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Summertime moisture divergence over the southwestern US and northwestern Mexico
Author(s) -
Anderson Bruce T.,
Roads John O.
Publication year - 2001
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 - 10.1029/2001gl012903
Subject(s) - divergence (linguistics) , moisture , precipitation , climatology , advection , monsoon , environmental science , water content , atmospheric sciences , geology , geography , meteorology , thermodynamics , philosophy , linguistics , physics , geotechnical engineering
This paper investigates large‐scale summertime moisture divergence associated with the southwestern branch of the North American monsoon. Diagnostic hydrologic estimates taken from thirty‐three years of seasonal mean reanalysis data indicate that over most of the southwestern United States and northwestern Mexico there is positive vertically‐integrated columnar (i.e. three dimensional) moisture divergence above approximately 700 mbar, implicitly suggesting that mid‐level moisture convergence related to advection from remote source regions cannot support seasonal mean precipitation over the southwestern US. Furthermore, estimates of the horizontal component of this moisture divergence indicate that the southwestern US is actually one of the largest upper‐air (<700 mbar) sources of moisture for the North American continent.