The role of the Mexican Plateau in shaping rainfall over Texas
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Previous studies have suggested that advection from the Mexican Plateau (MP) may influence rainfall over Texas in spring and summer; generally air ascends over the cordillera and descends over the southern plains. The two mechanisms may link the northern Mexico drought to Texas drought. Observations and the Community Earth System Model are used in this study to describe the 2011 Texas-northern-Mexico drought and examine the role of the MP on the hydro-climate over the southern US, providing implications for the linkage between the MP and rainfall over Texas. A control run and three experimental runs were performed with prescribed sea surface temperatures and sea ice fractions. The results show that when the MP becomes dry, rainfall declines locally and downstream. During the spring, the dry air brought to Texas by prevailing westerly winds suppresses local convection; but dry air advection from the highlands has little influence on rainfall over Texas during the summer when Texas is no longer in the downstream areas. During the summer, a warmer MP draws moist air over the peripheral low elevation areas to the highlands; it bends the low-level jet towards the highlands and an anti-cyclonic flow anomaly forms over the southern US, which causes air to diverge and tends to reduce rainfall over the southern US.