“…The currently available SMOS SSS data, both in the form of level 2 (L2) and level 3 (L3) products, have been validated against in situ measurements in a variety of circumstances. They may take the form of a direct comparison with co-located SSS measurements from Argo floats [31][32][33], thermosalinograph (TSG) [31,32,[34][35][36] and saildrones [31], the comparison with data from tropical moored buoys array at seasonal scale [37,38] and the global and regional comparison with in situ analyzed products [27,34,[39][40][41][42][43][44][45], as well as the SSS uncertainty estimations through a triple collocation of three independent SSS products [46,47]. However, the reliability of a comparison with both individual Argo floats and gridded Argo products has long been limited by the sparse sampling rate, especially near the coast [31,34,39,48], near large river mouths [41,42,49] and in the polar seas [32,35,36,40,43,50].…”