Articles | Volume 13, issue 2
https://doi.org/10.5194/amt-13-645-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/amt-13-645-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
11 Feb 2020
Research article |
| 11 Feb 2020
| 11 Feb 2020
Using ground radar overlaps to verify the retrieval of calibration bias estimates from spaceborne platforms
Irene Crisologo
CORRESPONDING AUTHOR
Institute of Environmental Sciences and Geography, University of Potsdam, Potsdam, Germany
Maik Heistermann
Institute of Environmental Sciences and Geography, University of Potsdam, Potsdam, Germany
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The calibration of ground-based weather radar (GR) can be improved a posteriori by comparing observed GR reflectivity to well-established spaceborne radar platforms (SR), such as TRMM or GPM. Our study shows that the consistency between GR and SR reflectivity measurements can be enhanced by considering the quality of GR data from areas where signals may have been blocked due to the surrounding terrain, and provides an open-source toolset to carry out corresponding analyses.
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Irene Crisologo, Robert A. Warren, Kai Mühlbauer, and Maik Heistermann
Atmos. Meas. Tech., 11, 5223–5236, https://doi.org/10.5194/amt-11-5223-2018, https://doi.org/10.5194/amt-11-5223-2018, 2018
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Berry Boessenkool, Gerd Bürger, and Maik Heistermann
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Maik Heistermann
Hydrol. Earth Syst. Sci., 21, 3455–3461, https://doi.org/10.5194/hess-21-3455-2017, https://doi.org/10.5194/hess-21-3455-2017, 2017
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In 2009, the "planetary boundaries" were introduced. They consist of nine global control variables and corresponding "thresholds which, if crossed, could generate unacceptable environmental change". The idea has been very successful, but also controversial. This paper picks up the debate with regard to the boundary on "global freshwater use": it argues that such a boundary is based on mere speculation, and that any exercise of assigning actual numbers is arbitrary, premature, and misleading.
K. Vormoor, D. Lawrence, M. Heistermann, and A. Bronstert
Hydrol. Earth Syst. Sci., 19, 913–931, https://doi.org/10.5194/hess-19-913-2015, https://doi.org/10.5194/hess-19-913-2015, 2015
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M. Heistermann, I. Crisologo, C. C. Abon, B. A. Racoma, S. Jacobi, N. T. Servando, C. P. C. David, and A. Bronstert
Nat. Hazards Earth Syst. Sci., 13, 653–657, https://doi.org/10.5194/nhess-13-653-2013, https://doi.org/10.5194/nhess-13-653-2013, 2013
M. Heistermann, S. Jacobi, and T. Pfaff
Hydrol. Earth Syst. Sci., 17, 863–871, https://doi.org/10.5194/hess-17-863-2013, https://doi.org/10.5194/hess-17-863-2013, 2013
Related subject area
Subject: Others (Wind, Precipitation, Temperature, etc.) | Technique: Remote Sensing | Topic: Validation and Intercomparisons
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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.
Saverio Paolella, Axel Von Engeln, Sebastiano Padovan, Riccardo Notarpietro, Christian Marquardt, Francisco Sancho, Veronica Rivas Boscan, Nicolas Morew, and Francisco Martin Alemany
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-82, https://doi.org/10.5194/amt-2024-82, 2024
Revised manuscript accepted for AMT
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This study evaluates the ability of the EUMETSAT Sentinel-6A RO-NTC processor to provide high quality bending angle profiles. The analysis spans from the signals SNR and phase noise to the determination of the optimal signals cut-off points in the tropospheric region. Some processor enhancements and the impact on the data quality is also discussed. Data were compared against ECMWF confirming the ability of the EUMETSAT RO processors in maintaining consistent and high-quality data.
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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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.
Cited articles
Baldini, L., Chandrasekar, V., and Moisseev, D.: Microwave radar signatures of
precipitation from S band to Ka band: application to GPM
mission, Eur. J. Remote Sens., 45, 75–88,
https://doi.org/10.5721/EuJRS20124508,
2012. a
Bech, J., Codina, B., Lorente, J., and Bebbington, D.: The sensitivity of
single polarization weather radar beam blockage correction to variability in
the vertical refractivity gradient, J. Atmos. Ocean.
Tech., 20, 845–855,
2003. a
Bolen, S. M. and Chandrasekar, V.: Methodology for aligning and comparing
spaceborne radar and ground-based radar observations, J. Atmos. Ocean. Tech., 20, 647–659,
2003. a
Bringi, V. N., Chandrasekar, V., Balakrishnan, N., and Zrnić, D. S.: An
Examination of Propagation Effects in Rainfall on Radar
Measurements at Microwave Frequencies, J. Atmos.
Ocean. Tech., 7, 829–840,
https://doi.org/10.1175/1520-0426(1990)007<0829:AEOPEI>2.0.CO;2,
1990. a
Cao, Q., Hong, Y., Qi, Y., Wen, Y., Zhang, J., Gourley, J. J., and Liao, L.:
Empirical conversion of the vertical profile of reflectivity from Ku-band
to S-band frequency, J. Geophys. Res.-Atmos., 118,
1814–1825, https://doi.org/10.1002/jgrd.50138,
2013. a
Carey, L. D., Rutledge, S. A., Ahijevych, D. A., and Keenan, T. D.: Correcting
Propagation Effects in C-Band Polarimetric Radar Observations
of Tropical Convection Using Differential Propagation Phase,
J. Appl. Meteorol., 39, 1405–1433,
https://doi.org/10.1175/1520-0450(2000)039<1405:CPEICB>2.0.CO;2,
2000. a
Collette, A.: Python and HDF5, O'Reilly, software, 2013. a
Crisologo, I. and Heistermann, M.: IreneCrisologo/inter-radar: First release,
https://doi.org/10.5281/zenodo.3596959,
https://github.com/IreneCrisologo/inter-radar/tree/0.1, 2020. a, b, c
Crisologo, I., Vulpiani, G., Abon, C. C., David, C. P. C., Bronstert, A., and
Heistermann, M.: Polarimetric rainfall retrieval from a C-Band weather
radar in a tropical environment (The Philippines), Asia-Pacific Journal
of Atmospheric Sciences, 50, 595–607, https://doi.org/10.1007/s13143-014-0049-y,
2014. a, b
Crisologo, I., Warren, R. A., Mühlbauer, K., and Heistermann, M.: Enhancing the consistency of spaceborne and ground-based radar comparisons by using beam blockage fraction as a quality filter, Atmos. Meas. Tech., 11, 5223–5236, https://doi.org/10.5194/amt-11-5223-2018, 2018. a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v
Deo, A., Munchak, S. J., and Walsh, K. J. E.: Cross Validation of Rainfall
Characteristics Estimated from the TRMM PR, a Combined PR–TMI
Algorithm, and a C-POL Ground Radar during the Passage of
Tropical Cyclone and Nontropical Cyclone Events over Darwin,
Australia, J. Atmos. Ocean. Tech., 35, 2339–2358,
https://doi.org/10.1175/JTECH-D-18-0065.1,
2018. a
Doviak, R. J. and Zrnić, D. S.: Doppler radar and weather observations,
Academic Press, Mineola, N.Y., 2nd ed., dover ed. edn., 2006. a
Einfalt, T., Szturc, J., and Ośródka, K.: The quality index for radar
precipitation data: a tower of Babel?, Atmos. Sci. Lett., 11,
139–144, https://doi.org/10.1002/asl.271,
2010. a
Friedrich, K., Hagen, M., and Einfalt, T.: A quality control concept for radar
reflectivity, polarimetric parameters, and Doppler velocity, J.
Atmos. Ocean. Tech., 23, 865–887,
2006. a
GDAL Development Team: GDAL – Geospatial Data Abstraction Library,
Version 2.2.3, available at: http://www.gdal.org/ (last access: January 2020), 2017. a
Gourley, J. J., Tabary, P., and Parent du Chatelet, J.: A Fuzzy Logic
Algorithm for the Separation of Precipitating from Nonprecipitating
Echoes Using Polarimetric Radar Observations, J.
Atmos. Ocean. Tech., 24, 1439–1451,
https://doi.org/10.1175/JTECH2035.1,
2007. a
Heistermann, M., Crisologo, I., Abon, C. C., Racoma, B. A., Jacobi, S., Servando, N. T., David, C. P. C., and Bronstert, A.: Brief communication “Using the new Philippine radar network to reconstruct the Habagat of August 2012 monsoon event around Metropolitan Manila”, Nat. Hazards Earth Syst. Sci., 13, 653–657, https://doi.org/10.5194/nhess-13-653-2013, 2013a. a, b
Heistermann, M., Jacobi, S., and Pfaff, T.: Technical Note: An open source library for processing weather radar data (wradlib), Hydrol. Earth Syst. Sci., 17, 863–871, https://doi.org/10.5194/hess-17-863-2013, 2013b. a
Hou, A. Y., Kakar, R. K., Neeck, S., Azarbarzin, A. A., Kummerow, C. D.,
Kojima, M., Oki, R., Nakamura, K., and Iguchi, T.: The Global
Precipitation Measurement Mission, B. Am.
Meteorol. Soc., 95, 701–722, https://doi.org/10.1175/BAMS-D-13-00164.1,
2013. a
Houze Jr., R. A., Brodzik, S., Schumacher, C., Yuter, S. E., and Williams,
C. R.: Uncertainties in oceanic radar rain maps at Kwajalein and
implications for satellite validation, J. Appl. Meteorol., 43,
1114–1132,
2004. a
Hunter, J. D.: Matplotlib: A 2D Graphics Environment, Computing in
Science Engineering, 9, 90–95, https://doi.org/10.1109/MCSE.2007.55, 2007. a
Iguchi, T., Kozu, T., Kwiatkowski, J., Meneghini, R., Awaka, J., and Okamoto,
K.: Uncertainties in the Rain Profiling Algorithm for the TRMM
Precipitation Radar, Journal of the Meteorological Society of Japan. Ser.
II, 87A, 1–30, https://doi.org/10.2151/jmsj.87A.1, 2009. a
Iguchi, T., Seto, S., Meneghini, R., Yoshida, N., Awaka, J., Le, M.,
Chandrasekar, V., Brodzik, S., and Kubota, T.: GPM/DPR Level-2
Algorithm Theoretical Basis Document, available at:
https://pmm.nasa.gov/resources/documents/gpmdpr-level-2-algorithm-theoretical-basis-document-atbd (last access: January 2020),
2018. a
Irving, D.: A Minimum Standard for Publishing Computational Results
in the Weather and Climate Sciences, B. Am.
Meteorol. Soc., 97, 1149–1158, https://doi.org/10.1175/BAMS-D-15-00010.1,
2016. a
Kawanishi, T., Kuroiwa, H., Kojima, M., Oikawa, K., Kozu, T., Kumagai, H.,
Okamoto, K., Okumura, M., Nakatsuka, H., and Nishikawa, K.: TRMM
Precipitation Radar, Adv. Space Res., 25, 969–972,
https://doi.org/10.1016/S0273-1177(99)00932-1,
2000. a
Lagmay, A. M. F., Bagtasa, G., Crisologo, I. A., Racoma, B. A. B., and David,
C. P. C.: Volcanoes magnify Metro Manila's southwest monsoon rains and
lethal floods, Front. Earth Sci., 2, 36,
https://doi.org/10.3389/feart.2014.00036,
2015. a
Louf, V., Protat, A., Warren, R. A., Collis, S. M., Wolff, D. B., Raunyiar, S.,
Jakob, C., and Petersen, W. A.: An Integrated Approach to Weather
Radar Calibration and Monitoring Using Ground Clutter and
Satellite Comparisons, J. Atmos. Ocean. Tech., 36,
17–39, https://doi.org/10.1175/JTECH-D-18-0007.1,
2019. a, b
McKinney, W.: Data structures for statistical computing in python, in:
Proceedings of the 9th Python in Science Conference, vol. 445,
51–56, Austin, TX, 2010. a
Michelson, D., Einfalt, T., Holleman, I., Gjertsen, U., Friedrich, Katja,
Haase, G., Lindskog, M., and Jurczyk, A.: Weather radar data quality in
Europe quality control and characterisation, Publications Office,
Luxembourg, 2005. a
Munchak, S. J.: Chapter 13 – Remote Sensing of Precipitation from
Airborne and Spaceborne Radar, in: Remote Sensing of Aerosols,
Clouds, and Precipitation, edited by: Islam, T., Hu, Y., Kokhanovsky, A.,
and Wang, J., 267–299, Elsevier,
https://doi.org/10.1016/B978-0-12-810437-8.00013-X,
2018. a
NASA: Release Notes for the PR Level 1 products, available at:
https://pps.gsfc.nasa.gov/Documents/ReleaseNote_PU1_productV05.pdf (last access: January 2020),
2017. a
Norman, K., Gaussiat, N., Harrison, D., Scovell, R., and Boscacci, M.: A quality index for radar data, EUMETNET OPERA Document, 2010. a
Oliphant, T. E.: Guide to NumPy, CreateSpace Independent Publishing Platform,
USA, 2nd edn., 2015. a
Park, S., Jung, S.-H., and Lee, G.: Cross Validation of TRMM PR
Reflectivity Profiles Using 3D Reflectivity Composite from the
Ground-Based Radar Network over the Korean Peninsula, J.
Hydrometeorol., 16, 668–687, https://doi.org/10.1175/JHM-D-14-0092.1,
2015. a
Rew, R., Davis, G., Emmerson, S., Cormack, C., Caron, J., Pincus, R., Hartnett,
E., Heimbigner, D., Appel, L., and Fisher, W.: Unidata NetCDF, available at:
http://www.unidata.ucar.edu/software/netcdf/ (last access: January 2020), 1989. a
Schwaller, M. R. and Morris, K. R.: A Ground Validation Network for the
Global Precipitation Measurement Mission, J. Atmos.
Ocean. Tech., 28, 301–319, https://doi.org/10.1175/2010JTECHA1403.1,
2011. a, b, c
Seo, B.-C., Krajewski, W. F., and Smith, J. A.: Four-dimensional reflectivity
data comparison between two ground-based radars: methodology and statistical
analysis, Hydrol. Sci. J., 59, 1320–1334,
https://doi.org/10.1080/02626667.2013.839872,
2014. a, b
Seto, S. and Iguchi, T.: Intercomparison of Attenuation Correction
Methods for the GPM Dual-Frequency Precipitation Radar, J.
Atmos. Ocean. Tech., 32, 915–926,
https://doi.org/10.1175/JTECH-D-14-00065.1,
2015.
a
Silberstein, D. S., Wolff, D. B., Marks, D. A., Atlas, D., and Pippitt, J. L.:
Ground Clutter as a Monitor of Radar Stability at Kwajalein, RMI,
J. Atmos. Ocean. Tech., 25, 2037–2045,
https://doi.org/10.1175/2008JTECHA1063.1,
2008. a
Villarini, G. and Krajewski, W. F.: Review of the Different Sources of
Uncertainty in Single Polarization Radar-Based Estimates of
Rainfall, Surv. Geophys., 31, 107–129,
https://doi.org/10.1007/s10712-009-9079-x,
2010. a
Virtanen, P., Gommers, R., Oliphant, T. E., Haberland, M., Reddy, T.,
Cournapeau, D., Burovski, E., Peterson, P., Weckesser, W., Bright, J., Walt,
S. v. d., Brett, M., Wilson, J., Millman, K. J., Mayorov, N., Nelson, A.
R. J., Jones, E., Kern, R., Larson, E., Carey, C. J., Polat, I., Feng, Y.,
Moore, E. W., VanderPlas, J., Laxalde, D., Perktold, J., Cimrman, R.,
Henriksen, I., Quintero, E. A., Harris, C. R., Archibald, A. M., Ribeiro,
A. H., Pedregosa, F., Mulbregt, P. v., and SciPy: SciPy 1.0-Fundamental
Algorithms for Scientific Computing in Python, CoRR, abs/1907.10121, available at:
http://arxiv.org/abs/1907.10121, 2019. a
Vulpiani, G., Marzano, F. S., Chandrasekar, V., Berne, A., and Uijlenhoet, R.: Rainfall rate retrieval in presence of path attenuation using C-band polarimetric weather radars, Nat. Hazards Earth Syst. Sci., 6, 439–450, https://doi.org/10.5194/nhess-6-439-2006, 2006. a
Vulpiani, G., Montopoli, M., Passeri, L. D., Gioia, A. G., Giordano, P., and
Marzano, F. S.: On the Use of Dual-Polarized C-Band Radar for
Operational Rainfall Retrieval in Mountainous Areas, J.
Appl. Meteorol. Climatol., 51, 405–425,
https://doi.org/10.1175/JAMC-D-10-05024.1,
2012. a
Wang, J. and Wolff, D. B.: Comparisons of Reflectivities from the TRMM
Precipitation Radar and Ground-Based Radars, J. Atmos.
Ocean. Tech., 26, 857–875, https://doi.org/10.1175/2008JTECHA1175.1,
2009. a
Warren, R. A., Protat, A., Siems, S. T., Ramsay, H. A., Louf, V., Manton,
M. J., and Kane, T. A.: Calibrating ground-based radars against TRMM and
GPM, J. Atmos. Ocean. Tech.,
https://doi.org/10.1175/JTECH-D-17-0128.1,
2018. a, b, c, d
Zhang, J., Qi, Y., Howard, K., Langston, C., and Kaney, B.: Radar quality index
(RQI) – A combined measure of beam blockage and VPR effects in a
national network, in: Proceedings, International Symposium on Weather
Radar and Hydrology, available at:
http://www.nssl.noaa.gov/projects/q2/tutorial/images/mosaic/WRaH_Proceedings_Zhang-et-al_v3.pdf (last access: January 2020),
2011. a
Short summary
Archives of radar observations often suffer from errors, one of which is calibration. However, it is possible to correct them after the fact by using satellite radars as a calibration reference. We propose improvements to this calibration method by considering factors that affect the data quality, such that poor quality data gets filtered out in the bias calculation by assigning weights. We also show that the bias can be interpolated in time even for days when there are no satellite data.
Archives of radar observations often suffer from errors, one of which is calibration. However,...
