Assessment of remotely-sensed sea-surface temperature and chlorophyll-a concentration in San Matías Gulf (Patagonia, Argentina)

Field measurements of surface temperature and chlorophyll-a concentration were used to evaluate for the first time the performance of the standard sea surface temperature and chlorophyll-a algorithms of the Moderate Resolution Imaging Spectroradiometer (MODIS) in San Matías Gulf, northern of the Argentine Patagonian Continental Shelf (between 40°47′S and 42°13′S). The fit of the temperature data to a Standard Major Axis (SMA) type II regression model indicated that a high proportion of the total variance (r2≥0.80) was explained by the model. For chlorophyll-a, the low correlation (r2=0.15) and high dispersion indicated a poor performance and a general overestimation of Chl-a by the OC3Mv5 algorithm as indicated by the Relative Percent Difference (RPD=113%). However, for stations located in the northern area of the gulf the result showed a higher correlation (r2=0.76) and less dispersion (RPD=31%). The feasible reasons and explanations for the performance of NLSST and OC3Mv5 algorithms are discussed. The results of the temporal variability analysis of SST and Chl-a in different areas of the gulf agreed with previous studies.

► Field measurements of sea temperature and chlorophyll-a were compared with MODIS standard algorithms (NLSST and OC3v5, respectively) for the first time in San Matías Gulf.
► A good fitting between the SST and the temperature records was observed.
► A poor agreement was found between satellite-derived chlorophyll-a data and in-situ observations.
► The results improved when data from northwestern area of the Gulf were analyzed.
► The temporal variability observed by remote sensors reproduces known patterns.