The realtime value of combined upper tropospheric inertial stability measurements and satellite-derived winds on tropical cyclone and convection forecasting
John R. Mecikalski, CIMSS/Univ. of Wisconsin, Madison, WI; and C. S. Velden
Beginning in early 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 and tropical cyclones. Recent studies have identified the strong influence regions of low upper tropospheric potential vorticity (i.e. low inertial stability) have on the invigoration of 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 and intensity changes of tropical cyclones, and 3) evaluate the value of upper tropospheric, isentropic inertial stability (340-365 K) for forecasting the behavior, intensity and momentum transports of deep convection in the tropics.
Preliminary results show 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. Our results will be reported on at the conference.
Poster Session 3, Operational Applications
Tuesday, 16 October 2001, 9:15 AM-11:00 AM
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