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Dissertation
Water budget studies with a mesoscale primitive equation model with a convective downdraft
Doctor of Philosophy (Ph.D.), Drexel University
1997
DOI:
https://doi.org/10.17918/00000667
Abstract
In order to perform realistic water budget studies, a downdraft parameterization that included the effects of water loading, melting of ice, evaporation of precipitation, and entrainment was added to the Kreitzberg and Perkey (1976) cumulus parameterization scheme in the Drexel Limited Area Mesoscale Prediction System (LAMPS). Testing of the revised parameterization was done for a case during the Severe Environmental Storms and Mesoscale Experiment 1979 (SESAME '79) and for a case that was part of the National Aeronautics and Space Administration's (NASA) Atmospheric Variability Experiment IV (AVE-IV). Comparing the model simulations with observed precipitation for both cases revealed that the downdraft improved the location and magnitude of precipitation maxima. The downdraft reduced the convective heating and drying above cloud base and increased the convective cooling and drying below cloud base. Each 24-hour simulation was then used to perform atmospheric water budget experiments over two domains of the same size. One was over the Mississippi River Valley and the other was over the eastern United States and adjacent parts of the Atlantic Ocean. The LAMPS baseline data sets of horizontal resolution 70 km and saved every 20 minutes were then degraded in time and space to assess the impact on the calculation of horizontal water fluxes and local tendencies over the budget areas. Experiments were also performed with simulated rawinsonde data created from the LAMPS baseline data set and then reanalyzed to the 70-km grid for the same water budget calculations. Both the water vapor and wind fields were found to be important in the calculation of the horizontal water fluxes. The condensate portion of the total water contributed in the range of +/-5 W m-2 to the horizontal wall mass rates, but for specific cases contributed up to 20 W m-2 to the magnitude of the local tendency. For errors in the absolute net horizontal wall mass rate to be less than or equal to 12 W m-2 required data at a horizontal resolution of at least 210 km and a temporal resolution of 3 hours or more.
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Details
- Title
- Water budget studies with a mesoscale primitive equation model with a convective downdraft
- Creators
- Kevin Gah Doty
- Contributors
- Carl William Kreitzberg (Advisor)Donald J. Perkey (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xxxi, 413 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Arts and Sciences; Physics; Drexel University
- Other Identifier
- 991014970315704721