Articles | Volume 8, issue 9
03 Sep 2015
Research article | 03 Sep 2015
Marine boundary layer drizzle properties and their impact on cloud property retrieval
P. Wu et al.
No articles found.
Baike Xi, Xiquan Dong, Xiaojian Zheng, and Peng Wu
Atmos. Meas. Tech. Discuss.,
Revised manuscript under review for AMTShort summary
This study develops an innovative method to determine the cloud phases over the Southern Ocean (SO) using the combination of radar and lidar measurements during the ship-based field campaign of MARCUS. Results from our study show that the low-level, deep, and shallow cumuli are dominant, and the mixed-phase clouds occur more than single phases over the SO. The mixed-phase cloud properties are similar to liquid-phase (ice-phase) clouds in the midlatitudes (polar) region of SO.
Xiaojian Zheng, Baike Xi, Xiquan Dong, Peng Wu, Timothy Logan, and Yuan Wang
Atmos. Chem. Phys., 22, 335–354,Short summary
This study uses ground-based observations to investigate the physical processes in the aerosol–cloud interactions in non-precipitating marine boundary layer clouds, over the eastern North Atlantic Ocean. Results show that the cloud responses to the aerosols are diminished with limited water vapor supply, while they are enhanced with increasing water vapor availability. The clouds are found to be most sensitive to the aerosols under sufficient water vapor and strong boundary layer turbulence.
Yuan Wang, Xiaojian Zheng, Xiquan Dong, Baike Xi, Peng Wu, Timothy Logan, and Yuk L. Yung
Atmos. Chem. Phys., 20, 14741–14755,Short summary
A recent aircraft field campaign near the Azores in the summer of 2017 provides ample observations of aerosols and clouds with detailed vertical information. This study utilizes those observational data in combination with the aerosol-aware large-eddy simulations and aerosol reanalysis data to examine the significance of the long-range-transported aerosol effect on marine-boundary-layer clouds. It is the first time that the ACE-ENA aircraft campaign data are used for this topic.
Dale M. Ward, Xiquan Dong, Baike Xi, Peng Wu, Xiaojian Zheng, and Yuan Wang
Atmos. Chem. Phys. Discuss.,
Preprint withdrawnShort summary
Marine boundary layer clouds in subtropical regions strongly impact global energy balance, but complete understanding of the processes that control their development remain elusive. We analyze aircraft in-situ measurements of clouds collected in a field campaign for cases that contain organized structures tens of kilometres in extent embedded within a larger overcast cloud field. Failure to account for these structures can lead to misrepresentation in models and satellite retrievals.
Xiaojian Zheng, Baike Xi, Xiquan Dong, Timothy Logan, Yuan Wang, and Peng Wu
Atmos. Chem. Phys., 20, 3483–3501,Short summary
The continental low-level stratiform cloud susceptibilities to aerosols were investigated under different absorptive aerosol regimes. The weakly absorbing aerosols, which are more hygroscopic, can better activate as cloud condensation nuclei. The favorable thermodynamic condition enhances the cloud susceptibility, while the cloud-layer heating effect induced by strongly absorbing aerosols dampens the cloud susceptibility. Overall, the clouds are more susceptible to the weakly absorbing aerosols.
Jingjing Tian, Xiquan Dong, Baike Xi, Christopher R. Williams, and Peng Wu
Atmos. Meas. Tech., 12, 3743–3759,Short summary
Liquid water path (LWP) is a combination of rain liquid water path (RLWP) and cloud liquid water path (CLWP) in stratiform precipitation systems. LWP partitioning is important but poorly understood. Here we estimate the RLWP and CLWP below the melting base simultaneously and separately using ceilometer and radar measurements. Results show that the occurrence of cloud particles below the melting base is low; however, when cloud particles exist, the CLWP value is much larger than the RLWP.
Peng Wu, Baike Xi, Xiquan Dong, and Zhibo Zhang
Atmos. Chem. Phys., 18, 17405–17420,Short summary
Prescribed autoconversion and accretion enhancement factors in GCM warm-rain parameterizations contribute partially to the too-frequent and too-light problem in precipitation simulation. The two factors should be regime- and resolution-dependent. A decreased autoconversion enhancement factor and increased accretion enhancement factor in the Morrison and Gettleman (2008) scheme can improve the simulated precipitation frequency and intensity. The two factors for other schemes are also suggested.
T. Logan, B. Xi, and X. Dong
Atmos. Chem. Phys. Discuss.,
Revised manuscript not accepted
T. Logan, B. Xi, X. Dong, Z. Li, and M. Cribb
Atmos. Chem. Phys., 13, 2253–2265,
Related subject area
Subject: Clouds | Technique: Remote Sensing | Topic: Data Processing and Information RetrievalTowards the use of conservative thermodynamic variables in data assimilation: a case study using ground-based microwave radiometer measurementsEmpirical model of multiple-scattering effect on single-wavelength lidar data of aerosols and cloudsAnalytic characterization of random errors in spectral dual-polarized cloud radar observationsAssessing synergistic radar and radiometer capability in retrieving ice cloud microphysics based on hybrid Bayesian algorithmsApplying self-supervised learning for semantic cloud segmentation of all-sky imagesCoincident in situ and triple-frequency radar airborne observations in the ArcticAnalysis of improvements in MOPITT observational coverage over CanadaImproving discrimination between clouds and optically thick aerosol plumes in geostationary satellite dataUsing artificial neural networks to predict riming from Doppler cloud radar observationsEvaluating cloud liquid detection against Cloudnet using cloud radar Doppler spectra in a pre-trained artificial neural networkPARAFOG v2.0: a near-real-time decision tool to support nowcasting fog formation events at local scalesInpainting radar missing data regions with deep learningImproved cloud detection for the Aura Microwave Limb Sounder (MLS): training an artificial neural network on colocated MLS and Aqua MODIS dataA kriging-based analysis of cloud Liquid Water Content using CloudSat dataTriple-frequency radar retrieval of microphysical properties of snowRetrieving microphysical properties of concurrent pristine ice and snow using polarimetric radar observationsComparison of mid-latitude single- and mixed-phase cloud optical depth from co-located infrared spectrometer and backscatter lidar measurementsPhysical characteristics of frozen hydrometeors inferred with parameter estimationCloud height measurement by a network of all-sky imagersIncreasing the spatial resolution of cloud property retrievals from Meteosat SEVIRI by use of its high-resolution visible channel: implementation and examplesWhy we need radar, lidar, and solar radiance observations to constrain ice cloud microphysicsEstimating the optical extinction of liquid water clouds in the cloud base regionW-band radar observations for fog forecast improvement: an analysis of model and forward operator errorsIdentification of snowfall microphysical processes from Eulerian vertical gradients of polarimetric radar variablesIdentifying insects, clouds, and precipitation using vertically pointing polarimetric radar Doppler velocity spectraMICRU: an effective cloud fraction algorithm designed for UV–vis satellite instruments with large viewing anglesA simplified method for the detection of convection using high-resolution imagery from GOES-16Introducing hydrometeor orientation into all-sky microwave and submillimeter assimilationVersion 4 CALIPSO Imaging Infrared Radiometer ice and liquid water cloud microphysical properties – Part II: Results over oceansVersion 4 CALIPSO Imaging Infrared Radiometer ice and liquid water cloud microphysical properties – Part I: The retrieval algorithmsObservation of cirrus clouds with GLORIA during the WISE campaign: detection methods and cirrus characterizationApplying machine learning methods to detect convection using Geostationary Operational Environmental Satellite-16 (GOES-16) advanced baseline imager (ABI) dataA new method to detect and classify polar stratospheric nitric acid trihydrate clouds derived from radiative transfer simulations and its first application to airborne infrared limb emission observationsA study of polarimetric error induced by satellite motion: application to the 3MI and similar sensorsA robust low-level cloud and clutter discrimination method for ground-based millimeter-wavelength cloud radarTwo-dimensional and multi-channel feature detection algorithm for the CALIPSO lidar measurementsAnalysis of 3D cloud effects in OCO-2 XCO2 retrievalsImproving cloud type classification of ground-based images using region covariance descriptorsGlobal cloud property models for real-time triage on board visible–shortwave infrared spectrometersApplying deep learning to NASA MODIS data to create a community record of marine low-cloud mesoscale morphologyMicrowave single-scattering properties of non-spheroidal raindropsDetermining cloud thermodynamic phase from the polarized Micro Pulse LidarImproved cloud detection over sea ice and snow during Arctic summer using MERIS dataA kernel-driven BRDF model to inform satellite-derived visible anvil cloud detectionCloud-top pressure retrieval with DSCOVR EPIC oxygen A- and B-band observationsEstimating total attenuation using Rayleigh targets at cloud top: applications in multilayer and mixed-phase clouds observed by ground-based multifrequency radarsA new Orbiting Carbon Observatory 2 cloud flagging method and rapid retrieval of marine boundary layer cloud propertiesCALIOP V4 cloud thermodynamic phase assignment and the impact of near-nadir viewing anglesDetection of the cloud liquid water path horizontal inhomogeneity in a coastline area by means of ground-based microwave observations: feasibility studySynergistic radar and radiometer retrievals of ice hydrometeors
Pascal Marquet, Pauline Martinet, Jean-François Mahfouf, Alina Lavinia Barbu, and Benjamin Ménétrier
Atmos. Meas. Tech., 15, 2021–2035,Short summary
Two conservative thermodynamic variables (moist-air entropy potential temperature and total water content) are introduced into a one-dimensional EnVar data assimilation system to demonstrate their benefit for future operational assimilation schemes, with the use of microwave brightness temperatures from a ground-based radiometer installed during the field campaign SOFGO3D. Results show that the brightness temperatures analysed with the new variables are improved, including the liquid water.
Valery Shcherbakov, Frédéric Szczap, Alaa Alkasem, Guillaume Mioche, and Céline Cornet
Atmos. Meas. Tech., 15, 1729–1754,Short summary
We performed extensive Monte Carlo (MC) simulations of lidar signals and developed an empirical model to account for the multiple scattering in the lidar signals. The simulations have taken into consideration four types of lidar configurations (the ground based, the airborne, the CALIOP, and the ATLID) and four types of particles (coarse aerosol, water cloud, jet-stream cirrus, and cirrus). The empirical model has very good quality of MC data fitting for all considered cases.
Alexander Myagkov and Davide Ori
Atmos. Meas. Tech., 15, 1333–1354,Short summary
This study provides equations to characterize random errors of spectral polarimetric observations from cloud radars. The results can be used for a broad spectrum of applications. For instance, accurate error characterization is essential for advanced retrievals of microphysical properties of clouds and precipitation. Moreover, error characterization allows for the use of measurements from polarimetric cloud radars to potentially improve weather forecasts.
Yuli Liu and Gerald G. Mace
Atmos. Meas. Tech., 15, 927–944,Short summary
We propose a suite of Bayesian algorithms for synergistic radar and radiometer retrievals to evaluate the next-generation NASA Cloud, Convection and Precipitation (CCP) observing system. The algorithms address pixel-level retrievals using active-only, passive-only, and synergistic active–passive observations. Novel techniques in developing synergistic algorithms are presented. Quantitative assessments of the CCP observing system's capability in retrieving ice cloud microphysics are provided.
Yann Fabel, Bijan Nouri, Stefan Wilbert, Niklas Blum, Rudolph Triebel, Marcel Hasenbalg, Pascal Kuhn, Luis F. Zarzalejo, and Robert Pitz-Paal
Atmos. Meas. Tech., 15, 797–809,Short summary
This work presents a new approach to exploit unlabeled image data from ground-based sky observations to train neural networks. We show that our model can detect cloud classes within images more accurately than models trained with conventional methods using small, labeled datasets only. Novel machine learning techniques as applied in this work enable training with much larger datasets, leading to improved accuracy in cloud detection and less need for manual image labeling.
Cuong M. Nguyen, Mengistu Wolde, Alessandro Battaglia, Leonid Nichman, Natalia Bliankinshtein, Samuel Haimov, Kenny Bala, and Dirk Schuettemeyer
Atmos. Meas. Tech., 15, 775–795,Short summary
An analysis of airborne triple-frequency radar and almost perfectly co-located coincident in situ data from an Arctic storm confirms the main findings of modeling work with radar dual-frequency ratios (DFRs) at different zones of the DFR plane associated with different ice habits. High-resolution CPI images provide accurate identification of rimed particles within the DFR plane. The relationships between the triple-frequency signals and cloud microphysical properties are also presented.
Heba S. Marey, James R. Drummond, Dylan B. A. Jones, Helen Worden, Merritt N. Deeter, John Gille, and Debbie Mao
Atmos. Meas. Tech., 15, 701–719,Short summary
In this study, an analysis has been performed to understand the improvements in observational coverage over Canada in the new MOPITT V9 product. Temporal and spatial analysis of V9 indicates a general coverage gain of 15–20 % relative to V8, which varies regionally and seasonally; e.g., the number of successful MOPITT retrievals in V9 was doubled over Canada in winter. Also, comparison with the corresponding IASI instrument indicated generally good agreement, with about a 5–10 % positive bias.
Daniel Robbins, Caroline Poulsen, Steven Siems, and Simon Proud
Atmos. Meas. Tech. Discuss.,
Revised manuscript accepted for AMTShort summary
A neural network (NN) based cloud mask for a geostationary satellite instrument, AHI, using collocated data is developed that is better at not classifying thick aerosols as cloud versus the Japanese Meteorological Association and the Bureau of Meteorology masks, identifying 1.11 and 1.28 times as many non-cloud pixels than each mask respectively. The improvement during the day likely comes from including the shortest wavelength bands from AHI in the NN mask, which the other masks do not use.
Teresa Vogl, Maximilian Maahn, Stefan Kneifel, Willi Schimmel, Dmitri Moisseev, and Heike Kalesse-Los
Atmos. Meas. Tech., 15, 365–381,Short summary
We are using machine learning techniques, a type of artificial intelligence, to detect graupel formation in clouds. The measurements used as input to the machine learning framework were performed by cloud radars. Cloud radars are instruments located at the ground, emitting radiation with wavelenghts of a few millimeters vertically into the cloud and measuring the back-scattered signal. Our novel technique can be applied to different radar systems and different weather conditions.
Heike Kalesse-Los, Willi Schimmel, Edward Luke, and Patric Seifert
Atmos. Meas. Tech., 15, 279–295,Short summary
It is important to detect the vertical distribution of cloud droplets and ice in mixed-phase clouds. Here, an artificial neural network (ANN) previously developed for Arctic clouds is applied to a mid-latitudinal cloud radar data set. The performance of this technique is contrasted to the Cloudnet target classification. For thick/multi-layer clouds, the machine learning technique is better at detecting liquid than Cloudnet, but if lidar data are available Cloudnet is at least as good as the ANN.
Jean-François Ribaud, Martial Haeffelin, Jean-Charles Dupont, Marc-Antoine Drouin, Felipe Toledo, and Simone Kotthaus
Atmos. Meas. Tech., 14, 7893–7907,Short summary
PARAFOG is a near-real-time decision tool that aims to retrieve pre-fog alert levels minutes to hours prior to fog onset. The second version of PARAFOG allows us to discriminate between radiation and stratus lowering fog situations. It is based upon the combination of visibility observations and automatic lidar and ceilometer measurements. The overall performance of the second version of PARAFOG over more than 300 fog cases at five different locations presents a good perfomance.
Andrew Geiss and Joseph C. Hardin
Atmos. Meas. Tech., 14, 7729–7747,Short summary
Radars can suffer from missing or poor-quality data regions for several reasons: beam blockage, instrument failure, and near-ground blind zones, etc. Here, we demonstrate how deep convolutional neural networks can be used for filling in radar-missing data regions and that they can significantly outperform conventional approaches in terms of realism and accuracy.
Frank Werner, Nathaniel J. Livesey, Michael J. Schwartz, William G. Read, Michelle L. Santee, and Galina Wind
Atmos. Meas. Tech., 14, 7749–7773,Short summary
In this study we present an improved cloud detection scheme for the Microwave Limb Sounder, which is based on a feedforward artificial neural network. This new algorithm is shown not only to reliably detect high and mid-level convection containing even small amounts of cloud water but also to distinguish between high-reaching and mid-level to low convection.
Jean-Marie Lalande, Guillaume Bourmaud, Pierre Minvielle, and Jean-François Giovannelli
Atmos. Meas. Tech. Discuss.,
Revised manuscript accepted for AMTShort summary
In this paper, we describe the implementation of an interpolation/prediction estimator applied to cloud properties derived from CloudSat observations. The objective is also to estimate the uncertainty associated with the estimated quantity. The model developed in this study can be valuable for satellite applications (GPS, telecommunication) as well as for cloud product comparison. We believe this paper is written in a didactic way so as to be profitable to anyone interested by kriging estimator.
Kamil Mroz, Alessandro Battaglia, Cuong Nguyen, Andrew Heymsfield, Alain Protat, and Mengistu Wolde
Atmos. Meas. Tech., 14, 7243–7254,Short summary
A method for estimating microphysical properties of ice clouds based on radar measurements is presented. The algorithm exploits the information provided by differences in the radar response at different frequency bands in relation to changes in the snow morphology. The inversion scheme is based on a statistical relation between the radar simulations and the properties of snow calculated from in-cloud sampling.
Nicholas J. Kedzuf, J. Christine Chiu, V. Chandrasekar, Sounak Biswas, Shashank S. Joshil, Yinghui Lu, Peter Jan van Leeuwen, Christopher Westbrook, Yann Blanchard, and Sebastian O'Shea
Atmos. Meas. Tech., 14, 6885–6904,Short summary
Ice clouds play a key role in our climate system due to their strong controls on precipitation and the radiation budget. However, it is difficult to characterize co-existing ice species using radar observations. We present a new method that separates the radar signals of pristine ice embedded in snow aggregates and retrieves their respective abundances and sizes for the first time. The ability to provide their quantitative microphysical properties will open up many research opportunities.
Gianluca Di Natale, Marco Barucci, Claudio Belotti, Giovanni Bianchini, Francesco D'Amato, Samuele Del Bianco, Marco Gai, Alessio Montori, Ralf Sussmann, Silvia Viciani, Hannes Vogelmann, and Luca Palchetti
Atmos. Meas. Tech., 14, 6749–6758,Short summary
The importance of cirrus and mixed-phase clouds in the Earth radiation budget has been proven by many studies. In this paper the properties that characterize these clouds are retrieved from lidar and far-infrared spectral measurements performed in winter 2018/19 on the Zugspitze (Germany). The synergy of lidar and spectrometer measurements allowed us to assess the exponent k of the power-law relationship between the backscattering and the extinction coefficients.
Alan J. Geer
Atmos. Meas. Tech., 14, 5369–5395,Short summary
Satellite observations sensitive to cloud and precipitation help improve the quality of weather forecasts. However, they are sensitive to things that models do not forecast, such as the shapes and sizes of snow and ice particles. These details can be estimated from the observations themselves and then incorporated in the satellite simulators used in weather forecasting. This approach, known as parameter estimation, will be increasingly useful to build models of poorly known physical processes.
Niklas Benedikt Blum, Bijan Nouri, Stefan Wilbert, Thomas Schmidt, Ontje Lünsdorf, Jonas Stührenberg, Detlev Heinemann, Andreas Kazantzidis, and Robert Pitz-Paal
Atmos. Meas. Tech., 14, 5199–5224,Short summary
Cloud base height (CBH) is important, e.g., to forecast solar irradiance and, with it, photovoltaic production. All-sky imagers (ASIs), cameras monitoring the sky above their point of installation, can provide such forecasts and also measure CBH. We present a network of ASIs to measure CBH. The network provides numerous readings of CBH simultaneously. We combine these with a statistical procedure. Validation attests to significantly higher accuracy of the combination compared to two ASIs alone.
Hartwig Deneke, Carola Barrientos-Velasco, Sebastian Bley, Anja Hünerbein, Stephan Lenk, Andreas Macke, Jan Fokke Meirink, Marion Schroedter-Homscheidt, Fabian Senf, Ping Wang, Frank Werner, and Jonas Witthuhn
Atmos. Meas. Tech., 14, 5107–5126,Short summary
The SEVIRI instrument flown on the European geostationary Meteosat satellites acquires multi-spectral images at a relatively coarse pixel resolution of 3 × 3 km2, but it also has a broadband high-resolution visible channel with 1 × 1 km2 spatial resolution. In this study, the modification of an existing cloud property and solar irradiance retrieval to use this channel to improve the spatial resolution of its output products as well as the resulting benefits for applications are described.
Florian Ewald, Silke Groß, Martin Wirth, Julien Delanoë, Stuart Fox, and Bernhard Mayer
Atmos. Meas. Tech., 14, 5029–5047,Short summary
In this study, we show how solar radiance observations can be used to validate and further constrain ice cloud microphysics retrieved from the synergy of radar–lidar measurements. Since most radar–lidar retrievals rely on a global assumption about the ice particle shape, ice water content and particle size biases are to be expected in individual cloud regimes. In this work, we identify and correct these biases by reconciling simulated and measured solar radiation reflected from these clouds.
Karolina Sarna, David P. Donovan, and Herman W. J. Russchenberg
Atmos. Meas. Tech., 14, 4959–4970,Short summary
We show a method for obtaining cloud optical extinction with a lidar system. We use a scheme in which a lidar signal is inverted based on the estimated value of cloud extinction at the far end of the cloud and apply a correction for multiple scattering within the cloud and a range resolution correction. By applying our technique, we show that it is possible to obtain the cloud optical extinction with an error better than 5 % up to 90 m within the cloud.
Alistair Bell, Pauline Martinet, Olivier Caumont, Benoît Vié, Julien Delanoë, Jean-Charles Dupont, and Mary Borderies
Atmos. Meas. Tech., 14, 4929–4946,Short summary
This paper presents work towards making retrievals on the liquid water content in fog and low clouds. Future retrievals will rely on a radar simulator and high-resolution forecast. In this work, real observations are used to assess the errors associated with the simulator and forecast. A selection method to reduce errors associated with the forecast is proposed. It is concluded that the distribution of errors matches the requirements for future retrievals.
Noémie Planat, Josué Gehring, Étienne Vignon, and Alexis Berne
Atmos. Meas. Tech., 14, 4543–4564,Short summary
We implement a new method to identify microphysical processes during cold precipitation events based on the sign of the vertical gradient of polarimetric radar variables. We analytically asses the meteorological conditions for this vertical analysis to hold, apply it on two study cases and successfully compare it with other methods informing about the microphysics. Finally, we are able to obtain the main vertical structure and characteristics of the different processes during these study cases.
Christopher R. Williams, Karen L. Johnson, Scott E. Giangrande, Joseph C. Hardin, Ruşen Öktem, and David M. Romps
Atmos. Meas. Tech., 14, 4425–4444,Short summary
In addition to detecting clouds, vertically pointing cloud radars detect individual insects passing over head. If these insects are not identified and removed from raw observations, then radar-derived cloud properties will be contaminated. This work identifies clouds in radar observations due to their continuous and smooth structure in time, height, and velocity. Cloud masks are produced that identify cloud vertical structure that are free of insect contamination.
Holger Sihler, Steffen Beirle, Steffen Dörner, Marloes Gutenstein-Penning de Vries, Christoph Hörmann, Christian Borger, Simon Warnach, and Thomas Wagner
Atmos. Meas. Tech., 14, 3989–4031,Short summary
MICRU is an algorithm for the retrieval of effective cloud fractions (CFs) from satellite measurements. CFs describe the amount of clouds, which have a significant impact on the vertical sensitivity profile of trace gases like NO2 and HCHO. MICRU retrieves small CFs with an accuracy of 0.04 over the entire satellite swath. It features an empirical surface reflectivity model accounting for physical anisotropy (BRDF, sun glitter) and instrumental effects. MICRU is also applicable to imager data.
Yoonjin Lee, Christian D. Kummerow, and Milija Zupanski
Atmos. Meas. Tech., 14, 3755–3771,Short summary
This study suggests two methods to detect convection using 1 min data from GOES-16: one method detects early convective clouds using their vertical growth rate and the other method detects mature convective clouds using their lumpy cloud top surfaces. Applying the two methods to 1-month data showed that the accuracy of the combined methods was 85.8 % and showed their potential to be used in regions where radar data are not available.
Vasileios Barlakas, Alan J. Geer, and Patrick Eriksson
Atmos. Meas. Tech., 14, 3427–3447,Short summary
Oriented nonspherical ice particles induce polarization that is ignored when cloud-sensitive satellite observations are used in numerical weather prediction systems. We present a simple approach for approximating particle orientation, requiring minor adaption of software and no additional calculation burden. With this approach, the system realistically simulates the observed polarization patterns, increasing the physical consistency between instruments with different polarizations.
Anne Garnier, Jacques Pelon, Nicolas Pascal, Mark A. Vaughan, Philippe Dubuisson, Ping Yang, and David L. Mitchell
Atmos. Meas. Tech., 14, 3277–3299,Short summary
The IIR Level 2 data products include cloud effective emissivities and cloud microphysical properties such as effective diameter (De) and ice or liquid water path estimates. This paper (Part II) shows retrievals over ocean and describes the improvements made with respect to version 3 as a result of the significant changes implemented in the version 4 algorithms, which are presented in a companion paper (Part I).
Anne Garnier, Jacques Pelon, Nicolas Pascal, Mark A. Vaughan, Philippe Dubuisson, Ping Yang, and David L. Mitchell
Atmos. Meas. Tech., 14, 3253–3276,Short summary
The IIR Level 2 data products include cloud effective emissivities and cloud microphysical properties such as effective diameter (De) and ice or liquid water path estimates. This paper (Part I) describes the improvements in the V4 algorithms compared to those used in the version 3 (V3) release, while results are presented in a companion paper (Part II).
Irene Bartolome Garcia, Reinhold Spang, Jörn Ungermann, Sabine Griessbach, Martina Krämer, Michael Höpfner, and Martin Riese
Atmos. Meas. Tech., 14, 3153–3168,Short summary
Cirrus clouds contribute to the general radiation budget of the Earth. Measuring optically thin clouds is challenging but the IR limb sounder GLORIA possesses the necessary technical characteristics to make it possible. This study analyses data from the WISE campaign obtained with GLORIA. We developed a cloud detection method and derived characteristics of the observed cirrus-like cloud top, cloud bottom or position with respect to the tropopause.
Yoonjin Lee, Christian D. Kummerow, and Imme Ebert-Uphoff
Atmos. Meas. Tech., 14, 2699–2716,Short summary
Convective clouds are usually associated with intense rain that can cause severe damage, and thus it is important to accurately detect convective clouds. This study develops a machine learning model that can identify convective clouds from five temporal visible and infrared images as humans can point at convective regions by finding bright and bubbling areas. The results look promising when compared to radar-derived products, which are commonly used for detecting convection.
Christoph Kalicinsky, Sabine Griessbach, and Reinhold Spang
Atmos. Meas. Tech., 14, 1893–1915,Short summary
For an airborne viewing geometry, radiative transfer simulations of infrared limb emission spectra in the presence of polar stratospheric clouds – nitric acid trihydrate (NAT), supercooled ternary solution, ice, and mixtures – were used to develop a size-sensitive NAT detection algorithm. Characteristic size-dependent spectral features in the 810–820 cm−1 region were exploited to subgroup the NAT into three size regimes: small NAT (≤ 1.0 μm), medium NAT (1.5–4.0 μm), and large NAT (≥ 3.5 μm).
Souichiro Hioki, Jérôme Riedi, and Mohamed S. Djellali
Atmos. Meas. Tech., 14, 1801–1816,Short summary
This research estimates the magnitude of a motion-induced error in the measurement of polarimetric state of light by a planned instrument on a future satellite. We discovered that the motion-induced error can not be cancelled out by spatiotemporal averaging, but it can be predicted from the along-track change of the intensity of light. With the estimated statistics and the simulation model, this research paves a way to provide pixel-level quality information in the future satellite products.
Xiaoyu Hu, Jinming Ge, Jiajing Du, Qinghao Li, Jianping Huang, and Qiang Fu
Atmos. Meas. Tech., 14, 1743–1759,Short summary
Cloud radars are powerful instruments that can probe detailed cloud structures. However, radar echoes in the lower atmosphere are always contaminated by clutter. We proposed a multi-dimensional probability distribution function that can effectively discriminate low-level clouds from clutter by considering their different features in several variables. We applied this method to the radar observations at the SACOL site and found the results have good agreement with lidar detection.
Thibault Vaillant de Guélis, Mark A. Vaughan, David M. Winker, and Zhaoyan Liu
Atmos. Meas. Tech., 14, 1593–1613,Short summary
We introduce a new lidar feature detection algorithm that dramatically improves the fine details of layers identified in the CALIOP data. By applying our two-dimensional scanning technique to the measurements in all three channels, we minimize false positives while accurately identifying previously undetected features such as subvisible cirrus and the full vertical extent of dense smoke plumes. Multiple comparisons to version 4.2 CALIOP retrievals illustrate the scope of the improvements made.
Steven T. Massie, Heather Cronk, Aronne Merrelli, Christopher O'Dell, K. Sebastian Schmidt, Hong Chen, and David Baker
Atmos. Meas. Tech., 14, 1475–1499,Short summary
The OCO-2 science team is working to retrieve CO2 measurements that can be used by the carbon cycle community to calculate regional sources and sinks of CO2. The retrieved data, however, are in need of improvements in accuracy. This paper discusses several ways in which 3D cloud metrics (such as the distance of a measurement to the nearest cloud) can be used to account for cloud effects in the OCO-2 CO2 data files.
Yuzhu Tang, Pinglv Yang, Zeming Zhou, Delu Pan, Jianyu Chen, and Xiaofeng Zhao
Atmos. Meas. Tech., 14, 737–747,Short summary
An automatic cloud classification method on whole-sky images is presented. We first extract multiple pixel-level features to form region covariance descriptors (RCovDs) and then encode RCovDs by the Riemannian bag-of-feature (BoF) method to output the histogram representation. Reults show that a very high prediction accuracy can be obtained with a small number of training samples, which validate the proposed method and exhibit the competitive performance against state-of-the-art methods.
Macey W. Sandford, David R. Thompson, Robert O. Green, Brian H. Kahn, Raffaele Vitulli, Steve Chien, Amruta Yelamanchili, and Winston Olson-Duvall
Atmos. Meas. Tech., 13, 7047–7057,Short summary
We demonstrate an onboard cloud-screening approach to significantly reduce the amount of cloud-contaminated data transmitted from orbit. We have produced location-specific models that improve performance by taking into account the unique cloud statistics in different latitudes. We have shown that screening clouds based on their location or surface type will improve the ability for a cloud-screening tool to improve the volume of usable science data.
Tianle Yuan, Hua Song, Robert Wood, Johannes Mohrmann, Kerry Meyer, Lazaros Oreopoulos, and Steven Platnick
Atmos. Meas. Tech., 13, 6989–6997,Short summary
We use deep transfer learning techniques to classify satellite cloud images into different morphology types. It achieves the state-of-the-art results and can automatically process a large amount of satellite data. The algorithm will help low-cloud researchers to better understand their mesoscale organizations.
Robin Ekelund, Patrick Eriksson, and Michael Kahnert
Atmos. Meas. Tech., 13, 6933–6944,Short summary
Raindrops become flattened due to aerodynamic drag as they increase in mass and fall speed. This study calculated the electromagnetic interaction between microwave radiation and non-spheroidal raindrops. The calculations are made publicly available to the scientific community, in order to promote accurate representations of raindrops in measurements. Tests show that the drop shape can have a noticeable effect on microwave observations of heavy rainfall.
Jasper R. Lewis, James R. Campbell, Sebastian A. Stewart, Ivy Tan, Ellsworth J. Welton, and Simone Lolli
Atmos. Meas. Tech., 13, 6901–6913,Short summary
In this work, the authors describe a process to determine the thermodynamic cloud phase using the Micro Pulse Lidar Network volume depolarization ratio measurements and temperature profiles from the Global Modeling and Assimilation Office GEOS-5 model. A multi-year analysis and comparisons to supercooled liquid water fractions derived from CALIPSO satellite measurements are used to demonstrate the efficacy of the method.
Larysa Istomina, Henrik Marks, Marcus Huntemann, Georg Heygster, and Gunnar Spreen
Atmos. Meas. Tech., 13, 6459–6472,
Benjamin R. Scarino, Kristopher Bedka, Rajendra Bhatt, Konstantin Khlopenkov, David R. Doelling, and William L. Smith Jr.
Atmos. Meas. Tech., 13, 5491–5511,Short summary
This paper highlights a technique for facilitating anvil cloud detection based on visible observations that relies on comparative analysis with expected cloud reflectance for a given set of angles. A 1-year database of anvil-identified pixels, as determined from IR observations, from several geostationary satellites was used to construct a bidirectional reflectance distribution function model to quantify typical anvil reflectance across almost all expected viewing, solar, and azimuth angles.
Bangsheng Yin, Qilong Min, Emily Morgan, Yuekui Yang, Alexander Marshak, and Anthony B. Davis
Atmos. Meas. Tech., 13, 5259–5275,Short summary
Cloud-top pressure (CTP) is an important cloud property for climate and weather studies. Based on differential oxygen absorption, both oxygen A-band and B-band pairs can be used to retrieve CTP. However, it is currently very challenging to perform a CTP retrieval accurately due to the complicated in-cloud penetration effect. To address this issue, we propose an analytic transfer inverse model for DSCOVR EPIC observations to retrieve CTP considering in-cloud photon penetration.
Frédéric Tridon, Alessandro Battaglia, and Stefan Kneifel
Atmos. Meas. Tech., 13, 5065–5085,Short summary
The droplets and ice crystals composing clouds and precipitation interact with microwaves and can therefore be observed by radars, but they can also attenuate the signal they emit. By combining the observations made by two ground-based radars, this study describes an original approach for estimating such attenuation. As a result, the latter can be not only corrected in the radar observations but also exploited for providing an accurate characterization of droplet and ice crystal properties.
Mark Richardson, Matthew D. Lebsock, James McDuffie, and Graeme L. Stephens
Atmos. Meas. Tech., 13, 4947–4961,Short summary
We previously combined CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) lidar data and reflected-sunlight measurements from OCO-2 (Orbiting Carbon Observatory 2) for information about low clouds over oceans. The satellites are no longer formation-flying, so this work is a step towards getting new information about these clouds using only OCO-2. We can rapidly and accurately identify liquid oceanic clouds and obtain their height better than a widely used passive sensor.
Melody A. Avery, Robert A. Ryan, Brian J. Getzewich, Mark A. Vaughan, David M. Winker, Yongxiang Hu, Anne Garnier, Jacques Pelon, and Carolus A. Verhappen
Atmos. Meas. Tech., 13, 4539–4563,Short summary
CALIOP data users will find more cloud layers detected in V4, with edges that extend further than in V3, for an increase in total atmospheric cloud volume of 6 %–9 % for high-confidence cloud phases and 1 %–2 % for all cloudy bins, including cloud fringes and unknown cloud phases. In V4 there are many fewer cloud layers identified as horizontally oriented ice, particularly in the 3° off-nadir view. Depolarization at 532 nm is the predominant parameter determining cloud thermodynamic phase.
Vladimir S. Kostsov, Dmitry V. Ionov, and Anke Kniffka
Atmos. Meas. Tech., 13, 4565–4587,Short summary
Previously, observations from satellites provided evidence for systematic differences between the values of the cloud liquid water path over land and water areas in northern Europe. An attempt is made to detect such differences by means of ground-based microwave measurements performed near the coastline of the Gulf of Finland. The results demonstrate the existence of the cloud liquid water path gradient, which is positive as in the case of the satellite measurements (larger values over land).
Simon Pfreundschuh, Patrick Eriksson, Stefan A. Buehler, Manfred Brath, David Duncan, Richard Larsson, and Robin Ekelund
Atmos. Meas. Tech., 13, 4219–4245,Short summary
The next generation of European operational weather satellites will carry a novel microwave sensor, the Ice Cloud Imager (ICI), which will provide observations of clouds at microwave frequencies that were not available before. We investigate the potential benefits of combining observations from ICI with that of a radar. We find that such combined observations provide additional information on the properties of the cloud and help to reduce uncertainties in retrieved mass and number densities.
Albrecht, B. A.: The effects of drizzle on the thermodynamic structure of the trade-wind boundary layer, J. Geophys. Res., 98, 7327–7337, 1993.
American Meteorological Society: Virga, Glossary of Meteorology, available at: http://glossary.ametsoc.org/wiki/Virga, last access: 24 August 2015.
Austin, P., Wang, Y., Pincus, R., and Kujala, V.: Precipitation in stratocumulus clouds: observations and modeling results, J. Atmos. Sci., 52, 2329–2352, 1995.
Chin, H., Rodriguez, D. J., Cederwall, R. T., Chuang, C. C., Grossman, A. S., Yio, J. J., Fu, Q., and Miller, M. A.: A microphysical retrieval scheme for continental low-level stratiform clouds: impacts of the subadiabatic character on microphysical properties and radiation budgets, Mon. Weather Rev., 128, 2511–2527, 2000.
Dong, X. and Mace, G. G.: Profiles of Low-level stratus cloud microphysics deduced from ground-based measurements, J. Atmos. Ocean. Tech., 20, 42–53, 2003.
Dong, X., Ackerman, T. P., Clothiaux, E. E., Pilewskie, P., and Han, Y.: Microphysical and radiative properties of stratiform clouds deduced from ground-based measurements, J. Geophys. Res., 102, 23829–23843, 1997.
Dong, X., Ackerman, T. P., and Clothiaux, E. E.: Parameterizations of microphysical and radiative properties of boundary layer stratus from ground-based measurements, J. Geophys. Res., 102, 31681–31393, 1998.
Dong, X., Minnis, P., Ackerman, T. P., Clothiaux, E. E., Mace, G. G., Long, C. N., and Liljegren, J. C.: A 25-month database of stratus cloud properties generated from ground-based measurements at the ARM SGP site, J. Geophys. Res., 105, 4529–4538, 2000.
Dong, X., Minnis, P., Mace, G. G., Smith Jr., W. L., Poellot, M., Marchand, R., and Rapp, A. D.: Comparison of stratus cloud properties deduced from surface, GOES, and aircraft data during the March 2000 ARM Cloud IOP, J. Atmos. Sci., 59, 3265–3284, 2002.
Dong, X., Xi, B., Kennedy, A., Minnis, P., and Wood, R.: A 19-month Marine Aerosol-Cloud_Radiation Properties derived from DOE ARM AMF deployment at the Azores: Part I: Cloud fraction and single-layered MBL cloud properties, J. Climate, 27, 3665–3682, https://doi.org/10.1175/JCLI-D-13-00553.1, 2014a.
Dong, X., Xi, B., and Wu, P.: Investigation of diurnal variation of MBL cloud microphysical properties at the Azores, J. Climate, 27, 8827–8835, 2014b.
Dong, X., Schwantes, A. C., Xi, B., and Wu, P.: Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores, J. Geophys. Res.-Atmos., 120, 6179–6191, https://doi.org/10.1002/2014JD022939, 2015.
Fielding, M. D., Chiu, J. C., Hogan, R. J., Feingold, G., Eloranta, E., O'Connor, E. J., and Cadeddu, M. P.: Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances, Atmos. Meas. Tech., 8, 2663–2683, https://doi.org/10.5194/amt-8-2663-2015, 2015.
Fox, N. I. and Illingworth, A. J.: The potential of a spaceborne cloud radar for the detection of stratocumulus clouds, J. Appl. Meteorol., 36, 676–687, 1997.
Frisch, A. S., Fairall, C. W., and Snider, J. B.: Measurement of stratus cloud and drizzle parameters in ASTEX with a Ka-band Doppler radar and a microwave radiometer, J. Atmos. Sci., 52, 2788–2799, 1995.
Hogan, R. J., Bouniol, D., Ladd, D. N., O'Connor, E. J., and Illingworth, A. J.: Absolute Calibration of 94/95-GHz Radars Using Rain, J. Atmos. Ocean. Tech., 20, 572–580, https://doi.org/10.1175/1520-0426(2003)20<572:ACOGRU>2.0.CO;2, 2003.
Kollias, P., Szyrmer, W., Rémillard, J., and Luke, E.: Cloud radar Doppler spectra in drizzling stratiform clouds:2. Observations and microphysical modeling of drizzle evolution, J. Geophys. Res., 116, D13203, https://doi.org/10.1029/2010JD015238, 2011.
Leon, D. C., Wang, Z., and Liu, D.: Climatology of drizzle in marine boundary layer clouds based on 1 year of data from CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), J. Geophys. Res., 113, D00A14, https://doi.org/10.1029/2008JD009835, 2008.
Liljegren, J. C., Clothiaux, E. E., Mace, G. G., Kato, S., and Dong, X.: A new retrieval for cloud liquid water path using a ground-based microwave radiometer and measurements of cloud temperature, J. Geophys. Res., 106, 14485–14500, 2001.
Mace, G. G. and Sassen, K.: A constrained algorithm for retrieval of stratocumulus cloud properties using solar radiation, microwave radio- meter, and millimeter cloud radar data, J. Geophys. Res., 105, 29099–29108, 2000.
O'Connor, E. J., Hogan, R. J., and Illingworth, A. J.: Retrieving stratocumulus drizzle parameters using Doppler radar and lidar, J. Appl. Meteorol., 44, 14–27, 2005.
O'Connor, E. J., Illingworth A. J., and Hogan R. J.: A technique for autocalibration of cloud lidar, J. Atmos. Oceanic Technol., 21, 777–786, 2004.
Rémillard, J., Kollias, P., Luke, E., and Wood, R.: Marine Boundary Layer Cloud Observations in the Azores, J. Clim., 25, 7381–7398. https://doi.org/10.1175/JCLI-D-11-00610.1, 2012.
Sauvageot, H. and Omar, J.: Radar reflectivity of cumulus clouds, J. Atmos. Ocean. Tech., 4, 264–272, 1987.
Wang, J.: Identifying Drizzle within Marine Stratus with W-Band Radar Reflectivity profiles, M.S. thesis, Dep. Of Atmos. Sci., Univ. of Wyoming, Laramie, USA, 2002.
Wang, J. and Geerts, B.: Identifying drizzle within marine stratus with W-band radar reflectivity, Atmos. Res., 69, 1–27, 2003.
Wood, R.: Parameterization of the effect of drizzle upon the droplet effective radius in stratocumulus clouds, Q. J. Roy. Meteor. Soc., 126, 3309–3324. https://doi.org/10.1002/qj.49712657015, 2000.
Wood, R.: Drizzle in stratiform boundary layer clouds, Part I: Vertical and horizontal structure, J. Atmos. Sci., 62, 3011–3033, 2005.
Wood, R.: Stratocumulus Clouds, Mon. Weather Rev., 140, 2373–2423. https://doi.org/10.1175/MWR-D-11-00121.1, 2012.
Wood, R., Wyant, M., Bretherton, C. S., Rémillard, J., Kollias, P., Fletcher, J., Stemmler, J., deSzoeke, S., Yuter, S., Miller, M., Mechem, D., Tselioudis, G., Chiu, C., Mann, J., O'Connor, E., Hogan, R., Dong, X., Miller, M., Ghate, V., Jefferson, A., Min, Q., Minnis, P., Palinkonda, R., Albrecht, B., Luke, E., Hannay, C., and Lin, Y.: Clouds, Aerosol, and Precipitation in the Marine Boundary Layer: An ARM Mobile Facility Deployment, B. Am. Meteorol. Soc., https://doi.org/10.1175/BAMS-D-13-00180.1, 2015.
Zhao, C., Xie, S., Klein, S. A., Protat, A., Shupe, M. D., McFarlane, S. A., Comstock, J. M., Delanoë, J., Deng, Min, Dunn, M., Hogan, R. J., Huang, D., Jensen, M. P., Mace, G. G., McCoy, R., O'Connor, E. J., Turner, D. D., and Wang, Z.: Toward understanding of differences in current cloud retrievals of ARM ground-based measurements, J. Geophys. Res., 117, D10206, https://doi.org/10.1029/2011JD016792, 2012.
How does drizzle underneath marine boundary layer (MBL) clouds affect cloud property retrievals? How much liquid water is depleted by virga and rain? To our knowledge, no previous studies have quantitatively estimated the impact of drizzle on cloud property retrievals. Cloud parameterization and radiative transfer modeling researchers will be interested since we give quantitative estimations of drizzle and cloud effective radius, no. concentration, liquid water content, and optical thickness.
How does drizzle underneath marine boundary layer (MBL) clouds affect cloud property retrievals?...