Caribbean Low Levl Jet UMD加勒比海低空急流 UMD.pptVIP

The Caribbean Low Level Jet variability during August and September and its relation with the regional hydroclimate Ernesto Mu?oz JunJul AugSep averages of 925 mb wind Strong easterly flow in Caribbean Sea during summer. CALLJ an extension of the North Atlantic trade winds amplified by regional gradients in SLP and temperature Few tidbits Low land areas of Central America are jungle. The Netherland Antilles (Aruba, Curazao) are dry and windy. Before the Pacific was called the South Ocean and the Atlantic the North Ocean The Caribbean and Central America Southern Gulf of Mexico, Isthmus and Gulf of Tehuantepec Motivation Previous studies of Caribbean hydroclimate mostly on precipitation from land stations. Lack of knowledge of role of Caribbean Low Level Jet on regional hydroclimate. Other LLJs are associated with moisture transport and downwind convection. Background (Giannini et al 2000, 2001) Giannini et al (2000, 2001) observe anomalous tropical inter-basin SLP gradient and SST gradient. Associated with less precip over Caribbean and Central America are warm Pacific and low SLPA vs cool Atlantic and high SLPA. Make association with drier Carib’n and divergence over region (except east of Costa Rica). Positive NAO in winter cools TNA SSTs that when followed by onset of ENSO in summer combines effect on less precip over Carib’n (4/6 for 1979-1999). Background (Taylor et al 2002) Taylor et al (2002) partitioned summer rainy season in a early rainy season (MJJ) and a late rainy season (ASO). Indicate that late rainfall season not affected so much by SSTA but by vertical wind shear (VWS). VWS inhibits convection. Data and Methods NARR and ERA40 reanalyses GPCP precipitation HadSST and ERSST sea surface temperature August and September anomalies from 1979-2001 climatology Calculated Caribbean Low Level Jet index as area average 12N-16N, 80W-70W. Calculated regressions and correlations Summer climatological conditions Jun-Jul and Aug-Sep averages of wind at 925 mb Str