The Memphis, TN Chapter of the American Meteorological Society (AMS) held its second meeting of the 1998-1999 year on 17 November 1998. The evening commenced with a brief business meeting. Items of interest included an announcement that both the NWS and the FAA's Program Support Facility are currently hiring new personnel. Dues were also collected for the 1998-1999 academic year.

The speakers for the evening were Erik Proseus and Mark Isaminger, both employed by MIT Lincoln Laboratory. Lincoln Lab currently operates four aviation weather related research field site locations in the USA, one of which is in Memphis. Proseus' talk focused on optimizing the ITWS (Integrated Terminal Weather System) microburst detection algorithm in dry environments, while Isaminger discussed the results of optimizing the ITWS APEDIT (Anomalous Propagation Editing) algorithm. Proseus' study explores the contention that in a typically wet environment an adaptive VIL (Vertically Integrated Liquid Water) threshold would be more effective in the detection of low-reflectivity events. In dry environments, the detection algorithm performance diminishes on low reflectivity days due to extremely low VIL values. Therefore a sounding test is used to determine if the atmosphere is wet or dry Two different event validation tests are needed in a dry environment: on dry days a reflectivity test rather than a VIL test would be utilized; and on wet days, a lower VIL threshold would be used. Isaminger's presentation examined the APEDIT algorithm failure mechanisms in detail to identify possible site-adaptable parameter changes that can be used to improve the performance for mixed weather/AP events. While the current parameter set edits the majority of AP, there were cases where the performance was significantly degraded, especially if the AP returns were located near weather echoes or clear-air data in the composite maps.

By modifying the parameter set to be more aggressive resulted in a significant increase in AP editing performance with only a slight increase in the editing of weather (mostly reduced by one level) Both of these studies will also be presented at the AMS' Eighth Conference on Aviation, Range, and Aerospace Meteorology in Dallas, TX on January 10-15 1999. This was an excellent opportunity to learn more about the performance of these two critical ITWS algorithms.

Respectfully submitted,
Benjamin Boorman
Secretary / Treasurer

Minutes Approved,
Mark Isaminger
Chairman