PhD Proposal: Brian Carroll
TITLE: Observations of Low-level Jet Physics and Impacts
ABSTRACT: A low-level jet (LLJ) is a nocturnal lower-tropospheric wind speed maximum. LLJs are known to occur frequently in many locations around the world, and can span 300 km or more in length and width. LLJ advection of moisture and heat as well as convergence at jet termination promotes convection, and thus LLJs are known to be linked to mesoscale convective systems in some regions. High wind speeds also facilitate long-range transport and mixing down of atmospheric constituents to affect air quality and other surface variables.
Despite their importance, theoretical and forecasting models have historically had difficulties with accurately representing LLJs. A new unified theoretical model and recent advances in the Weather Research and Forecasting (WRF) model show promise for better representation of LLJs. This research will utilize recent intensive remote sensing and in situ observations to evaluate current models. Data from the Plains Elevated Convection at Night (PECAN) field campaign will also be used to study aspects of jet formation and impacts. Relationships between measured daytime boundary layer and evening transition properties and subsequent LLJ characteristics will be investigated, as they directly affect jet formation. The breadth of the data set also provides the opportunity for a six-week statistical study of LLJ moisture transport over the Great Plains with unprecedented high resolution.