|
COLD LAND PROCESSES EXPERIMENT (CLPX) FACT SHEET
Introduction
Snow not only transforms the ground into an attractive winter white blanket, it’s also important in providing water needs for people throughout the year. The Cold Land Processes Experiment (CLPX) mission is studying snow to better understand its role in the hydrologic cycle.
Scientists and students from six federal agencies and many universities will study snowpacks of the Colorado Rockies from the ground, air and space to improve forecasts of springtime water supply and snowmelt floods and to study how snow-covered areas affect the Earth’s weather and climate.
The 2003 NASA-NOAA (National Oceanic and Atmospheric Administration) Cold Land Processes Experiment (CLPX) runs from February 19-25 and March 25-31. Background data collection for the experiment began in the fall of 2001, and data collection will be completed in the summer of 2003.
The CLPX is a research mission concerned with frozen landscapes, where water is frozen either seasonally or permanently. Cold land regions, known as the cryosphere, form a major component of the Earth's hydrologic system, and interact significantly with global weather and climate. This is the second year of intensive snow measurements in Colorado’s mountains and high-elevation rangelands. The mission includes digging hundreds of snow pits to analyze snow water content, temperature, and crystal formation at different depths.
Nine satellites and three airplanes are being used during the experiment. They will provide a look at snow cover, snow grain size, wet and dry snow, reflected solar energy from snow cover, and the freeze/thaw process.
Dozens of scientists will be using skis, snowmobiles, and aircraft to survey and sample snow during the CPLX field experiment They will also use microwave measurements from satellites and aircraft to measure characteristics of snow pack and the freeze/thaw state of the land surface.
Researchers from NASA’s Goddard Space Flight Center, Jet Propulsion Laboratory, and Dryden Flight Research Center will conduct the experiment with NOAA scientists from the National Weather Service’s National Operational Hydrologic Remote Sensing Center (NWS/NOHRSC) Other participants include scientists at 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.
Why Study Snow?
The primary goal of CLPX is to determine the best methods of finding the liquid water equivalent of snow using remote sensing techniques. By knowing the amount of liquid in snow, scientists can better determine the amount of water going into the ground during the melting season.
Remote sensing of snow is a challenge, since different techniques are required for wet and dry snow. Once on the ground, snow can be relatively light and dry, or it can be heavy and wet. For the same snow depth, lighter snow has less water content, while heavier snow has a higher water content. On the ground, scientists can determine the water content simply by measuring the snow depth and then weighing the snow. From space, snow measurement is made more complicated by factors such as the snow wetness, the size of individual snow grains within the snow pack, and other materials such as vegetation that are seen along with the snow.
Snow is very crucial to the Western U.S., where 40-65% of the precipitation falls as snow, and more than 80% of the runoff can come from the snowpack. Bettering our ability to measure the water quantity stored as snow and knowing more about snowmelt processes will enable better utilization of water resources.
The importance of cold land processes extends far beyond water resources. Snow-covered areas also interact significantly with the global weather and climate system, the land, and the lower atmosphere that supports life. The influence of seasonally and permanently frozen land surfaces extends to engineering in cold regions, trafficability for humans and other species, and a variety of hazards (e.g. avalanches) and costs (e.g. heat for buildings, snow removal, etc.) associated with living in cold lands. The Cold Land Processes Mission will use remote sensing to measure critical components of these permanently frozen lands, known as the terrestrial cryosphere.
The data collected during the CPLX mission will improve our fundamental understanding of the hydrology, meteorology, and ecology of the frozen lands. Also, it will provide a baseline set of observations that can be used to gage future changes in the extent and characteristics of major components of the frozen lands.
The CLPX studies will ultimately help scientists to design better sensors to measure the water content of snow from space. In the future, new remote sensing measurements coupled with water and weather forecast models should improve prediction of water supplies, floods, weather and climate.
What Aspects of Snow Will Satellites Study from Space?
Measurements from space provide a look at the big picture needed for climate models. Satellites that will be utilized during CLPX include IKONOS in February and April 2003 to measure snow cover, Landsat from October 2002 through June 2003 to look at snow cover and grain size, the Advanced Very High Resolution Radiometer aboard NOAA’s Geostationary Operational Environmental Satellites (GOES) satellites that will look at snow cover from October 2002 through June 2003; and three instruments from NASA’s Terra satellite.
Terra’s satellite instruments include: the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Multi-Angle Spectroradiometer (MISR) and the Moderate-Resolution Imaging Spectroradiometer (MODIS). These instruments will all be in operation over the experiment area from October 2002 through June 2003. ASTER will look at snow cover and grain size, MISR will look at solar energy reflected and radiated by the snow cover, and MODIS will capture images of snow cover.
Five other satellites will be used to observe wet and dry snow cover. RadarSAT will be observing wet snow cover and freeze and thaw processes in February and April 2003. The European Space Agency’s Envisat satellite instrument, the Advanced Synthetic Aperture Radar (ASAR) will be observing dry snow cover and freeze and thaw processes in February and April 2003.
The QuikSCAT instrument aboard NASA’s Seawinds satellite, the Special Sensor Microwave Imager (SSM/I) aboard Defense Meteorological Satellite Program (DMSP) satellite, and the Advanced Microwave Scanning Radiometer (AMSR-E) instrument aboard NASA’s Aqua satellite will all look at dry snow cover between October 2002 and June 2003.
What Aircraft Will Be Used, And What Will They Measure?
There will be three aircraft used during the mission, NASA’s DC-8, NASA’s P-3, and NOAA’s AC690. The DC-8 will observe snow extent, depth, water equivalent, snow wetness and the freeze and thaw conditions. From NASA’s 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. The P-3 will observe snow extent, water equivalent, wetness and the freeze and thaw conditions. The AC690 will be used to assess snow water equivalent and soil moisture. The AC690 is used to conduct airborne snow surveys using a gamma detection system. The system measures natural terrestrial gamma radiation over specific flight lines for the purpose of determining soil moisture and snow water equivalent. This data is used in near real time by hydrologists and water supply managers to make better flood forecasts and water supply
predictions.
Science Themes
There are four major science questions for this mission:
1. How does the extent of snow and frozen ground affect weather and climate?
2. Can the components of the terrestrial cryosphere be observed from space accurately enough to identify meaningful climatic trends?
3. To what extent can snow and frozen ground information, deduced from remote sensing data, improve models of cold season processes, hydrologic forecasts and forecasts of high latitude ecosystem functions?
4. To what accuracy can snow water equivalent be estimated from remote sensing data, and is this sufficient for hydrological applications?
Measurement Instruments
Measurements from four aircraft and NASA’s Terra and Aqua satellites will gather snow data for this mission by remote sensing. The data gathered on the ground and from the aircraft will then be compared to that obtained by the satellites to evaluate the space-borne snow measurements of Terra’s Moderate Imaging Spectroradiometer instrument, and Aqua’s Advanced Microwave Scanning Radiometer instrument. By determining the accuracy of the satellites and developing improved snow sensors, researchers hope to someday be able to measure snow quantity and frozen ground from space anywhere in the world without a ground team.
NASA will be flying their DC-8 and P3-8 Airborne Laboratories and Twin Otter aircraft, with a variety of microwave imaging and other sensors, including NASA’s Airborne Synthetic Aperture Radar (AIRSAR), Polarimetric Scatterometer (POLSCAT), and Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) sensors and the Polarimetric Scanning Radiometer (PSR) from NOAA’s Environmental Technology Laboratory. The NOAA Airborne Snow Survey Program will also be flying the National Weather Service’s GAMMA snow water equivalent sensors.
CLPX
During the winter of 2002 dozens of scientists on the ground, in the air and using satellite observations began a multi-year experiment to study winter snow packs on the Colorado side of the Rocky Mountains. The experiment continues this year as the scientists return to Colorado to make additional measurements. The purpose of this NASA- and NOAA-funded experiment is to improve the estimation of snow amount and forecasting of spring flooding due to snowmelt, and to study the role of cold lands within the Earth's climate.
During the 2002 field campaigns, the scientists focused on dry-snow conditions. Most of the airborne measurements were made in February, when cold weather typically results in cold, dry snow. This year, scientists will focus on wet snow conditions. Most measurements will be repeated in February 2003 to compare to last year, but the major focus is on March, when warmer weather typically results in warmer and wetter snowpacks. Scientists expect to see large differences in the remote sensing measurements between the dry- and wet-snow conditions.
Measurements made during the first CLPX mission last year have already been useful for understanding how to update water and weather forecast models with observed snow information. The data allowed scientists to quantify the large natural variability of snow characteristics over short distances, which is important for understanding how well a ground observation of snow conditions represents larger areas. Weather and water forecast models have to take this into account when ground observations are used to correct or validate the models. This new information is also critical for designing new remote sensing instruments to measure snow from space.
The information derived from this mission will allow better understanding of the formation and evolution of snowpacks, especially the processes involving the timing of snowmelt. During CLPX, scientists on the ground will be carefully monitoring the changes in snow conditions that occur, as the remote sensing instruments observe the snow from a distance. As snowpacks transition from dry to wet, and snowmelt begins, these changes will be evident in the remote sensing measurements. Scientists will use this information to develop new techniques to not just measure the water content of the snow pack from space, but to also determine when snowmelt occurs.
Colorado as the Site for CPLX
The experiment will be conducted in the central Rocky Mountains of the western United States, where there is a wide 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. It contains a wide range of terrain characteristics in a relatively small area. There is also a long record of research on cold-season processes in the area, including several current projects by researchers at local universities and federal agencies.
This area is often characterized by its rugged mountain topography and deep mountain snow packs, but in fact it contains many different topographic, climatic, hydrologic, and ecologic characteristics that can be used as surrogates for cold land regions throughout the globe. Steep elevation and inclines and declines in the topography of the land result in rapid changes in these characteristics over short distances. Deep seasonal snow packs are primarily limited to higher elevations. Much of the study area is more likely to have relatively shallow snow packs, on the order of 0.5-meter or less. On the high elevation rangelands such as North Park, snow packs tend to be shallow and wind swept, with extensive frozen ground.
There also is a strong infrastructure of transportation, lodging, food, fuel, power, and medical facilities in the area that will prove to be useful to the scientists as the research progresses.
CPLX Program Management
The overall CLPX objectives stem directly from NASA's Earth Science Enterprise Research Strategy to address hydrologic variability and consequences of climate and terrestrial change wit the ultimate goal to improve prediction of the hydrologic cycle and management of our nation's water resources.
The CLPX is sponsored by NASA’s Terrestrial Hydrology Program and the Earth Observing System Program, and by NOAA’s Office of Global Programs to address broad interagency objectives in hydrology, water resources, ecology, and atmospheric sciences NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of our nation’s coastal and marine resources.
Related Web Sites
For more information, photographs and images, see:
http://www.gsfc.nasa.gov/topstory/20020216coldland.html
CLPX Homepage:
http://www.nohrsc.nws.gov/~cline/clp.html
NASA Land Surface Hydrology Program:
http://lshp.gsfc.nasa.gov/aboutls.html
NOAA: http://www.noaa.gov
U.S. Army Corps of Engineers Research and Development Center:
http://www.crrel.usace.army.mil
USDA Frasier Experimental Forest:
http://www.fs.fed.us/rm/fraser/
Satellite Websites:
Aqua
http://aqua.gsfc.nasa.gov
Defense Meteorological Satellite Program
http://dmsp.ngdc.noaa.gov/dmsp.html
Envisat
http://envisat.esa.int/
GOES
http://rsd.gsfc.nasa.gov/goes/
IKONOS
http://www.spaceimaging.com/products/ikonos/
Landsat
http://landsat.gsfc.nasa.gov/
Radarsat
http://www.ccrs.nrcan.gc.ca/ccrs/data/satsens/radarsat/rsatndx_e.html
SeaWinds
http://winds.jpl.nasa.gov
Terra
http://terra.nasa.gov/
Aircraft Websites:
NASA’s DC-8 Aircraft
http://www.dfrc.nasa.gov/Gallery/Photo/DC-8/HTML/EC99-44896-13.html
NASA’s P-3 Aircraft
http://www.wff.nasa.gov/~apb/p3.htm
NOAA’s AC690 Aircraft
http://www.hurricanehunters.noaa.gov/aircraft_turbo.htm
Last Revised: 27 February 2003
|
