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Snow
covered evergreens
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SNOW
SCIENCE, NOT SPORT, IN THE ROCKIES - For
more images, click here.
This
month, dozens of scientists on the ground, in the air and
using satellite observations will begin a multi-year experiment
to study winter snow packs on the Colorado side of the Rocky
Mountains. The purpose of this NASA-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.
Scientists
and students from six federal agencies and many universities
will be using skis, snowmobiles and aircraft to survey and
sample snow during this NASA Cold Land Processes Experiment
(CLPX). They will also use microwave measurements from satellites
and aircraft to measure characteristics of the snow pack and
the freeze/thaw state of the land surface.
The
CLPX is a research mission concerned with frozen landscapes,
where water is frozen either seasonally or permanently because
of water stored in snow and ice cover. Cold land regions form
an important component of the Earth's hydrologic cycle, and
interact significantly with water resources, global weather
and climate.
Teams
of scientists and technicians from three NASA facilities --
the Goddard Space Flight Center, Greenbelt, Md.; Jet Propulsion
Laboratory, Pasadena, Calif.; and Dryden Flight Research Center,
Edwards, Calif. -- will take part in this campaign. They will
join scientists from the NOAA/National Weather Service's National
Operational Hydrologic Remote Sensing Center (NWS/NOHRSC),
the U.S. Department of Agriculture's 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.
"We
will be making intensive measurements of snow in Colorado's
mountains and high-elevation rangelands, including digging
hundreds of snow pits to analyze snow water content, temperature
and crystal formation at different depths," explained
Don Cline, a scientist with the NWS/NOHRSC who leads the CLPX.
"We'll use this information to better understand the
formation and evolution of snow packs, especially the processes
and timing of snowmelt. Observing the transitions in snow,
water and energy in such frozen landscapes will ultimately
help us design better sensors to measure the water content
of snow from space."
Michael
Jasinski, former manager of NASA's Terrestrial Hydrology Program
at NASA Headquarters, Washington, said, "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. Our ultimate goal is to
improve prediction of the hydrologic cycle and management
of our nation's water resources."
The
CLPX field campaign will employ two aircraft and measurements
from NASA's Terra and Aqua satellites to gather snow data
by remote sensing. The data gathered on the ground and from
the aircraft will then be compared to the information obtained
by the satellites. Aqua is being launched this year and will
be operational for the 2003 campaign. 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 for the global views needed by forecast
models.
Dryden
Flight Research Center will be flying its DC-8 "Airborne
Laboratory" with a variety of microwave imaging and other
sensors. The NWS/NOHRSC Airborne Snow Survey Program will
also be flying similar snow detection sensors on a NOAA aircraft
to capture cold land properties during mid-winter. The experiment
will be conducted in the central Rocky Mountains where there
is a wide array of different terrain, snow, soil and ecological
characteristics. Background data collection for the experiment
began in the fall of 2001. The first field campaign runs from
February 19 to 25 and March 24 to 30, 2002, to observe the
same areas when the snow and ice begin to melt. This schedule
will then be repeated in 2003.
The
mission is sponsored by the NASA Terrestrial Hydrology Program
and the Earth Observing System Program to address broad NASA
Earth Science Enterprise objectives in hydrology, water resources,
ecology and atmospheric sciences.
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FOURTEEN
NESTED STUDY AREAS FOR THE COLD LAND PROCESSES FIELD EXPERIMENT
This map depicts the largest five of fourteen study areas
in north central Colorado and south central Wyoming where
researchers will be conducting snow studies over a 2-year
period beginning in February 2002. This is a ground and airborne
mission whose purpose is to gain a better understanding of
how snow processes work. More than 60 researchers will be
sampling snow packs to measure water content and determine
how snow changes with time - including how it melts and how
long it takes to melt. Better understanding of snow processes
will aid snowmelt prediction, flood forecasting, avalanche
forecasting, and agricultural applications.
The Large Regional Study Area (blue boundary) and Small Regional
Study Area (red boundary will be the focus of satellite remote
sensing data collection and modeling studies. Ground and airborne
measurements will be focused on three 25-km x 25-km study
areas: North Park, Rabbit Ears, and Fraser. Within each of
these three areas, there are three smaller (1-km x 1-km) Intensive
Study Areas (ISA).
Why
these study areas?
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. Consequently, a wide range of
snow and frozen ground characteristics can be expected in
the region. This gives researchers a broader view of cold-season
processes in a single experiment, and also means that ground
and airborne campaigns can be conducted efficiently.
· There is a long record of research on cold-season
processes in this area, including several current projects
by researchers at local universities and federal agencies.
This helps provide an important historical context for the
CLPX. Also, there are several research facilities in the area
that offer a unique infrastructure to support the objectives
of the experiment, such as the US Forest Service Fraser Experimental
Forest facilities in the Fraser study area.
· There is a strong infrastructure of transportation,
lodging, food, fuel, power, and medical facilities in the
area. There are numerous airports within the area that provide
services relevant to the experiment. Primary and secondary
road networks are well maintained during the winter months,
allowing access throughout the study area. These are all important
assets for conducting a large wintertime field experiment.
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 topographic
gradients 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.
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A
CLOSER LOOK AT THE BUFFALO PASS INTENSIVE STUDY AREA (ISA)
IN THE RABBIT EARS STUDY AREA
The
nine ISAs were selected to represent a broad spectrum of environmental
characteristics. These 1-km x 1-km areas can each be characterized
by a dominant characteristic. For example, this image shows
the sparse forest cover of the Buffalo Pass ISA, in the Rabbit
Ears Study Area, looking North. The red boundary is a very
rough approximation of the study area. The Continental Divide
runs N-S along the right edge of the image. Researchers can
use information from this ISA as a surrogate for many forested
areas around the world. Similarly, the other ISAs have dominant
characteristics that range from dense forest cover to flat,
open grasslands, which will help scientists relate results
from the CLPX to other parts of the world.
The
Buffalo Pass ISA contains a SNOTEL site (for SNOwpack TELemetry),
part of an automated system to collect snow pack and related
climatic data in the Western United States, operated by the
Natural Resources Conservation Service (NRCS). The "Tower"
SNOTEL (shown by red arrow) often measures some of the deepest
snow packs in Colorado. The SNOTEL network infrastructure
helps the CLPX research tie into a historical record of snow
pack conditions that goes back 60-70 years. This is essential
for understanding the climatic aspects of cold land processes.
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KEY:
Tair -Air temperature
Tsoil - Soil temperature
Albedo - amount of energy reflected back to space from
the snowcover
Click
on pic to enlarge
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TIMING
OF THE EXPERIMENT
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 northern Colorado provides a broad range
of snow pack conditions, seasonal variations also help ensure
that a broad range of conditions are encountered. This image
shows some of the major changes to meteorology, hydrology,
and ecosystems that occur as the seasons change. 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. The field campaigns will be conducted
in 2002 and 2003.
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GROUND
MEASURUREMENT OF SNOW PROPERTIES
One of the major ground activities during the CLPX will be
extensive measurement of snow pack characteristics. This image
shows the wall of a typical snow pit on a steep slope, with
a depth and temperature measurement. In many locations, snow
pits may exceed 2-m in depth. Scientists will dig hundreds
of these snow pits throughout the nine ISAs to measure snow
depth, density, temperature, grain size, and other snow properties.
These properties influence remotely sensed measurements of
snow from space. Better understanding of what spaceborne sensors
"see" is critical for improving the measurements.
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More
than 60 scientists and students will be involved in making
ground measurements during the experiment. Depending on the
study area, they will use skis, snowshoes, and over-snow vehicles
to get around the area. This will often be difficult work
for these researchers, as each will be carrying 20-30 lb packs
with shovels, probes, scales, and other equipment, and the
terrain is often rugged. This image shows Kelly Elder, of
the US Forest Service and one of the CLPX Coordinators, recording
measurements at the Walton Creek ISA, also in the Rabbit Ears
study area.
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NASA'S
FLYING LABORATORY
This image shows the NASA DC-8 "Flying Laboratory,"
with the AIRSAR instrument on board (NASA Photo EC98-44444-4).
The instrument is visible on the fuselage just aft of the
wing. The NASA DC-8, supported by NASA's Earth Science Enterprise
and operated by the Dryden Flight Research Center in Edwards,
CA, will fly high-altitude and low-altitude flights over the
three CLPX study areas, collecting data from three instruments
on board. The NASA AIRSAR instrument will collect synthetic
aperture radar measurements of snow and frozen ground. The
NASA POLSCAT instrument will collect Ku-band scatterometer
measurements. The NOAA PSR-A instrument, also flown aboard
the DC-8 during the 2002 campaigns, will collect passive microwave
measurements.
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NATIONAL
WEATHER SERVICE'S AIRBORNE SNOW SURVEY AIRCRAFT
This image shows the NOAA AC690A aircraft. The aircraft, supported
by NOAA's Aircraft Operations Center in Tampa, FL and piloted
by NOAA Corps commissioned officers, is used operationally
by the National Weather Service's National Operational Hydrologic
Remote Sensing Center (NOHRSC) in Chanhassen, MN to measure
snow water equivalent throughout the Nation. The NOHRSC's
GAMMA instrument measures terrestrial and atmospheric gamma
radiation, which is used to determine snow water equivalent.
The AC690A will fly a dense network of flight lines throughout
each of the CLPX study areas, at a routine altitude of 500'
above the ground.
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