The Winter Icing and Storms Project, (WISP) Conducted Along the Colorado Front Range for the Winter Seasons of 1990, 1991, 1993, and 1994
Entry ID:
WISP_NCAR
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Summary
The WISP home page address on the WWW is http://www.rap.ucar.edu/projects/
The Winter Icing and Storms Project (WISP) was conducted in the
Colorado Front range area from February 1 - March 31 1990 (WISP90),
January 15 - April 5 1991 (WISP91), February 15 - March 15 1993
(WISP93), and January 25 - March 25 1994 (WISP94). ... The main goals of
the project are to: 1) study the processes leading to the formation
and depletion of supercooled liquid water (SLW) in winter storms; and
2) improve forecasts of aircraft icing. During the WISP90 and WISP91
field seasons, 2 research aircraft, 4 Doppler radars, 49 Mesonet
stations, 7 CLASS sounding systems, 3 microwave radiometers, and a
number of other facilities were deployed in the Front Range area. A
comprehensive dataset was obtained on 8 anticyclonic storms, 16
cyclonic storms, and 9 frontal passages. Thirty-six scientists
representing the National Center for Atmospheric Research (NCAR),
National Oceanic and Atmospheric Administration (NOAA) Environmental
Research Laboratory (ERL), University of Wyoming, University of North
Dakota, and the Colorado State University participated in the field
program.
In 1988, the Federal Aviation Administration (FAA) funded the NCAR
Research Applications Program (RAP) to plan a multiyear program to
improve aircraft icing forecasting. Through a series of meetings with
investigators interested in icing and other winter storm problems, a
comprehensive research plan was formulated that included field
research, forecasting exercises, and products and displays concerning
testing and evaluation. The FAA Icing Forecasting Improvement Program
Experimental Design (Politovich 1989) was completed in Fall 1989,
afterwhich the 6-year program began. As the program evolved, it became
clear that excellent opportunities existed for collaboration between
investigators interested in aircraft icing, and those interested in
understanding the physical processes active in Front Range winter
storms. It was decided to form a larger research program that would
encompass these broader interests, hence, WISP. The investigators
agreed that the central unifying objective for WISP should be a better
understanding of the processes responsible for the production and
depletion of SLW, which is of primary concern to both research and
operational communities.
In addressing the objectives, SLW formation/depletion and aircraft
icing, WISP studied two main areas. The first, Storm Dynamics,
considered anticyclonic storms, cyclonic storms, local topographic
forcing, conditional symmetric instability, cold-air damming/barrier
jets, synoptic and mesoscale fronts, and diabatic processes. The
second area, Cloud Microphysics, focused on the formation of ice
crystals, depletion of SLW, and production of large drops.
An array of instruments were used in WISP90 and WISP91. Two research
aircraft, the University of Wyoming King Air and the University of
North Dakota (UND) Citation II carried several instruments taking
cloud physics, thermodynamics, and air-motion measurements. WISP90
utilized the NCAR CP-4 C-band and S-band Mile High Radar, while the
Colorado State University (CSU) CHILL S-band, the UND C-band, and the
NCAR CP-2 radar operated during WISP91, measuring reflectivity and
Doppler velocity. The NOAA Wave Propagation Laboratory (WPL) operated
3 ground-based vertically pointing microwave radiometers sensitive to
water vapor, precipitable (total path) water vapor, liquid water, and
integrated liquid water. Wind-profiling radars provided vertical
profiles of horizontal wind velocity. Using the Radio Acoustic
Sounding System (RASS) (Westwater and Kropfli 1989), the radars also
measured profiles of virtual temperature with the same resolution as
the wind profiles. The new-generation National Weather Service (NWS)
laser ceilometer obtained cloud-base height
measurements. Zenith-viewing infrared radiometers were operated for
WISP90 for cloud identification and during WISP91 for quantitative
measurement of cloud-base temperature. Portable Automated Mesonet (PAM
II) and Program for Regional Observing and Forecasting Systems (PROFS)
surface weather stations reported temperature, dew point, pressure,
humidity, wind speed and direction, peak wind, rainfall, snowfall, and
global sky radiation. NCAR Cross-chain LORAN Atmospheric Sounding
System (CLASS) stations were deployed retrieving pressure,
temperature, dew point, and wind speed and direction. A network of
voluntary snowfall observers in the field collected snow accumulation,
snowfall rate, liquid equivalent, crystal habit, degree of riming,
aggregate formation and size, wind speed and direction, snow start/end
times, rainfall, and lightning.
Research using the WISP90 and WISP91 data is currently ongoing. The
Valentine's Day storm during WISP90 characterized by the invasion of a
polar air mass, overrun by southwesterly to southerly flow aloft
represented an anticyclonic upslope storm. Heavy snowfall of 40-80
inch depth fell along the Front range from Cheyenne, Wyoming, to
Denver, during the deep, cyclonic storm of March 6-7 1990. SLW
droplets with diameters greater than 50 um were observed. A shallow
cold front 3.5 km MSL caused temperatures to drop more than 10 degrees
in a six-hour period January 19 1991. Ice crystal formation and
evolution associated with a well-defined shallow upslope cloud
developed during the Valentine's Day storm of 1990 as seen from the
University of Wyoming King Air aircraft. During the two years of WISP
field-data collection, a persistent problem encountered in formulating
local nowcasts and forecasts was frequent mediocre and occasionally
poor performance of NMC-based models such as the Nested Grid Model
(NGM). This was clear March 29-30 1991 where significant snowfall was
predicted by both the NGM and the Limited Fine-Mesh (LFM) models
associated with an amplifying short wave approaching from the
northwest.
The WISP93 experiment was an instrument testing (IT) project called
WISP-IT. New instrumentation was tested to be used in the WISP94
experiment.
The WISP94 experiment featured 25 researchers from NCAR's Research
Application Program, NOAA, and several universities searching for the
secrets that cause supercooled water droplets and ice crystals to form
in clouds. WISP94 focused on the origins of in-cloud ice. Air samples
taken from just outside ice-bearing clouds are being rushed to a cloud
chamber at Colorado State University where scientists are recreating
the ice-production process that the air would have encountered within
the cloud. This technique coupled with improved processing methods for
ice-nucleus filter samples should yield a better understanding of
nucleation mechanisms at work in winter storms.
The WISP team has identified shallow stratus decks as the source of
the largest supercooled droplets, those with diameters from 50 to
several hundred microns (0.002 to 0.01 inches). A number of innovative
new instruments have sampled clouds from aboard the University of
Wyoming's King Air and NCAR's Electra research aircraft. A U-band
radar on the King Air operated jointly by the universities of Wyoming
and Massachusetts will help resolve the fine-scale structure near
cloud tops that may be responsible for generating the large
droplets. Both aircraft flew to Kansas and Nebraska for very
successful probes of extensive stratus decks. The King Air also
studied intense snow and ice storms in Oklahoma
Geographic Coverage
Spatial coordinates
| N: 42.0 |
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S: 38.0 |
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E: -102.0 |
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W: -106.0 |
Temporal Coverage
Start Date:
1990-02-01
Stop Date:
1994-03-25
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Location Keywords
Science Keywords
ISO Topic Category
Platform
Instrument
Project
Ancillary Keywords
Originating Center
Data Center
Distribution
Distribution Media:
On-line
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Personnel
ROY
JENNE
Role:
TECHNICAL CONTACT
Phone:
(303) 497-1215
Fax:
(303) 497-1137
Email:
jenne at ucar.edu
Contact Address:
NCAR/SCD/DSS
P.O. Box 3000
City:
Boulder
Province or State:
CO
Postal Code:
80307
Country:
USA
ROY
RASMUSSEN
Role:
INVESTIGATOR
Phone:
(303) 497-8430
Email:
RASMUS at NCAR.UCAR.EDU
Email:
RASMUS at RAP.UCAR.EDU
Contact Address:
National Center for Atmospheric Research
P. O. Box 3000
City:
Boulder
Province or State:
CO
Postal Code:
80307
Country:
USA
SCOTT
A.
RITZ
Role:
DIF AUTHOR
Phone:
301-614-5126
Fax:
301-614-5268
Email:
Scott.A.Ritz at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City:
Greenbelt
Province or State:
Maryland
Postal Code:
20771
Country:
USA
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Publications/References
Politovich, M.K., 1989: 'Aircraft Icing Caused by Large Supercooled Droplets'.
J. Appl. Meteor., 28, 856-868.
Rasmussen, R., M. Politovich, J. Marwitz, W. Sand, J. McGinley, J. Smart, R.
Pielke, S. Rutledge, D. Wesley, G. Stossmeister, B. Bernstein, K. Elmore, N.
Powell, E. Westwater, B. B. Stankov, and D. Burrows, 1992: 'Winter Icing and
Storms Project'. Bull. Amer. Meteor. Soc., 73, 951-974.
Westwater, E.R., and R.A. Kropfli, 1989: 'Remote Sensing Techniques of the Wave
Propagation Laboratory for the Measurement of Supercooled Liquid Water:
Applications to Aircraft Icing'. NOAA Tech. Memo. ERL WPL-163, 28 pp.
Creation and Review Dates
Last DIF Revision Date:
2008-08-14
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Links
