A method for estimating momentum fluxes of deep precipitating convection using profiling Doppler radar

Abstract

[1] This paper outlines a novel approach for obtaining estimates of momentum fluxes for deep precipitating convection. This method relies on data collected by vertically incident profiling Doppler radars but may be applied to aircraft-or space-based radar systems. This work represents a significant step forward toward the evaluation of convective momentum transports across regional scales using data from operational satellite systems (e.g., the Tropical Rainfall Measuring Mission (TRMM) instrument . The method is tested against numerically simulated convection using the University of WisconsinNonhydrostatic Modeling System (UW-NMS) mesoscale and cloud-resolving model. The radar-estimated momentum fluxes are found to match in sign and relative magnitude through the depth of the convective clouds studied compared to those obtained from model simulation.

Estimating convective momentum fluxes using geostationary satellite data

“…Therefore, the use of this model is very appropriate for the simulation of atmospheric convection. The convective momentum budgets produced by the UW‐NMS are domain averaged without the Coriolis terms included [ Mecikalski , 2003]. The momentum budget is given by This equation is ideal for numerical simulations because the first term on the right‐hand side (RHS) closes off the calculation on a square grid, which represents the horizontal advection across the model domain.…”

“…Therefore, the use of this model is very appropriate for the simulation of atmospheric convection. The convective momentum budgets produced by the UW-NMS are domain averaged without the Coriolis terms included [Mecikalski, 2003]. The momentum budget is given by…”

“…Despite the extensive historical research on evaluating momentum fluxes and transports in deep convection using mainly in situ measurements and numerical simulations, it remains a quantity that is difficult to estimate. Numerous studies describe procedures for computing these fluxes from aircraft measurements of wind [ Zipser et al , 1981; LeMone , 1983; LeMone et al , 1984], as well as from airborne and ground‐based Doppler data [e.g., Jorgensen et al , 1991; Zrnic et al , 1993; Matejka and Bartels , 1996; Mecikalski , 2003]. Most of the observational studies are the result of aircraft flights within and near deep convective storms.…”

“… Mecikalski [2003] outlines a method for estimating the horizontal wind perturbations from the RD‐69 Disdromet disdrometer calibrated UHF 915 MHz profiler. This technique correlates the first‐order signals of updraft tilt and precipitation fall angle relative to Earth with the gross momentum transport character of the radar‐observed convection.…”