Prevailing Synoptic Patterns for Persistent Positive Temperature Anomaly Episodes in the United States

서지정보

· 발행기관 : 대한지리학회
· 수록지 정보 : 대한지리학회지 / 43권 / 5호 / 701 ~ 714페이지
· 저자명 : 최종남, 최광용, Thomas Williams

초록

This study examines the prevailing synoptic-scale mechanisms favorable for long-lived summer Persistent
Positive Temperature Anomalies (PPTAs) as well as winter PPTAs in the United States. Such long-lived PPTAs usually
occur in the south-central region of the United States in summer, but in the southwestern part of the United States in
winter. Composite analyses of surface and pressure level data demonstrate that the formation of both winter and
summer PPTAs is closely related to the movement of subtropical high pressure systems in the Pacific Ocean and
Atlantic Ocean, respectively. The occurrence of long-lived summer PPTAs usually coincides with an extremely stable
atmospheric condition caused by persistent blocking by mid- to upper-tropospheric anticyclones. Significant surface
forcing is also easily identified through relatively high Bowen ratios at the surface. Warm air advection is, however,
weak and appears to be an insignificant element in the formation of long-lived summer PPTAs. On the other hand,
synergistic warming effects associated with adiabatic heating under an anticyclonic blocking system as well as
significant warm air advection characterize the favorable synoptic environments for long-lived winter PPTAs. However,
the impact of surface forcing mechanisms on winter PPTAs is insignificant.

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