Collaborative Research: P2C2--Synthesizing Asian Monsoon Hydroclimate & Indo-Pacific Variability on Seasonal to Multi-Decadal Timescales Using Tree-Rings & Coupled Climate

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This project broadly seeks to use multi-parameter tree ring records from Laos and Vietnam in central Mainland Southeast Asia (MSEA) to reconstruct discrete spring, summer, autumn and winter climate variability for comparison to observations and model simulations and to understand the dynamics and drivers of climate and surface ocean variability in the region. The long-term perspective of central MSEA variability from the proxy records will be synthesized with the simulations for a more dynamically-based understanding of past and future changes in atmospheric and upper-ocean properties throughout Southeast Asia and the Maritime Continent.Specifically, the research team aims to use measurements of early and late wood width and density from blue light intensity in tree ring samples to reconstruct seasonal to multi-decadal records of the Palmer Drought Severity Index (PDSI), Standardized Precipitation Evapotranspiration Index (SPEI), rainfall, and boreal winter maximum temperature over the past five to ten centuries. Links between central MSEA and Indo-Pacific atmospheric and surface ocean properties over the past centuries will be evaluated using observational/reanalysis products and coupled climate model simulations because model resolution may not fully capture climate and ocean variability within individual monsoon seasons.The Asian Monsoon impacts roughly two-thirds of the global population. Multi-model assessments of regional climate under anthropogenic warming predict changes to the Asian Monsoon that are expected to impact regional climate and ocean variability. These multi-model assessments also predict a transition to a more El Nino-like state, which is expected to variably alter precipitation, temperature and ocean circulation patterns globally. The present understanding of past changes in monsoon strength and precipitation and the resulting consequences for Indian Ocean surface variability limits climatologist’s ability to accurately forecast regional climate impacts at various timescales.The potential Broader Impacts (B.I.) include better understanding of variability and long-term trends in rainfall and drought from Southeast Asia and the Indo-Pacific region. Such information has important implications for surrounding countries whose largely agrarian societies depend on reliable monsoon rainfall. The project also supports a new investigator and student participation in Woods Hole and UCAR SOARS summer programs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.