P5.45
Motivating the use of remotely-sensed data sources for estimating convective momentum transports
John R. Mecikalski, CIMSS/Univ. of Wisconsin, Madison, WI
With the advent of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), and airborne and upward/downward-looking Doppler radar [ER-2-based Dopplers (EDOP) and Disdrometers] instruments, which can sense the (sub-)cumulus scale aspects of convective systems, the time has come to begin assessing momentum transport qualities using these remotely-sensed datasets. As TRMM and Doppler measurements observe convection over a range of scales, from 4 km to 10's of meters, a cloud-resolving numerical model becomes a necessary tool when attempting to construct a parameterization of convective momentum flux driven by remotely-sensed data sources. The modeled budgets of remotely observed convection are used to rigorously evaluate which terms in the momentum budget may be measureable from a given radar data set. This approach requires an understanding of the attributes of a given radar observation (ground-, aircraft-, or satellite-based).
This study will address the following: 1) Use TRMM PR, TRMM Visible and Infrared Scanner (VIRS), vertically-looking Disdrometer and downward-looking EDOP Doppler data, along with numerical model simulations of the large scale environment, to elucidate the momentum transport characteristics of tropical convective systems, and 2) Use these data to formalize a momentum transport scheme which relies on remotely-sensed data for several main inputs.
For this study, TRMM PR data are analyzed to identify the tilts and orientiations of convective updrafts for convection occurring during the TExas-FLorida UNderflights (TEFLUN-A/B) experiments. Using a cloud-resolving model of the same convection to obtain a complete momentum budget, the relative contributions of updrafts to the momentum budget (measureable with TRMM PR) are determined. This is followed by an analysis of Disdrometer and EDOP data to obtain further information on the modeled convection's real structure at fine resolution (~30 m) based on Doppler reflectivities and velocities, and cloud microphysical properties. A parameterization scheme for momentum flux which relies on radar data as input, in addition to information from the large scale environment (i.e vertical wind shear, inertial stability), will be the end result. Such a parameterization will be validated and refined using real observations collected during recent field experiments (e.g., CAMEX-3), and by numerical simulations. Constructing the momentum transport parameterization for realtime use is the plan.
Poster Session 5, New Technology and Methods (Continued)
Thursday, 18 October 2001, 9:15 AM-11:00 AM
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