An Overview of WISP94

With Notes on ATD Participation

For an NCAR Staff Notes article on WISP94, click here.

The Winter Icing and Storms Project, 1994 (WISP94) was conceived, organized and managed by the NCAR Research Applications Program (RAP). Many other entities participated in the Project, including the University of Wyoming, Colorado State University, the University of Illinois, the National Oceanic and Atmospheric Administration, MMM and ATD (Divisions within NCAR), and a few others. Funding was provided by the Federal Aviation Administration and United Airlines, with facility support and additional grant support from the National Science Foundation.

ATD involvement consisted of fielding radar, aircraft, and sounding systems, as well as providing miscellaneous support in areas related to the ATD field systems.

WISP94 was a carry-on, and an evolution, from the earlier RAP WISP experiments: WISP90, WISP91, and WISPIT. Experimental goals were more sophisticated than in the earlier endeavors, and the WISP94 instrumentation expanded upon capabilities available in those previous experiments.

The following is an overview of WISP94 goals. Information was taken from various planning documents authored by Marcia Politovich, Roy Rasmussen, and other RAP personnel. Please contact RAP directly for any additional scientific information.

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WISP94 General Goals

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WISP94 was done in conjuction with several RAP tag-on experiments: Snowcast94 (snow "nowcasts" provided to United AirLines, and development of automated concepts for forecast guidance), and United AirLines Snowfall Detection (in support of ground de-icing procedures).

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ATD's Role

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CP4

This NCAR 5-cm radar was sited near South Roggen, CO. It's primary mission was to provide data for precipitation estimation (both coverage and amount) and wind field reconstruction; a secondary role was in support of nowcasting. CP4 operated for over 320 hours in direct support of WISP94. For details of CP4 operation in WISP94, see the document WISP94 Operations Report for NCAR Radars.

CLASS

SSSF supported WISP94 with five fixed and one mobile CLASS. Approximately 500 soundings were taken with these systems, and an additional 75 with a RAP mobile CLASS. Soundings were used for forecast model initialization, diagnosis of large-scale thermodynamic fields, and wind measurements. Two areas of study were added that had not been investigated in previous WISP programs: a station near Craig, CO, was used to test a technique for forecasting wave-cloud formation along the Front Range; a station at Chugwater was used to investigate cold surges from the Laramie gap which quickly move down the Front Range.

Electra Aircraft (info from 1994 Annual Scientific Report)

The Electra provided flight support for WISP-94 between 1 February and 25 March 1994. Flight measurements centered around wave clouds and upslope clouds. The main focus of these studies was the initiation of ice in winter clouds, storm structure, and precipitation development. The NCAR Electra carried standard RAF instrumentation as well as additional instruments installed from several universities. Newly developed "cloud scope" instruments from Desert Research Institute (DRI) were successfully flown on five missions. Cloud condensation nuclei (CCN) spectra were measured by instruments provided by DRI and the University of Wyoming, in collaboration with MMM. Ice crystals were collected both for isotope analysis at Yale University and for study of crystal habits. Air samples were collected for ice nucleation studies at Colorado State University, and filter pack samples were collected for subsequent ice nuclei studies in a thermal diffusion chamber. The Counterflow Virtual Impactor (CVI) was successfully used to collect and study hydrometeors in both liquid and ice phases. This instrument, developed at RAF in collaboration with the University of Washington, was first deployed to study the ice phase in orographic wave clouds and in upslope clouds. The initial results are encouraging, indicating that a CVI/hygrometer combination can provide an effective measurement of condensed water content in clouds down to 0.05 g m-3.