Spatial and temporal variability of chlorophyll-a concentration in the South Eastern Arabian Sea (SEAS)

Satellite remote sensing is being effectively used in monitoring the ocean surface. Among the ocean observing satellite sensors, ocean colour sensors make use of visible band of electromagnetic spectrum (shorter wavelength). The use of shorter wavelength ensures fine spatial resolution of these parameters to depict oceanographic characteristics of any region having significant spatio-temporal variability. The Southeastern Arabian Sea (SEAS; encompassing between 70.5-77.5oE longitude and 8-15oN latitude) is such an area showing very significant spatio-temporal oceanographic and atmospheric variability due to the seasonally reversing surface winds and currents (Shankar et al., 2002; Shetye et al., 1990

Fundamentals of ocean colour remote sensing

Remote sensing refers to collection of information about an object without being in direct contact with the object. Remote sensing aids in measuring remote areas which are inaccessible by any other means and offer less expense than in-situ measurements. Remote sensing facilitates creation of long time series and extended measurement. This has the advantage that several parameters can be measured at same time and satellite-based remote sensing measurements allow global observations. Remote sensing has its own advantages and disadvantages. The limitation includes indirect measurements of large areas which are not of interest to the user. The automated instrument degradation creates retrieval errors and are affected by several factors/processes, and not only by the object of interest. Additional assumptions and models are needed for the interpretation of the measurements and before using these models in oceanographic studies, it is extremely important to validate the performance of the various ocean colour algorithms with in-situ observations (Swirgon et al., 2015)

Upwelling over the eastern Arabian Sea

Upwelling is a vital oceanographic phenomena determining the biological productivity of the coastal oceanic provinces in a greater extent. The annual pelagic fisheries of coastal rim countries, adjacent to the eastern boundary of the Ocean, over the trade wind zone are greatly dependent on upwelling. Over the North India Ocean (NIO), west coast of India, adjacent to the eastern Arabian Sea is well known for its seasonal occurrence of upwelling and downwelling annually. Over the past, several authors have studied upwelling along the west coast of India (Banse 1959, 1968; Sharma 1978; Johannessen et al., 1987