Changes in the moistening properties of convection associated with variations in the ENSO and IOD from 2005 and 2006

We use TES measurements of the isotopic composition of water vapor to examine how changes in the distribution of convection and precipitation control water vapor amount over the Indian Ocean. Measurements of the Outgoing longwave radiation (OLR) and vertical velocity from NCEP/NCAR Reanalysis and cloud ice water content from the Microwave Limb Sounder (MLS) show distinct variations in convection due to a phase shift of both El Niño - Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). These variations in convection are associated with changes in precipitation and water amount over the WIO and EIO depending on the phases of ENSO and/or the IOD. Over the EIO during the drought induced by the interplay of ENSO and positive IDO in 2006, it is drier and less depleted ascribed to less frequent and/or weaker deep convective activity and subsequent precipitation compared to 2005. By contrast, over the WIO in 2006, an increase in water vapor and precipitation but little fractionation in water vapor of clear sky compared to 2005 is likely associated with an increase in both enhanced deep and shallow convection, caused by the positive IOD.