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On the Role of Pacific‐Atlantic SST Contrast and Associated Caribbean Sea Convection in August–October U.S. Regional Rainfall Variability
Author(s) -
Kim Dongmin,
Lee SangKi,
Lopez Hosmay,
Foltz Gregory R.,
Misra Vasubandhu,
Kumar Arun
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl087736
Subject(s) - climatology , precipitation , baroclinity , anomaly (physics) , subtropics , sea surface temperature , diabatic , oceanography , convection , geology , subtropical ridge , environmental science , geography , meteorology , physics , condensed matter physics , fishery , adiabatic process , biology , thermodynamics
This study investigates the large‐scale atmospheric processes that lead to U.S. precipitation variability in late summer to midfall (August–October; ASO) and shows that the well‐recognized relationship between North Atlantic Subtropical High and U.S. precipitation in peak summer (June–August) significantly weakens in ASO. The working hypothesis derived from our analysis is that in ASO convective activity in the Caribbean Sea, modulated by the tropical Pacific‐Atlantic sea surface temperature (SST) anomaly contrast, directly influences the North American Low‐Level Jet and thus U.S. precipitation east of the Rockies, through a Gill‐type response. This hypothesis derived from observations is strongly supported by a long‐term climate model simulation and by a linear baroclinic atmospheric model with prescribed diabatic forcings in the Caribbean Sea. This study integrates key findings from previous studies and advances a consistent physical rationale that links the Pacific‐Atlantic SST anomaly contrast, Caribbean Sea convective activity, and U.S. rainfall in ASO.