Analysis of Daytime Cloud Fraction Spatiotemporal Variation over the Arctic from 2000 to 2019 from Multiple Satellite Products

Author(s):
Liu, Xinyan; He, Tao; Sun, Lin; Xiao, Xiongxin; Liang, Shunlin; Li, Siwei
Publication title: Journal of Climate
2022
 | Volume: 35 | Issue: 23
2022
DOI: 10.1175/JCLI-D-22-0007.1
Abstract:
Abstract Insufficient understanding of complex Arctic cloud properties introduced large errors in estimating radiant energy balance parameters at the … Abstract Insufficient understanding of complex Arctic cloud properties introduced large errors in estimating radiant energy balance parameters at the regional and global scales. Comprehensive and reliable cloud information is necessary for improving the accuracy of flux inversion. This study evaluated daytime cloud fraction (CF) uncertainties from 16 available satellite products and estimated the spatiotemporal distributions of Arctic daytime CF during 2000–19. Our results show that the differences among multiple products had significant temporal and spatial heterogeneities. Temporally, the maximum and minimum interproduct discrepancies occurred in April and the summer months, respectively. Spatially, the largest uncertainties were seen over Greenland. Substantial inconsistency also occurred on the central and Pacific sides of the Arctic Ocean. The active satellite product tended to capture more clouds in these two regions. We found that the inconsistencies caused by sensor differences were smaller than those caused by algorithm differences; that is, for MODIS based CF products, the inconsistencies caused by different sensors and different algorithms are ±2% and ±5%, while for AVHRR-based products, these inconsistencies are ±6% and ±15%, respectively. The annual average daytime CF in sunlit months was 70.9% ± 2.93% and increased over the Arctic during study periods. These upward trends might cool the Arctic by approximately 0.05–0.5 W m−2 decade−1. In terms of the spatiotemporal distributions, the CF over the ocean is higher than that over the land, and the former increased significantly while the latter decreased; the CF trends of most products are positive in June and July but are opposite in other months. From this study, the findings based on multiple products would be more robust than that based on a single or few datasets. Significance Statement This study aimed to comprehensively understand and obtain more robust general characteristics of the temporal and spatial distributions of Arctic daytime cloud fraction by comparing and analyzing the consistencies and discrepancies of multisource satellite products. It is important because the cloud fraction is a nonnegligible modulator of Earth’s energy budget and climate change. Although the Arctic is the most climate-sensitive region, existing studies lack a comprehensive assessment of the cloud fraction over the entire Arctic. We analyzed 16 different cloud products and found that although the inconsistencies were inevitable, most products showed similar spatiotemporal distribution and trend distribution of daytime CF. This study provided a new idea for Arctic CF research under the existing conditions. more
Atmosphere CM-SAF Climate Data Records Validation

Analysis of Mineral Aerosol in the Surface Layer over the Caspian Lowland Desert by the Data of 12 Summer Field Campaigns in 2002-2020

Author(s):
Chkhetiani, Otto G.; Vazaeva, Natalia V.; Chernokulsky, Alexander, V; Shukurov, Karim A.; Gubanova, Dina P.; Artamonova, Maria S.; Maksimenkov, Leonid O.; Kozlov, Fedor A.; Kuderina, Tatyana M.
Publication title: ATMOSPHERE
2021
 | Volume: 12 | Issue: 8
2021
DOI: 10.3390/atmos12080985
Abstract:
In-situ knowledge on characteristics of mineral aerosols is important for weather and climate prediction models, particularly for modeling such proces… In-situ knowledge on characteristics of mineral aerosols is important for weather and climate prediction models, particularly for modeling such processes as the entrainment, transport and deposition of aerosols. However, field measurements of the dust emission flux, dust size distribution and its chemical composition under realistic wind conditions remain rare. In this study, we present experimental data over annual expeditions in the arid and semi-arid zones of the Caspian Lowland Desert (Kalmykia, south of Russia); we evaluate characteristics of mineral aerosol concentration and fluxes, estimate its chemical composition and calculate its long-distance transport characteristics. The mass concentration in different years ranges from several tens to several hundred of mu g m(-3). The significant influence of wind velocity on the value of mass and counting concentration and on the proposed entrainment mechanisms is confirmed. An increased content of anthropogenic elements (S, Sn, Pb, Bi, Mo, Ag, Cd, Hg, etc.), which is characteristic for all observation points in the south of the European Russia, is found. The trajectory analysis show that long-range air particles transport from the Caspian Lowland Desert to the central regions of European Russia tends to increase in the recent decades. more
Application Atmosphere CM-SAF Climate Data Records

Analysis of current validation practices in Europe for space-based climate data records of essential climate variables

Author(s):
Zeng, Y.; Su, Z.; Calvet, J.-C.; Manninen, T.; Swinnen, E.; Schulz, J.; Roebeling, R.; Poli, P.; Tan, D.; Riihelä, A.; Tanis, C.-M.; Arslan, A.-N.; Obregon, A.; Kaiser-Weiss, A.; John, V.O.; Timmermans, W.; Timmermans, J.; Kaspar, F.; Gregow, H.; Barbu, A.-L.; Fairbairn, D.; Gelati, E.; Meurey, C.
Publication title: International Journal of Applied Earth Observation and Geoinformation
2015
 | Volume: 42
2015
DOI: 10.1016/j.jag.2015.06.006
Abstract:
The Climate Data Records (CDRs) of Essential Climate Variables (ECVs) that are based on satellite observations need to be precisely described. In part… The Climate Data Records (CDRs) of Essential Climate Variables (ECVs) that are based on satellite observations need to be precisely described. In particular, when these products are delivered to end-users, the error characteristics information and how this information is obtained (e.g., through a validation process) need to be documented. Such validation information is intended to help end-users understanding to what extent the product is suitable for their specific applications. Based on how different European initiatives approached the validation of CDR and ECV products, we reviewed several aspects of the current validation practices. Based on the analysis of current practices, essentials of validation are discussed. A generic validation process is subsequently proposed, together with a quality indicator. more
EUM-Secr International cooperation Validation

Analysis of Spanish Radiometric Networks with the Novel Bias-Based Quality Control (BQC) Method

Author(s):
Urraca, Ruben; Antonanzas, Javier; Sanz-Garcia, Andres; Martinez-de-Pison, Francisco Javier
Publication title: Sensors
2019
 | Volume: 19 | Issue: 11
2019
DOI: 10.3390/s19112483
Abstract:
Different types of measuring errors can increase the uncertainty of solar radiation measurements, but most common quality control (QC) methods do not … Different types of measuring errors can increase the uncertainty of solar radiation measurements, but most common quality control (QC) methods do not detect frequent defects such as shading or calibration errors due to their low magnitude. We recently presented a new procedure, the Bias-based Quality Control (BQC), that detects low-magnitude defects by analyzing the stability of the deviations between several independent radiation databases and measurements. In this study, we extend the validation of the BQC by analyzing the quality of all publicly available Spanish radiometric networks measuring global horizontal irradiance (9 networks, 732 stations). Similarly to our previous validation, the BQC found many defects such as shading, soiling, or calibration issues not detected by classical QC methods. The results questioned the quality of SIAR, Euskalmet, MeteoGalica, and SOS Rioja, as all of them presented defects in more than 40% of their stations. Those studies based on these networks should be interpreted cautiously. In contrast, the number of defects was below a 5% in BSRN, AEMET, MeteoNavarra, Meteocat, and SIAR Rioja, though the presence of defects in networks such as AEMET highlights the importance of QC even when using a priori reliable stations. more
Application Atmosphere CM-SAF Climate Data Records

Analysis of the main source regions of moisture transport events with the new ESA CCI/CM-SAF total column water vapour climate data record (v2)

Author(s):
Eiras-Barca, Jorge; Algarra, Iago; Nieto, Raquel; Schroder, Marc; Hegglin, Michaela, I; Gimeno, Luis
Publication title: QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
2022
 | Volume: 148 | Issue: 748
2022
DOI: 10.1002/qj.4358
Abstract:
This study makes use of the new total column water vapour data record (CDR-2 (v2)), developed by the European Space Agency (ESA) in coordination with … This study makes use of the new total column water vapour data record (CDR-2 (v2)), developed by the European Space Agency (ESA) in coordination with the Satellite Application Facility on Climate Monitoring (CM SAF), to analyse the adequacy of the integrated vertical water vapour column (IWV) data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 and ERA-Interim reanalyses in regions of critical interest for moisture transport mechanisms. This information is critical for the initialization of moisture transport models-both Eulerian and Lagrangian-used to study the main mechanisms and predict the future evolution of moisture transport events. In particular, almost 40,000 atmospheric river (AR) and nocturnal low-level jet (NLLJ) events identified on a global scale between 2002 and 2017 have been used to study the variability between the cited reanalyses and CDR-2, in terms of both bias in the observed values of IWV during each particular event and daily temporal correlation fields. Although some notable discrepancies are reported in the main tropical rainforest regions, it is observed that, in regions of high interest for both ARs and NLLJs, the degree of agreement between the reanalyses and CDR-2 is high. The bias observed in the regions of interest is generally low, and the temporal correlation in the IWV fields is above 0.8 in most areas. ERA5 appears to show slightly better performance than ERA-Interim when resolving the moisture column, and both show greater similarity to CDR-2 in the midlatitudes compared with tropical regions. The probability density functions constructed on an event-to-event basis reinforce these ideas. We conclude that the evaluations presented here using CDR-2 serve to strengthen avaliable evidence that the ECMWF reanalyses can safely be used in the initializations of Lagrangian dispersion models and Eulerian moisture tracer simulations-commonly used for the analysis of main advection mechanisms-in the vast majority of regions critical to the study of ARs and LLJs. They can also safely be used for the detection of moisture source-sink regions in the study of the global hydrological cycle in these regions. more
Atmosphere CM-SAF Climate Data Records Validation

Analysis of Radio Frequency Interference in Metop ASCAT Backscatter Measurements

Author(s):
Ticconi, Francesca; Anderson, Craig; Figa-Saldana, Julia; Wilson, John Julian William; Bauch, Helmut
Publication title: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
2017
 | Volume: 10 | Issue: 5
2017
DOI: 10.1109/JSTARS.2016.2640561
Abstract:
The advanced scatterometer (ASCAT) is a radar system carried on board the ESA/EUMETSAT METOP series of satellites. It is designed for the purpose of r… The advanced scatterometer (ASCAT) is a radar system carried on board the ESA/EUMETSAT METOP series of satellites. It is designed for the purpose of retrieving wind field over oceans. It also provides information on surface soil moisture content and sea ice. Although ASCAT uses a linear frequency modulated pulse with a center frequency of 5.255 GHz (C-band), it is subject to radio frequency interference (RFI). This paper analyses seven years of ASCAT data and shows an increase of the number of noise outliers and an increase of the noise background level over specific land areas. This suggests that the outliers are not a natural occurrence, but are due to RFI from ground-based equipments. As regards the observed increase of the noise background level, it is not straightforward to associate possible RFI sources which could have caused it. However, since the ASCAT has a dynamic range of about 30 dB, the worse measured increase of 1 dB in the noise floor has almost no impact on performance, in particular, on soil moisture retrieval. In addition, the effect of the noise outliers on the estimate of the ASCAT receiver filter shape function used in the processing is also examined and is found to introduce errors of up to 0.4 dB. However, the occurrence of the noise outliers is generally very low, typically two out of 60 000 noise measurements per day, so the impact on the operational use of ASCAT data for wind vector retrieval is limited. more
Climate Data Records EUM-Secr Method

Analysis of the Thermodynamic Phase Transition of Tracked Convective Clouds Based on Geostationary Satellite Observations

Author(s):
Coopman, Q.; Hoose, C.; Stengel, M.
Publication title: Journal of Geophysical Research: Atmospheres
2020
 | Volume: 125 | Issue: 11
2020
DOI: 10.1029/2019JD032146
Abstract:
Clouds are liquid at temperature greater than 0°C and ice at temperature below −38°C. Between these two thresholds, the temperature of the cloud therm… Clouds are liquid at temperature greater than 0°C and ice at temperature below −38°C. Between these two thresholds, the temperature of the cloud thermodynamic phase transition from liquid to ice is difficult to predict and the theory and numerical models do not agree: Microphysical, dynamical, and meteorological parameters influence the glaciation temperature. We temporally track optical and microphysical properties of 796 clouds over Europe from 2004 to 2015 with the space-based instrument Spinning Enhanced Visible and Infrared Imager on board the geostationary METEOSAT second generation satellites. We define the glaciation temperature as the mean between the cloud top temperature of those consecutive images for which a thermodynamic phase change in at least one pixel is observed for a given cloud object. We find that, on average, isolated convective clouds over Europe freeze at −21.6°C. Furthermore, we analyze the temporal evolution of a set of cloud properties and we retrieve glaciation temperatures binned by meteorological and microphysical regimes: For example, the glaciation temperature increases up to 11°C when cloud droplets are large, in line with previous studies. Moreover, the correlations between the parameters characterizing the glaciation temperature are compared and analyzed and a statistical study based on principal component analysis shows that after the cloud top height, the cloud droplet size is the most important parameter to determine the glaciation temperature. ©2020. American Geophysical Union. All Rights Reserved. more
Application Atmosphere CM-SAF Climate Data Records

Analyzing the Thermodynamic Phase Partitioning of Mixed Phase Clouds Over the Southern Ocean Using Passive Satellite Observations

Author(s):
Coopman, Q.; Hoose, C.; Stengel, M.
Publication title: Geophysical Research Letters
2021
 | Volume: 48 | Issue: 7
2021
DOI: 10.1029/2021GL093225
Abstract:
The thermodynamic phase transition of clouds is still not well understood, therefore, the partitioning of ice and liquid in mixed phase clouds is ofte… The thermodynamic phase transition of clouds is still not well understood, therefore, the partitioning of ice and liquid in mixed phase clouds is often misrepresented in numerical models. We use 12 years of cloud observations from the geostationary Spinning Enhanced Visible and InfraRed Imager over the Southern Ocean to detect clouds which contain both liquid and ice pixels at their tops and we retrieve microphysical and radiative properties in each cloud object. The results show that large cloud droplet effective radius coincides with high ice fraction and high ice optical thickness for cloud top temperatures higher than −8 °C. We also found that the density of ice pixel clusters increases with the cloud ice fraction, for ice fraction lower than 0.5, suggesting a multiplication of ice pockets in line with previous studies, particularly efficient for clouds with high perimeter fractal dimension. © 2021. The Authors. more
Atmosphere CM-SAF Climate Data Records Validation

Anatomy of the uncertainty of satellite vicarious calibration using radiosondes: concepts and preliminary results for microwave radiometric observations

Author(s):
Cimini, D.; Barlakas, V.; Carminati, F.; De Angelis, F.; Di Paola, F.; Fassò, A.; Gallucci, D.; Gentile, S.; Hewison, T.; Larosa, S.; Madonna, F.; Mattioli, V.; Montopoli, M.; Romano, F.; Rosoldi, M.; Viggiano, M.; Von Engeln, A.; Ricciardelli, E.
Publication title: Bulletin of Atmospheric Science and Technology
2024
 | Volume: 5 | Issue: 1
2024
DOI: 10.1007/s42865-024-00073-y
Abstract:
Calibration of satellite observations is crucial for ensuring the quality of retrieved products essential for meteorological and climate applications.… Calibration of satellite observations is crucial for ensuring the quality of retrieved products essential for meteorological and climate applications. Calibration is obtained and monitored through a cascade of stages, including postlaunch vicarious calibration/validation activities through comparison with independent reference measurements. Here, the vicarious calibration method using radiative transfer simulations based on reference radiosondes is considered in the framework of the calibration/validation activities for the Microwave Imager (MWI) and the Ice Cloud Imager (ICI) to be launched with the Second Generation of the EUMETSAT Polar System. This paper presents an overview of the uncertainty characterizing the vicarious calibration of MWI and ICI using radiosondes as performed within the EUMETSAT-funded VICIRS study. The uncertainty characterization is pursued following a metrological approach, providing a preliminary estimation of all the identified sources. The same approach is used to develop a rigorous method for estimating the number of comparison pairs (i.e., observations vs. simulations) needed to reach a certain level of accuracy in bias determination. © The Author(s) 2024. more
Atmosphere NWP-SAF Software for CDR development Validation
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