://doi.org/10.5194/amt-2024-186, 2024
Revised manuscript accepted for AMT
Short summary
Short summary
Atmospheric stability indicates whether air vertical motion is dumped or amplified. This is important for wind energy applications as it affects wind turbine wakes and thus the yield of wind parks. The paper provides an assessment of stability metrics measured by ground-based microwave radiometers in different climatological conditions and with instrument types, on- and offshore. Results indicate that special precaution may be required offshore to achieve typical onshore performances.
Tessa E. Rosenberger, David D. Turner, Thijs Heus, Girish N. Raghunathan, Timothy J. Wagner, and Julia Simonson
Atmos. Meas. Tech., 17, 6595–6602, https://doi.org/10.5194/amt-17-6595-2024, https://doi.org/10.5194/amt-17-6595-2024, 2024
Short summary
Short summary
This work used model output to show that considering the changes in boundary layer depth over time in the calculations of variables such as fluxes and variance yields more accurate results than cases where calculations were done at a constant height. This work was done to improve future observations of these variables at the top of the boundary layer.
Julia Danzer, Magdalena Pieler, and Gottfried Kirchengast
Atmos. Meas. Tech., 17, 4979–4995, https://doi.org/10.5194/amt-17-4979-2024, https://doi.org/10.5194/amt-17-4979-2024, 2024
Short summary
Short summary
We investigated the potential of radio occultation (RO) data for climate-oriented wind field monitoring, focusing on the equatorial band within ±5° latitude. In this region, the geostrophic balance breaks down, and the equatorial balance approximation takes over. The study encourages the use of RO wind fields for mesoscale climate monitoring for the equatorial region, showing a small improvement in the troposphere when including the meridional wind in the zonal-mean total wind speed.
Jérôme Kopp, Alessandro Hering, Urs Germann, and Olivia Martius
Atmos. Meas. Tech., 17, 4529–4552, https://doi.org/10.5194/amt-17-4529-2024, https://doi.org/10.5194/amt-17-4529-2024, 2024
Short summary
Short summary
We present a verification of two products based on weather radars to detect the presence of hail and estimate its size. Radar products are remote detection of hail, so they must be verified against ground-based observations. We use reports from users of the Swiss Weather Services phone app to do the verification. We found that the product estimating the presence of hail provides fair results but that it should be recalibrated and that estimating the hail size with radar is more challenging.
Bahareh Rahimi and Ulrich Foelsche
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-81, https://doi.org/10.5194/amt-2024-81, 2024
Revised manuscript accepted for AMT
Short summary
Short summary
This study explores the use of GNSS-RO data to improve understanding of the vertical structure of humidity in Atmospheric Rivers (ARs). Specific humidity profiles and IWV values from GNSS-RO are evaluated to assess if this method offers additional insights into ARs' vertical characteristics. The results suggest that combining GNSS-RO data, with its high vertical resolution, with SSMI/S data, known for high horizontal resolution, provides a more complete view of the 3D structure of ARs.
Hai Nguyen, Derek Posselt, Igor Yanovsky, Longtao Wu, and Svetla Hristova-Veleva
Atmos. Meas. Tech., 17, 3103–3119, https://doi.org/10.5194/amt-17-3103-2024, https://doi.org/10.5194/amt-17-3103-2024, 2024
Short summary
Short summary
Accurate global wind estimation is crucial for weather prediction and environmental modeling. Our study investigates a method to refine atmospheric motion vectors (AMVs) by comparing them with high-precision active-sensor winds. Leveraging supervised learning, we discovered that using high-precision active-sensor data can significantly reduce biases in passive-sensor winds in addition to providing estimates of the wind errors, thereby improving their reliability.
Liqin Jin, Mauro Ghirardelli, Jakob Mann, Mikael Sjöholm, Stephan Thomas Kral, and Joachim Reuder
Atmos. Meas. Tech., 17, 2721–2737, https://doi.org/10.5194/amt-17-2721-2024, https://doi.org/10.5194/amt-17-2721-2024, 2024
Short summary
Short summary
Three-dimensional wind fields can be accurately measured by sonic anemometers. However, the traditional mast-mounted sonic anemometers are not flexible in various applications, which can be potentially overcome by drones. Therefore, we conducted a proof-of-concept study by applying three continuous-wave Doppler lidars to characterize the complex flow around a drone to validate the results obtained by CFD simulations. Both methods show good agreement, with a velocity difference of 0.1 m s-1.
Ewa Agnieszka Krajny, Leszek Ośródka, and Marek Jan Wojtylak
Atmos. Meas. Tech., 17, 2451–2464, https://doi.org/10.5194/amt-17-2451-2024, https://doi.org/10.5194/amt-17-2451-2024, 2024
Short summary
Short summary
The use of sodar data to support an air quality forecasting system is encouraging.
The sodar model is a complement to forecasting methods because it is useful due to its simplicity and speed of calculations. It does not require emission data, for which it is difficult to quickly verify temporal and spatial variability.
The use of simple formulas of regression models in forecasting, while maintaining their multivariate nature, facilitates the optimisation of the prediction process.
Lei Liu, Natalia Bliankinshtein, Yi Huang, John R. Gyakum, Philip M. Gabriel, Shiqi Xu, and Mengistu Wolde
Atmos. Meas. Tech., 17, 2219–2233, https://doi.org/10.5194/amt-17-2219-2024, https://doi.org/10.5194/amt-17-2219-2024, 2024
Short summary
Short summary
We conducted a radiance closure experiment using a unique combination of two hyperspectral radiometers, one operating in the microwave and the other in the infrared. By comparing the measurements of the two hyperspectrometers to synthetic radiance simulated from collocated atmospheric profiles, we affirmed the proper performance of the two instruments and quantified their radiometric uncertainty for atmospheric sounding applications.
Kyriakoula Papachristopoulou, Ilias Fountoulakis, Alkiviadis F. Bais, Basil E. Psiloglou, Nikolaos Papadimitriou, Ioannis-Panagiotis Raptis, Andreas Kazantzidis, Charalampos Kontoes, Maria Hatzaki, and Stelios Kazadzis
Atmos. Meas. Tech., 17, 1851–1877, https://doi.org/10.5194/amt-17-1851-2024, https://doi.org/10.5194/amt-17-1851-2024, 2024
Short summary
Short summary
The upgraded systems SENSE2 and NextSENSE2 focus on improving the quality of solar nowcasting and forecasting. SENSE2 provides real-time estimates of solar irradiance across a wide region every 15 min. NextSENSE2 offers short-term forecasts of irradiance up to 3 h ahead. Evaluation with actual data showed that the instantaneous comparison yields the most discrepancies due to the uncertainties of cloud-related information and satellite versus ground-based spatial representativeness limitations.
Giandomenico Pace, Alcide di Sarra, Filippo Cali Quaglia, Virginia Ciardini, Tatiana Di Iorio, Antonio Iaccarino, Daniela Meloni, Giovanni Muscari, and Claudio Scarchilli
Atmos. Meas. Tech., 17, 1617–1632, https://doi.org/10.5194/amt-17-1617-2024, https://doi.org/10.5194/amt-17-1617-2024, 2024
Short summary
Short summary
This study investigates the performances of 17 formulas to determine the clear sky longwave downward irradiance in the Arctic environment. The formulas need to be tuned to the environmental conditions of the studied region and, to date, few of them have been developed and/or tested in the Arctic. The best formulas provide biases and root mean squared errors respectively smaller than 1 and 5 W m-2. We intend to use these results to estimate the longwave cloud radiative perturbation.
Bruna Barbosa Silveira, Emma Catherine Turner, and Jérôme Vidot
Atmos. Meas. Tech., 17, 1279–1296, https://doi.org/10.5194/amt-17-1279-2024, https://doi.org/10.5194/amt-17-1279-2024, 2024
Short summary
Short summary
A fast radiative transfer model, used to speed up the full spectral simulation of meteorological satellite channels in weather forecast models, is tested using 25 000 modelled atmospheres. The differences between calculations from the fast and the high-resolution reference models are examined for nine historic weather satellite instruments. The study confirms that a reduced set of 83 atmospheric profiles is robust enough to estimate the scale of the differences obtained from the larger sample.
Simon Pfreundschuh, Clément Guilloteau, Paula J. Brown, Christian D. Kummerow, and Patrick Eriksson
Atmos. Meas. Tech., 17, 515–538, https://doi.org/10.5194/amt-17-515-2024, https://doi.org/10.5194/amt-17-515-2024, 2024
Short summary
Short summary
The latest version of the GPROF retrieval algorithm that produces global precipitation estimates using observations from the Global Precipitation Measurement mission is validated against ground-based radars. The validation shows that the algorithm accurately estimates precipitation on scales ranging from continental to regional. In addition, we validate candidates for the next version of the algorithm and identify principal challenges for further improving space-borne rain measurements.
Linda Bogerd, Hidde Leijnse, Aart Overeem, and Remko Uijlenhoet
Atmos. Meas. Tech., 17, 247–259, https://doi.org/10.5194/amt-17-247-2024, https://doi.org/10.5194/amt-17-247-2024, 2024
Short summary
Short summary
Algorithms merge satellite radiometer data from various frequency channels, each tied to a different footprint size. We studied the uncertainty associated with sampling (over the Netherlands using 4 years of data) as precipitation is highly variable in space and time by simulating ground-based data as satellite footprints. Though sampling affects precipitation estimates, it doesn’t explain all discrepancies. Overall, uncertainties in the algorithm seem more influential than how data is sampled.
Hua Lu, Min Xie, Wei Zhao, Bojun Liu, Tijian Wang, and Bingliang Zhuang
Atmos. Meas. Tech., 17, 167–179, https://doi.org/10.5194/amt-17-167-2024, https://doi.org/10.5194/amt-17-167-2024, 2024
Short summary
Short summary
Observations of vertical wind in regions with complex terrain are essential, but they are always sparse and have poor representation. Data verification and quality control are conducted on the wind profile radar and Aeolus wind products in this study, trying to compensate for the limitations of wind field observations. The results shed light on the comprehensive applications of multi-source wind profile data in complicated terrain regions with sparse ground-based wind observations.
Timothy J. Wagner, Thomas August, Tim Hultberg, and Ralph A. Petersen
Atmos. Meas. Tech., 17, 1–14, https://doi.org/10.5194/amt-17-1-2024, https://doi.org/10.5194/amt-17-1-2024, 2024
Short summary
Short summary
Commercial passenger and freight aircraft need to know the temperature and pressure of the environments they fly through in order to safely operate. In this paper, we investigate how these observations can be used to evaluate and monitor the performance of satellite observations. Normally weather balloons are used for this, but in places like the United States there are many more airplane flights than weather balloon launches. This makes it much easier to compare them to satellites.
Maria Lívia L. M. Gava, Simone M. S. Costa, and Anthony C. S. Porfírio
Atmos. Meas. Tech., 16, 5429–5441, https://doi.org/10.5194/amt-16-5429-2023, https://doi.org/10.5194/amt-16-5429-2023, 2023
Short summary
Short summary
This study assesses the effectiveness of two geostationary satellite-based sunshine duration datasets over Brazil. Statistical parameters were used to evaluate the performance of the products. The results showed generally good agreement between satellite and ground observations, with some regional discrepancies. Overall, both satellite products offer reliable data for various applications, which benefit from their high spatial resolution and low time latency.
Hubert Luce, Lakshmi Kantha, and Hiroyuki Hashiguchi
Atmos. Meas. Tech., 16, 5091–5101, https://doi.org/10.5194/amt-16-5091-2023, https://doi.org/10.5194/amt-16-5091-2023, 2023
Short summary
Short summary
The potential ability of clear air radars to measure turbulence kinetic energy (TKE) dissipation rate ε in the atmosphere is a major asset of these instruments because of their continuous measurements. In the present work, we successfully tested the relevance of a model relating ε to the width of the Doppler spectrum peak and wind shear for shear-generated turbulence and we provide a physical interpretation of an empirical model in this context.
Sheila Kirkwood, Evgenia Belova, Peter Voelger, Sourav Chatterjee, and Karathazhiyath Satheesan
Atmos. Meas. Tech., 16, 4215–4227, https://doi.org/10.5194/amt-16-4215-2023, https://doi.org/10.5194/amt-16-4215-2023, 2023
Short summary
Short summary
We compared 2 years of wind measurements by the Aeolus satellite with winds from two wind-profiler radars in Arctic Sweden and coastal Antarctica. Biases are similar in magnitude to results from other locations. They are smaller than in earlier studies due to more comparison points and improved criteria for data rejection. On the other hand, the standard deviation is somewhat higher because of degradation of the Aeolus lidar.
Haichen Zuo and Charlotte Bay Hasager
Atmos. Meas. Tech., 16, 3901–3913, https://doi.org/10.5194/amt-16-3901-2023, https://doi.org/10.5194/amt-16-3901-2023, 2023
Short summary
Short summary
Aeolus is a satellite equipped with a Doppler wind lidar to detect global wind profiles. This study evaluates the impact of Aeolus winds on surface wind forecasts over tropical oceans and high-latitude regions based on the ECMWF observing system experiments. We find that Aeolus can slightly improve surface wind forecasts for the region > 60° N, especially from day 5 onwards. For other study regions, the impact of Aeolus is nearly neutral or limited, which requires further investigation.
Holger Baars, Joshua Walchester, Elizaveta Basharova, Henriette Gebauer, Martin Radenz, Johannes Bühl, Boris Barja, Ulla Wandinger, and Patric Seifert
Atmos. Meas. Tech., 16, 3809–3834, https://doi.org/10.5194/amt-16-3809-2023, https://doi.org/10.5194/amt-16-3809-2023, 2023
Short summary
Short summary
In 2018, the Aeolus satellite of the European Space Agency (ESA) was launched to improve weather forecasts through global measurements of wind profiles. Given the novel lidar technique onboard, extensive validation efforts have been needed to verify the observations. For this reason, we performed long-term validation measurements in Germany and Chile. We found significant improvement in the data products due to a new algorithm version and can confirm the general validity of Aeolus observations.
Hubert Luce, Lakshmi Kantha, Hiroyuki Hashiguchi, Dale Lawrence, Abhiram Doddi, Tyler Mixa, and Masanori Yabuki
Atmos. Meas. Tech., 16, 3561–3580, https://doi.org/10.5194/amt-16-3561-2023, https://doi.org/10.5194/amt-16-3561-2023, 2023
Short summary
Short summary
Doppler radars can be used to estimate turbulence kinetic energy dissipation rates in the atmosphere. The performance of various models is evaluated from comparisons between UHF wind profiler and in situ measurements with UAVs. For the first time, we assess a model supposed to be valid for weak stratification or strong shear conditions. This model provides better agreements with in situ measurements than the classical model based on the hypothesis of a stable stratification.
Chengfeng Feng and Zhaoxia Pu
Atmos. Meas. Tech., 16, 2691–2708, https://doi.org/10.5194/amt-16-2691-2023, https://doi.org/10.5194/amt-16-2691-2023, 2023
Short summary
Short summary
This study demonstrates the positive impacts of assimilating Aeolus Mie-cloudy and Rayleigh-clear near-real-time horizontal line-of-sight winds on the analysis and forecasts of Hurricane Ida (2021) and a mesoscale convective system associated with an African easterly wave using the mesoscale community Weather Research and Forecasting model and the NCEP Gridpoint Statistical Interpolation-based three-dimensional ensemble-variational hybrid data assimilation system.
Tim Trent, Richard Siddans, Brian Kerridge, Marc Schröder, Noëlle A. Scott, and John Remedios
Atmos. Meas. Tech., 16, 1503–1526, https://doi.org/10.5194/amt-16-1503-2023, https://doi.org/10.5194/amt-16-1503-2023, 2023
Short summary
Short summary
Modern weather satellites provide essential information on our lower atmosphere's moisture content and temperature structure. This measurement record will span over 40 years, making it a valuable resource for climate studies. This study characterizes atmospheric temperature and humidity profiles from a European Space Agency climate project. Using weather balloon measurements, we demonstrated the performance of this dataset was within the tolerances required for future climate studies.
Benjamin Witschas, Christian Lemmerz, Alexander Geiß, Oliver Lux, Uwe Marksteiner, Stephan Rahm, Oliver Reitebuch, Andreas Schäfler, and Fabian Weiler
Atmos. Meas. Tech., 15, 7049–7070, https://doi.org/10.5194/amt-15-7049-2022, https://doi.org/10.5194/amt-15-7049-2022, 2022
Short summary
Short summary
In August 2018, the first wind lidar Aeolus was launched into space and has since then been providing data of the global wind field. The primary goal of Aeolus was the improvement of numerical weather prediction. To verify the quality of Aeolus wind data, DLR performed four airborne validation campaigns with two wind lidar systems. In this paper, we report on results from the two later campaigns, performed in Iceland and the tropics.
Olivier Bock, Pierre Bosser, and Carl Mears
Atmos. Meas. Tech., 15, 5643–5665, https://doi.org/10.5194/amt-15-5643-2022, https://doi.org/10.5194/amt-15-5643-2022, 2022
Short summary
Short summary
Integrated water vapour measurements are often compared for the calibration and validation of instruments or techniques. Measurements made at different altitudes must be corrected to account for the vertical variation of water vapour. This paper shows that the widely used empirical correction model has severe limitations that are overcome using the proposed model. The method is applied to the inter-comparison of GPS and satellite microwave radiometer data in a tropical mountainous area.
Anthony J. Mannucci, Chi O. Ao, Byron A. Iijima, Thomas K. Meehan, Panagiotis Vergados, E. Robert Kursinski, and William S. Schreiner
Atmos. Meas. Tech., 15, 4971–4987, https://doi.org/10.5194/amt-15-4971-2022, https://doi.org/10.5194/amt-15-4971-2022, 2022
Short summary
Short summary
The Global Positioning System (GPS) radio occultation (RO) technique is a satellite-based method for producing highly accurate vertical profiles of atmospheric temperature and pressure. RO profiles are used to monitor global climate trends, particularly in that region of the atmosphere that includes the lower stratosphere. Two data sets spanning 1995–1997 that were produced from the first RO satellite are highly accurate and can be used to assess global atmospheric models.
Ze Chen, Yufang Tian, Yinan Wang, Yongheng Bi, Xue Wu, Juan Huo, Linjun Pan, Yong Wang, and Daren Lü
Atmos. Meas. Tech., 15, 4785–4800, https://doi.org/10.5194/amt-15-4785-2022, https://doi.org/10.5194/amt-15-4785-2022, 2022
Short summary
Short summary
Small-scale turbulence plays a vital role in the vertical exchange of heat, momentum and mass in the atmosphere. There are currently three models that can use spectrum width data of MST radar to calculate turbulence parameters. However, few studies have explored the applicability of the three calculation models. We compared and analysed the turbulence parameters calculated by three models. These results can provide a reference for the selection of models for calculating turbulence parameters.
Damao Zhang, Jennifer Comstock, and Victor Morris
Atmos. Meas. Tech., 15, 4735–4749, https://doi.org/10.5194/amt-15-4735-2022, https://doi.org/10.5194/amt-15-4735-2022, 2022
Short summary
Short summary
The planetary boundary layer is the lowest part of the atmosphere. Its structure and depth (PBLHT) significantly impact air quality, global climate, land–atmosphere interactions, and a wide range of atmospheric processes. To test the robustness of the ceilometer-estimated PBLHT under different atmospheric conditions, we compared ceilometer- and radiosonde-estimated PBLHTs using multiple years of U.S. DOE ARM measurements at various ARM observatories located around the world.
Rachel Robey and Julie K. Lundquist
Atmos. Meas. Tech., 15, 4585–4622, https://doi.org/10.5194/amt-15-4585-2022, https://doi.org/10.5194/amt-15-4585-2022, 2022
Short summary
Short summary
Our work investigates the behavior of errors in remote-sensing wind lidar measurements due to turbulence. Using a virtual instrument, we measured winds in simulated atmospheric flows and decomposed the resulting error. Dominant error mechanisms, particularly vertical velocity variations and interactions with shear, were identified in ensemble data over three test cases. By analyzing the underlying mechanisms, the response of the error behavior to further varying flow conditions may be projected.
Donato Summa, Fabio Madonna, Noemi Franco, Benedetto De Rosa, and Paolo Di Girolamo
Atmos. Meas. Tech., 15, 4153–4170, https://doi.org/10.5194/amt-15-4153-2022, https://doi.org/10.5194/amt-15-4153-2022, 2022
Short summary
Short summary
The evolution of the atmospheric boundary layer height (ABLH) has an important impact on meteorology. However, the complexity of the phenomena occurring within the ABL and the influence of advection and local accumulation processes often prevent an unambiguous determination of the ABLH. The paper reports results from an inter-comparison effort involving different sensors and techniques to measure the ABLH. Correlations between the ABLH and other atmospheric variables are also assessed.
Haichen Zuo, Charlotte Bay Hasager, Ioanna Karagali, Ad Stoffelen, Gert-Jan Marseille, and Jos de Kloe
Atmos. Meas. Tech., 15, 4107–4124, https://doi.org/10.5194/amt-15-4107-2022, https://doi.org/10.5194/amt-15-4107-2022, 2022
Short summary
Short summary
The Aeolus satellite was launched in 2018 for global wind profile measurement. After successful operation, the error characteristics of Aeolus wind products have not yet been studied over Australia. To complement earlier validation studies, we evaluated the Aeolus Level-2B11 wind product over Australia with ground-based wind profiling radar measurements and numerical weather prediction model equivalents. The results show that the Aeolus can detect winds with sufficient accuracy over Australia.
Carmen González, José M. Vilaplana, José A. Bogeat, and Antonio Serrano
Atmos. Meas. Tech., 15, 4125–4133, https://doi.org/10.5194/amt-15-4125-2022, https://doi.org/10.5194/amt-15-4125-2022, 2022
Short summary
Short summary
Monitoring ultraviolet (UV) radiation is important since it can have harmful effects on the biosphere. Array spectroradiometers are increasingly used to measure UV as they are more versatile than scanning spectroradiometers. In this study, the long-term performance of the BTS-2048-UV-S-WP array spectroradiometer was assessed. The results show that the BTS can reliably measure both the UV index and UV radiation in the 300–360 nm range. Moreover, the BTS was stable and showed no seasonal behavior.
Charlotte Rahlves, Frank Beyrich, and Siegfried Raasch
Atmos. Meas. Tech., 15, 2839–2856, https://doi.org/10.5194/amt-15-2839-2022, https://doi.org/10.5194/amt-15-2839-2022, 2022
Short summary
Short summary
Lidars can measure the wind profile in the lower part of the atmosphere, provided that the wind field is horizontally uniform and does not change during the time of the measurement. These requirements are mostly not fulfilled in reality, and the lidar wind measurement will thus hold a certain error. We investigate different strategies for lidar wind profiling using a lidar simulator implemented in a numerical simulation of the wind field. Our findings can help to improve wind measurements.
Katherine E. Lukens, Kayo Ide, Kevin Garrett, Hui Liu, David Santek, Brett Hoover, and Ross N. Hoffman
Atmos. Meas. Tech., 15, 2719–2743, https://doi.org/10.5194/amt-15-2719-2022, https://doi.org/10.5194/amt-15-2719-2022, 2022
Short summary
Short summary
Winds that are crucial to weather forecasting derived from two different techniques – tracking satellite images (AMVs) and direct measurement of molecular and aerosol motions by Doppler lidar (Aeolus satellite winds) – are compared. We find that AMVs and Aeolus winds are highly correlated. Aeolus Mie-cloudy winds have great potential value as a comparison standard for AMVs. Larger differences are found in the Southern Hemisphere related to higher wind speed and higher vertical variation in wind.
Marijn Floris van Dooren, Anantha Padmanabhan Kidambi Sekar, Lars Neuhaus, Torben Mikkelsen, Michael Hölling, and Martin Kühn
Atmos. Meas. Tech., 15, 1355–1372, https://doi.org/10.5194/amt-15-1355-2022, https://doi.org/10.5194/amt-15-1355-2022, 2022
Short summary
Short summary
The remote sensing technique lidar is widely used for wind speed measurements for both industrial and academic applications. Lidars can measure wind statistics accurately but cannot fully capture turbulent fluctuations in the high-frequency range, since they are partly filtered out. This paper therefore investigates the turbulence spectrum measured by a continuous-wave lidar and analytically models the lidar's measured spectrum with a Lorentzian filter function and a white noise term.
Alain Protat, Valentin Louf, Joshua Soderholm, Jordan Brook, and William Ponsonby
Atmos. Meas. Tech., 15, 915–926, https://doi.org/10.5194/amt-15-915-2022, https://doi.org/10.5194/amt-15-915-2022, 2022
Short summary
Short summary
This study uses collocated ship-based, ground-based, and spaceborne radar observations to validate the concept of using the GPM spaceborne radar observations to calibrate national weather radar networks to the accuracy required for operational severe weather applications such as rainfall and hail nowcasting.
Wagner Wolff, Aart Overeem, Hidde Leijnse, and Remko Uijlenhoet
Atmos. Meas. Tech., 15, 485–502, https://doi.org/10.5194/amt-15-485-2022, https://doi.org/10.5194/amt-15-485-2022, 2022
Short summary
Short summary
The existing infrastructure for cellular communication is promising for ground-based rainfall remote sensing. Rain-induced signal attenuation is used in dedicated algorithms for retrieving rainfall depth along commercial microwave links (CMLs) between cell phone towers. This processing is a source of many uncertainties about input data, algorithm structures, parameters, CML network, and local climate. Application of a stochastic optimization method leads to improved CML rainfall estimates.
Cited articles
Allan, D. W.: Statistics of atomic frequency standards, Proc. IEEE, 54, 221–230, 1966.
Anthes, R. A., Rocken, C., and Kuo, Y. H.: Applications of COSMIC to meteorology and climate, Terr. Atmos. Ocean. Sci., 11, 115–156, 2000.
Anthes, R. A., Ector, D., Hunt, D. C., Kuo, Y.-H., Rocken, C., Schreiner, W. S., Sokolovskiy, S. V., Syndergaard, S., Wee, T.-K., Zeng, Z., Bernhardt, P. A., Dymond, K. F., Chen, Y., Liu, H., Manning, K., Randel, W. J., Trenberth, K. E., Cucurull, L., Healy, S. B., Ho, S.-P., McCormick, C., Meehan, T. K., Thompson, D. C., and Yen, N. L.: The COSMIC/FORMOSAT-3 mission: early results, B. Am. Meteorol. Soc., 89, 313–333, https://doi.org/10.1175/BAMS-89-3-313, 2008.
Aparicio, J. M. and Laroche, S.: An evaluation of the expression of the atmospheric refractivity for GPS signals, J. Geophys. Res., 116, D11104, https://doi.org/10.1029/2010JD015214, 2011.
Aparicio, J. M., Deblonde, G., Garand, L., and Laroche, S.: Signature of the atmospheric compressibility factor in COSMIC, CHAMP and GRACE radio occultation data, J. Geophys. Res., 114, D16144, https://doi.org/10.1029/2008JD011156, 2009.
Bassiri, S. and Hajj, G.: Higher-order ionospheric effects on the global positioning system observables and means of modeling them, Manuscr. Geodaet., 18, 280–289, 1993.
Bengtsson, L., Hagemann, S., and Hodges, K. I.: Can climate trends be calculated from reanalysis data?, J. Geophys. Res., 109, D11111, https://doi.org/10.1029/2004JD004536, 2004.
Betts, A. K., Zhao, M., Dirmeyer, P. A., and Beljaars, A. C. M.: Comparison of ERA40 and NCEP/DOE near-surface data sets with other ISLSCP-II data sets, J. Geophys. Res., 111, D22S04, https://doi.org/10.1029/2006JD007174, 2006.
Bilitza, D.: International reference ionosphere 2000, Radio Sci., 36, 261–275, 2001.
Bromwich, D. H. and Fogt, R. L.: Strong trends in the skill of the ERA-40 and NCEP-NCAR reanalyses in the high and midlatitudes of the Southern Hemisphere, 1958–2001, J. Climate, 17, 4603–4619, 2004.
Budden, K. G.: The Propagation of Radio Waves, Cambridge University Press, New York, USA, 669 pp., 1985.
Buontempo, C., Jupp, A., and Rennie, M. P.: Operational NWP assimilation of GPS radio occultation data, Atmos. Sci. Lett., 9, 129–133, 2008.
Chasovitin, Y. K., Gulyaeva, T. L., Deminov, M. G., and Ivanova, S. E.: Russian standard model of ionosphere (SMI), Proc. of COST251 Workshop, 30–31 March 1998, Side, Turkey, 161–172, 1998.
Compo, G. P., Whitaker, J. S., Sardeshmukh, P. D., Matsui, N., Allan, R. J., Yin, X., Gleason, B. E., Vose, R. S., Rutledge, G., Bessemoulin, P., Brönnimann, S., Brunet, M., Crouthamel, R. I., Grant, A. N., Groisman, P. Y., Jones, P. D., Kruk, M. C., Kruger, A. C., Marshall, G. J., Maugeri, M., Mok, H. Y., Nordli, Ø., Ross, T. F., Trigo, R. M., Wang, X. L., Woodruff, S. D., and Worley, S. J.: The twentieth century reanalysis project, Q. J. Roy. Meteor. Soc., 137, 1–28, https://doi.org/10.1002/qj.776, 2011.
Cucurull, L.: Improvement in the use of an operational constellation of GPS radio-occultation receivers in weather forecasting, Weather Forecast., 25, 749–767, 2010.
Cucurull, L. and Derber, J.: Operational implementation of COSMIC observations into NCEP's global data assimilation system, Weather Forecast., 23, 702–711, 2008.
Danforth, C. M., Kalnay, E., and Miyoshi, T.: Estimating and correcting global weather model error, Mon. Weather Rev., 135, 281–299, 2007.
Danzer, J., Scherllin-Pirscher, B., and Foelsche, U.: Systematic residual ionospheric errors in radio occultation data and a potential way to minimize them, Atmos. Meas. Tech., 6, 2169–2179, https://doi.org/10.5194/amt-6-2169-2013, 2013.
Dee, D. P. and Uppala, S. M.: Variational bias correction of satellite radiance data in the ERA- Interim reanalysis, Q. J. Roy. Meteor. Soc., 135, 1830–1841, https://doi.org/10.1002/qj.493, 2009.
Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M. A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A. C. M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A. J., Haimberger, L., Healy, S. B., Hersbach, H., Hólm, E. V., Isaksen, L., Kållberg, P., Köhler, M., Matricardi, M., McNally, A. P., Monge-Sanz, B. M., Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, J.-N., and Vitart, F.: The ERA-Interim reanalysis: configuration and performance of the data assimilation system, Q. J. Roy. Meteor. Soc., 137, 553–597, https://doi.org/10.1002/qj.828, 2011.
Desroziers, G., Berre, L., Chapnik, B., and Poli, P.: Diagnosis of observation, background and analysis-error statistics in observation space, Q. J. Roy. Meteor. Soc., 131, 3385–3396, https://doi.org/10.1256/qj.05.108, 2005.
Ebita, A., Kobayashi, S., Ota, Y., Moriya, M., Kumabe, R., Onogi, K., Harada, Y., Yasui, S., Miyaoka, K., Takahashi, K., Kamahori, H., Kobayashi, C., Endo, H., Soma, M., Oikawa, Y., and Ishimizu, T.: The Japanese 55 year reanalysis "JRA-55": an interim report, SOLA, 7, 149–152, https://doi.org/10.2151/sola.2011-038, 2011.
Feng, D. D. and Herman, B. M.: Remotely sensing the Earth's atmosphere using the Global Positioning System (GPS) - The GPS/MET data analysis, J. Atmos. Ocean. Tech., 16, 989–1002, https://doi.org/10.1175/1520-0426(1999)016<0989:RSTESA>2.0.CO;2, 1999.
Foelsche, U., Borsche, M., Steiner, A. K., Gobiet, A., Pirscher, B., Kirchengast, G., Wickert, J., and Schmidt, T.: Observing upper troposphere–lower stratosphere climate with radio occultation data from the CHAMP satellite, Clim. Dynam., 31, 49–65, https://doi.org/10.1007/s00382-007-0337-7, 2008.
Foelsche, U., Syndergaard, S., Fritzer, J., and Kirchengast, G.: Errors in GNSS radio occultation data: relevance of the measurement geometry and obliquity of profiles, Atmos. Meas. Tech., 4, 189–199, https://doi.org/10.5194/amt-4-189-2011, 2011.
Folland, C. K., Karl, T. R., Christy, J. R., Clarke, R. A., Gruza, G. V., Jouzel, J., Mann, M. E., Oerlemans, J., Salinger, M. J., and Wang, S.-W.: Observed climate variability and change, in: Climate Change 2001, The Scientific Basis: Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai, X., Maskell, K., and Johnson, C. A., Cambridge University Press, Cambridge, UK and New York, USA, 99–181, 2001.
Fritsche, M., Dietrich, R., Knöfel, C., Rülke, A., and Vey, S.: Impact of higher-order ionospheric terms on GPS estimates, Geophys. Res. Lett., 32, L23311, https://doi.org/10.1029/2005GL024342, 2005.
GCOS (Global Climate Observing System): GCOS reference upper-air network (GRUAN): justification, requirements, siting and instrumentation options, GCOS Report No. 112, Geneva, Switzerland, 42 pp., 2007.
GCOS (Global Climate Observing System): Guidelines for the generation of datasets and products meeting GCOS requirements, GCOS Report No. 143, Geneva, Switzerland, 10 pp., 2010.
GCOS (Global Climate Observing System): Systematic observation requirements for satellite-based data products for climate: 2011 Update, GCOS Report No. 154, Geneva, Switzerland, 138 pp., 2011.
Gerber, E. P., Butler, A., Calvo, N., Charlton-Perez, A., Giorgetta, M., Manzini, E., Perlwitz, J., Polvani, L. M., Sassi, F., Scaife, A. A., Shaw, T. A., Son, S.-W., and Watanabe, S.: assessing and understanding the impact of stratospheric dynamics and variability on the earth system, B. Am. Meteorol. Soc., 93, 845–859, https://doi.org/10.1175/BAMS-D-11-00145.1, 2012.
Gobiet, A., Foelsche, U., Steiner, A. K., Borsche, M., Kirchengast, G., and Wickert, J.: Climatological validation of stratospheric temperatures in ECMWF operational analyses with CHAMP radio occultation data, Geophys. Res. Lett., 32, L12806, https://doi.org/10.1029/2005GL022617, 2005.
Gorbunov, M. E.: Ionospheric correction and statistical optimization of radio occultation data, Radio Sci., 37, 1084, https://doi.org/10.1029/2000RS002370, 2002.
Gorbunov, M. E. and Kornblueh, L.: Principles of variational assimilation of GNSS radio occultation data, Report No. 350, Max Planck Inst. for Meteorol., Hamburg, Germany, 34 pp., 2003.
Gorbunov, M. E., Lauritsen, K. B., Rhodin, A., Tomassini, M., and Kornblueh, L.: Radio holographic filtering, error estimation, and quality control of radio occultation data, J. Geophys. Res., 111, D10105, https://doi.org/10.1029/2005JD006427, 2006.
Gorbunov, M. E., Shmakov, A. V., Leroy, S. S., and Lauritsen, K. B.: COSMIC radio occultation processing: cross-center comparison and validation, J. Atmos. Ocean. Tech., 28, 737–751, https://doi.org/10.1175/2011JTECHA1489.1, 2011.
Graversen, R. G., Mauritsen, T., Tjernström, M., Källén, E., and Svensson, G.: Vertical structure of recent Arctic warming, Nature, 451, 53–56, 2008.
Hajj, G. A., Lee, L. C., Pi, X., Romans, L. J., Schreiner, W. S., Straus, P. R., and Wang, C.: COSMIC GPS ionospheric sensing and space weather, Terr. Atmos. Ocean. Sci., 11, 235–272, 2000.
Hajj, G. A., Kursinski, E. R., Romans, L. J., Bertinger, W. I., and Leroy, S. S.: A technical description of atmospheric sounding by GPS occultations, Atmos. Sol.-Terr. Phys., 64, 451–469, 2002.
Hajj, G. A., Ao, C. O., Iijima, B. A., Kuang, D., Kursinski, E. R., Mannucci, A. J., Meehan, T. K., Romans, L. J., de la Torre Juarez, M., and Yunck, T. P.: CHAMP and SAC-C atmospheric occultation results and intercomparisons, J. Geophys. Res., 109, D06109, https://doi.org/10.1029/2003JD003909, 2004.
Hartmann, D. L., Klein Tank, A. M. G., Rusticucci, M., Alexander, L. V., Brönnimann, S., Charabi, Y., Dentener, F. J., Dlugokencky, E. J., Easterling, D. R., Kaplan, A., Soden, B. J., Thorne, P. W., Wild, M., and Zhai, P. M.: Observations: atmosphere and surface, in: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Stocker, T. F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S. K., Boschung, J., Nauels, A., Xia, Y., Bex, V., and Midgley, P. M., Cambridge University Press, Cambridge, UK and New York, NY, USA, 159–254, 2013.
Healy, S. B.: Radio occultation bending angle and impact parameter errors caused by horizontal refractive index gradients in the troposphere: a simulation study, J. Geophys. Res., 106, 11875–11889, 2001.
Healy, S. B.: Operational assimilation of GPS radio occultation measurements at ECMWF, ECMWF Newslett., 111, 6–11, 2007.
Healy, S. B.: Forecast impact experiment with a constellation of GPS radio occultation receivers, Atmos. Sci. Lett., 9, 111–118, 2008.
Healy, S. B.: Refractivity coefficients used in the assimilation of GPS radio occultation measurements, J. Geophys. Res., 116, D01106, https://doi.org/10.1029/2010JD014013, 2011.
Hedin, A. E.: Extension of the MSIS thermosphere model into the middle and lower atmosphere, J. Geophys. Res., 96, 1159–1172, 1991.
Ho, S.-P., Kirchengast, G., Leroy, S., Wickert, J., Mannucci, A. J., Steiner, A., Hunt, D., Schreiner, W., Sokolovskiy, S., Ao, C., Borsche, M., von Engeln, A., Foelsche, U., Heise, S., Iijima, B., Kuo, Y.-H., Kursinski, E. R., Pirscher, B., Ringer, M., Rocken, C., and Schmidt, T.: Estimating the uncertainty of using GPS radio occultation data for climate monitoring: intercomparison of CHAMP refractivity climate records from 2002 to 2006 from different data centers, J. Geophys. Res., 114, D23197, https://doi.org/10.1029/2009JD011969, 2009.
Ho, S.-P., Hunt, D., Steiner, A. K., Mannucci, A. J., Kirchengast, G., Gleisner, H., Heise, S., von Engeln, A., Marquardt, C., Sokolovskiy, S., Schreiner, W., Scherllin-Pirscher, B., Ao, C., Wickert, J., Syndergaard, S., Lauritsen, K. B., Leroy, S., Kursinski, E. R., Kuo, Y.-H., Foelsche, U., Schmidt, T., and Gorbunov, M.: Reproducibility of GPS radio occultation data for climate monitoring: profile-to-profile intercomparison of CHAMP climate records from 2002 to 2008 from six data centers, J. Geophys. Res., 117, D18111, https://doi.org/10.1029/2012JD017665, 2012.
Hocke, K., Pavelyev, A. G., Yakovlev, O. I., Barthes, L., and Jakowski, N.: Radio occultation data analysis by the radioholographic method, J. Atmos. Sol.-Terr. Phys., 61, 1169–1177, 1999.
Høeg, P., Hauchecorne, A., Kirchengast, G., Syndergaard, S., Belloul, B., Leitinger, R., and Rothleitner, W.: Derivation of atmospheric properties using a radio occultation technique, Sci. Report 95-4, Danish Meteorol. Inst., Copenhagen, Denmark, 208 pp., 1995.
Hollingsworth, A. and Lönnberg, P.: The statistical structure of short-range forecast errors as determined from radiosonde data. Part I: The wind field, Tellus A, 38, 111–136, 1986.
Jung, T., Tompkins, A. M., and Rodwell, M. J.: Some aspects of systematic error in the ECMWF model, Atmos. Sci. Lett., 6, 133–139, https://doi.org/10.1002/asl.105, 2005.
Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Leetmaa, A., Reynolds, R., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Jenne, R., and Joseph, D.: The NCEP/NCAR 40 year reanalysis project, B. Am. Meteorol. Soc., 77, 437–471, 1996.
Kanamitsu, M., Ebisuzaki, W., Woollen, J., Yang, S.-K., Hnilo, J. J., Fiorino, M., and Potter, G. L.: NCEP-DOE AMIP-II reanalysis (R-2), B. Am. Meteorol. Soc., 83, 1631–1643, 2002.
Karl, T. R., Hassol, S. J., Miller, C. D., and Murray, W. L. (Eds.): Temperature trends in the lower atmosphere: steps for understanding and reconciling differences, a report by the climate change science program and the subcommittee on global change, Washington, DC, USA, 180 pp., 2006.
Kirchengast, G.: End-to-end GNSS Occultation Performance Simulator (EGOPS) overview and exemplary applications, Wissenschaftl. Ber. No. 2/1998, Inst. for Meteorol. and Geophys., Univ. of Graz, Austria, 138 pp., 1998.
Kobayashi, S., Matricardi, M., Dee, D. P., and Uppala, S. M.: Toward a consistent reanalysis of the upper stratosphere based on radiance measurements from SSU and AMSU-A, Q. J. Roy. Meteor. Soc., 135, 2086–2099, 2009.
Kuo, Y.-H., Wee, T.-K., Sokolovskiy, S., Rocken, C., Schreiner, W., Hunt, D., and Anthes, R. A.: Inversion and error estimation of GPS radio occultation data, J. Meteorol. Soc. Jpn., 82, 507–531, 2004.
Kursinski, E. R., Hajj, G. A., Hardy, K. R., Schofield, J. T., and Linfield, R.: Observing Earth's atmosphere with radio occultation measurements, J. Geophys. Res., 102, 23429–23465, 1997.
Ladstädter, F., Steiner, A. K., Foelsche, U., Haimberger, L., Tavolato, C., and Kirchengast, G.: An assessment of differences in lower stratospheric temperature records from (A)MSU, radiosondes, and GPS radio occultation, Atmos. Meas. Tech., 4, 1965-1977, https://doi.org/10.5194/amt-4-1965-2011, 2011.
Langland, R. H., Maue, R. N., and Bishop, C. H.: Uncertainty in atmospheric temperature analyses, Tellus A, 60, 598–603, https://doi.org/10.1111/j.1600-0870.2008.00336.x, 2008.
Larson, V. E., Wood, R., Field, P. R., Golaz, J.-C., Vonder Harr, T. H., and Cotton, W. R.: Systematic biases in the microphysics and thermodynamics of numerical models that ignore subgrid-scale variability, J. Atmos. Sci., 58, 1117–1128, 2001.
Liu, H. and Zou, X.: Improvements to a GPS radio occultation ray-tracing model and their impacts on assimilation of bending angle, J. Geophys. Res., 108, 4548, https://doi.org/10.1029/2002JD003160, 2003.
Lohmann, M. S.: Analysis of global positioning system (GPS) radio occultation measurement errors based on Satellite de Aplicaciones Cientificas-C (SAC-C) GPS radio occultation data recorded in open-loop and phase-locked-loop mode, J. Geophys. Res., 112, D09115, https://doi.org/10.1029/2006JD007764, 2007.
Manney, G. L., Allen, D. M., Krüger, K., Naujokat, B., Santee, M. L., Sabutis, J. L., Pawson, S., Swinbank, R., Randall, C. E., Simmons, A. J., and Long, C.: Diagnostic comparison of meteorological analyses during the 2002 Antarctic winter, Mon. Weather Rev., 133, 1261–1278, https://doi.org/10.1175/MWR2926.1, 2005.
Marshall, G. J.: Trends in Antarctic geopotential height and temperature: a comparison between radiosonde and NCEP-NCAR reanalysis data, J. Climate, 15, 659–674, 2002.
Marshall, G. J.: Trends in the southern annular mode from observations and reanalyses, J. Climate, 16, 4134–4143, 2003.
Mass, C. F., Baars, J., Wedam, G., Grimit, E., and Steed, R.: Removal of systematic model bias on a model grid, Weather Forecast., 23, 438–459, 2008.
Melbourne, W. G., Davis, E. S., Duncan, C. B., Hajj, G. A., Hardy, K. R., Kursinski, E. R., Meehan, T. K., and Young, L. E.: The application of spaceborne GPS to atmospheric limb sounding and global change monitoring, Jet. Propul. Lab. Pub. 94–18, Pasadena, CA, USA, 147 pp., 1994.
Newman, M., Sardeshmukh, P. D., and Bergman, J. W.: An assessment of the NCEP, NASA, and ECMWF reanalyses over the tropical West Pacific warm pool, B. Am. Meteorol. Soc., 81, 41–48, 2000.
Onogi, K., Tsutsui, J., Koide, H., Sakamoto, M., Kobayashi, S., Hatsushika, H., Matsumoto, T., Yamazaki, N., Kamahori, H., Takahashi, K., Kadokura, S., Wada, K., Kato, K., Oyama, R., Ose, T., Mannoji, N., and Taira, R.: The JRA-25 reanalysis, J. Meteorol. Soc. Jpn., 85, 369–432, 2007.
Picone, J. M., Hedin, A. E., Drob, D. P., and Aikin, A. C.: NRLMSISE-00 empirical model of the atmosphere: statistical comparisons and scientific Issues, J. Geophys. Res., 107, 1468, https://doi.org/10.1029/2002JA009430, 2002.
Poli, P. and Joiner, J.: Effects of horizontal gradients on GPS radio occultation observation operators. I: Ray tracing, Q. J. Roy. Meteor. Soc., 130, 2787–2805, https://doi.org/10.1256/qj.03.228, 2004.
Poli, P., Healy, S. B., and Dee, D. P.: Assimilation of Global Positioning System radio occultation data in the ECMWF ERA-Interim reanalysis, Q. J. Roy. Meteor. Soc., 136, 1972–1990, https://doi.org/10.1002/qj.722, 2010.
Randel, W., Udelhofen, P., Fleming, E., Geller, M., Gelman, M., Hamilton, K., Karoly, D., Ortland, D., Pawson, S., Swinbank, R., Wu, F., Baldwin, M., Chanin, M.-L., Keckhut, P., Labitzke, K., Remsberg, E., Simmons, A., and Wu, D.: The SPARC intercomparison of middle atmosphere climatologies, J. Climate, 17, 986–1003, 2004.
Reichler, T. and Kim, J.: Uncertainties in the climate mean state of global observations, reanalyses, and the GFDL climate model, J. Geophys. Res., 113, D05106, https://doi.org/10.1029/2007JD009278, 2008.
Rennie, M. P.: The impact of GPS radio occultation assimilation at the Met Office, Q. J. Roy. Meteor. Soc., 136, 116–131, https://doi.org/10.1002/qj.521, 2010.
Renwick, J. A.: Trends in the Southern Hemisphere polar vortex in NCEP and ECMWF reanalyses, Geophys. Res. Lett., 31, L07209, https://doi.org/10.1029/2003GL019302, 2004.
Rieder, M. J. and Kirchengast, G.: Error analysis and characterization of atmospheric profiles retrieved from GNSS occultation data, J. Geophys. Res., 106, 31755–31770, 2001.
Rüeger, J. M.: Refractive index formulae for electronic distance measurement with radio and millimetre waves, Tech. Rep. S-68, School of Surv. and Spatial Inf. Syst., Univ. of N. S. W., Sydney, N. S. W., Australia, 2002.
Saha, S.: Response of NMC MRF Model to systematic-error correction within integration, Mon. Weather Rev., 120, 345–360, 1992.
Saha, S., Moorthi, S., Pan, H.-L., Wu, X., Wang, J., Nadiga, S., Tripp, P., Kistler, R., Woollen, J., Behringer, D., Liu, H., Stokes, D., Grumbine, R., Gayno, G., Wang, J., Hou, Y.-T., Chuang, H.-Y., Juang, H.-M. H., Sela, J., Iredell, M., Treadon, R., Kleist, D., Van Delst, P., Keyser, D., Derber, J., Ek, M., Meng, J., Wei, H., Yang, R., Lord, S., Van Den Dool, H., Kumar, A., Wang, W., Long, C., Chelliah, M., Xue, Y., Huang, B., Schemm, J.-K., Ebisuzaki, W., Lin, R., Xie, P., Chen, M., Zhou, S., Higgins, W., Zou, C.-Z., Liu, Q., Chen, Y., Han, Y., Cucurull, L., Reynolds, R. W., Rutledge, G., and Goldberg, M.: The NCEP climate forecast system reanalysis, B. Am. Meteorol. Soc., 91, 1015–1057, https://doi.org/10.1175/2010Bams3001.1, 2010.
Schreiner, W., Sokolovskiy, S., Hunt, D., Rocken, C., and Kuo, Y.-H.: Analysis of GPS radio occultation data from the FORMOSAT-3/COSMIC and Metop/GRAS missions at CDAAC, Atmos. Meas. Tech., 4, 2255–2272, https://doi.org/10.5194/amt-4-2255-2011, 2011.
Screen, J. A. and Simmonds, I.: Erroneous arctic temperature trends in the ERA-40 reanalysis: a closer look, J. Climate, 24, 2620–2627, https://doi.org/10.1175/2010JCLI4054.1, 2011.
Seeber, G.: Satellite Geodesy, Walter de Gruyter, Berlin, Germany, 531 pp., 1993.
Simmons, A., Hortal, M., Kelly, G., McNally, A., Untch, A., and Uppala, S. M.: ECMWF analyses and forecasts of stratospheric winter polar vortex break-up: September 2002 in the Southern Hemisphere and related events, J. Atmos. Sci., 62, 668–689, 2005.
Smith, E. K. and Weintraub, S.: The constants in the equation of atmospheric refractive index at radio frequencies, Proc. IRE, 41, 1035–1037, 1953.
Sokolovskiy, S. V.: Effect of superrefraction on inversions of radio occultation signals in the lower troposphere, Radio Sci., 38, 1058, https://doi.org/10.1029/2002RS002728, 2003.
Steiner, A. K. and Kirchengast, G.: Error analysis for GNSS radio occultation data based on ensembles of profiles from end-to-end simulations, J. Geophys. Res., 110, D15307, https://doi.org/10.1029/2004JD005251, 2005.
Steiner, A. K., Hunt, D., Ho, S.-P., Kirchengast, G., Mannucci, A. J., Scherllin-Pirscher, B., Gleisner, H., von Engeln, A., Schmidt, T., Ao, C., Leroy, S. S., Kursinski, E. R., Foelsche, U., Gorbunov, M., Heise, S., Kuo, Y.-H., Lauritsen, K. B., Marquardt, C., Rocken, C., Schreiner, W., Sokolovskiy, S., Syndergaard, S., and Wickert, J.: Quantification of structural uncertainty in climate data records from GPS radio occultation, Atmos. Chem. Phys., 13, 1469–1484, https://doi.org/10.5194/acp-13-1469-2013, 2013.
Sterl, A.: On the (in)homogeneity of reanalysis products, J. Climate, 17, 3866–3873, 2004.
Syndergaard, S.: Retrieval analysis and methodologies in atmospheric limb sounding using the GNSS radio occultation technique, Sci. Report 99-6, Danish Meteorol. Inst., Copenhagen, Denmark, 131 pp., 1999.
Syndergaard, S.: On the ionosphere calibration in GPS radio occultation measurements, Radio Sci., 35, 865–883, 2000.
Thorne, P. W. and Vose, R. S.: Reanalyses suitable for characterizing long-term trends: are they really achievable?, B. Am. Meteorol. Soc., 91, 353–361, https://doi.org/10.1175/2010JCLI4054.1, 2010.
Thorne, P. W., Parker, D. E., Christy, J. R., and Mears, C. A.: Uncertainties in climate trends: lessons from upper-air temperature records, B. Am. Meteorol. Soc., 86, 1437, https://doi.org/10.1175/BAMS-86-10-1437, 2005.
Trenberth, K. E. and Stepaniak, D. P.: A pathological problem with NCEP reanalyses in the stratosphere, J. Climate, 15, 690–695, 2002.
Trenberth, K. E., Stepaniak, D. P., Hurrell, J. W., and Fiorino, M.: Quality of reanalyses in the tropics, J. Climate, 14, 1499–1510, 2001.
Uppala, S. M., Kållberg, P. W., Simmons, A. J. et al.: The ERA-40 re-analysis, Q. J. Roy. Meteor. Soc., 131, 2961–3012, https://doi.org/10.1256/qj.04.176, 2005.
von Engeln, A.: A first test of climate monitoring with radio occultation instruments: Comparing two processing centers, Geophys. Res. Lett., 33, L22705, https://doi.org/10.1029/2006GL027767, 2006.
Ware, R., Exner, M., Feng, D., Gorbunov, M., Hardy, K., Herman, B., Kuo, Y., Meehan, T., Melbourne, W., Rocken, C., Schreiner, W., Sokolovskiy, S., Solheim, F., Zou, X., Anthes, R., Businger, S., and Trenberth, K.: GPS sounding of the atmosphere from low Earth orbit: preliminary results, B. Am. Meteorol. Soc., 77, 19–40, 1996.
Wee, T.-K. and Kuo, Y.-H.: A noise-aware combination of dual-frequency measurements from GPS radio occultation, J. Geophys. Res., 118, 12852–12868, https://doi.org/10.1002/2013JD019840, 2013.
Wee, T.-K. and Kuo, Y.-H.: Advanced stratospheric data processing of radio occultation with a variational combination for multifrequency GNSS signals, J. Geophys. Res., 119, 11011–11039, https://doi.org/10.1002/2014JD022204, 2014.
Wee, T.-K., Kuo, Y.-H., and Lee, D.-K.: Development of a curved ray tracing method for modeling of phase paths from GPS radio occultation: a two-dimensional study, J. Geophys. Res., 115, D24119, https://doi.org/10.1029/2010JD014419, 2010.
Wee, T.-K., Kuo, Y.-H., Lee, D.-K., Liu, Z., Wang, W., and Chen, S.-Y.: Two overlooked biases of the advanced research WRF (ARW) model in geopotential height and temperature, Mon. Weather Rev., 140, 3907–3918, https://doi.org/10.1175/MWR-D-12-00045.1, 2012.
Wickert, J., Schmidt, T., Beyerle, G., König, R., Reigber, C., and Jakowski, N.: The radio occultation experiment aboard CHAMP: operational data analysis and validation of vertical atmospheric profiles, J. Meteorol. Soc. Jpn., 82, 381–395, 2004.
