08 October 2015

Regional Precipitation Simulations for the Mid-1970s Shift and Early-2000s Hiatus

Summary

The emerging science of decadal climate prediction, though still in its early stages, has shown encouraging signs of being able to predict sea surface temperature (SST) patterns in certain ocean regions beyond the interannual timescale and up to about ten years in advance.  A fundamental feature of these retrospective deacadal climate predictions is the simulation of the SST anomalies associated with the phase of the Interdecadal Pacific Oscillation (IPO).  Though predicting SST patterns in the oceans is of academic interest due to the science problems involved with being able to simulate coupled processes in the climate system that produce those SST patterns, what is of more relevance for society is to address what can be predicted over land areas where people live.  To address this problem, regional precipitation over selected land areas in south Asia, Australia, and North America, known to be affected by SST patterns over the Pacific, is studied in initialized climate model retrospective decadal prediction experiments.  It is shown that there is qualitatively better agreement with observations for regional precipitation anomalies in those regions, predicted 3 to 7 years in advance, compared to uninitialized climate models.  Though the signals are small, the anomalies are consistent with our physical process-based understanding of precipitation responses over certain land areas during different IPO phases. 

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