February 18, 2003 — For a second year, NOAA will again join university students and scientists from five federal agencies in the Cold Land Processes Field Experiment in the Colorado Rockies to study snowpacks from the ground, air and space in an effort to better understand water, weather and climate in cold land areas. These areas, also known as the “terrestrial cryosphere,” are areas where water is frozen either seasonally or permanently and snow, ice and frozen soils and vegetation are common. The CLPX is lead by Don Cline, a NOAA National Weather Service scientist at the National Operational Hydrologic Remote Sensing Center in Chanhassen, Minn. The CLPX is sponsored by the NOAA Office of Global Programs and both NASA's Terrestrial Hydrology and Earth Observing System Programs, to address broad interagency objectives in hydrology, water resources, ecology and atmospheric sciences. Ultimately, acquiring a greater understanding of snow processes will aid in snowmelt prediction, flood forecasting, avalanche forecasting, agricultural applications and improved management of the nation’s water resources. CLPX will also assist in the developing more effective remote sensing techniques to study and monitor the nation’s snow covered landscapes.

The Terrestrial Cryosphere
The terrestrial cryosphere represents a significant proportion of the Earth’s land surface. Coarse-resolution satellite data estimate that on average more than 60 percent of the northern hemisphere land surface has snow cover in midwinter. More than 30 percent of Earth’s total land surface has seasonal snow, and about 10 percent is covered permanently by snow and ice. Seasonally and permanently frozen soils occur throughout higher latitudes and at high elevations, and are estimated to occur over approximately 35 percent of the Earth’s land surface. Permanently frozen soils (known as “permafrost”) underlie approximately 26 percent of the Earth’s land surface. However, because these areas are dynamic; the spatial extents of frozen and thawed areas vary significantly on daily, seasonal and interannual time scales.

Why is the Terrestrial Cryosphere Important?
The terrestrial cryosphere is important because it forms a major component of the Earth's hydrologic system, and has significant influence on global weather and climate. Seasonal snow cover and glaciers store large amounts of fresh water, and are therefore critical components of the hydrologic cycle. Likewise, seasonal and permanent frost in soils reduce both infiltration into and migration of water through soils, thus severely reducing the amount of water that can be stored in soils. By reducing infiltration, frozen soils can dramatically increase the runoff generated from melting snow, and are often associated with devastating snowmelt floods.The importance of seasonally and permanently frozen land surfaces extends far beyond hydrologic processes. These areas also influence global weather and climate systems, the geosphere and the biosphere. For example, depending on whether surface water is in the liquid or frozen state, there can be important consequences for surface albedo and net radiation, as well as for latent energy exchanges. The high albedo of snow covers reflects much of the incoming solar radiation away from the Earth’s surface, resulting in less energy to warm the surface than when there is no snow cover. Cold snowpacks also act as a significant energy sink, since large amounts of available energy are needed to raise snowpack temperatures and melt the snow. This use of energy influences weather patterns and air mass characteristics “downstream” of snow-covered regions. Permanently frozen areas are also important components of global biogeochemical budgets. In fact, it is estimated that one third of global carbon is immobilized within permafrost soils. The influence of seasonally and permanently frozen land surfaces even extends to engineering in cold regions, trafficability for humans and other animals, and a variety of hazards and costs associated with living in cold lands.

CLPX Objectives
The CLPX will improve the fundamental understanding of the hydrology, meteorology, climate and ecology of the terrestrial cryosphere. It will also provide a baseline set of observations that can be used to gauge future changes in the extent and characteristics of the terrestrial cryosphere. With regard to remote sensing science and technology, CLPX will answer the following questions: Can remote sensing provide information about the freeze/thaw state of the land surface and about the physical characteristics of snow, with sufficient accuracy and timeliness to significantly improve hydrologic forecasts and snow models, mesoscale numerical weather prediction models and global ecological and biogeochemical models?

CLPX Methodology
This month, NOAA scientists from the National Operational Hydrologic Remote Sensing Center and the NOAA Environmental Technology Laboratory will again join researchers from NASA's Goddard Space Flight Center and Jet Propulsion Laboratory, the USDA Forest Service, the U.S. Army Corps of Engineers Cold Region Research and Engineering Lab, the U.S. Geological Survey, the USDA Agricultural Research Service and graduate students from universities around the world in conducting the second year of this two-year experiment. NOAA Corps commissioned officers from the NOAA Aircraft Operations Center will pilot the NOAA Turbo Commander aircraft to collect airborne snow water equivalent data for the experiment. Joining them will be three other aircraft from NASA’s Dryden Flight Research Center (DC-8 and Twin Otter) and Wallops Flight Facility, which will be collecting a variety of airborne synthetic aperture radar, passive microwave, and optical remote sensing data for the CLPX. The experiment will be conducted in the central Rocky Mountains of the western United States, where large physiographic gradients provide the rich array of different terrain, snow, soil and ecological characteristics. This region of northern Colorado and southern Wyoming provides an ideal "natural laboratory" for snow research because:

• It contains a wide range of terrain characteristics in a relatively small area, thus giving researchers a broader view of cold-season processes in a small geographic area;
• There is a long record of research on cold-season processes in this area, thus providing an important historical context for the CLPX;
• There is a strong infrastructure of transportation, lodging, food, fuel, power and medical facilities in the area that can provide services relevant to the experiment; and
• The study area contains many different topographic, climatic, hydrologic and ecologic characteristics that can be used as surrogates for cold land regions throughout the globe.

The CLPX is designed to take advantage of seasonal variations in snow and frozen soil conditions. In the same way that the diverse terrain of the study area provides a broad range of snow pack conditions, seasonal variations will allow researches to study the same geographic area under a variety of atmospheric conditions. Field campaigns will be conducted in late winter (mid-February) — when predominantly frozen conditions and dry snow covers are expected, and ecosystems are mostly dormant — and again in early spring (late-March) — when transitional (e.g., frozen and thawed) conditions and predominantly wet snow covers are expected, and ecosystem activities increase. Background data collection for this two-year experiment began in the fall of 2001. The first field campaigns ran from Feb. 19 to 25 and March 24 to 30, 2002, to observe the study areas under both dry snow and wet snow conditions. This schedule will be repeated again in 2003.

A Multi-sensor, Multi-scale Approach
The experimental design is a multi-sensor, multi-scale approach to providing the comprehensive data set necessary to address several experiment objectives. Within a framework of this diverse study area intensive ground, airborne and spaceborne observations will be collected.

• Ground Observations: More than 60 scientists and students will assist in taking ground measurements during CLPX. Depending on the study area, they will use skis, snowshoes and over-snow vehicles to reach designated study sites. Conducting research on this already rugged terrain will be difficult, since scientists will be carrying 20-30 pound packs (with shovels, probes, scales, radios, GPS units, and safety equipment). One of the major objectives of the CLPX will be to survey snow pack characteristics to measure water content and determine how snow changes with time — including how it melts and how long it takes to melt. To accomplish this, researchers will dig hundreds of snow pits to analyse snow water content, density, temperature, grain size and crystal formation at different depths. Some pits exceed 3 meters depth. Because variations in snow properties influence remotely sensed measurements of snow from space, gaining knowledge as to what space-borne sensors “see” on the ground will be critical in improving the use of remote sensing techniques in this arena.

• Air and Space-borne Observations: Researchers also will use remote sensing techniques from both aircraft and satellites (i.e., NASA's Terra and Aqua satellites) to measure characteristics of snowpack and the freeze/thaw state of the land surface. NASA will be flying its DC-8 "Airborne Laboratory," P3-B, and Twin Otter aircraft, with a variety of microwave imaging and other sensors. The NOAA National Operational Hydrologic Remote Sensing Center Airborne Snow Survey Program will be flying snow detection sensors onboard NOAA Turbo Commander aircraft to capture cold land properties throughout the CLPX study areas. The NOAA Turbo Commander aircraft, supported by the NOAA Aircraft Operations Center, NOAA Marine and Aviation Operations and piloted by NOAA Corps commissioned officers, is used operationally by the NOHRSC to measure snow water equivalent throughout the nation. Specifically, NOHRSC's GAMMA instrument will measure terrestrial and atmospheric gamma radiation, which will be used to determine snow water equivalents.

The data gathered on the ground and from NOAA/NASA aircraft will then be compared to that obtained by satellites to evaluate the space-borne snow measurements from NASA satellites (i.e., Terra's Moderate Imaging Spectroradiometer instrument (MODIS) and Aqua's Advanced Microwave Scanning Radiometer (AMSR) instrument). By determining the accuracy of the satellites and using that information to develop improved snow sensors, researchers may someday be able to measure snow quantity and frozen ground from space anywhere in the world—without a ground team.

The information acquired from CLPX will be used to better understand the formation and evolution of snowpacks, especially the processes involving the timing and extent of snowmelt. This in turn will aid in snowmelt prediction (the processes and timing of snowmelt), flood forecasting, avalanche forecasting, agricultural applications and improved management of the nation’s water resources. According to Don Cline, NOAA scientist at NOHRSC and leader of the CLPX, the “measurements we made during CLPX last year have already been extremely useful for helping us understand how to update water and weather forecast models with observed snow information. The NOHRSC is currently demonstrating a new Snow Information System, which uses all available ground, airborne and satellite snow data to update a state-of-the-art snow model for the continental U.S. The CLPX data collected just last year has helped us to use operationally available snow data much more effectively”. Likewise, observing the transitions in snow, water and energy in frozen landscapes will ultimately help researches design better sensors to measure the water content of snow from space. Ultimately, CLPX will allow researches to develop models, which will extend local-scale understanding of water fluxes, storage and transformations to regional and global scales.

Relevant Web Sites
NOAA CLPX

NASA Land Surface Hydrology Program

U.S. Army Corps of Engineers Research and Development Center

USDA Frasier Experimental Forest

For reporters who would like to attend the media day at the CLPX:
To arrange field dates, contact: Kent Laborde or Scott Smullen, NOAA Public Affairs, Telephone: (202) 482-5757 or (202) 482-1097

Media Contacts:
Kent Laborde, NOAA, (202) 482-5757 or Scott Smullen, NOAA, (202) 482-6090