Abstract:
Surface water mixing in the Bay of Bengal (BOB) inferred from spatio-temporal distribution of δ18O and
salinity based on synthesis of 194 new samples together with published data is reported. In general, both
δ18O and salinity have low values in northern part of the BOB, progressively increasing towards SW. The
lowest values are observed during July–September (southwest monsoon season) and the highest in premonsoon.
The most prominent δ18O–salinity relationship is seen for samples collected during June to October
when the Himalayan river influx dominates. When this influx decreases in other seasons the δ18O–salinity
relationship is poor.
The δ18O–δD regression of samples north of 10°N is similar to the GMWL. However, for samples south of
~10°N, this regression has a significantly lower slope. This is interpreted as due to absence of direct riverine
inflow in this region of the BOB, coupled with –ve (P−E; Precipitation minus Evaporation) almost throughout
the year.
This study shows that the seasonal distribution of δ18O and salinity over the northern BOB is dominantly
governed by the variation in the (P+R−|E|) in spite of the fact that ocean currents transfer several times
more water between the two basins of northern Indian Ocean.
