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Dissertation
Comparison of the first order frontal model with aircraft data and numerical simulations
Doctor of Philosophy (Ph.D.), Drexel University
1997
DOI:
https://doi.org/10.17918/00008382
Abstract
A comparison of aircraft data to the first order frontal model is made. Data collected by WP-3D research aircraft during the ERICA Field Project (Experiment on Rapidly Intensifying Cyclones Over the Atlantic) is scanned to find data recorded during constant altitude transects of atmospheric fronts. Statistics are compiled on magnitude of the change of equivalent potential temperature, potential temperature, virtual temperature, and the front normal and front parallel components of wind and on the width of the fronts. Single value decomposition of the data is performed to smooth the data and analyze the signal without the smallest scale features or noise. At least 90 percent of the signal is retained. The fronts defined by the individual components are normalized to compare with the first order frontal model. The first order frontal model is one of three zones, two constant, but different, valued zones of either equivalent potential temperature, potential temperature, virtual temperature, and the front normal and front parallel components of wind separated by a zone of strong, linear gradient of the observable. Several numerical experiments are performed using the numerical weather prediction computer model, LAMPS90 (Limited Area Mesoscale Prediction System), to simulate the development of the storm which occurred during IOP2 of ERICA (13 December 1988 to 15 December 1998). LAMPS90 has a long history of simulations using grid spacing of 140km and 70km. For this study, simulations at higher resolution (smaller grid spacing) are desirable, therefore simulations were performed at 140km, 70km and 35km grid spacing to check the stability and reproducibility of the results of the model at higher resolutions. Various simulations of different grid domain size and initial times times performed and the implications are discussed. The mesoscale features of the model simulations are then analyzed. The general appearance and characteristics of the fronts produced by the simulations are examined. Transects of the model fronts at constant altitude of equivalent potential temperature, potential temperature, and the front normal and front parallel components of wind are compared to the first order frontal model. Finally, transects of the model simulation are compared to transects of the observed data collected by the WP-3D aircraft. It is concluded that the first order frontal model adequately describes the thermal characteristics of the transects through the front. The average width of the cold fronts at low levels is 54 km and the average width of the warm fronts at low levels is 88 km. The change in equivalent potential temperature across the cold front is 9 K and across the warm front is 11 K. The average change the front normal component of wind is 14 m/s across the cold fronts and is 20 m/s across the warm fronts. The average change in the front parallel component of wind is 20 m/s across the cold fronts and is 23 m/s across the warm fronts. (Abstract shortened by UMI.).
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Details
- Title
- Comparison of the first order frontal model with aircraft data and numerical simulations
- Creators
- Joseph Jude Trout
- Contributors
- Carl William Kreitzberg (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xx, 179 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Arts and Sciences; Drexel University
- Other Identifier
- 991021888982004721