This project will focus on in situ and remote sensing measurements of wintertime clouds over the Park Range of the Rocky Mountains in northern Colorado. These clouds are generally mixed-phase; the combination of ice, liquid and water vapor presents challenges both to measurements and modeling, and consequently, to understanding their impact on atmospheric radiation and on precipitation. The Colorado Airborne Multi-Phase Cloud Study (CAMPS) will use the Wyoming King Air research aircraft instrumented with both remote (cloud radar and cloud lidar) and in situ sensors (cloud and particle probes, total water hygrometer) to elucidate the vertical and horizontal structure of cold mixed-phase clouds.
Intellectual Merit:
The data gathered during CAMPS will include information about macro- and microphysical parameters of mixed-phase clouds obtained by both in situ and remote-sensing methods. These data will be analyzed to address a number of important questions about the structure, properties and impacts of mixed-phase clouds. Specific goals include:
1. To assess the vertical and horizontal structure and spatial and temporal variation of cloud properties (particle size distribution, ice and liquid water content, particle habit) in liquid, mixed-phase and precipitating clouds at a mid-latitude continental site with complex terrain during winter.
2. To assess the impact of topography and associated variations in vertical forcing on cloud generation and cloud properties.
3. To develop a data set that provides the information necessary for improving the representation of mixed-phase clouds in cloud-resolving and climate models.
4. To provide correlative data for validation of the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program mobile facility and the National Aeronautics and Space Administration A-Train satellite-borne remote sensors.
5. To provide observational confirmation of the redistribution of snowfall associated with riming inhibition due to enhanced CCN.
Broader Impacts:
Ultimately, by enhancing the community's understanding of cloud-scale processes, the data from CAMPS will be the basis for improvements in the representation of clouds in global climate models. This will lead to more accurate calculations of current and future climate. In addition the CAMPS project will contribute to both formal and informal education at a number of levels. At least one graduate student from each of the participating universities will be involved with the field work and/or data analysis related to this project. The investigators will include undergraduates from their institutions in flight-planning and/or meteorology exercises related to CAMPS when possible. Formal educational opportunities for elementary school students will be coordinated by the Storm Peak Laboratory staff, including visits to the laboratory and aircraft and classroom exercises. Outreach activities will include signage at the Steamboat Springs Ski Resort, an interactive display at the gondola building and coordination with the 2011 Steamboat Weather Summit.
Water, and hydrological processes, play a critical role in the U.S. intermountain west where societal demands can be high relative to the supply and where large swings in annual precipitation are common. The influence of orographically-induced mountain waves on cloud phase and precipitation processes in this area has received relatively little focus, and these complex processes have thus been a challenge to represent in numerical models. Observational studies linking mountain waves to orographic precipitation are particularly lacking, especially studies that are able to capture the spatial and vertical covariability of atmospheric dynamical and microphysical properties. Together these properties determine the spatial distribution of precipitation relative to a mountain range and thus are important for basin-scale hydrology. To address these deficiencies, the Colorado Airborne Multi-Phase Cloud Study (CAMPS) was conducted in winter 2010-2011 around the Park Range in Northern Colorado. CAMPS consisted of a heavily instrumented aircraft, complete with in situ instruments for sampling cloud particles and remote-sensing instruments for observing atmosphere and cloud profiles above and below the aircraft. These measurements were made in collaboration with an observational campaign sponsored by the Department of Energy that included similar observational assets operating from the surface. This grant supported the participation of a total water measuring instrument from the University of Colorado and a variety of different analyses examining the observational data sets. The first primary outcome of this project was the successful completion of the aircraft observing campaign. Project team members were instrumental in designing flight patterns, specifying instrument suites, and making flight-time decisions. As a result, the project obtained 29 successful flights, primarily focused on the Park Range region. Most aircraft instruments operated successfully for most flights and the various aircraft data sets have been made available on the University of Wyoming aircraft web page. These measurements have been used by investigators beyond the team represented by this project. Subsequent scientific analyses have harnessed these aircraft and collaborating measurements to study the spatial organization of clouds and dynamics relative to the Park Range. Analyses focused primarily on conditions of westerly winds that impinged on the primarily north-south mountain barrier. A collection of instruments was used to characterize the response of the atmosphere to the mountain barrier, specifically identifying atmospheric conditions that allow for mountain waves propagating above and/or downstream from the barrier. Aircraft-based radar measurements and flight-level observations provided a detailed perspective on these waves, as well as small-scale dynamical features that impact the local snowfall distribution. Statistical analyses were used to relate the properties of clouds, especially the occurrence of liquid water and snowfall, to the mountain-induced dynamics. The atmosphere generally lifts as westerly winds impinge on the mountain range, and then it dives down behind the mountains. Cloud liquid water preferentially occurs in lifting airmasses, contributing to enhanced snowfall at and slightly windward of the mountain ridge. In cases where mountain-forced waves propagate to the lee of the mountain range, liquid water occurs in the upward moving cells of these waves, contributing to precipitation formation downwind of the mountain ridge. The fractionation of cloud phase, its role in precipitation, and its relation to the mountain waves are all unique scientific contributions from this study. Many other process-level details have also been documented in a manner that can inform the representation of these processes in numerical models. Beyond the specific scientific outcomes, this project promoted the development of future scientists. Specifically, a graduate student was supported as he successfully completed his Ph. D. As part of his research project the student gained valuable experience in developing an instrument for use in atmospheric research, in participating in field work, and in scientific analysis and documentation. Upon completion of his Ph. D, that student continued working on this project as a post-doctoral researcher and was able to collaborate internationally on a number of scientific analyses. This project was also the first opportunity for the PI to be a post-doctoral research mentor, helping to develop future mentoring capabilities. Together, CAMPS has been successful on a number of levels. This success is a result of the long data set collected in a variety of conditions related to mountain flow and resultant cloud-precipitation processes. This has offered a statistical perspective on the problem that has been generally lacking in the past and has allowed for a broadly representative characterization of orographic, mixed-phase precipitation processes. CAMPS has benefited from a comprehensive and complementary suite of aircraft-based measurements and direct collaboration with a ground-based experiment that supported extension of the science beyond this individual project. Lastly, the project has provided the opportunity for research and collaboration by a mixture of young and experienced scientists. While this project has been successful on these many levels, CAMPS observations can, and should, be further exploited in future analyses by this research team and others in the research community.
