Browsing by Author "Pielke, Roger A., author"
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Item Open Access A numerical and climatological investigation of deep convective cloud patterns in south Florida(Colorado State University. Libraries, 1985-07) McQueen, Jeffery T., author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherClimatological characteristics of thunderstorm activity over South Florida are presented by processing and compositing digital visible and infrared satellite imagery collected during the summer of 1983. To describe the physical processes associated with the occurrence and patterning of the satellite observed deep convection, averaged quantities of numerous synoptic variables were calculated for days which made up the satellite composites. A three-dimensional mesoscale model is also utilized to investigate the physical processes associated with the deep convection patterns over South Florida. The model incorporates the interaction between the sea breeze forcings and the synoptic flow as well as the effects of variations in the ground surface characteristics. The satellite composite results demonstrated that the deep cumulonimbus activity over South Florida on synoptically undisturbed days during the summer is strongly focused in specific geographic regions of the peninsula. Moisture availability on the synoptic scale was found to be the most important control on the percentage of afternoon deep convective cloud activity. Also, strongly correlated with the amount of afternoon deep convective cloudiness over the peninsula was the morning (0800 EST) deep cumulus activity over water. The specific locations of thunderstorm activity were mainly found near maximums in sea breeze and local scale convergence of low-level moisture and wind. The patterns of these sea breeze fields are controlled by the different types of ground surface, and by the speed and direction of the synoptic flow.Item Open Access A numerical study of the impact of land use modification on local rainfall over Manila(Colorado State University. Libraries, 1993) Anglo, Emmanuel G., author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access A synoptic climatology of eastern North America with mesoscale resolution(Colorado State University. Libraries, 1990-12-11) Moran, Michael D., author; Wesley, Douglas Alan, author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherA subjective synoptic classification scheme has been used to categorize the dominant daily synoptic weather pattern for each grid square in a 5-square X 7-square grid placed over eastern North America for the five-year period from 1975 to 1979. Seven synoptic categories were used in the classification scheme: (1) warm sector of an extratropical cyclone; (2) region of overrunning north of a warm front; (3) region of cyclonic isobaric curvature behind a cold front; (4) polar anticyclone; (5) subtropical anticyclone or ridge; (6) tropical cyclone; and (7) unclassifiable pattern. The grid extends from 36°N to 48.5°N and from 68°W to 89°W; this area includes much of the Great Lakes region, Ohio Valley, St. Lawrence Valley, central and northern Appalachians, and U.S. northeastern seaboard. One of four surface geostrophic wind-speed classes was also assigned to each grid cell for each of the 1,826 study days. A variety of statistics have been calculated for this climatological data set, including joint frequency tables, category persistence probabilities, and category transition probabilities. A comparison of statistics for different grid squares, rows, or columns reveals mesoscale variations in the synoptic climatology with latitude, longitude, and season. For instance, the seasonal movement of the polar front and its mean position over this region can be identified, as can the northward and westward extent of the Bermuda High. Climatic modifications due to the presence of the Great Lakes and the Appalachian Mountains are also evident in the statistics. This climatology was prepared in order to determine the frequency of occurrence of synoptic conditions which favor the generation of terrain-forced mesoscale circulations such as lake-land breezes and mountain-valley winds, as part of a larger investigation into the impact of mesoscale atmospheric circulations on the long-range transport of air pollutants. However, this climatology can also be applied to such areas as air pollution potential evaluations, wind energy 'prospecting', and environmental impact assessments.Item Open Access Acid deposition in Colorado: a potential or current problem; local versus long-distance transport into the state(Colorado State University. Libraries, 1986) Pielke, Roger A., author; Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisherA compendium of papers presented at a workshop sponsored by the Cooperative Institute for Research in the Atmosphere, Colorado State University in Fort Collins, Colorado on August 13-15, 1986.Item Open Access An investigation of the effects of topography on Colorado Front Range winter storms(Colorado State University. Libraries, 1991) Wesley, Douglas Alan, author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Climate of Colorado(Colorado State University. Libraries, 2003-01) Doesken, Nolan J., author; Pielke, Roger A., author; Bliss, Odilia A. P., author; Colorado Climate Center, Atmospheric Science Department, publisherItem Open Access Impact of soil moisture and vegetation distribution on July 1989 climate using a regional climate model(Colorado State University. Libraries, 1995) Copeland, Jeffrey H., author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Numerical simulation of the influence of the large-scale monsoon flow on the diurnal weather patterns over Kenya(Colorado State University. Libraries, 1992) Mukabana, Joseph R., author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access The effect of soil moisture and vegetation heterogeneity on a Great Plains dryline: a numerical study(Colorado State University. Libraries, 1995) Shaw, Brent L., author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access The influence of deep cumulus convection on sea breeze dynamics over south Florida(Colorado State University. Libraries, 1988) Song, J. L., author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access The relationship of the North American Monsoon to tropical and North Pacific sea surface temperatures as revealed by observational analyses(Colorado State University. Libraries, 2000-04) Castro, Christopher Lawrence, author; McKee, Thomas B., author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisherThe North American Monsoon is a seasonal shift of upper and low level pressure and wind patterns which brings summertime moisture into the Southwest United States and ends the late spring wet period in the Great Plains. The climatology and interannual variability of the North American Monsoon are examined using the NCEP/NCAR Reanalysis (1948-98). The diurnal and seasonal evolution of 500-mb geopotential height, integrated moisture flux, and integrated moisture flux convergence are constructed using a five-day running mean for the months May through September. All of the years are used to calculate an average daily Z-score which removes the diurnal, seasonal, and intraseasonal variability. The average Z-score centered about the date is correlated with three Pacific SST indices associated with the El Niño Southern Oscillation (ENSO) and the North Pacific Oscillation (NPO). These indices are: Niño 3, a North Pacific index, and a North American Monsoon index (M) which combines the previous two. Regional time evolving precipitation indices for the Southwest and Great Plains, which consider the total number of wet or dry stations in a region, are also correlated with the SST indices. The new reanalysis climatology reveals: the time of maximum northward extent of the monsoon is late July, a diurnal cycle in atmospheric moisture which reflects the evolution of summer thunderstorms, the presence of the Baja and Great Plains low level jets, and the seasonal dependence of atmospheric moisture on monsoon ridge position. These results are in agreement with previous, more comprehensive reanalysis climatologies using shorter lengths of record. Pacific SSTs are related to a sequence of teleconnection patterns over North America through the summer. The relationship to the atmospheric circulation is strongest at monsoon onset, when the Pacific Transition pattern controls the large-scale distribution of moisture across the western U.S. A high (low) NPO phase and El Niño (La Nina) conditions favor a trough (ridge) over the northern Rocky Mountains, northern Great Plains. In the Great Plains the spring wet season is lengthened (shortened) and early summer rainfall and integrated moisture flux convergence are above (below) average. In the Southwest monsoon onset is late (early) and early summer rainfall and integrated moisture flux convergence are below (above) average. Relationships with the Pacific SST indices decay in the later part of the monsoon. These idealized climatological responses associated with high and low values of the M index were observed in the Midwest Flood of 1993 and the Drought of 1988, respectively. Tropical and North Pacific SSTs are related to atmospheric moisture and precipitation in the western U.S. to varying degrees depending on location. In the Great Plains, North Pacific SSTs are dominant factor, while in the Southwest tropical and North Pacific SSTs are equally important. Though the M index is the better diagnostic for North American Monsoon, only the time-coincident relationships with atmospheric circulation and moisture are statistically significant. A statistically significant relationship exists between spring Niño- 3 and the atmospheric circulation pattern over North America at monsoon onset.Item Open Access The sensitivity of a general circulation model to large scale vegetation changes(Colorado State University. Libraries, 1995) Chase, Thomas N. (Thomas Newell), 1962-, author; Pielke, Roger A., author; Department of Atmospheric Science, Colorado State University, publisher