HR: 15:30h
AN: A33B-07    [Abstracts]
TI: Investigating the regional influence of the monsoonal convection in Northwest Mexico
AU: * barlow, m
EM: Mathew_Barlow@uml.edu
AF: University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854, United States
AU: Hoell, A
EM: andrew.hoell@gmail.com
AF: University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854, United States
AB: The influence of the monsoonal convection in Northwest Mexico on regional circulation and rainfall is examined by increasing the monsoonal convection in an atmospheric general circulation model and examining the regional impacts of that change relative to a control run with no modifications. The NCAR Community Atmospheric Model (CAM), version 3, is used as the atmospheric model and the monsoonal convection is enhanced by locally increasing the diabatic heating in the model, an approach that has proven successful in other regions. Previous research has linked the onset of the monsoonal convection in Northwest Mexico with decreased rainfall in a broad swath across the Northwest, Central, and western-Gulf Coast regions of the US. However, the dynamics of this relationship are not clear, especially the question of whether the monsoonal convection actively forces the suppression of US rainfall or whether some third factor, such as the interaction of the westerlies with the North American Cordillera, influences both regions. Here we assess the direct impact of the monsoonal convection by investigating the changes that occur when the monsoonal convection is substantially increased in the model. (Only the diabatic heating is altered in the model and only over Northwest Mexico; otherwise the model is unmodified and the circulation progresses freely.) The modified run with increased monsoonal convection over Northwest Mexico does indeed have suppressed rainfall in the Central US relative to the control run, demonstrating that the monsoonal convection can play a forcing role, at least in the model. The associated changes to regional circulation and their influence on US rainfall are examined in terms of dynamically-forced vertical motion, thermodynamically-forced vertical motion, moisture transport, and convective available potential energy.
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3314 Convective processes
DE: 3337 Global climate models (1626, 4928)
DE: 3354 Precipitation (1854)
DE: 3374 Tropical meteorology
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly