4C.2
Structure of the highly sheared tropical storm chantal during camex-4
Gerald M. Heymsfield, NASA/GSFC, Greenbelt, MD; and J. B. Halverson, M. L. Black, F. D. Marks, E. J. Zipser, L. Tian, L. Belcher, P. Bui, and E. Im
On 20 August 2001 during the Convection and Moisture Experiment 4 (CAMEX-4), the NASA ER-2 and DC-8, and NOAA P3 aircraft conducted a coordinated Quantitative Precipitation Estimation (QPE) mission focused on convection in Tropical Storm Chantal. The storm was westward moving and was forecasted to intensify and to landfall near the Mexico-Belize border late on 20 August. Chantal failed to intensify and instead exhibited a highly sheared structure with the an open low-level circulation and intense convection well to the northeast of this circulation center. The paper focuses on the wind and precipitation structure in this convective region to gain insight on why this storm did not develop as expected. This preliminary work will use a blend of aircraft and satellite observations to describe the three-dimensional structure of this sheared storm.
The NASA and NOAA aircraft initially performed an asymmetric “figure 4” pattern to sample the vortex and precipitation region, and then focused on the rain band to the northeast of the circulation center. The ER-2 Doppler Radar (EDOP) and DC-8 Precipitation Radar (PR-2) made several passes over the intense convection, while the P3 covered this same region with its radars. The downlooking NASA radars provided high vertical resolution information on Chantal’s rain region and highly active convection. The convection sampled continued during the aircraft flights with tops up to 17 km, updrafts exceeding 15 m/s, and overshooting of the tropopause. The preliminary analyses show interesting wind structure, with strong horizontal wind shears and a pronounced upper-level divergent outflow region across the convective region. The precipitation and wind structure provided by the NASA aircraft will be described within the context provided by the NOAA P3 radar measurements.
Session 4C, HL2001/CAMEX-4
Tuesday, 30 April 2002, 8:30 AM-10:30 AM
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