Global structure of Bidecadal precipitation variability in boreal winter

Abstract

Three global monthly precipitation datasets, including gauge measurements, gauge/satellite merged analysis (CMAP), and NCEP/NCAR reanalysis, are analyzed with respect to Bi-Decadal Oscillation (BDO) in boreal winter during the 20th century. Correlation and coherency analyses between the precipitations and the strength of the Aleutian low, which is an action center of the BDO, reveal substantial impacts of the BDO on precipitations around the Pacific Ocean. The covariability of the precipitations is prominent for Hawaii, mid-latitude eastern North America, Florida and eastern-China/Southern-Japan, and at some other regions including the Southern Hemisphere. The most coherent BDO precipitation pattern common to the CMAP and reanalysis features significant anomalies over the tropical (10°-30°N), central (30°-50°N) and northern (50°-70°) North Pacific with alternating polarities. The influence of the BDO on Hawaii winter droughts and salinity in the North Pacific is discussed.