Dust observations in El Paso, Texas during the 2005 North American Monsoon season

Previous statistical analyses of historical precipitation and dust storm frequency data, performed by the authors, suggest an anti-correlation between these two parameters in El Paso Del Norte. Precipitation during the North American Monsoon appears to be significantly reduced in the presence of dust storms. During the 2005 North American Monsoon season, a possible link was examined between dust storms and precipitation in El Paso Del Norte. An analysis of surface observations of mineral aerosols, aerosol optical depth, and precipitation is presented. Surface aerosol number densities were obtained using the CLIMET CI-550 laser particle counter. Moreover, aerosol optical depths were inferred from spectral measurements of solar irradiances utilizing the MFRSR multi-filter rotating shadowband radiometer. Precipitation data was obtained from the National Weather Service and Comisión Internacional de Limites y Aguas (México). In addition, total columnar aerosol size distributions were derived using the University of Texas at El Paso Inversion Code. Case studies were selected among clear and dusty days and the differences in precipitation amounts, aerosol optical depths, surface dust concentrations, and columnar size distributions were compared. These data sets were used to evaluate the evolution of aerosol number densities in the presence of the monsoon and to determine whether summertime precipitation events associated with the monsoon were suppressed when surface and columnar dust concentrations were high.