Chlorophyll concentration studies in the Thane creek, Mumbai, India, through remote sensing: comparison of ground truth and OCM (IRS-P4) data

摘要

The chemical analysis of the marine water samples was used along with IRS-P4 (OCM) data to prepare chlorophyll concentration maps for the Thane creek, Mumbai, India. The chlorophyll a +phaeopigment ([C+P]) retrieval was done using a bio-optical algorithm, which was applied to detect the concentration from Ocean Colour Monitor data. Marine water samples were collected on March 15, 2001, March 21, 2001, March 23, 2001 and March 25, 2001 synchronised with the IRS-P4 satellite overpass. Standard methods were used to chemically analyse the samples. The Chlorophyll distribution map from OCM data was prepared using Erdas Imagine 8.4 and SeaDas 4.0. The results show that the chlorophyll values range from 3.204mg/m~3 to 35.24mg/m~3. Discrepancies between the chlorophyll values derived using existing atmospheric model (developed by Space Application Centre, Ahmedabad, India), and those obtained from the analysis of the marine samples were removed by correlating them statistically and by applying a simple correction derived from this correlation. Lower chlorophyll values found near the mouths of the creek tributaries could be attributed to higher industrial waste discharges whereas comparatively higher values of chlorophyll seen further north in the Thane creek, are due to the nutrient disposals from domestic and food industrial sources.