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Established as a multipurpose network, the Oklahoma Mesonet operates more than 110 surface observing stations that send data every 5 min to an operations center for data quality assurance, product generation, and dissemination. Quality-assured data are available within 5 min of the observation time. Since 1994, the Oklahoma Mesonet has collected 3.5 billion weather and soil observations and produced millions of decision-making products for its customers.

[1] North American Land Data Assimilation System (NLDAS) land surface models have been run for a retrospective period forced by atmospheric observations from the Eta analysis and actual precipitation and downward solar radiation to calculate land hydrology. We evaluated these simulations using in situ observations over the southern Great Plains for the periods of May-September of 1998 and 1999 by comparing the model outputs with surface latent, sensible, and ground heat fluxes at 24 Atmospheric Radiation Measurement/Cloud and Radiation Testbed stations and with soil temperature and soil moisture observations at 72 Oklahoma Mesonet stations. The standard NLDAS models do a fairly good job but with differences in the surface energy partition and in soil moisture between models and observations and among models during the summer, while they agree quite well on the soil temperature simulations. To investigate why, we performed a series of experiments accounting for differences between model-specified soil types and vegetation and those observed at the stations, and differences in model treatment of different soil types, vegetation properties, canopy resistance, soil column depth, rooting depth, root density, snow-free albedo, infiltration, aerodynamic resistance, and soil thermal diffusivity. The diagnosis and model enhancements demonstrate how the models can be improved so that they can be used in actual data assimilation mode.

Soil moisture is an important component in many hydrologic and land–atmosphere interactions. Understanding the spatial and temporal nature of soil moisture on the mesoscale is vital to determine the influence that land surface processes have on the atmosphere. Recognizing the need for improved in situ soil moisture measurements, the Oklahoma Mesonet, an automated network of 116 remote meteorological stations across Oklahoma, installed Campbell Scientific 229-L devices to measure soil moisture conditions. Herein, background information on the soil moisture measurements, the technical design of the soil moisture network embedded within the Oklahoma Mesonet, and the quality assurance (QA) techniques applied to the observations are provided. This project also demonstrated the importance of operational QA regarding the data collected, whereby the percentage of observations that passed the QA procedures increased significantly once daily QA was applied.

During late July and early August 2008, an intense heat wave occurred in Oklahoma City. To quantify the impact of the urban heat island (UHI) in Oklahoma City on observed and apparent temperature conditions during the heat wave event, this study used observations from 46 locations in and around Oklahoma City. The methodology utilized composite values of atmospheric conditions for three primary categories defined by population and general land use: rural, suburban, and urban. The results of the analyses demonstrated that a consistent UHI existed during the study period whereby the composite temperature values within the urban core were approximately C warmer during the day than the rural areas and over C warmer at night. Further, when the warmer temperatures were combined with ambient humidity conditions, the composite values consistently revealed even warmer heat-related variables within the urban environment as compared with the rural zone.

This m anuscript has b een reproduced from th e microfilm master. UMI films th e te x t directly from th e original or copy subm itted. Thus, som e thesis an d d issertatio n copies are in typewriter face, while o th e rs may be from any type of co m p u te r printer.T h e q u ality of this re p ro d u c tio n is d e p e n d e n t u p o n th e quality of th e c o p y su b m itte d . Broken or indistinct print, colored o r poor quality illustrations a n d photographs, print bleedthrough, su b sta n d a rd margins, and improper alig n m en t can adversely affect reproduction.In th e unlikely event that the author did not se n d UMI a complete manuscript an d th e re are missing p ag es, th e se will b e n o ted . Also, if unauthorized copyright material had to be rem oved, a n o te will indicate the deletion.O v ersize materials (e.g., m aps, draw ings, ch arts) are reproduced by sectio n in g the original, beginning a t th e u p p er left-hand com er and continuing from left to right in equal sections with small overlaps.ProQ uest Information a n d Learning 30 0 North Zeeb Road, Ann Arbor, Ml 4810 6 -1 3 4 6 USA 800-521-0600 UM1'UNIVERSITY OF OKLAHOMA GRADUATE COLLEGE T h e Im p a c t o f O k l a h o m a 's W in t e r W h e a t B e l t ON THE MESOSCALE ENVIRONMENT A b s t r a c tThe research documented in this manuscript demonstrates that Oklahoma's winter wheat belt has a significant impact on the near-surface, mesoscale environm ent during growth and after harvest. Differences in near-surface atmospheric variables across the wheat belt and its adjacent lands are documented using the following methods: (1) ' Senescence is the period from full maturity of the plant until its death.

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Agriculture is a $2 billion component of the state economy in Oklahoma. As a result, meteorological, climatological, and agricultural communities should benefit from an improved understanding of soil moisture conditions and how those conditions vary spatially and temporally. The Oklahoma Mesonet is an automated observing network that provides realtime hydrometeorological observations at 115 stations across Oklahoma. In 1996, sensors were installed at 60 Mesonet sites to provide near-real-time observations of soil moisture.This study focuses on 6 years of soil moisture data collected between 1997 and 2002 to analyse the annual cycle and temporal characteristics of soil moisture across Oklahoma. The statewide analysis of the annual cycle of soil moisture revealed four distinct soil moisture phases. In addition, the four statewide phases were also observed in each of the nine climate divisions across Oklahoma, although the temporal characteristics of each phase were unique for each division. Further analysis demonstrated that, at shallow soil depths (5 and 25 cm), the spatial variability of soil moisture across Oklahoma was most homogeneous during the winter and spring periods and most heterogeneous during the summer and autumn periods. Conversely, at greater depths (60 and 75 cm), soil moisture was most heterogeneous during the winter period and the most homogeneous during the late spring.