Date of Award

5-23-2013

Document Type

Restricted Access Thesis

Degree Name

Master of Science in Applied Meteorology

Department

Department of Atmospheric Sciences and Chemistry

Thesis Advisor

James P. Koermer

Committee Member

Eric G. Hoffman

Committee Member

John B. Eylander

Abstract

The ability for meteorologists to predict icing events is severely limited due to the complexity of the phenomena, which is unfortunate given the potential for vast economic impact as a result of ice accretion on air planes, electrical wires and other manmade structures. The goal of this study is to utilize a mathematical model that can consistently and accurately predict low level icing intensity in cold, alpine environments at any time based upon Global Forecast System(GFS)initialization. This was achieved by linking the Advanced Research Weather Research and Forecasting(WRF) model and the NASA developed the LEWis ICE (LEWICE) ice accretion software to produce a mathematical forecast for ice events, specifically in the White Mountain Range in New Hampshire. Initialized with the GFS forecast data, the Advanced Research WRF (ARW) is used to calculate a 12-hour forecast and export the results to the LEWICE. The LEWICE software utilizes the ambient temperature, wind speed, outside pressure, and liquid water content from the ARW forecast at the 0, 3, 6, 9, 12 hour time steps after forecast initialization, and calculates icing intensity over the 45 minutes after the start of the hour assuming constant meteorological conditions. The theoretical ice would be accreted onto a cylindrical object within LEWICE to mimic the in situ measurements from three ice detectors on three mountains in the White Mountain Region of New Hampshire. The three ice detectors will continually record ice accretion data through the 2011-2012 winter. These data will be compared directly to the output of the ARW/LEWICE linked model to determine accuracy of the model. Also, sensitivity testing will be performed on the moisture microphysics schemes to determine whether one microphysics scheme performed better in resolving the icing conditions. This study concluded that the microphysics scheme used made little difference in the amount of ice accreted on the cylinder over the 45 minute accretion period over any of the icing scenarios examined. The differences between the six schemes were on average, less than 5% for any given time step. In terms of the amount of ice accreted, the model did predict the ice accretion when ice was recorded on Mount Washington. Although not entirely accurate, the amount of ice was generally the same being well within the same order of magnitude. This preliminary success with the first attempt at a mathematical icing model bodes well for the future of ice accretion models and their abilities to accurately predict icing scenarios.

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