Modeling spatio-temporal variability of suspended matter and its relation with hydrodynamic parameters in the northern Bay of Bengal

Abstract

Variation of the non-algal suspended particulate matter (SM) was assessed, both on a spatial and temporal scale using satellite datasets. Located on one of the biggest deltas around the world, enormous rivers, and sediment discharge make this region’s suspended matters more prone to variations. Noticeable latitudinal transformations were found in SM as it ceased to exist after 21.5° N, with discrete seasonal changes that included summer SM concentration as high as 90–95 g/m3, while in winter it was 70–75 g/m3 on average near the river mouth. Such contrasting values are because of the variation in input from the nearby major rivers including Ganges–Brahmaputra, which in terms brings suspended load, particulate matters, nutrients, and other material fluxes along with it. However, other regions had a seasonally averaged concentration of 36 g/m3. Temporal analysis of SM revealed that it consisted of an increasing pattern between 2004 and 2010, but it gradually altered to decreasing trends from 2012 to 2018. Secchi depth, chlorophyll-a, nitrate, phosphate, silicate, sea level anomaly, current speed, temperature, and salinity are the hydrodynamic parameters those are considered in this article to find which one is well correlated with SM. Nitrate and silicate proved a significant positive correlation with SM, whereas chlorophyll-a, salinity, and Secchi depths were negatively correlated over the whole period. Eventually, further wavelet analysis gave rise to an interesting sign of the SM on chlorophyll-a for specific regimes of the time.