Date of Award

3-1997

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

Michael K. Walters, PhD

Abstract

This thesis looked at using new relative humidity (RH) climatologies to improve the Air Force Global Weather Center's (AFGWC) contrail forecasts. To study the effect of the new RH climatolgies, the currently used empirical relative humidity (RH) profile is replaced with a more accurate climatological one, the Stratospheric And Gaseous Experiment II (SAGE II). The study begins by examining accuracy and bias of forecast contrail bases generated by the empirical and SAGE II RH profiles on 42 days. Both sets of forecast bases are shown to be statistically similar with a series of hypothesis tests. Additional RH profiles, from 0% to 100%, are then tested to gage their effect on forecast base. Again, little statistical difference in forecast bases are noted between the additional pro files. In general, a high forecast base bias is shown for contrail algorithms derived from the Appleman theory. This thesis also reveals the dependence of forecast bases on RH and lapse rate. Lapse rates ranging from 20C/km to 90C/km and forecast bases generated by RH values of 0% and 100% are used to show how RH variations of more than 30% may only vary forecasts by less than 1,000 feet. The thesis demonstrated the AFGWC cannot improve its contrail forecasts by using a more accurate climatological RH profile, the AFGWC contrail forecast algorithm has an inherent high forecast base bias, and the degree to which forecast bases are affected by RH greatly depends on the atmospheric lapse rate.

AFIT Designator

AFIT-GM-ENP-97M-08

DTIC Accession Number

ADA323228

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