NASA News

National Aeronautics and

Space Administration

P.O. Box 273

Edwards, California 93523

Phone 661-276-3449

For Release:

February 15, 2002

Frederick A. Johnsen, News Chief

NASA Dryden Flight Research Center

Phone: (661) 276-2998

RELEASE: 02-08

NASA’s Airborne Science DC-8 aircraft departs its sunny Mojave Desert home in California on Feb. 17 to take part in a NASA-sponsored study of frozen landscapes. The IceSAR (Synthetic Aperture Radar) mission will use microwave remote sensing instruments on the aircraft to measure critical components of selected cold areas of the northern United States where land is frozen either seasonally or permanently.

Data gathered from this study will provide a better understanding of how the snow process works, how it changes with time, how snow melts and how long it takes to melt. Insight into these processes will help with snowmelt calculation, flood predictions, and avalanche forecasting. It will also have agricultural applications.

The first of two IceSAR flight phases, the Cold Land Processes Experiment (CLPX), will involve the NASA DC-8 in flights from Colorado Springs, Colo., over specific areas of northern Colorado in February. The Earth’s hydrology — or water system — is significantly affected by cold land areas and their interaction with global weather and climate.

The DC-8, from NASA’s Dryden Flight Research Center, Edwards, Calif., is fitted with three instruments for the hydrology study. From the Jet Propulsion Laboratory, Pasadena, Calif., the Airborne Synthetic Aperture Radar (AIRSAR) will give the DC-8 team an all-weather, side-looking imaging radar able to penetrate clouds and collect data at night. AIRSAR will measure snow depth and extent, as well as snow wetness and water equivalent, along with freeze and thaw conditions.

Ground data collection will take place at three northern Colorado sites with diverse topographic, vegetation and snow traits. Snow and ice characteristics collected will be compared with the airborne AIRSAR data taken simultaneously.

"AIRSAR is NASA’s radar technology testbed," said David Imel, principal investigator for the instrument. "During the IceSAR mission, we will not only acquire data useful to scientists for their studies of snow and ice, but we will also be testing new radar technology developed for this mission and collecting data that could be used to design future spaceborne synthetic aperture radar missions."

"NASA’s DC-8 is the only aircraft outfitted to perform this type of mission," said IceSAR mission manager Walter Klein. "The AIRSAR was designed and built by JPL for use aboard the DC-8."

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The DC-8 will also carry the JPL PoleScat, or polarmetric scatterometer, an instrument that will collect Ku-band scatterometer measurements. This will record ice crystal structure and snow layering. PoleScat is a year-old instrument and is flying on the DC-8 for the first time according to Steve Dinardo, PoleScat instrument manager.

A Polarimetric Scanning Radiometer (PSR) from the National Oceanic and Atmospheric Administration’s (NOAA) will collect passive microwave measurements at five frequencies and multiple polarizations. PSR is designed for satellite instrument validation and will be flown on the NASA DC-8 during CLPX to obtain high-resolution data of snow and its effect on satellite signatures. Scientists hope to develop an understanding of how a satellite using the same sensing channels would respond to snow depth, to enable accurate measurement of the amount of moisture in the snow pack. Data will provide the degree of emitted energy of ice and snow crystals by measuring and recording the microwave brightness of snow and ice.

"This is a superb partnership between NOAA and NASA," said Al Gasiewski, principal investigator for the PSR. "NOAA provides an instrument that complements those of NASA and NASA provides the aircraft platform and other sensors. The data will be used to support development of NASA satellites. Ultimately NOAA will use the data from the satellite for operational snow monitoring."

Flights for the second phase over the Great Lakes will be based in Madison, Wis., from Feb. 26 - March 1 and March 8 - March 25. The Great Lakes Winter Experiment (GLAWEX), measuring the extent and thickness of ice, will be coordinated with United States Coast Guard icebreakers, in radio contact with the DC-8.

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For more information:

Photos of the DC-8 are available on the Internet under NASA Dryden Research Aircraft Photo Archive, Dryden News and Feature Photos, URL: