Generated using version 3.2 of the official AMS L ATEX template 1 2 Dynamical causes of the 2010/11 Texas-northern Mexico drought 3

• Main Authors: Richard Seager, Lisa Goddard
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pacific; North Atlantic; North Atlantic oscillation
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.307.9227; http://www.ldeo.columbia.edu/res/div/ocp/drought/PDFS/Seager_etal_TexMex.pdf

The causes of the Texas-northern Mexico drought during 2010-11 are examined using observations, reanalyses and model simulations. The drought began in fall 2010 and winter 2010/11 as a La Niña event developed in the tropical Pacific Ocean. Climate models forced by observed sea surface temperatures (SSTs) produced dry conditions in fall 2010 through spring 2011 strongly influenced by transient eddy moisture flux divergence related to a northward shift of the Pacific-North America storm track, typical of La Niña events. In contrast the observed drought was not associated with such a clear shift of the transient eddy fields and instead was significantly influenced by internal atmospheric variability including the negative North Atlantic Oscillation of winter 2010/11 which created mean flow moisture divergence and drying over the southern Plains and southeast. The models suggest that drought continuation into summer 2011 was not strongly SST-forced. Mean flow circulation and moisture divergence anomalies were responsible for the summer 2011 drought, arising from either internal atmospheric variability or a response to dry summer soils not captured by the models. Summer of 2011 was one of the two driest and hottest summers over recent