WRF Simulations of Water Vapor Content for TC Ingrid (September 2013)

Atmospheric water vapor is a potent greenhouse gas, and its variations in the upper troposphere and lower stratosphere (UTLS) have important climate impacts. The water vapor budget of tropical cyclones (TCs) and their impact on the UTLS remain understudied. This paper describes high-resolution simulations of TC Ingrid during September 2013 using the Weather Research and Forecasting (WRF) model to calculate the water vapor budget. Using Ingrid as an example provides a better understanding of water vapor transport into the UTLS by TCs, helping to answer a question posed during NASA’s Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling through Regional Surveys (SEAC4RS), specifically whether water vapor transport in TCs hydrates or dehydrates the UTLS. Our WRF simulations of TC Ingrid closely correspond to the National Hurricane Center’s Best Track data. We also evaluate model results of the water vapor budget with in situ airborne data of Ingrid collected during the SEAC4RS mission. Satellite imagery also is used to validate the simulated structure of Ingrid. We show spatial and temporal changes of UTLS water vapor throughout Ingrid's lifecycle to determine whether and how TCs hydrate or dehydrate the UTLS. Results show that TCs do transport large quantities of water vapor into the UTLS, and overshooting deep convection is an especially potent transport method. The paper sheds light on mechanisms that inject water vapor into the UTLS and on the widespread horizontal and vertical transports of water vapor within TCs.