Climatology Reports
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Item Open Access Components of infrared net radiation in a mountain valley(Colorado State University. Libraries, 1977-10) McKee, Thomas B., author; Whiteman, C. D. (Charles David), 1948-, author; Department of Atmospheric Science, Colorado State University, publisherThe infrared components of the surface radiation budget in a mountain valley have been investigated theoretically. Calculations were based on a set of winter and summer atmospheric soundings specifying temperature and moisture content and for two valley models including a linear valley model and a circularly symmetric valley model. Radiance and irradiance calculations are compared with similar calculations for flat terrain. Downward irradiances at the valley center were shown to be higher than for flat terrain and were due to radiation from the valley sidewalls. The largest effect was obtained for a dry winter atmosphere with the sidewalls warmer than the valley bottom. Downward irradiance was increased by 16% over the flat terrain case and the net irradiance at the valley center was decreased by 24% which would lead to a decreased surface cooling. Calculations were made for five spectral intervals including the 6.5 micron water band (4.4 - 7 .8μ), the water vapor continuum or atmospheric window (7. 8 - 13. 4μ), the 15 micron carbon dioxide band (13. 4 - 16. 3μ), a small window (16. 3 - 20. 2μ), and the rotational water bands (20. 2 - 48. 8μ). Only the two bands described as windows contribute significantly to the changes in downward irradiance. The remaining three spectral intervals are nearly opaque to transmission of radiation from the valley sidewalls to the valley center.Item Open Access Climate data continuity with ASOS: 1994 annual report for the period September 1993-August 1994(Colorado State University. Libraries, 1994-12) McKee, Thomas B., author; Doesken, Nolan J., author; Kleist, John D., author; Colorado Climate Center, Department of Atmospheric Science, Colorado State University, publisherItem Open Access A snapshot of Colorado's climate during the 20th century(Colorado State University. Libraries, 1991-06) Kleist, John D., author; Doesken, Nolan J., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Rooftop and ground standard temperatures: a comparison of physical differences(Colorado State University. Libraries, 2000-07) Griffith, Brian D., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherAccuracy and continuity of surface air temperature measurements are critical for many meteorological activities including short-term weather forecasting, warnings, and climate monitoring. In the United States and worldwide, most air temperature observations have historically been taken at a height of approximately 1.25 to 1.5 meters above the ground over a grass surface. In the last two decades, there has been a rapid expansion of nonfederal weather station networks to support state, regional and community needs. Many of these new weather stations are located on rooftops for reasons of security or convenience. Mixing these rooftop observations indiscriminately with observations from standard screen-height can pose significant issues for weather forecasting and verification, weather and climate analysis and climate applications such as energy demand planning and forecasting by large public utilities. This study establishes the physical mechanisms which cause a rooftop sensor to have a temperature bias relative to a nearby ground sensor. From a surface energy balance perspective, the physical characteristics of a surface are analyzed and related to temperature bias. This study identifies the surfaces and conditions leading to rooftop temperature bias in both maximum and minimum temperatures. These concepts are verified through both surface radiating temperature measurements and air temperature measurements contrasting roof and ground temperatures. Guidelines are then proposed to establish which roofs are unsuitable for temperature measurements and under what conditions a rooftop is vulnerable to temperature bias. Results indicate that overcast skies lead to small rooftop to ground differences in both surface radiating temperature and air temperature. Observations show differences of approximately 1 degree C or less in radiating temperature and less than 1 degree C in air temperature. An exception was observed where a wall effect led to more than a 2 degree C difference in air temperatures between roof and ground. Clear or partly cloudy skies allow larger rooftop temperature biases to develop. Roof to ground differences in surface radiating temperatures of up to 30 degrees C were observed. Although air temperature measurements were not made at all locations, observations show roof to ground differences of 3 degrees C for radiating temperature differences of 14 degrees C. The potential for even greater roof-ground air temperature differences exists at sites where radiating temperatures are further apart.Item Open Access The climate of Fort Collins, Colorado: the year in review: 1992 water year, 1 October 1991-30 September 1992(Colorado State University. Libraries, 1992-12) Doesken, Nolan J., author; McKee, Thomas B., author; Colorado Climate Center, Department of Atmospheric Science, Colorado State University, publisherItem Open Access Economic impacts and analysis methods of extreme precipitation estimates for eastern Colorado(Colorado State University. Libraries, 1986-08) Changnon, David, author; McKee, Thomas B., author; Cooperative Institute for Research in the Atmosphere, Colorado State University, publisherDams are designed to store water and to ensure human safety and as such they must withstand, in their lifetimes, any extreme precipitation event in their drainage basin. Correct estimation of this event is critical because on one hand it must provide an adequate level of safety to not occur, but it must not be any greater than needed since the high costs of dam construction and modifications are directly related to the magnitude of the estimated extreme event. Most frequently the extreme precipitation event is labeled as the Probable Maximum Precipitation, or PMP. National and state concerns over the adequacy of existing dams in the United States as well as increased development of the Front Range led to state dam risk reclassification and federal redefinition of new PMP values issued for Colorado in 1984. The study area included the region from the Continental Divide to the 103rd Meridian. Study of the implementation of PMP values and their potential economic impacts in Colorado reveals that an enormous cost will result in Colorado. Techniques for estimating cost of modifications for spillways were developed. Among 162 high risk dams, the estimated total cost for modification was approximately $184 million. The economic value of this precipitation estimate is $9.45 million per inch change of rainfall in this limited study area. In one elevation region, 7000 to 9000 feet, the costs is approximately $15.76 million per inch change of rainfall. Regional cost analyses revealed the South Platte River Division had the greatest costs. Inherent limitations in the PMP procedure and the cost of spillway modifications have made evaluating other alternatives necessary. Special aspects of estimates for extreme precipitation, such as snowmelt runoff versus extreme precipitation events and climate variations were examined. Four methods for estimating extreme precipitation events were evaluated; the traditional PMP, the paleogeological, the cloud/mesoscale dynamic model, and the statistical approaches. A collection of approaches were recommended for Colorado dam design in three elevation regions: the plains, the foothills, and the mountains.Item Open Access Cooperative solar radiation data collection program, Fort Collins, Colorado, June 1985-May 1986(Colorado State University. Libraries, 1986-09) Doesken, Nolan J., author; Kleist, John D., author; Swartz, Douglas K., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Precipitation probabilities for selected Colorado locations(Colorado State University. Libraries, 1986-07) Kleist, John D., author; Doesken, Nolan J., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Fort Collins solar radiation data: January 1980 through December 1982(Colorado State University. Libraries, 1983-12) Johnson-Pasqua, Christopher M., author; Cox, Stephen K., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Climate profile for the McCallum Emria study area(Colorado State University. Libraries, 1981-03) McKee, Thomas B., author; Doesken, Nolan J., author; Smith, Freeman M. (Freeman Minson), 1939-, author; Kleist, John D., author; Colorado Climate Center, Department of Atmospheric Science, Colorado State University, publisherItem Open Access Development of climate profiles for reclamation(Colorado State University. Libraries, 1981-04) McKee, Thomas B., author; Doesken, Nolan J., author; Smith, Freeman M. (Freeman Minson), 1939-, author; Kleist, John D., author; Colorado Climate Center, Department of Atmospheric Science, Colorado State University, publisherItem Open Access Fort Collins solar radiation data: January 1978 through December 1979(Colorado State University. Libraries, 1980-08) Cox, Stephen K., author; McKee, Thomas B., author; Martin, Pauline J., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Climate data continuity with ASOS: report for the period September 1994-March 1996(Colorado State University. Libraries, 1996-05) McKee, Thomas B., author; Doesken, Nolan J., author; Kleist, John, author; Colorado Climatology Office, Department of Atmospheric Science, Colorado State University, publisherItem Open Access Colorado growing season(Colorado State University. Libraries, 1977-08) Benci, John F., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Colorado monthly temperature and precipitation summary for period 1951-1970(Colorado State University. Libraries, 1977-03) Benci, John F., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Monthly and water year climatology for selected stations in northwestern Colorado(Colorado State University. Libraries, 1977-06) Benci, John F., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Fort Collins solar radiation data: May 1975 through December 1976(Colorado State University. Libraries, 1978-08) Cox, Stephen K., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Probability of extreme 24-hour precipitation events in Fort Collins(Colorado State University. Libraries, 1976-11) McKee, Thomas B., author; Benci, John F., author; Mielke, Paul W., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Monthly and water year precipitation climatology for selected stations in southwestern Colorado(Colorado State University. Libraries, 1976-09) Benci, John F., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherItem Open Access Use of the Palmer index and other water supply indexes for drought monitoring in Colorado(Colorado State University. Libraries, 1983-03) Doesken, Nolan J., author; Kleist, John D., author; McKee, Thomas B., author; Department of Atmospheric Science, Colorado State University, publisherThe Colorado Drought Response Plan of 1981 assigned drought monitoring responsibilities to a special intergovernmental technical working group called the Colorado Water Availability Task Force (WATF). The intent of this group is to use existing data sources and information products to monitor Colorado's water supplies. The information assembled and interpreted by the WATF is then used by State decision makers to guide State government's response to drought. The Palmer Index, developed in the 1960's, has become a credible tool for monitoring drought and assessing drought severity on the national scale. It reasonably depicts soil moisture conditions using a simple hydrologic balance accounting for precipitation, evapotranspiration, runoff and soil moisture recharge. However, experiences of the WATF have revealed that Palmer Index values, currently generated weekly through the growing season by the National Climatic Data Center for 5 climatic divisions in Colorado, were only marginally useful for drought monitoring. The regions were too large and climatically diverse, and input temperature and precipitation data were not adequately controlled to produce consistent and meaningful results. With the encouragement arid cooperation of the WATF this project was undertaken to adapt the Palmer Index model to Colorado. The original program was brought to Colorado, the state was broken down into 25 climatically similar regions, and a simple routine for adjusting input data to correct for missing data and station moves was implemented. The existing model was then used to generate 30 years of monthly Palmer Index values for all 25 regions of the state. A thorough examination of these new Palmer Indexes has been performed. Comparisons with the original indexes show noticeable differences and considerable small scale detail which previously could not be resolved. With the new smaller regions it is now reasonable to use contour analysis of Palmer Index values to visually describe local variations in drought severity across Colorado. Two case studies were conducted to show how the new indexes compared to original index values during severe drought situations: 1) the end of the 1956 drought on the Eastern Plains, and 2) the 1976-1977 winter drought in the Colorado mountains. A particular application of the Palmer Index was given special attention. Palmer Index values were correlated with dryland winter wheat yields. The best correlations with annual yields were obtained using June 1 or July 1 Palmer Index values. Good correlations were obtained in most of the major wheat growing areas but especially in the northeastern counties of Colorado. Better correlations were obtained using indexes calculated for the new areas than were obtaining using the original index values. The WATF agreed that the capability to calculate Palmer Indexes here in Colorado, with our own choice of climatic divisions, greatly increases the utility of this drought monitoring tool. More refinements are possible, and further study conducted jointly with agricultural interests would be desirable. This index is already of sufficient value to the WATF to justify the low cost required to produce it on a routine monthly basis.