The growth rate function is necessary to determine the energy transfer from wind to waves. Analytically, the growth rate function is determined from the Phillips model, for which the mean velocity profile over water surface is important. The analytical model of Phillips using logarithmic form of the mean velocity profile has not been successful. In the present study, two different mean velocity profile models have been used. One of them, based on a mixing length formulation, is found to be appropriate. This profile is related to the sea state, through two approaches, thus enabling the growth rate function from the analytical model to be linked to the sea state. The growth rate function obtained from the analytical model, using this profile, is found to be comparable to that obtained from empirical relations based on pressure measurements when a correction is made to one of the Phillips coefficients. / M.S.

The nature and effects of windy conditions in a city are first discussed, recording meteorological data are introduced, and existing criteria for the acceptability of a wind environment with regard to pedestrian comfort are described. General features of wind-tunnel techniques are reviewed. A study of the wind environment at a specific site, the center of Charlotte, NC, is made by combining meteorological data taken at a nearby airport with results obtained from wind-tunnel tests conducted on a model of that specific site. Finally, conclusions are drawn concerning the consistency and applicability of currently used pedestrian comfort criteria. / Master of Science

This dissertation will specifically address the issue of improving the quality of satellite scatterometer retrieved ocean surface vector winds (OVW), especially in the presence of strong rain associated with tropical cyclones. A novel active/passive OVW retrieval algorithm is developed that corrects Ku-band scatterometer measurements for rain effects and then uses them to retrieve accurate OVW. The rain correction procedure makes use of independent information available from collocated multi-frequency passive microwave observations provided by a companion sensor and also from simultaneous C-band scatterometer measurements. The synergy of these active and passive measurements enables improved correction for rain effects, which enhances the utility of Ku-band scatterometer measurements in extreme wind events. The OVW retrieval algorithm is based on the next generation instrument conceptual design for future US scatterometers, i.e. the Dual Frequency Scatterometer (DFS) developed by NASA’s Jet Propulsion Laboratory. Under this dissertation research, an end-to-end computer simulation was developed to evaluate the performance of this active/passive technique for retrieving hurricane force winds in the presence of intense rain. High-resolution hurricane wind and precipitation fields were simulated for several scenes of Hurricane Isabel in 2003 using the Weather Research and Forecasting (WRF) Model. Using these numerical weather model environmental fields, active/passive measurements were simulated for instruments proposed for the Global Change Observation Mission- Water Cycle (GCOM-W2) satellite series planned by the Japanese Aerospace Exploration Agency. Further, the quality of the simulation was evaluated using actual hurricane measurements from the Advanced Microwave Scanning Radiometer and iv SeaWinds scatterometer onboard the Advanced Earth Observing Satellite-II (ADEOS-II). The analysis of these satellite data provided confidence in the capability of the simulation to generate realistic active/passive measurements at the top of the atmosphere. Results are very encouraging, and they show that the new algorithm can retrieve accurate ocean surface wind speeds in realistic hurricane conditions using the rain corrected Ku-band scatterometer measurements. They demonstrate the potential to improve wind measurements in extreme wind events for future wind scatterometry missions such as the proposed GCOM-W2.