Assessment of seasonal and year-to-year surface salinity signals retrieved from SMOS and Aquarius missions in the Bay of Bengal

Abstract

International audienc

Modulation of the Ganges‐Brahmaputra River Plume by the Indian Ocean Dipole and Eddies Inferred From Satellite Observations

“…Despite this good overall agreement, SMAP SSS can display large fresh biases (up to 4 pss) for a couple of points in the lower salinity range. These large differences may arise from the very strong near‐surface stratification often found in the BoB (i.e., the satellite represents the top millimeter while we use in situ data within 1–5 m depth; Akhil et al, ). A reviewer also pointed out that a potential cause for the saltier Argo salinity measurements in the upper 5 m is Argo CTD mixing near‐surface (shallower than 5 m) waters with waters from 4 to 5 m depth, which might be the depth when Argo floats shut off the pumping.…”

“…SMAP thus provides synoptic, intraseasonal to interannual monitoring of the “river in the sea,” a capability not afforded by in situ data (Figure ). SMAP SSS also presents an advantage over existing satellite SSS retrievals from SMOS, which excluded data from much of the northern BoB due to data quality issues, and Aquarius/SAC‐D, which did not have sufficient resolution to resolve coastal signals (Akhil et al, ).…”

“…These missions include the European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) (Mecklenburg et al, ) and National Aeronautics and Space Administration (NASA) Aquarius/Sac‐D missions (Lagerloef et al, ) launched in 2009 and 2011, respectively. SMOS has a 33 km spatial resolution that is in principle sufficient to monitor this “river in the sea.” Unfortunately, while SMOS SSS data are amenable for open ocean applications, the current SMOS SSS retrievals are of poor quality in the BoB due to significant contamination by Radio Frequency Interference (RFI) and land signals (Akhil et al, ; Boutin et al, ; Subrahmanyam et al, ). In comparison, Aquarius performs much better for monitoring large‐scale SSS patterns in the BoB (Akhil et al, ), but is however not suitable to monitor the GB freshwater plume due to its lower (∼110 km) spatial resolution and because measurements within 150 km of the coast are usually contaminated by land signals (Aquarius User Guide, ).…”

“…SMOS has a 33 km spatial resolution that is in principle sufficient to monitor this “river in the sea.” Unfortunately, while SMOS SSS data are amenable for open ocean applications, the current SMOS SSS retrievals are of poor quality in the BoB due to significant contamination by Radio Frequency Interference (RFI) and land signals (Akhil et al, ; Boutin et al, ; Subrahmanyam et al, ). In comparison, Aquarius performs much better for monitoring large‐scale SSS patterns in the BoB (Akhil et al, ), but is however not suitable to monitor the GB freshwater plume due to its lower (∼110 km) spatial resolution and because measurements within 150 km of the coast are usually contaminated by land signals (Aquarius User Guide, ). The Aquarius mission also ended in June 2015 due to a power failure of the SAC‐D spacecraft carrying the Aquarius sensor.…”

Comparison of the Retrieval of Sea Surface Salinity Using Different Instrument Configurations of MICAP

“…Moreover, research on seasonal and interannual variations of SSS in near-coastal and middle/high latitudes is relatively limited due to the low-quality satellite-derived SSS measurements in these regions [18], reinforcing the requirement for accurate SSS measurements to possibly capture the seasonal and interannual variations of SSS. Developing a new payload to obtain high-quality global observations of SSS is necessary.…”