Analysis of the East Asian cold surge using a 15-year Navy data set

Abstract

The East Asian winter monsoon cold surge is examined using Navy tropical Global Band Analysis data for January-March of 1975-1988. Multiple-set Canonicle Correlation (MCC) analysis, single-point correlation analysis, and composite analysis are used to determine the the cold surge structure over a broad domain that includes the western Pacific and eastern Indian ocean. The results show that the structure of the cold surge is manifested in MCC modes 1 and 2 of surface V calculated over both the East and South China Seas. Single-point correlation and composite analyses indicate that the surge can be viewed as a single mode over a rather broad region, with an average period of 8 days, that includes simultaneous eastward propagating longwaves across the East China Sea and northwestern Pacific, and equatorward propagating surge waves across the South China Sea. Composite analyses during strong events also reveal cross-equatorial surge influence present at low levels and increases in divergence over the maritime continent at 200 hPa. MCC modes 3 and 4 calculated over a small spatial domain that includes the East China Sea describe 3-day eastward propagating waves with wavelengths on the order of 1500-2000 km. Associated with these shorter waves are modest surge waves that also propagate equatorward across the South China Sea.