Indo-Pacific Warm Pool variability over the last millennium

Co-Author: Shreya Dhame
The Indo-Pacific Warm Pool (IPWP) significantly influences rainfall distribution and tropical cyclone activity in the tropics. The IPWP warmed and expanded steadily until the late 1900s, followed by a weaker trend or hiatus, as observed in the global mean temperature. Previous studies have identified contributions from anthropogenic forcings (mainly greenhouse gas increase) and natural causes (Pacific Decadal Oscillation) to the observed IPWP warming and expansion in the last 50 years. In addition to the long term trend, decadal variability in IPWP intensity and size has been known to directly influence Hadley and Walker circulations, and modulate the inter-annual variability of El Nino Southern Oscillation (ENSO). Our research focus is to understand the how intrinsic processes in the Indian and Pacific Oceans affect the IPWP variability on interannual to multi-decadal timescales. The CESM1(CAM5) Last Millennium Ensemble (LME) with its extended time-scale of simulations provides a unique testing platform for modelling long-term changes of IPWP.