Precipitation isotopes? response to the atmospheric processes over the mainland and the island region in the northern Indian Ocean: Implications to the paleo-monsoon study

The isotopic composition of precipitation was studied over a terrestrial environment in western India and an island region in the Bay of Bengal. We have examined the precipitation isotopes' response to the surface temperature and the tropospheric warming during the monsoon season. We observed that tropospheric temperature and surface temperature are positively correlated over the ocean while they are negatively correlated over the land. As a result, the precipitation isotopes in these environments show the opposite behavior to surface temperature variability. Despite this difference, precipitation isotopes in both environments respond positively to the tropospheric temperature variability, though the relationship is weaker in the terrestrial environment. The precipitation isotopic response to tropospheric temperature may provide an alternative to the precipitation and precipitation isotope relation widely used in past monsoon reconstruction.