Water Vapor and Water Vapor Isotopic Evolution Over the Contiguous United States in Summer

Water vapor plays a significant role in the radiative and dynamical balance of the upper troposphere and lower stratosphere (UT/LS) and is a key constituent in determining this region’s response to climate forcing. The concentration of water vapor in the stratosphere also impacts the dosage of UV radiation reaching the surface through water’s control of heterogeneous stratospheric ozone depletion. Satellite measurements from MLS and ACE-FTS show a distinct hot spot of water vapor over parts of North America and sometimes over Asia, both associated seemingly with the monsoonal regions. During the Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) campaign the NASA ER-2 made high resolution measurements of water vapor, it’s isotopologues, as well as a variety of tracers and meteorological variables both in background air and after recent and aged convection. Flights were conducted over two years and throughout the late spring and summer periods. Using this unprecedented data set we examine the evolution of water vapor over the contiguous United States to better understand the dominant mechanisms that control its concentration including exploring the relationship between the strength of the monsoon and the enhancement in water vapor.