The North American Monsoon GPS Transect Experiment 2013

Abstract

Northwest Mexico experiences large variations in water vapor on seasonal time scales in association with the North American monsoon (NAM), as well as during the monsoon associated with upper tropospheric troughs, mesoscale convective systems, tropical easterly waves and tropical cyclones. Together these events provide more than half of the annual rainfall to the region. A sufficient density of meteorological observations is required to properly observe, understand and forecast the important processes contributing to the development of organized convection over northwest Mexico. Stability of observations over long time periods is also of interest to monitor seasonal and longer timescale variability in the water cycle. For more than a decade the United States Global Positioning System (GPS) has been used to obtain tropospheric precipitable water vapor (PWV) for applications in the atmospheric sciences. There is particular interest in establishing these systems where conventional operational meteorological networks are not possible due to lack of financial or human resources to support the network. Here, we provide an overview of The North American Monsoon GPS Transect Experiment 2013 in northwest Mexico for the study of mesoscale processes and the impact of PWV observations on high-resolution model forecasts of organized convective events during the 2013 monsoon season. Some highlights are presented, as well as a look forward at GPS networks with surface meteorology (GPS-Met) planned for the region that will be capable of capturing a wider range of water vapor variability in both space and time across Mexico and into the Southwest United States.