Influence of Oceanic Features around Inlet on the Thermohaline Variability in the Cochin Estuary during 2011 and 2012

摘要

Thermohaline variability in the Cochin estuary primarily depends on the mixing of fresh water downstream and sea water intrusion upstream. Knowledge of sea water intrusion into the estuary is important for functioning of ecological systems. Therefore this study explored the possibility of monitoring sea water intrusion into the estuary using open ocean thermohaline properties obtained from satellite data. Recently, an extensive observational program has been carried out during 2011 and 2012 in the Cochin estuary to collect temperature and salinity profiles on a fortnightly interval with a station spacing of approximately 100m. Notable temporal variability in salinity is observed in the depth time plots constructed using profiles collected during high tide.Salinity intrusion into Harbor Mouth, during summer and winter monsoon period, exhibits considerable year to year variability. The retreat of summer monsoon rainfall and reduction in the freshwater water discharge resulted in a gradual increase in the salinity both in the surface and bottom. Earlier studies reported that the thermohaline variability on semi-diurnal and diurnal scales is solely due to tidal inflow and out flow.The present study looked into the influence of open ocean thermohaline properties around inlet as observed in the Sea Surface Salinity and Sea Surface Temperature derived from satellite data on the salinity variability in the estuary.