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Open Access
1988 CIRA satellite research workshop
(Colorado State University. Libraries, 1988) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
This document reports on a Satellite Research Workshop sponsored by the Cooperative Institute for Research in the Atmosphere (CIRA) that was held at the Colorado State University's Pingree Park campus from September 21-23, 1988. The workshop was designed to investigate research and applications opportunities using data from the next generation GOES and TIROS satellites.
Open Access
A cloud free vault
(Colorado State University. Libraries, 1975) Weaver, John F., author
A severe squall line, with several isolated storms near its southernmost end, was observed near Grover, Colorado, on the afternoon of 22 July 73 by the NHRE storm monitoring system. The northern segment of the squall line was oriented parallel to cloud level winds (i.e., northeast-southwest), while the southern segment was aligned north-south. The northern segment developed an extensive cloud free vault intruding into the cloud base above the lifting condensation level (LCL) between the precipitation and the updraft pedestal. No downdraft or gust front was observed from the northern segment. Downdrafts and a gust front characterized by a pressure jump of +3 mb and peak winds of 60 knots were produced by both the southern segment and the isolated storms.
Open Access
A modeling study of visibility in the Grand Canyon
(Colorado State University. Libraries, 1986-08) Weissbluth, Michael Jeffrey, author; Cox, Stephen K., author; Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Using a backward version of the Monte Carlo Radiative Transfer model, radiance values in the Grand Canyon were simulated to within the precision of ten percent. The contiguous spectral contrast was introduced to distinguish between adjacent areas of the same target and compared to the apparent spectral contrast. The contiguous spectral contrast is a valuable tool in evaluating visibility because in some cases, the target became more distinguishable when viewed against the sky while the target features became less distinguishable. Average equilibrium radiance values were calculated and incorporated into the Koschmieder estimate; the Koschmieder estimate was deemed to be of limited value in the Grand Canyon because of the violation of the assumptions used to derive the estimate. It was shown that first order scattering results alone could be used to estimate apparent spectral contrast to within a 10% accuracy; higher order scattering must be considered when radiance values are calculated for the Grand Canyon scene.
Open Access
A physical/optical model for atmospheric aerosols with application to visibility problems
(Colorado State University. Libraries, 1990-01) Tsay, Si-Chee, author; Stephens, Graeme L., author; Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
The objectives of this report are to describe a conceptually simple but accurate model for efficiently computing the optical properties of atmospheric aerosols. Aerosol characteristics such as size distribution, solubility, mixture and the atmospheric moisture effect are taken into account when computing its optical properties. The dependence of the latter on aerosol microstructure is also discussed. The optical properties of aerosols are computed by employing numerically stable algorithms for obtaining Mie solutions to coated spheres. Resulting bulk quantities such as the extinction/backscatter coefficient, the probability of scattering, and the scattering phase matrix can be incorporated into multiple scattering schemes of radiative transfer for visibility investigations and other types of studies.
Open Access
A study of tropical cyclone structural evolution
(Colorado State University. Libraries, 2006) Maclay, Katherine S., author; Vonder Haar, Thomas H., author; Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
The destructive potential of a tropical cyclone is highly dependent on both the intensity and size of the storm. There has been extensive research done on intensity and intensity change, but far less work has focused on tropical cyclone structure and structural changes. The recent highly active Atlantic tropical seasons reemphasize the need for a better understanding of tropical cyclone structural evolution. This is particularly true of the 2005 season which produced a number of storms, such as Katrina, Rita, and Wilma, that not only became extremely intense, but also grew substantially in size during intensification. In contrast to these giants are the storms such as Hurricanes Charley (2004) and Emily (2005), which reached equal intensity, but remained fairly small in size. The goal of this study is to gain a better understanding of what causes these different structural evolutions in tropical cyclones. The inner core (0-200 km) wind-fields of Atlantic and Eastern Pacific tropical cyclones from 1995-2005 from aircraft reconnaissance flight-level data is used to calculate the low-level inner core kinetic energy. An inner core kinetic energy-intensity relationship is defined which describes the general trend of tropical cyclone inner core kinetic energy (KE) with respect to intensity. However, this mean KE/intensity relationship does not define the evolution of an individual storm. The KE deviations from the mean relationship for each storm are used to determine the cases where a storm is experiencing significant structural changes. The evolution of the KE deviations from the mean with respect to intensity indicates that hurricanes generally either grow and weaken or maintain their intensity, or strengthen but do not grow at the same time. The data is sorted by the state of intensification (intensifying, weakening, or maintaining intensity) and structure change (growing or non-growing), defining six sub-groups. The dynamic, thermodynamic, and internal conditions for the storm sub-groups are analyzed with the aid of statistical testing in order to determine what conditions are significantly different for growing versus non-growing storms in each intensification regime. These results reveal that there are two primary types of growth processes. The first is through eyewall replacement cycles, an internally dominated process, and the second via external forcing from the synoptic environment. As a supplement to this study, a new tropical cyclone classification system based on inner core KE is presented as a complement to the Saffir-Simpson hurricane scale.
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.), publisher
A 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.
Open Access
An observational study of summer surface wind flow over northeast Colorado
(Colorado State University. Libraries, 1983-11) Toth, James J., author; Johnson, Richard H., author; Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Analysis of summer surface winds over northeast Colorado, using data from the Program for Regional Observing and Forecasting Services (PROFS), has been carried out to investigate the diurnal wind flow pattern over the broad drainage area of the South Platte River. The pattern, similar to the classic descriptions of valley wind flows, appears in monthly averages as well as on most individual days. Unique features of the flow are documented, in particular the upslope/downslope transitions which begin near the foothills of the Front Range of the Rocky Mountains and propagate eastward. Previous conceptual models of the afternoon and evening wind flow over northeast Colorado are verified. The afternoon upslope flow is often responsible for enhanced convective cloud cover in preferred locations during the summer. It is suggested that the development of moist convection modifies the diurnal flow and contributes to the late afternoon and early and evening transition to downslope flow. This study has pointed out the need for further investigations of this problem.
Open Access
Annual report for 1987 from the Cooperative Institute for Research in the Atmosphere, Colorado State University, to Marine Meteorology Section, Ocean Sciences Division of the Office of Naval Research on studies of space/time variability of marine atmospheric boundary layer characteristics
(Colorado State University. Libraries, 1988-03) Vonder Haar, Thomas H., author; Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
Characterization of carbonaceous aerosol during the Big Bend Regional Aerosol and Visibility Observational study
(Colorado State University. Libraries, 2001-12) Brown, Steven G., author; Herckes, Pierre, author; Kreidenweis, Sonia M., author; Collett, Jeffrey L., Jr., author
The Big Bend Regional Aerosol and Visibility Observational (BRAVO) study was a four month field campaign (July-October 1999) to investigate aerosol particle properties, sources, and impacts on regional visibility in Big Bend National Park, Texas. Daily PM2.5 aerosol samples were collected on pre-fired quartz fiber filters for detailed molecular analysis of the aerosol organic carbon fraction. Aerosol black carbon concentrations during BRAVO were measured with an aethalometer. The molecular characterization of the organic carbon fraction of aerosol present during the BRAVO study was performed using gas chromatography - mass spectroscopy (GC-MS). Organic carbon concentrations on individual days were too low for a detailed analysis by GC-MS. Therefore, multi-day composite samples, selected based on common air mass trajectories and temporal proximity, were extracted and analyzed for numerous compounds, including n-alkanes, polycyclic aromatic hydrocarbons (PAH), and alkanoic acids. Low alkane Carbon Preference Indices (CPIs) during July through September reflect similar concentrations of n-alkanes containing odd and even numbers of carbon atoms and indicate that anthropogenic emissions were important contributors to carbonaceous aerosol during this period, when air masses generally were advected from the east over Texas and Mexico. In October, CPIs increased, reflecting increased influence of odd carbon numbered alkanes and suggesting a predominant biogenic aerosol influence with air masses arriving from the north and the south. Plant wax contributions to odd carbon number alkanes (C25-C33) were estimated to range between 26% and 78%, with the highest contributions occurring in October with air masses arriving from the north and south. Periods with transport from eastern Texas and northeastern Mexico had much smaller plant wax contributions. Alkanoic acids were the most abundant compound class, with CPIs that were high throughout the study. The high acid CPI suggests that the alkanoic acids may be largely biogenic in origin, a finding consistent with other studies. Caution is required in interpreting the acid CPI, however, as alkanoic acids can also be formed as secondary products of atmospheric reactions. Polycyclic aromatic hydrocarbons (P AH) were usually not found in abundance, suggesting that upwind combustion emissions were not important contributors to carbonaceous aerosol or that P AH were removed by reaction or deposition in transit. Higher P AH concentrations during one period indicated a more significant contribution from fresh combustion emissions. Molecular source tracer (hopanes for vehicle emissions, levoglucosan for wood combustion, cholesterol for meat cooking) concentrations were generally not detected. Based on analytical detection limits for these species, it was estimated that wood smoke contributed no more than 1% of the total Organic Carbon (OC) present, vehicle exhaust contributed no more than 4%, and smoke from meat cooking contributed less than 13%. The presence of other wood smoke tracer molecules, however, suggests a possibly greater influence from wood combustion and possible chemical instability of levoglucosan during multi-day transport in an acidic atmosphere. Several observations suggest that secondary production contributed significantly to BRAVO carbonaceous aerosol. Examination of ratios of aerosol organic carbon to elemental carbon indicates that secondary organic aerosol may have contributed between 45% and 90% of the total BRAVO aerosol organic carbon. High ratios of saturated/unsaturated C18 acids, an abundance of nonanoic acid, and high concentrations of 6,10,14 trimethylpentadecan-2-one (an indicator of secondary aerosol production from vegetation emissions) all support the conclusion that secondary aerosol formation was important in the region. Total black carbon (BC) concentrations ranged from below detection limit (71 ng/m3) to 267 ng/m3, averaging 129 ng/m3. Fine (< 1 μm) aerosol BC concentrations averaged 114 ng/m3, and comprised 89% of the total BC. BC concentrations correlated reasonably well with aerosol sulfate concentrations, suggesting similar source regions for these species.
Open Access
CIRA '99, vol. 11
(Colorado State University. Libraries, 1999) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA '99, vol. 12
(Colorado State University. Libraries, 1999) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA 2000, vol. 13
(Colorado State University. Libraries, 2000) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA 2000, vol. 14
(Colorado State University. Libraries, 2000) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA 2001, vol. 15
(Colorado State University. Libraries, 2001) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA annual report FY 03/04
(Colorado State University. Libraries, 2004) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA annual report FY 04/05
(Colorado State University. Libraries, 2005) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA annual report FY 05/06
(Colorado State University. Libraries, 2006) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA annual report FY 06/07
(Colorado State University. Libraries, 2007) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA annual report FY 07/08
(Colorado State University. Libraries, 2008) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
Open Access
CIRA annual report FY 08/09
(Colorado State University. Libraries, 2009) Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher