Characterization and Validation of ECOSTRESS Sea Surface Temperature Measurements at 70 m Spatial Scale

Author(s):
Wethey, D.S.; Weidberg, N.; Woodin, S.A.; Vazquez-Cuervo, J.
Publication title: Remote Sensing
2024
 | Volume: 16 | Issue: 11
2024
DOI: 10.3390/rs16111876
Abstract:
The ECOSTRESS push-whisk thermal radiometer on the International Space Station provides the highest spatial resolution temperature retrievals over the… The ECOSTRESS push-whisk thermal radiometer on the International Space Station provides the highest spatial resolution temperature retrievals over the ocean that are currently available. It is a precursor to the future TRISHNA (CNES/ISRO), SBG (NASA), and LSTM (ESA) 50 to 70 m scale missions. Radiance transfer simulations and triple collocations with in situ ocean observations and NOAA L2P geostationary satellite ocean temperature retrievals were used to characterize brightness temperature biases and their sources in ECOSTRESS Collection 1 (software Build 6) data for the period 12 January 2019 to 31 October 2022. Radiometric noise, non-uniformities in the focal plane array, and black body temperature dynamics were characterized in ocean scenes using L1A raw instrument data, L1B calibrated radiances, and L2 skin temperatures. The mean brightness temperature biases were −1.74, −1.45, and −1.77 K relative to radiance transfer simulations in the 8.78, 10.49, and 12.09 µm wavelength bands, respectively, and skin temperatures had a −1.07 K bias relative to in situ observations. Cross-track noise levels range from 60 to 600 mK and vary systematically along the focal plane array and as a function of wavelength band and scene temperature. Overall, radiometric uncertainty is most strongly influenced by cross-track noise levels and focal plane non-uniformity. Production of an ECOSTRESS sea surface temperature product that meets the requirements of the SST community will require calibration methods that reduce the biases, noise levels, and focal plane non-uniformities. © 2024 by the authors. more
Application Climate Data Records NWP-SAF OSI-SAF Ocean Software for CDR development

Characterization of Sunshine Duration in Western Equatorial Africa: In Situ Measurements versus SARAH-2 Satellite Estimates

Author(s):
Philippon, N.; Ouhechou, A.; Camberlin, P.; Trentmann, J.; Fink, A.H.; Maloba, J.D.; Morel, B.; Samba, G.
Publication title: Journal of Applied Meteorology and Climatology
2022
 | Volume: 61 | Issue: 2
2022
DOI: 10.1175/JAMC-D-21-0072.1
Abstract:
Western Equatorial Africa is one of the least sunny areas in the world. Yet, this has attracted little research so far. As in many other parts of Afri… Western Equatorial Africa is one of the least sunny areas in the world. Yet, this has attracted little research so far. As in many other parts of Africa, light availability is mainly estimated using in situ measurements of sunshine duration (SDU). Therefore, this study conducts the first characterization of SDU evolution during the annual cycle for the region. It also evaluates the skill of satellite-based estimates of SDU from the Surface Solar Radiation Data Set-Heliosat, edition 2.1 (SARAH-2.1). Mean annual SDU levels are low: Less than 5 h day21 at the regional scale, with the sunniest stations in the northeast (Cameroon and Central African Republic) and the least sunny in an ∼150-km-wide coastal strip in Gabon and Republic of the Congo (RoC). For most of the stations except the southeast ones in the Democratic Republic of Congo, the lowest SDU levels are recorded in July-September, during the main dry season, with persistent overcast conditions. They are as low as 2.5 h day21, especially on the windward slopes of the Massifs du Chaillu and du Mayombé, and of the Batéké Plateaus in Gabon and RoC. Although the mean annual and monthly spatial patterns are well reproduced in SARAH-2.1, SDU levels are systematically overestimated by 1-2 h day21. The largest positive biases are recorded during the December-February dry season, especially at the northernmost stations. Analyses at the daily time scale show that SARAH-2.-1 biases arise from a twofold problem: The number of dark days (SDU <1 h day2-1) is 50%lower than observed whereas that of sunny days (SDU > 9 h day21) is 50%higher than observed. © 2022 American Meteorological Society. more
Atmosphere CM-SAF Climate Data Records Validation

Characterization of Tropical Cyclone Intensity Using the HY-2B Scatterometer Wind Data

Author(s):
Liu, Siqi; Lin, Wenming; Portabella, Marcos; Wang, Zhixiong
Publication title: Remote Sensing
2022
 | Volume: 14 | Issue: 4
2022
DOI: 10.3390/rs14041035
Abstract:
The estimation of tropical cyclone (TC) intensity using Ku-band scatterometer data is challenging due to rain perturbation and signal saturation in th… The estimation of tropical cyclone (TC) intensity using Ku-band scatterometer data is challenging due to rain perturbation and signal saturation in the radar backscatter measurements. In this paper, an alternative approach to directly taking the maximum scatterometer-derived wind speed is proposed to assess the TC intensity. First, the TC center location is identified based on the unique characteristics of wind stress divergence/curl near the TC core. Then the radial extent of 17-m/s winds (i.e., R17) is calculated using the wind field data from the Haiyang-2B (HY-2B) scatterometer (HSCAT). The feasibility of HSCAT wind radii in determining TC intensity is evaluated using the maximum sustained wind speed (MSW) in the China Meteorological Administration best-track database. It shows that the HSCAT R17 value generally better correlates with the best-track MSW than the HSCAT maximum wind speed, therefore indicating the potential of using the HSCAT data to improve the TC nowcasting capabilities. more
Application Atmosphere NWP-SAF Software for CDR development

Characterizing Buoy Wind Speed Error in High Winds and Varying Sea State with ASCAT and ERA5

Author(s):
Wright, Ethan E.; Bourassa, Mark A.; Stoffelen, Ad; Bidlot, Jean-Raymond
Publication title: REMOTE SENSING
2021
 | Volume: 13 | Issue: 22
2021
DOI: 10.3390/rs13224558
Abstract:
Buoys provide key observations of wind speed over the ocean and are routinely used as a source of validation data for satellite wind products. However… Buoys provide key observations of wind speed over the ocean and are routinely used as a source of validation data for satellite wind products. However, the movement of buoys in high seas and the airflow over waves might cause inaccurate readings, raising concern when buoys are used as a source of wind speed comparison data. The relative accuracy of buoy winds is quantified through a triple collocation (TC) exercise comparing buoy winds to winds from ASCAT and ERA5. Differences between calibrated buoy winds and ASCAT are analyzed through separating the residuals by anemometer height and testing under high wind-wave and swell conditions. First, we converted buoy winds measured near 3, 4, and 5 m to stress-equivalent winds at 10 m (U10S). Buoy U10S from anemometers near 3 m compared notably lower than buoy U10S from anemometers near 4 and 5 m, illustrating the importance of buoy choice in comparisons with remote sensing data. Using TC calibration of buoy U10S to ASCAT in pure wind-wave conditions, we found that there was a small, but statistically significant difference between height adjusted buoy winds from buoys with 4 and 5 m anemometers compared to the same ASCAT wind speed ranges in high seas. However, this result does not follow conventional arguments for wave sheltering of buoy winds, whereby the lower anemometer height winds are distorted more than the higher anemometer height winds in high winds and high seas. We concluded that wave sheltering is not significantly affecting the winds from buoys between 4 and 5 m with high confidence for winds under 18 ms(-1). Further differences between buoy U10S and ASCAT winds are observed in high swell conditions, motivating the need to consider the possible effects of sea state on ASCAT winds. more
Atmosphere Climate Data Records OSI-SAF Validation

Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT

Author(s):
Belmonte Rivas, Maria; Stoffelen, Ad
Publication title: Ocean Science
2019
 | Volume: 15 | Issue: 3
2019
DOI: 10.5194/os-15-831-2019
Abstract:
Abstract. This paper analyzes the differences between ERA-Interim and ERA5 surface winds fields relative to Advanced Scatterometer (ASCAT) ocean vecto… Abstract. This paper analyzes the differences between ERA-Interim and ERA5 surface winds fields relative to Advanced Scatterometer (ASCAT) ocean vector wind observations, after adjustment for the effects of atmospheric stability and density, using stress-equivalent winds (U10S) and air–sea relative motion using ocean current velocities. In terms of instantaneous root mean square (rms) wind speed agreement, ERA5 winds show a 20 % improvement relative to ERA-Interim and a performance similar to that of currently operational ECMWF forecasts. ERA5 also performs better than ERA-Interim in terms of mean and transient wind errors, wind divergence and wind stress curl biases. Yet, both ERA products show systematic errors in the partition of the wind kinetic energy into zonal and meridional, mean and transient components. ERA winds are characterized by excessive mean zonal winds (westerlies) with too-weak mean poleward flows in the midlatitudes and too-weak mean meridional winds (trades) in the tropics. ERA stress curl is too cyclonic in midlatitudes and high latitudes, with implications for Ekman upwelling estimates, and lacks detail in the representation of sea surface temperature (SST) gradient effects (along the equatorial cold tongues and Western Boundary Current (WBC) jets) and mesoscale convective airflows (along the Intertropical Convergence Zone and the warm flanks for the WBC jets). It is conjectured that large-scale mean wind biases in ERA are related to their lack of high-frequency (transient wind) variability, which should be promoting residual meridional circulations in the Ferrel and Hadley cells. more
Application Atmosphere Climate Data Records OSI-SAF

CLAAS: the CM SAF cloud property data set using SEVIRI

Author(s):
Stengel, M.; Kniffka, A.; Meirink, J. F.; Lockhoff, M.; Tan, J.; Hollmann, R.
Publication title: Atmospheric Chemistry and Physics
2014
 | Volume: 14 | Issue: 8
2014
DOI: 10.5194/acp-14-4297-2014
Abstract:
Abstract. An 8-year record of satellite-based cloud properties named CLAAS (CLoud property dAtAset using SEVIRI) is presented, which was derived withi… Abstract. An 8-year record of satellite-based cloud properties named CLAAS (CLoud property dAtAset using SEVIRI) is presented, which was derived within the EUMETSAT Satellite Application Facility on Climate Monitoring. The data set is based on SEVIRI measurements of the Meteosat Second Generation satellites, of which the visible and near-infrared channels were intercalibrated with MODIS. Applying two state-of-the-art retrieval schemes ensures high accuracy in cloud detection, cloud vertical placement and microphysical cloud properties. These properties were further processed to provide daily to monthly averaged quantities, mean diurnal cycles and monthly histograms. In particular, the per-month histogram information enhances the insight in spatio-temporal variability of clouds and their properties. Due to the underlying intercalibrated measurement record, the stability of the derived cloud properties is ensured, which is exemplarily demonstrated for three selected cloud variables for the entire SEVIRI disc and a European subregion. All data products and processing levels are introduced and validation results indicated. The sampling uncertainty of the averaged products in CLAAS is minimized due to the high temporal resolution of SEVIRI. This is emphasized by studying the impact of reduced temporal sampling rates taken at typical overpass times of polar-orbiting instruments. In particular, cloud optical thickness and cloud water path are very sensitive to the sampling rate, which in our study amounted to systematic deviations of over 10% if only sampled once a day. The CLAAS data set facilitates many cloud related applications at small spatial scales of a few kilometres and short temporal scales of a~few hours. Beyond this, the spatiotemporal characteristics of clouds on diurnal to seasonal, but also on multi-annual scales, can be studied. more
Atmosphere CM-SAF Climate Data Records Validation

CLARA-A2: the second edition of the CM SAF cloud and radiation data record from 34 years of global AVHRR data

Author(s):
Karlsson, Karl-Göran; Anttila, Kati; Trentmann, Jörg; Stengel, Martin; Fokke Meirink, Jan; Devasthale, Abhay; Hanschmann, Timo; Kothe, Steffen; Jääskeläinen, Emmihenna; Sedlar, Joseph; Benas, Nikos; van Zadelhoff, Gerd-Jan; Schlundt, Cornelia; Stein, Diana; Finkensieper, Stefan; Håkansson, Nina; Hollmann, Rainer
Publication title: Atmospheric Chemistry and Physics
2017
 | Volume: 17 | Issue: 9
2017
DOI: 10.5194/acp-17-5809-2017
Abstract:
Abstract. The second edition of the satellite-derived climate data record CLARA (The CM SAF Cloud, Albedo And Surface Radiation dataset from AVHRR dat… Abstract. The second edition of the satellite-derived climate data record CLARA (The CM SAF Cloud, Albedo And Surface Radiation dataset from AVHRR data – second edition denoted as CLARA-A2) is described. The data record covers the 34-year period from 1982 until 2015 and consists of cloud, surface albedo and surface radiation budget products derived from the AVHRR (Advanced Very High Resolution Radiometer) sensor carried by polar-orbiting, operational meteorological satellites. The data record is produced by the EUMETSAT Climate Monitoring Satellite Application Facility (CM SAF) project as part of the operational ground segment. Its upgraded content and methodology improvements since edition 1 are described in detail, as are some major validation results. Some of the main improvements to the data record come from a major effort in cleaning and homogenizing the basic AVHRR level-1 radiance record and a systematic use of CALIPSO-CALIOP cloud information for development and validation purposes. Examples of applications studying decadal changes in Arctic summer surface albedo and cloud conditions are provided. more
Atmosphere CM-SAF Climate Data Records Land Validation

CLAAS-3: The third edition of the CM SAF cloud data record based on SEVIRI observations

Author(s):
Benas, N.; Solodovnik, I.; Stengel, M.; Huser, I.; Karlsson, K.-G.; Hakansson, N.; Johansson, E.; Eliasson, S.; Schroder, M.; Hollmann, R.; Meirink, J.F.
Publication title: Earth System Science Data
2023
 | Volume: 15 | Issue: 11
2023
DOI: 10.5194/essd-15-5153-2023
Abstract:
CLAAS-3, the third edition of the Cloud property dAtAset using SEVIRI (Spinning Enhanced Visible and InfraRed Imager), was released in December 2022. … CLAAS-3, the third edition of the Cloud property dAtAset using SEVIRI (Spinning Enhanced Visible and InfraRed Imager), was released in December 2022. It is based on observations from SEVIRI, on board geostationary satellites Meteosat-8, 9, 10 and 11, which are operated by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). CLAAS-3 was produced and released by the EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF), which aims to provide high-quality satellite-based data records suitable for climate monitoring applications. Compared to previous CLAAS releases, CLAAS-3 is expanded in terms of both temporal extent and cloud properties included, and it is based on partly updated retrieval algorithms. The available data span the period from 2004 to present, covering Europe; Africa; the Atlantic Ocean; and parts of South America, the Middle East and the Indian Ocean. They include cloud fractional coverage, cloud-top height, phase (liquid or ice) and optical and microphysical properties (water path, optical thickness, effective radius and droplet number concentration), from instantaneous data (every 15min) to monthly averages. In this study we present an extensive evaluation of CLAAS-3 cloud properties, based on independent reference data sets. These include satellite-based retrievals from active and passive sensors, ground-based observations and in situ measurements from flight campaigns. Overall results show very good agreement, with small biases attributable to different sensor characteristics, retrieval/sampling approaches and viewing/illumination conditions. These findings demonstrate the fitness of CLAAS-3 to support the intended applications, which include evaluation of climate models, cloud characterisation and process studies focusing especially on the diurnal cycle and cloud filtering for other applications. The CLAAS-3 data record is publicly available via the CM SAF website at 10.5676/EUM_SAF_CM/CLAAS/V003 (Meirink et al., 2022). © 2023 Copernicus GmbH. All rights reserved. more
Atmosphere CM-SAF Climate Data Records Validation

Climate data integration into wheat performance evaluation reveals large inter-varietal responses

Author(s):
Raymond, Joanna; Penfield, Steven; Lovett, Andrew; Mackay, Ian; Philpott, Haidee; Simpson, Conor John Christopher; Dorling, Stephen
Publication title: Environmental Research: Food Systems
2024
 | Volume: 2 | Issue: 1
2024
DOI: 10.1088/2976-601X/ad90e4
Abstract:
There is an urgent need to adapt crop breeding strategies to boost resilience in the face of a growing food demand and a changing climate. Achieving t… There is an urgent need to adapt crop breeding strategies to boost resilience in the face of a growing food demand and a changing climate. Achieving this requires an understanding of how weather and climate variability impacts crop growth and development. Using the United Kingdom (UK) as an example, we evaluate changes in the UK agroclimate and analyse how these have influenced domestic wheat production. Here we quantify spatial and temporal variability and changes in weather and climate across growing seasons over the last four decades (1981–2020). Drawing on variety trial data, we then use statistical modelling to explore the interaction between genotype and agroclimate variation. We show that changes in the UK agroclimate present both risks, and opportunities for wheat growers, depending on location. From 1981–2020, in Wales, the West Midlands, large parts of the North West, and Northern Ireland, there was an overall increase in frost risk in early spring of 0.15 additional frost days per year, whilst in the east early frost risk decreased by up to 0.29 d per year. Meanwhile, over the period 1987–2020, surface incoming shortwave radiation during grainfill increased in the east by up to 13% but decreased in Western areas by up to 15%. We show significant inter-varietal differences in yield responses to growing degree days, heavy rainfall, and the occurrence of late frost. This highlights the importance of evaluating variety-climate interactions in variety trial analyses, and in climate-optimised selection of crops and varieties by growers. This work provides guidance for future research on how climate change is affecting the UK agroclimate and resulting impacts on winter cereal production. more
Application Atmosphere CM-SAF Climate Data Records Terrestrial

CLARA-A3: The third edition of the AVHRR-based CM SAF climate data record on clouds, radiation and surface albedo covering the period 1979 to 2023

Author(s):
Karlsson, Karl-Göran; Stengel, Martin; Meirink, Jan Fokke; Riihelä, Aku; Trentmann, Jörg; Akkermans, Tom; Stein, Diana; Devasthale, Abhay; Eliasson, Salomon; Johansson, Erik; Håkansson, Nina; Solodovnik, Irina; Benas, Nikos; Clerbaux, Nicolas; Selbach, Nathalie; Schröder, Marc; Hollmann, Rainer
Publication title: Earth System Science Data
2023
 | Volume: 15 | Issue: 11
2023
DOI: 10.5194/essd-15-4901-2023
Abstract:
This paper presents the third edition of The Satellite Application Facility on Climate Monitoring's (CM SAF) cloud, albedo, and surface radiation data… This paper presents the third edition of The Satellite Application Facility on Climate Monitoring's (CM SAF) cloud, albedo, and surface radiation dataset from advanced very-high-resolution radiometer (AVHRR) data, CLARA-A3. The content of earlier CLARA editions, namely cloud, surface albedo, and surface radiation products, has been extended with two additional surface albedo products (blue- and white-sky albedo), three additional surface radiation products (net shortwave and longwave radiation, and surface radiation budget), and two top of atmosphere radiation budget products (reflected solar flux and outgoing longwave radiation). The record length is extended to 42 years (1979–2020) by also incorporating results from the first version of the advanced very high resolution radiometer imager (AVHRR/1). A continuous extension of the climate data record (CDR) has also been implemented by processing an interim climate data record (ICDR) based on the same set of algorithms but with slightly changed ancillary input data. All products are briefly described together with validation results and intercomparisons with currently existing similar CDRs. The extension of the product portfolio and the temporal coverage of the data record, together with product improvements, is expected to enlarge the potential of using CLARA-A3 for climate change studies and, in particular, studies of potential feedback effects between clouds, surface albedo, and radiation. The CLARA-A3 data record is hosted by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) CM SAF and is freely available at https://doi.org/10.5676/EUM_SAF_CM/CLARA_AVHRR/V003 (Karlsson et al., 2023b). more
Atmosphere CM-SAF Climate Data Records EUM-Secr Land Method OSI-SAF Validation
Subscribe to