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- Title
Variability of satellite Sea Surface Salinity under rainfall.
- Authors
Supply, Alexandre; Boutin, Jacqueline; Reverdin, Gilles; Vergely, Jean-Luc; Katsumata, Masaki
- Abstract
Two L-Band (1.4GHz) microwave radiometer missions, the Soil Moisture and Ocean Salinity(SMOS) and the Soil Moisture Active and Passive (SMAP) missions, currently providesalinity measurements in the first centimeter below the sea surface. At this depth, salinityvariability at hourly temporal scales is dominated by the impact of precipitation.The dependency of the salinity freshening with the instantaneous rain rate (RR)observed between 50˚ S and 50˚ N, with SMOS and SMAP salinities, is verysimilar. We investigate the influence of rain history on salinity anomalies. By using rain ratesretrieved from several microwave satellites measurements including Advanced MicrowaveScanning Radiometer 2 (AMSR-2), and Special Sensor Microwave Imager Sounder 17(SSMIS-17 and SSMIS-16) and by taking advantage of their different crossing times, weestimate the temporal cross-correlation function between salinity freshening and rain rate fordifferent time lags in various tropical and high latitudes regions. Whatever the region, themagnitude of the salinity anomaly associated with precipitation is dominated by theinstantaneous RR for each area. The apparent correlation between salinity anomaly and rainhistory can be explained by RR auto-correlation. The relationship between salinity anomaly (ΔS) and RR is then investigated in differentregions, with RR provided using three different algorithms (the Unified Microwave OceanRetrieval Algorithm (UMORA), the Goddard profiling algorithm (GPROF) andIntegrated MultisatellitE Retrievals for GPM (IMERG)). Differences in RR distributionbetween the various algorithms lead to differences of up to a factor 2 in ΔS versus RRslopes. For a given RR product, we also observe that part of the variability in ΔS versus RRrelationships is related to the variability in wind speed regimes as detected by SMAP windspeed. These results are compared with Sea Surface Salinity (SSS), rain andwave measured in-situ during field campaign as SPURS-2 2017 cruise and Mirai 2018cruise using collocation methods. Preliminary investigations considering the effect of rainheterogeneity and wind speed on freshening using a prognostic model (Bellenger et al, 2017)will be presented.
- Subjects
SEAWATER salinity; SALINITY; RAINFALL; COLLOCATION methods; PRECIPITATION anomalies; RAINFALL anomalies; OCEAN travel
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article