HR: 1400h
AN: H53C-01    [Abstracts]
TI: Midsummer Drought in Mexico and Central America and its Relationship With the Eastern Pacific Gap Winds
AU: * ROMERO-CENTENO, R
EM: rosario@atmosfera.unam.mx
AF: CENTRO DE CIENCIAS DE LA ATMOSFERA UNIVERSIDAD NACIONAL AUTONOMA DE MEXICO, CIRCUITO EXTERIOR S/N, CIUDAD UNIVERSITARIA, DEL. COYOACAN, MEXICO CITY, DF 04510, Mexico
AU: ZAVALA-HIDALGO, J
EM: jzavala@atmosfera.unam.mx
AF: CENTRO DE CIENCIAS DE LA ATMOSFERA UNIVERSIDAD NACIONAL AUTONOMA DE MEXICO, CIRCUITO EXTERIOR S/N, CIUDAD UNIVERSITARIA, DEL. COYOACAN, MEXICO CITY, DF 04510, Mexico
AU: RAGA, G
EM: raga@servidor.unam.mx
AF: CENTRO DE CIENCIAS DE LA ATMOSFERA UNIVERSIDAD NACIONAL AUTONOMA DE MEXICO, CIRCUITO EXTERIOR S/N, CIUDAD UNIVERSITARIA, DEL. COYOACAN, MEXICO CITY, DF 04510, Mexico
AB: The low-level circulation in the Northeastern Tropical Pacific (NETP) is affected by three main wind systems: the northerly and southerly trade winds and the wind jets coming through the Tehuantepec, Papagayo and Panama mountain gaps. The seasonal and intraseasonal evolution of these wind systems determines the low-level circulation over the NETP on these timescales. QSCAT wind data (July 1999-December 2006) show that the low- level circulation over the central region of the NETP is mainly directed westward from November to May and undergoes wind direction changes during summer, from weak westerlies in June to easterlies in July and August and changing back to westerlies in September-October. This change in the circulation pattern during midsummer is associated with the Tehuantepec and Papagayo wind jets, which slightly strengthen favored by the westward elongation and intensification of the Azores-Bermuda high. There is a high correlation, in the seasonal, monthly and synoptic timescales, among the zonal winds over the central region of the NETP, the Tehuantepec and Papagayo wind jets, the meridional pressure gradients in the Isthmus of Tehuantepec and the Caribbean Sea, and the precipitation rates in central-southern Mexico and Central America, where the midsummer drought occurs. The westward low-level circulation observed over the central-eastern region of the NETP during midsummer, that occurs simultaneously with the strengthening of the wind jets, induces westward moisture fluxes in the lower layers of the atmosphere, displaces convergence areas away from the coasts, and causes the relatively strong convergence in the easternmost NETP to remain confined south of the area of influence of the wind jets and associated westward winds over the central NETP. These factors determine, to a large extent, the midsummer drought in central-southern Mexico and Central America.
DE: 1807 Climate impacts
DE: 1812 Drought
DE: 1840 Hydrometeorology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
DE: 1854 Precipitation (3354)
SC: Hydrology [H]
MN: 2007 Joint Assembly