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An intensified seasonal transition in the Central U.S. that enhances summer drought
Author(s) -
Wang S.Y. Simon,
Santanello Joseph,
Wang Hailan,
Barandiaran Daniel,
Pinker Rachel T.,
Schubert Siegfried,
Gillies Robert R.,
Oglesby Robert,
Hilburn Kyle,
Kilic Ayse,
Houser Paul
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2014jd023013
Subject(s) - climatology , environmental science , precipitation , troposphere , shortwave radiation , atmospheric sciences , subsidence , trough (economics) , geology , geography , meteorology , radiation , paleontology , physics , quantum mechanics , structural basin , economics , macroeconomics
In the long term, precipitation in the Central U.S. decreases by 25% during the seasonal transition from June to July. This precipitation decrease has intensified since 1979 and such intensification could have enhanced spring drought occurrences in the Central U.S., in which conditions quickly evolve from being abnormally dry to exceptionally dry. Various atmospheric and land reanalysis data sets were analyzed to examine the trend in the June–July seasonal transition. The intensified deficit in precipitation is accompanied by increased downward shortwave radiation flux, tropospheric subsidence, enhanced evaporative fraction, and elevated planetary boundary layer height, all of which can lead to surface drying. The change in tropospheric circulation was characterized by an anomalous ridge over the western U.S. and a trough on either side—a pattern known to suppress rainfall in the Central U.S. This trending pattern shows similarity with the progression of the 2012 record drought.