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This page contains a single entry from the blog posted on April 18, 2012 8:10 AM.

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MS Defense - Jaime Compton

Jaime successfully defended his Masters thesis on April 18, 2012.

Determination of Planetary Boundary Layer Height from Ground Based Wind Profiler and Lidar Measurements using the Covariance Wavelet Transform (CWT)

This thesis documents the application of the Covariance Wavelet Transform (CWT) to lidar and, for the first time to our knowledge, wind profiler data to examine the possibility of accurate and continuous planetary boundary layer height (PBLH) measurements on short temporal resolution (one and fifteen minute averages respectively). Comparisons between PBLHs derived from the Elastic Lidar Facility (ELF) through application of the CWT and daytime radiosonde launches from Beltsville and RFK Stadium as part of the September 2009 NOAA/ARL and NCEP field study show an R2 = 0.84 correlation. PBLHs from ELF aided in diagnosing issues with the automatic PBLH calculation from Aircraft Communications Addressing and Reporting System (ACARS) profiles in the Real-Time Mesoscale Analysis used by plume dispersion modelers.

The lowest two kilometers of the atmosphere are only probed infrequently in time and sparsely in the United States. In particular, the 00Z and 12Z launches of radiosondes are particularly ill-posed to obtain PBLH mixing, and depth at the peak of the heating cycle in the daytime. This is reflected by comparisons between PBLHs from ELF and PBLHs from radiosonde launches from Dulles International Airport and Aberdeen Proving Ground at 00 and 12Z which show a R2 = 0.39 correlation.

Determining the mixing in the PBL was one goal of a study of the spatial and diurnal variations of the PBL height over Maryland for July 2011, during NASA’s Earth Venture mission DISCOVER-AQ. A semi-automated PBLH detection algorithm utilizing the CWT for wind profiler data was developed. This algorithm was tested on data from the 915 MHz wind profiler at Beltsville, Maryland, and compared against PBLHs derived from ground based radiosondes measured at Beltsville. Comparisons were also done between PBLHs derived from ground based lidars at UMBC and Beltsville. Results from the comparison show an R2 = 0.87, 0.89, and 0.91 correlation between the radiosonde PBLHs and the lidars and wind profiler PBLHs, respectively.

Accurate determination of the PBLH by applying the CWT to lidar and wind profilers will allow for improved air quality forecasting and understanding of regional pollution dynamics.

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