The Patterns of Meteorological Fields to Identify Intraseasonal Precipitation Variability in Central America

The intraseasonal variability of precipitation in Central America is dominated by the midsummer drought (MSD). This important feature of the regional climate exhibits strong interannual variability and a close relationship with large-scale climate modes, such as the El Niño-Southern Oscillation (ENSO), Caribbean low-level jet (CLLJ), mountain-gap winds. We investigate the intraseasonal variability of the MSD and associated wind anomalies using NASA’s Tropical Rainfall Measuring Mission (TRMM) precipitation and wind observations from Multiangle Imaging RadioSpectrometer (MISR) and Quick Scatterometer (QuikSCAT) between 1998 and 2013. A strong interannual variability of MSD is found, and, more than one MSD events may occur during a single rainy season. Intensity of the North Atlantic Subtropical High, easterly wind at low troposphere, and anomalies of moist static energy in the eastern Nicaragua and Costa Rica are all related to the interannual variability of the MSD. The MISR cloud motion vectors and Qukscat surface winds illuminate the balanced convection related to the MSD over the Pacific Coast of Central America. Our results indicate that accurate representation of the Central American mountain-gap winds in Mexico and Nicaragua is critical in simulating the intraseasonal variability of precipitation over the region.