Observations and Modeling of Evapotranspiration across North Carolina

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dc.contributor.advisor Sethu Raman, Committee Chair en_US
dc.contributor.advisor S. Pal Arya, Committee Member en_US
dc.contributor.advisor Jerry Davis, Committee Member en_US
dc.contributor.author Puryear, Margaret W. P. en_US
dc.date.accessioned 2010-04-02T18:05:42Z
dc.date.available 2010-04-02T18:05:42Z
dc.date.issued 2005-07-19 en_US
dc.identifier.other etd-07152005-111006 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/1636
dc.description.abstract Evapotranspiration (ET) is measured at 14 stations in North Carolina using an ET gage, which allows distilled water to evaporate through a waterproof surface acting as the reference crop alfalfa. These stations are part of the State Climate Office of North Carolina's Environment and Climate Observing Network (ECONet) and are distributed throughout the state's three broad climate regions: mountains, Piedmont and coastal plain. Observations from the ET gage at Lake Wheeler were compared with the gradient method to show that the ET gage observations are accurate and reliable. Averages of reference evapotranspiration, precipitation, soil moisture and temperature are analyzed for spatial trends. Daily reference evapotranspiration values are also compared with precipitation, soil moisture, temperature and humidity at one location in each of the three climate regions. Evapotranspiration decreases initially when precipitation occurs. This is due to the increase in atmospheric humidity and decrease in temperature. After precipitation ends, evapotranspiration increases due to the increase in the water supply. Daily pan evaporation values at two sites from years 2003 and 2004 were compared with evapotranspiration at the same locations. Effective precipitation was calculated for 2004 at each of the 14 evapotranspiration measuring stations. Two different empirical methods for estimating evapotranspiration were used for comparison with observations: Priestley-Taylor and Penman-Monteith. An appropriate value for the Priestley-Taylor parameter was estimated. Estimates of ET from these empirical methods indicated that the Penman-Monteith method overestimated ET as compared to observations and the Priestley-Taylor method gave better results. A mesoscale numerical simulation was performed for the period, 00Z July 18, 2004 to 00Z July 24, 2004 using the MM5 model with a domain centered over North Carolina. Spatial distribution of evapotranspiration was obtained and comparisons made between model predictions and observations of latent heat flux, soil moisture, soil temperature, wind speed, and air temperature. Latent heat flux was estimated using model parameters and empirical methods and compared with observations. A special focus on the simulations of days July 21 through July 24 included one day prior to a precipitation event, two days during the event, and one day after the precipitation ended. The model has a tendency to overestimate the latent heat flux in the coastal plain and eastern Piedmont, due to the overestimation of precipitation in this area. The mountains had the highest latent heat flux predicted by the model. Across the state, the Priestley-Taylor method using simulated parameters performed better than the Penman-Monteith method. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject hydrological cycle en_US
dc.subject transpiration en_US
dc.subject pan evaporation en_US
dc.subject evaporation en_US
dc.subject land-air interaction en_US
dc.title Observations and Modeling of Evapotranspiration across North Carolina en_US
dc.degree.name MS en_US
dc.degree.level thesis en_US
dc.degree.discipline Marine, Earth and Atmospheric Sciences en_US

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