Convective Events and Water Vapor Transport during the North American Monsoon GPS Hydrometeorological Network Experiment 2017

Outbreaks of deep convective activity during the North American Monsoon in northwestern Mexico and the southwestern U.S. are critically dependent on strong fluxes of moisture (e.g., Gulf Surges), topographically generated diurnal circulations, as well as dynamical forcing mechanisms such as upper-level troughs. Given the generally sparse observational networks in northern Mexico, identifying and quantifying moisture source regions for these outbreak is difficult. Debates over moisture regions have arisen again in recent years, several arguing for the increased importance of transport from the Gulf of Mexico/Central America and the Atlantic Ocean, relative to the Pacific Ocean/Gulf of California. The North American Monsoon GPS Hydrometeorological Network 2017, an international collaborative, ~3-month campaign, between several Mexican and U.S. institutions was strongly motivated by this debate as well as understanding terrrestrial surface and vegetation influences on deep convection.

In this presentation, we briefly describe the North American Monsoon GPS Hydrometeorological Network 2017 and then present results with respect to deep convective outbreaks over the the Network region (~ 27N-32N, 105W-115W) as well as the “Chiricahua Gap” region (Ralph and Galarneau 2017 MWR). Distributions of widespread deep convective events in terms of “intensity” are generated employing GOES satellite IR, precipitation intensity measured at Network sites, as well as lightning Vaisala GLD 360 data. Water vapor transport is then determined in terms of convective events intensity, both statistically and through direct calculation, employing the 10 experimental GPS meteorological sites as well as TLALOCNet and Suominet GPS-Met sites in addition to regional radiosondes. The proof-of-concept campaign is part of a larger US-Mexico research effort to quantify water vapor fluxes, understand sources of advected versus surface fluxes of water vapor, and improve the understanding of convection and the hydrological cycle in the arid and semi-arid zones of the North American Monsoon.

Ralph, F.M. and T.J. Galarneau, 2017: The Chiricahua Gap and the Role of Easterly Water Vapor Transport in Southeastern Arizona Monsoon Precipitation. J. Hydrometeor., 18, 2511–2520, https://doi.org/10.1175/JHM-D-17-0031.1