Mapping the spatial extent of the Central American mid-summer drought with MODIS and GOES imagery

Many parts of Central America and southern Mexico experience an extended dry period within the longer period of summer rains. This mid-summer drought (MSD), usually during July and August, shows a complicated spatial structure, reflecting the interaction of the large-scale synoptic flow and the varied topography of the region. We have used MODIS imagery (250 m resolution) and GOES 10 km imagery for the years 1983 to 2006 to describe the spatial structure of the cloudiness associated with the MSD. Compositing results using specific periods and also by using different indices (trade wind intensity and cloudiness over specific domains) will be shown. The importance (and challenge) of identifying suitable indices that represent the MSD will be discussed.