Browsing by Subject "Radar meteorology"
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Item A dual-wavelength feed for a parabolic reflector antenna(Texas Tech University, 1979-05) Turner, Clyde DavidNot availableItem A high-resolution radar analysis of a tropical cloud cluster(Texas Tech University, 1985-05) Desrochers, Paul RIn this study, a high-resolution radar analysis of a tropical cloud cluster was conducted. A number of computer programs were designed which organized the radar data into various analysis formats, such as PPIs, RHIs and EPRHIs (End Point Range Height Indicator). Each of the analysis methods was found to be useful for a specific task. For example, the high-resolution composite PPI was useful for tracking precipitation features of the cloud cluster. In general, the horizontal resolution of the high-resolution analysis schemes was 1 km. This was found to be sufficient to define the structure of small convective cells, and to detect convective cells as small as 1 km in horizontal extent. Scale interactions between convection and the anvil of the tropical cloud cluster were observed through the high-resolution analysis. Anvil development during the cluster's intensifying stage was observed to be dependent upon blowoff from convective towers. This was a favorable interaction for the anvil. However, convection did not always interact advantageously with the anvil. A line of convection that moved under the anvil associated with another line of convection was seen to cause partial destruction to the anvil. Later, during the cloud cluster's mature and dissipating stages, small scale convection developed inside the anvil. This convection was not destructive to the anvil.Item A study of clouds using satellite radiance data in comparison with raingage network and radar observations(Texas Tech University, 1980-06) Chao, Shih-ChengThe objective of this study was to use Geostationary Operational Environmental Satellite (GOES) visible and infrared radiance data to determine cloud characteristics, including cloud population, albedo, cloud top temperature and height, as well as the changes of cloud parameters with time. Verification of the satellite-derived results was achieved by comparison with the corresponding raingage network measurements and observations by radar. Four cases, 22, 24 and 27 June and 8 July 1977, have been chosen for this study. All four occurred during the operational period of the 1977 Texas HIPLEX (High Plains Cooperative Program) field season when visible and infrared images and digital radiance data, surface and rawinsonde data, precipitation analyses from the raingage network as well as PPI and RHI radar displays were available. In the first portion of this study, visible radiance data were used to determine cloud populations, percent cloud cover and cloud albedos, while cloud top temperatures were computed from the infrared data. Cloud top heights have been determined by using the cloud top temperature and comparing with rawinsonde data obtained from the nearest station. The second portion of the study compared the results derived from satellite data with raingage network measurements and radar observations in the Texas HIPLEX area. The analysis indicated that the information derived from satellite, radar and raingage data correlated closely on the four case study days. The precipitation analyses indicated that two of the four case study days had heavy rain but the others had little or none. Synoptic, subsynoptic, and small-scale features were investigated to determine the mechanisms of precipitation. PPI radar displays from a WSR-57 radar at Midland and both digital PPI and RHI data from a M-33 radar at Snyder were used in this investigation. On 22 June a squall line, a subsynoptic feature, and on 8 July a cold front, a synoptic feature, triggered the development of a line of convective clouds which produced the observed precipitation.Item Analysis of level II doppler radar data for an episode of severe weather on 25-26 May 1994(Texas Tech University, 1996-08) Burgett, Wesley SThis thesis is an investigation of a severe weather outbreak on the High Plains of West Texas on 25-26 May 1994. Archive Level II data was analyzed from the Lubbock, Texas (KLBB) Doppler radar for the period 1548 GMT on 25 May through 0511 GMT on 27 May 1994. Reflectivity and velocity data from this time period were read from 8-mm data cartridges using the WVS (WSR-88D Visualization System) program. The radar data was then used to determine the structure, strength, and movement of storms over the two-day period. Particular emphasis of this study was placed on reflectivity and velocity data for the Northfield tornadic supercell (25 May) and the Reese non-tornadic supercell (26 May). The two storms developed in markedly different weather scenarios, with the Northfield storm producing two tornadoes and the Reese storm generating significant quantities of large hail. The Northfield supercell formed ahead of a cold front in a moisture convergence maximum between Amarillo and Childress. In contrast, the Reese supercell developed on an 850-mb boundary (cold front) in a region of upslope flow ahead of an advancing squall line. Outflow from storms that produced significant downburst damage in Lubbock County interacted with the Northfield supercell just prior to tornado formation. This outflow provided a source of low-level speed and directional shear for tornado production in the Northfield storm. The Reese supercell lacked a low-level source of rotation which is why no tornadoes or a mesocyclone was observed in the Level II data. The movement of supercell thunderstorms on 25 May was controlled by strong southwesterly steering currents at the mid- and upper-levels of the atmosphere. In contrast, the three supercells of 26 May lacked significant steering currents in the mid-levels. This most likely explains why outflow boundaries controlled the movement of the three supercells. No outflow boundaries were detected near the Reese supercell after 2300 GMT which explains why the storm remained quasi-stationary for over three hours.Item Analysis of rainwater flux in the IFA during TOGA coare using shipboard radar rainfall estimates(Texas Tech University, 1996-05) Doggett, Arthur L.Mass and heat fluxes in the warm pool region of the West Pacific Ocean play an important role in the determination of global climate. To better understand the relationship between the atmosphere and ocean in this region of the world, the Tropical Ocean Global Atmosphere (TOGA) program conducted the Coupled Ocean Atmosphere Response Experiment (COARE). During the Intensive Observing Period (lOP) of TOGA COARE, island- and ship-based observations were coUected for a four-month period. As part of this experiment, shipboard Doppler radar data were coUected. These data were primarily coUected to produce rainfall estimates for the TOGA COARE domain during the lOP. This dissertation describes the development of a data set of high spatial and temporal resolution that was produced from the data collected by the MTT radar on the University of Southern California's R/V John V. Vickers. These data were quality controUed, and correction schemes were developed for both the reflectivity and radial velocity data.Item Comparison of raingage-recorded and radar-derived rainfall amounts(Texas Tech University, 1995-12) Kensey, Matthew JThis thesis compares raingage-recorded rainfall data with radar-derived rainfall estimations from the Lubbock WSR-88D. This study analyzes four cases using the original radar parameters, and two cases with altered radar parameters. Data were plotted and contoured on maps of the region of interest for overall rainfall amount and areal coverage comparisons. Also, individual gages were selected for a time-series comparison of raingage and radar data. Scatter-plot diagrams were created using a linear regression to determine the statistical significance of the data. Using alternate radar parameters, two cases were selected to determine whether different parameters would produce better results. The overall agreement between the two data platforms is very good in terms of areal coverage. However, the radar-estimated amounts varied widely compared with the raingage data. In general, the radar data were within a factor of two of the raingage data, in cases of both underestimation and overestimation. When the Z-R relationship of the WSR- 88D was changed, the results improved significantly.Item Evolution of a mesoscale convective system(Texas Tech University, 1990-12) Tesmer, Jeffrey RansdellThis thesis presents a description of the evolution of the second of three mesoscale convective systems that passed over the PRE-ST0RM mesonetwork on 3-4 June 1985 Three NC-^JK CP-3 and CP-4 Doppler radar volume scans along with Wichita (NWS) WSR-57 radar scans were analyzed with surface wind and pressure data to explain the complex precipitation structure from 2100 to 0200 GMT The precipitation pattern contained a convective line, a northeastward extension of convection called the northeast band, stratiform precipitation m the northern half of the system, and smaller precipitation structures in the eastern portion of the system Detailed analysis of this system shows that the intersection of the convective line and the northeast band produced strong upward motion within an area of intense convection that influenced the surface pressure pattern and the internal circulation generated by the mesoscale convective system.Item High-resolution dual-doppler analyses of the 29 May 2001 Kress, Tx, cyclic supercell(Texas Tech University, 2004-12) Beck, Jeffrey RNot availableItem Improved resolution in azimuth for a weather radar(Texas Tech University, 1981-12) Hill, James DennisNot availableItem Microcomputer simulations of mesoscale precipitation patterns(Texas Tech University, 1985-05) Novia, Robert DA microcomputer simulation of mesoscale precipitation patterns over the Texas South Plains was developed to investigate the variations in a Z-R relationship that are due to the imperfect correspondence between radar and raingage rainfall estimates. Synthetic rain cells were specified in a fashion that depicts the linear structure of squall lines, which account for a large percentage of the total Texas South Plains convective rainfall. The results indicate that gage-radar sampling differences inflict large errors on a Z-R relationship, particularly when gradients of precipitation rate are sharp and the temporal variations in cell strength are great. Raingage measurement variations within a radar bin, variations of radar reflectivity for a succession of bins, and the advection of the precipitation pattern were each found to have the potential to cause Z-R variations of over 30 mm/hr. Attempts to suggest observing system adjustments to diminish such variations were not successful. Evaluated gage-radar sampling differences in the vicinity of strong convection were found to have the potential to be the dominant cause of Z-R relationship variations and responsible for at least part of the difficulty associated with fitting a power law relationship to convective rainfall data.Item Topographic influences on Amarillo radar echo climatology(Texas Tech University, 1980-08) Marshall, Timothy P.A radar climatology within 185 km (100 nm) surrounding Amarillo, Texas, has been assembled for the spring convective season (May and June) from 1975 through 1978. The objective has been to obtain significant evidence supporting the importance of the Caprock escarpment in initiating convection. Included is a data extraction technique that accounts, in part, for range bias effects. Conditions favoring convection were identified in terms of synoptic patterns and use of daily sounding data from Amarillo. Semi-quantitative correlations of initial echo occurrences with topographic roughness has revealed four potential source regions favorable for convective development.