期刊
MONTHLY WEATHER REVIEW
卷 138, 期 9, 页码 3454-3473出版社
AMER METEOROLOGICAL SOC
DOI: 10.1175/2010MWR3362.1
关键词
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资金
- NOAA [NA07WA0458]
- National Science Foundation [ATM-0434189]
- Div Atmospheric & Geospace Sciences
- Directorate For Geosciences [0935830] Funding Source: National Science Foundation
This observational study investigates statistical and synoptic-dynamic relationships between regime transitions, defined as a North Atlantic Oscillation (NAO) or Pacific-North American pattern (PNA) index change from at least a 1 standard deviation anomaly to at least a 1 standard deviation anomaly of opposite sign within 7 days, and cool-season (November-April) northeastern U.S. (NE) precipitation. A statistical analysis is performed of daily cool-season NE precipitation during all NAO and PNA transitions for 1948-2003, and a composite analysis and case study of a major cool-season NE precipitation event occurring during a positive-to-negative NAO transition are conducted. Datasets used are the 0.25 degrees NCEP Unified Precipitation Dataset, the 2.5 degrees NCEP-NCAR reanalysis, and the 1.125 degrees 40-yr ECMWF Re-Analysis (ERA-40). Results of the statistical analysis suggest that cool-season NE precipitation tends to be enhanced during positive-to-negative NAO and negative-to-positive PNA transitions, and suppressed during negative-to-positive NAO and positive-to-negative PNA transitions. Of the four types of regime transitions, only the positive-to-negative NAO transition is associated with substantially more frequent major cool-season NE precipitation events compared to climatology. Results of the composite analysis and case study indicate that a surface cyclone and cyclonic wave breaking associated with the major NE precipitation event can help produce a high-latitude blocking pattern over the North Atlantic characteristic of a negative NAO pattern via thermal advection, potential vorticity transport, and diabatic processes.
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