FORECAST VERTICAL VELOCITY AND TEMPERATURE, HORIZONTAL WIND DIRECTION, AND WIND VELOCITY ERROR COUPLING WITHIN UPPER TROPOSPHERE

Date

2012-12

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Abstract

The Pennsylvania State University (PSU) Fifth Generation Mesoscale Model (MM5) and Weather Research and Forecasting (WRF) models have predicted temperature, horizontal wind direction, and velocity for aviation purposes. In situ observations have not been utilized to assess MM5 and WRF upper troposphere temperature, horizontal wind direction, and velocity prediction. Regression analysis of MM5 and WRF forecast and aircraft observed data from seven flights in February and April 2009 over North America, Europe, and Southwest Asia between 6000-7600 meters above sea level indicated temperature, horizontal wind direction, and velocity errors were coupled to forecast vertical velocities less than 100 kilometers laterally of the modeled flight tracks between 39-59 degrees north latitude. Temperature error and forecast vertical velocity coupling occurred over land, surface elevations of 0-499 meters above sea level, different vegetative, and urban surface type in MM5 and WRF forecasts. Horizontal wind direction and forecast vertical velocity coupling was indicated in WRF forecasts over land, water, and surface elevations of 400-499 meters above sea level. Horizontal wind velocity and forecast vertical velocity coupling was found over land, inversely over water, surface elevations of 100-199 meters above sea level, and non-urban surface type in MM5 and WRF forecasts between 0-99, 400-499, and 700-999 meters above sea level. Temperature and forecast vertical velocity coupling in MM5 and WRF forecasts may stem from erroneous long wave radiation upwelling parameterization, evapotranspiration errors in the land surface model, and entrainment in the cumulus parameterization schemes. Incorrect model parameterization schemes may be affecting temperature differentials across frontal zones erroneously forecasting vertical velocity causing horizontal wind direction and velocity coupling to forecast vertical velocity in MM5 and WRF forecasts.

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Keywords

Weather Research and Forecasting (WRF), MM5, Aircraft, Upper Troposphere, Temperature, Wind Velocity, Wind Direction, In-situ observations

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