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MJO and the Record-Breaking East Coast Snowstorms in 2009/2010. Ja-Yeon Moon 1 , Bin Wang 1 , and Kyung-Ja Ha 2 1 IPRC, 2 Pusan National University. (a) OLR(Jan 31~Feb 7, 2010), GPH200 (+4days). (b) SAT, GPH850 (+4days). C. B. A. (c) OLR( A , B ), Snowfall( C ).
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MJO and the Record-Breaking East Coast Snowstorms in 2009/2010 Ja-Yeon Moon1, Bin Wang1, and Kyung-Ja Ha2 1IPRC, 2Pusan National University (a) OLR(Jan 31~Feb 7, 2010), GPH200 (+4days) (b) SAT, GPH850 (+4days) C B A (c) OLR(A, B), Snowfall(C) 1DEC 6 11 16 21 26 1JAN 6 11 16 21 26 1FEB 6 11 16 21 26 2009 2010 Intraseasonal anomalies of (a) OLR (shading) and 200hPa GPH (geopotential height, contour), (b) Surface air temperature (SAT) and 850hPa GPH, and (c) time series of area-averaged intraseaonal anomalies of OLR over “A”, “B”, and daily snowfall amount (inches) averaged over eastern US (“C”) from 1 December 2009 to 28 February 2010. The eastern United States saw several record-breaking snowfall events in the 2009/10 winter. They can be traced to the central and eastern Pacific, which experienced unusually large swings in OLR and remarkable wet-dry-wet cycles from late December to mid-February. Whenever the MJO convection reached the central Pacific, a teleconnection pattern extended to North America, resulting in a westward-tilted deep anomalous trough anchored over the eastern US, producing a low-level pressure dipole anomaly with an anticyclone (cyclone) centered at the US west (east) coast. The warm moist air from the tropics, mixed with the cold air from high-latitudes, resulted in favorable conditions for extremely heavy snowfall.