Diagnosing tropical cyclones and deep convection using upper tropospheric inertial stability and cloud-motion wind vectors
John R. Mecikalski, CIMSS/Univ. of Wisconsin, Madison, WI; and C. S. Velden
Beginning in 2001, fields of inertial stability were being produced in realtime at the Cooperative Institute for Meteorological Satellite Studies (CIMSS). These data, combined with GOES-satellite derived winds, visible and infrared imagery from GOES and the Tropical Rainfall Measuring Mission (TRMM) Visible and InfraRed Scanner (VIRS), are used to assess the correlations and influences of inertial stability on the temporal behavior of deep convection. Recent studies have identified the strong influence regions of low upper tropospheric potential vorticity (i.e. low inertial stability) have on the invigoration of deep convection, as well on determining the structural qualities (e.g., momentum transport) of the enhanced convection. Winds derived from geostationary satellite are ideal for measuring convective outflows (and the correlation with low PV) since they measure the entire wind flow, both the balanced and especially the unbalanced components.
Specifically, this study will address the following issues as they are determined to be valuable for tropical weather forecasting: 1) assess the correlations between regions of low inertial stability (low potential vorticity; near zero PVU), convective outflows and the intensification of moist convective systems, 2) develop an understanding of the affect (both temporally and spatially) a region of low inertial stability has on influencing the anvil-level outflow characteristics of tropical cyclones, and 3) evaluate the value of areal-averaged upper tropospheric, isentropic inertial stability (340-365 K) for forecasting the behavior, intensity and momentum transports of deep convection in the tropics.
Our analysis to date suggests that regional low inertial stability can be used as to assess when and if deep convection will develop, intensify or expand in coverage. With respect to tropical cyclones, our diagnostics show promise for 0-12 hour nowcasting of storm intensity changes, especially when combined with satellite-derived winds. One end goal by summer 2002 will be a suite of realtime products that optimally present satellite-derived winds, inertial stability and satellite imagery for tropical convection forecasting. Our results will be reported on at the conference.
Extended Abstract (2.7M)
Poster Session 1, Tropical Cyclones, Large-scale Dynamics and Convection
Monday, 29 April 2002, 11:00 AM-12:30 PM
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