Open AccessEvaporation‐precipitation changes in the eastern Arabian Sea for the last 68 ka: Implications on monsoon variability
Author(s) -
Govil Pawan,
Naidu Pothuri Divakar
Publication year - 2010
Publication title -
paleoceanography
Language(s) - English
Resource type - Journals
eISSN - 1944-9186
pISSN - 0883-8305
DOI - 10.1029/2008pa001687
Subject(s) - monsoon , upwelling , geology , precipitation , oceanography , climatology , glacial period , sea surface temperature , holocene , monsoon of south asia , east asian monsoon , marine isotope stage , salinity , bay , sea level , δ18o , last glacial maximum , stable isotope ratio , interglacial , geomorphology , geography , physics , quantum mechanics , meteorology
Variations in sea surface temperature (SST), δ 18 O of sea water ( δ 18 Ow), and salinity were reconstructed for the past 68 ka using a sediment core (AAS9/21) from the eastern Arabian Sea (EAS) in order to understand the changes in evaporation and precipitation associated with the monsoon system. The Mg/Ca‐derived SST record varies by ∼4°C; it shows that marine isotope stage (MIS) 4 was warmer than MIS 3, that the Last Glacial Maximum was 4°C cooler than the present, and that there was a 2°C increase within the Holocene. MIS 4 records higher δ 18 Ow and salinity values than MIS 2, suggesting variable flow of low‐salinity Bay of Bengal flow into the EAS during glacial periods. The transition from MIS 4 to MIS 3 was marked with a conspicuous shift from higher to lower δ 18 Ow values, which reflects a decrease in the evaporation‐precipitation budget in the EAS, perhaps due to the strengthening of southwest monsoon. Monsoon reconstructions based on δ 18 Ow reveal that monsoon‐driven precipitation was higher during MIS 3 and MIS 1 and was lower during MIS 2 and MIS 4. This is consistent with earlier monsoon reconstructions based on upwelling indices from the western Arabian Sea. However, the amplitude of monsoon fluctuations derived through upwelling indices and δ 18 Ow varies significantly, which may indicate spatial variability of monsoon rainfall.