Regional Features of the Arctic Sea Ice Area Changes in 2000–2019 versus 1979–1999 Periods

Author(s):
Matveeva, Tatiana A.; Semenov, Vladimir A.
Publication title: Atmosphere
2022
 | Volume: 13 | Issue: 9
2022
DOI: 10.3390/atmos13091434
Abstract:
One of the most striking manifestations of ongoing climate change is a rapid shrinking of the Arctic sea ice area (SIA). An important feature of the o… One of the most striking manifestations of ongoing climate change is a rapid shrinking of the Arctic sea ice area (SIA). An important feature of the observed SIA loss is a nonlinear rate of a decline with an accelerated decrease in the 2000–2019 period relative to a more gradual decline in 1979–1999. In this study, we perform a quantitative assessment and comparison of the spatial-temporal SIA changes during these two periods. It was found that winter Arctic SIA loss is primarily associated with changes in the Barents Sea, where the SIA decline in 2000–2019 has accelerated more than three-fold in comparison with 1979–1999. In summer and autumn, rates of SIA decline in 2000–2019 increased most strongly in the Kara, Beaufort Seas, the Northwestern Passage, and inner Arctic Ocean. The amplitude of the SIA seasonal cycle has also increased in 2000–2019 in comparison with the earlier period, with the largest changes in the inner Arctic Ocean, the Kara, Laptev, East Siberian and Beaufort Seas in summer and in the Barents Sea in winter. The results may reflect a transition to a new dynamic state in the recent two decades with the triggering of positive feedbacks in the Arctic climate system. more
Application Climate Data Records Cryosphere OSI-SAF

Remote sensing of cloud top pressure/height from SEVIRI: analysis of ten current retrieval algorithms

Author(s):
Hamann, U.; Walther, A.; Baum, B.; Bennartz, R.; Bugliaro, L.; Derrien, M.; Francis, P. N.; Heidinger, A.; Joro, S.; Kniffka, A.; Le Gléau, H.; Lockhoff, M.; Lutz, H.-J.; Meirink, J. F.; Minnis, P.; Palikonda, R.; Roebeling, R.; Thoss, A.; Platnick, S.; Watts, P.; Wind, G.
Publication title: Atmospheric Measurement Techniques
2014
 | Volume: 7 | Issue: 9
2014
DOI: 10.5194/amt-7-2839-2014
Abstract:
Abstract. The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth… Abstract. The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth's water cycle. Therefore, there is an urgent need for accurate cloud observations to validate climate models and to monitor climate change. Passive satellite imagers measuring radiation at visible to thermal infrared (IR) wavelengths provide a wealth of information on cloud properties. Among others, the cloud top height (CTH) – a crucial parameter to estimate the thermal cloud radiative forcing – can be retrieved. In this paper we investigate the skill of ten current retrieval algorithms to estimate the CTH using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard Meteosat Second Generation (MSG). In the first part we compare ten SEVIRI cloud top pressure (CTP) data sets with each other. The SEVIRI algorithms catch the latitudinal variation of the CTP in a similar way. The agreement is better in the extratropics than in the tropics. In the tropics multi-layer clouds and thin cirrus layers complicate the CTP retrieval, whereas a good agreement among the algorithms is found for trade wind cumulus, marine stratocumulus and the optically thick cores of the deep convective system. In the second part of the paper the SEVIRI retrievals are compared to CTH observations from the Cloud–Aerosol LIdar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) instruments. It is important to note that the different measurement techniques cause differences in the retrieved CTH data. SEVIRI measures a radiatively effective CTH, while the CTH of the active instruments is derived from the return time of the emitted radar or lidar signal. Therefore, some systematic differences are expected. On average the CTHs detected by the SEVIRI algorithms are 1.0 to 2.5 km lower than CALIOP observations, and the correlation coefficients between the SEVIRI and the CALIOP data sets range between 0.77 and 0.90. The average CTHs derived by the SEVIRI algorithms are closer to the CPR measurements than to CALIOP measurements. The biases between SEVIRI and CPR retrievals range from −0.8 km to 0.6 km. The correlation coefficients of CPR and SEVIRI observations vary between 0.82 and 0.89. To discuss the origin of the CTH deviation, we investigate three cloud categories: optically thin and thick single layer as well as multi-layer clouds. For optically thick clouds the correlation coefficients between the SEVIRI and the reference data sets are usually above 0.95. For optically thin single layer clouds the correlation coefficients are still above 0.92. For this cloud category the SEVIRI algorithms yield CTHs that are lower than CALIOP and similar to CPR observations. Most challenging are the multi-layer clouds, where the correlation coefficients are for most algorithms between 0.6 and 0.8. Finally, we evaluate the performance of the SEVIRI retrievals for boundary layer clouds. While the CTH retrieval for this cloud type is relatively accurate, there are still considerable differences between the algorithms. These are related to the uncertainties and limited vertical resolution of the assumed temperature profiles in combination with the presence of temperature inversions, which lead to ambiguities in the CTH retrieval. Alternative approaches for the CTH retrieval of low clouds are discussed. more
Atmosphere CM-SAF Climate Data Records Validation

Relationship between precipitation and cloud properties in different regions of Southwest China

Author(s):
Wang, Yuting; Zhao, Pengguo; Zhao, Chuanfeng; Xiao, Hui; Mo, Shuying; Yuan, Liang; Wei, Chengqiang; Zhou, Yunjun
Publication title: International Journal of Climatology
2024
 | Volume: 44 | Issue: 7
2024
DOI: 10.1002/joc.8455
Abstract:
The relationship between precipitation and cloud properties in Southwest China are investigated by using the CLARA-A2 cloud parameters data and TRMM-3… The relationship between precipitation and cloud properties in Southwest China are investigated by using the CLARA-A2 cloud parameters data and TRMM-3B43 precipitation data from 1998 to 2015. Ice water path (IWP) and cloud top height (CTH) are significantly and positively correlated with precipitation in all regions, indicating that ice-phase processes and cloud development processes are the critical processes influencing precipitation. Precipitation is also directly associated with cloud fractional coverage (CFC) due to the significant positive correlation between CFC and precipitation in all regions except the Sichuan Basin (SCB). A positive correlation between liquid water path (LWP) and precipitation is found in the Eastern Tibetan Plateau (ETP) and Yunnan-Kweichow Plateau (YKP), but not in the Western Tibetan Plateau (WTP) and SCB. Notably, the response of precipitation to LWP is not as good as that to IWP in SCB. Precipitation is significantly negatively correlated with ice effective radius (IREF) in WTP and ETP and positively correlated with liquid effective radius (LREF) in ETP, YKP and SCB. IREF and LREF are closely related to cloud microphysical processes. Specifically, small IREF could accelerate the Bergeron process and thus increase precipitation, while large LREF is closely related to the cloud droplets coalescence process. Results indicate that the difference in precipitation between the cold and warm seasons is related to convective available potential energy (CAPE) and low troposphere relative humidity (RH). High CAPE and RH favour the precipitation occurrence in Southwest China. The influence of CAPE and RH on precipitation is more significant in the ETP than that in the WTP, owing to the orographic lifting and moisture transport from the Indian Ocean. Thermodynamic and humidity conditions have a greater impact on precipitation by influencing LREF, LWP and IWP in YKP. In SCB, precipitation shows a strong dependence on CAPE, IWP and LREF, but not on RH. more
Application Atmosphere CM-SAF Climate Data Records

Relevance of warm air intrusions for Arctic satellite sea ice concentration time series

Author(s):
Rostosky, P.; Spreen, G.
Publication title: Cryosphere
2023
 | Volume: 17 | Issue: 9
2023
DOI: 10.5194/tc-17-3867-2023
Abstract:
Winter warm air intrusions entering the Arctic region can strongly modify the microwave emission of the snow-covered sea ice system due to temperature… Winter warm air intrusions entering the Arctic region can strongly modify the microwave emission of the snow-covered sea ice system due to temperature-induced snow metamorphism and ice crust formations, e.g., after melt-refreeze events. Common microwave radiometer satellite sea ice concentration retrievals are based on empirical models using the snow-covered sea ice emissivity and thus can be influenced by strong warm air intrusions. Here, we carry out a long-Term study analyzing 41 years of winter sea ice concentration observations from different algorithms to investigate the impact of warm air intrusions on the retrieved ice concentration. Our results show that three out of four algorithms underestimate the sea ice concentration during (and up to 10 d after) warm air intrusions which increase the 2 m air temperature (daily maximum) above-5 C. This can lead to sea ice area underestimations in the order of 104 to 105 km2. If the 2 m temperature during the warm air intrusions crosses-2 C, all algorithms are impacted. Our analysis shows that the strength of these strong warm air intrusions increased in recent years, especially in April. With a further climate change, such warm air intrusions are expected to occur more frequently and earlier in the season, and their influence on sea ice climate data records will become more important. © 2023 Copernicus GmbH. All rights reserved. more
Application Climate Data Records Cryosphere OSI-SAF Ocean

Remote sensing of solar surface radiation-a reflection of concepts, applications and input data based on experience with the effective cloud albedo

Author(s):
Müller, R.; Pfeifroth, U.
Publication title: Atmospheric Measurement Techniques
2022
 | Volume: 15 | Issue: 5
2022
DOI: 10.5194/amt-15-1537-2022
Abstract:
Accurate solar surface irradiance (SSI) data are a prerequisite for efficient planning and operation of solar energy systems. Respective data are also… Accurate solar surface irradiance (SSI) data are a prerequisite for efficient planning and operation of solar energy systems. Respective data are also essential for climate monitoring and analysis. Satellite-based SSI has grown in importance over the last few decades. However, a retrieval method is needed to relate the measured radiances at the satellite to the solar surface irradiance. In a widespread classical approach, these radiances are used directly to derive the effective cloud albedo (CAL) as basis for the estimation of the solar surface irradiance. This approach was already introduced and discussed in the early 1980s. Various approaches are briefly discussed and analysed, including an overview of open questions and opportunities for improvement. Special emphasis is placed on the reflection of fundamental physical laws and atmospheric measurement techniques. In addition, atmospheric input data and key applications are briefly discussed. It is concluded that the well-established observation-based CAL approach is still an excellent choice for the retrieval of the cloud transmission. The coupling with lookup-table-based clear-sky models enables the estimation of solar surface irradiance with high accuracy and homogeneity. This could explain why, despite its age, the direct CAL approach is still used by key players in energy meteorology and the climate community. For the clear-sky input data, it is recommended to use ECMWF forecast and reanalysis data. © 2022 Richard Müller. more
Atmosphere CM-SAF Climate Data Records Validation

Resilience of Cultural Heritage in Extreme Weather Conditions: The Case of the UNESCO Villa Romana del Casale Archaeological Site’s Response to the Apollo Medicane in October 2021

Author(s):
Gervasi, Osvaldo; Murgante, Beniamino; Misra, Sanjay; Rocha, Ana Maria A. C.; Garau, Chiara; Prestileo, Fernanda; Mascitelli, Alessandra; Meli, Guido; Petracca, Marco; Giorgi, Claudio; Melfi, Davide; Puca, Silvia; Dietrich, Stefano
2022
 | Volume: 13380
2022
DOI: 10.1007/978-3-031-10542-5_35
Application Climate Data Records H-SAF Land

Remote Sensing Time Series Analysis: A Review of Data and Applications

Author(s):
Fu, Y.; Zhu, Z.; Liu, L.; Zhan, W.; He, T.; Shen, H.; Zhao, J.; Liu, Y.; Zhang, H.; Liu, Z.; Xue, Y.; Ao, Z.
Publication title: Journal of Remote Sensing (United States)
2024
 | Volume: 4
2024
DOI: 10.34133/remotesensing.0285
Abstract:
Remote sensing time series research and applications are advancing rapidly in land, ocean, and atmosphere science, demonstrating emerging capabilities… Remote sensing time series research and applications are advancing rapidly in land, ocean, and atmosphere science, demonstrating emerging capabilities in space-based monitoring methodologies and diverse application prospects. This prompts a comprehensive review of remote sensing time series observations, time series data reconstruction, derived products, and the current progress, challenges, and future directions in their applications. The high-frequency new data, i.e., a constellation strategy, increasing computing power and advancing deep learning algorithms, are driving a paradigm shift from traditional point-in-time mapping to near-real-time monitoring tasks, and even to modeling integration of parameter inversion and prediction in land, water, and air science. Correspondingly, the 3 main projects, namely, the Global Climate Observing System, the United States Geological Survey/National Aeronautics and Space Administration (USGS/NASA) Landsat Science team, and the China Global Land Surface Satellite (GLASS) team, along with other time series-derived products, have found widespread applications in the research of Earth’s radiation balance and human–land systems. They have also been utilized for tasks such as land use change detection, assessing coastal effects, ocean environment monitoring, and supporting carbon neutrality strategies. Moreover, the 3 critical challenges and future directions were highlighted including multimode time series data fusion, deep learning modeling for task-specific domain adaptation, and fine-scale remote sensing applications by using dense time series. This review distills historical and current developments spanning the last several decades, providing an insightful understanding into the advancements in remote sensing time series data and applications. Copyright © 2024 Yingchun Fu et al. more
Application Atmosphere CM-SAF Climate Data Records LSA-SAF

Resolving the 21st century temperature trends of the upper troposphere–lower stratosphere with satellite observations

Author(s):
Ladstädter, Florian; Steiner, Andrea K.; Gleisner, Hans
Publication title: Scientific Reports
2023
 | Volume: 13 | Issue: 1
2023
DOI: 10.1038/s41598-023-28222-x
Abstract:
Historically, observational information about atmospheric temperature has been limited due to a lack of suitable measurements. Recent advances in sate… Historically, observational information about atmospheric temperature has been limited due to a lack of suitable measurements. Recent advances in satellite observations provide new insight into the fine structure of the free atmosphere, with the upper troposphere and lower stratosphere comprising essential components of the climate system. This is a prerequisite for understanding the complex processes of this part of the atmosphere, which is also known to have a large impact on surface climate. With unprecedented resolution, latest climate observations reveal a dramatic warming of the atmosphere. The tropical upper troposphere has already warmed about 1 K during the first two decades of the 21st century. The tropospheric warming extends into the lower stratosphere in the tropics and southern hemisphere mid-latitudes, forming a prominent hemispheric asymmetry in the temperature trend structure. Together with seasonal trend patterns in the stratosphere, this indicates a possible change in stratospheric circulation. © 2023, The Author(s). more
Application Atmosphere Climate Data Records ROM-SAF

Retrieval error estimation of surface albedo derived from geostationary large band satellite observations: Application to Meteosat-2 and Meteosat-7 data

Author(s):
Govaerts, Y. M.; Lattanzio, A.
Publication title: Journal of Geophysical Research
2007
 | Volume: 112 | Issue: D5
2007
DOI: 10.1029/2006JD007313
Abstract:
The extraction of critical geophysical variables from multidecade archived satellite observations, such as those acquired by the European Meteosat Fir… The extraction of critical geophysical variables from multidecade archived satellite observations, such as those acquired by the European Meteosat First Generation satellite series, for the generation of climate data records is recognized as a pressing challenge by international environmental organizations. This paper presents a statistical method for the estimation of the surface albedo retrieval error that explicitly accounts for the measurement uncertainties and differences in the Meteosat radiometer characteristics. The benefit of this approach is illustrated with a simple case study consisting of a meaningful comparison of surface albedo derived from observations acquired at a 20 year interval by sensors with different radiometric performances. In particular, it is shown how it is possible to assess the magnitude of minimum detectable significant surface albedo change. more
Climate Data Records EUM-Secr Land Method

River runoff estimation with satellite rainfall in Morocco

Author(s):
Tramblay, Yves; El Khalki, El Mahdi; Ciabatta, Luca; Camici, Stefania; Hanich, Lahoucine; Saidi, Mohamed El Mehdi; Ezzahouani, Abdellatif; Benaabidate, Lahcen; Mahé, Gil; Brocca, Luca
Publication title: Hydrological Sciences Journal
2023
 | Volume: 68 | Issue: 3
2023
DOI: 10.1080/02626667.2023.2171295
Abstract:
In African countries, the lack of observed rainfall data is a major obstacle for efficient water resources management. The objective of this study is … In African countries, the lack of observed rainfall data is a major obstacle for efficient water resources management. The objective of this study is to evaluate satellite rainfall products’ ability to estimate river runoff over 12 basins in Morocco using four hydrological models: IHACRES, MISDc, GR4J, and CREST. Satellite products available with a short latency are compared: EUMETSAT H SAF, SM2RAIN-ASCAT, and IMERG. The best results to reproduce river runoff were obtained with SM2RAIN-ASCAT in combination with the IHACRES model, with the highest Kling-Gupta efficiency criterion and probability of detection of extreme runoff. The hydrological model performances differed across catchments and satellite rainfall products, which highlights the need to carefully select hydrological models for a given application. Thus, it is advisable to evaluate satellite rainfall products with different types of hydrological models. This first evaluation over Moroccan basins suggests that SM2RAIN-ASCAT could be a reliable alternative to observed rainfall for hydrological modelling. more
Atmosphere Climate Data Records H-SAF Validation
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