Determination of Frontal Structure in the Mid-Atlantic Region from WSR-88DDoppler Radar Velocity Azimuth Displays

摘要

This research develops a technique for using the WSR-88D Doppler Radar to studycold air damming events in the mid-Atlantic region. Of particular use is the Velocity-Azimuth Display Wind Profile (VWP), which is a time-height plot of horizontal winds above the radar at 300 m intervals. VWPs were gathered from seven stations across the region for this study. A thermal retrieval technique is employed using the vertical wind shears obtained from VWPs, along with the thermal wind equation, to retrieve the horizontal thermal gradients triangle down, T and the associated horizontal thermal advections. VWP winds are height referenced, so the rawinsonde stations are used for conversion to pressure coordinates. Multiple height map analyses of thermal fields are constructed as well as single station time-height analyses of temperature gradients, thermal advections, and isentropes. Several methods were explored for the recovery of the horizontal temperature field from the triangle down,T-wind relationship. The retrieval technique is applied to two cold air damming events: December 18-19, 1995 and January 6-7, 1996. Both of these events were major winter storms for the east coast of the United States. The resulting thermal fields are verified by comparing them with surface analyses, NWS upper air analyses, and mesoscale model initial analyses and forecast fields. The comparisons of the retrieved thermal fields with currently available products was good, and shows the technique to be of use.