Soil Moisture:
Science Motivation
Make overheads of one or two of the following images to illustrate the
science motivation:
Satellite Validation
- General: Satellite microwave sensors that might be used to
study global soil moisture are just now being launched and are still
being flight tested (Canada's RADARSAT, ERS-2). Aircraft microwave
sensors, like NASA's Push-Broom Microwave Radiometer (PBMR), illustrate
the kind of data we might get from space. Note the large contrast
between DRY and WET conditions and how the WET pattern follows the
underlying contours of Anticedent Precipitation Index (API) contours
indicating mm of residual rainfall. Microwave sensors are only sensitive
to near-surface (0-5 cm) soil moisture in open or sparsely covered
areas and this is why we would like students to collect their data
in these types of locations.
- Specific:
The PBMR made about seven 15 km long passes over the ARS Walnut Gulch
Experimental Watershed (in AZ) on two dates in 1990. Day-of-Year
212 was hot and dry (except in the town of Tombstone, lower left); while
DOY 216 was cool and wet after two rainfall events, indicated
qualitatively by the API contours.
Agricultural and Vegetation Needs
- General: Student-derived near-surface soil moisture can be
contoured and used to produce maps, like this one, that will be valuable
for studying seasonal variations in soil moisture and could be used to
initialize GCM's. Maps of soil moisture like this one are very rare,
particularly in today's world as all major governments are cutting funding
of base-line environmental data collection.
- Specific: An extensive
network of agricultural soil moisture stations over the Former Soviet
Union have been interpolated to illustrate the major seasonal and regional
differences in soil moisture observed over many years. This illustration
is derived from depth-profile measurements that estimate the amount of
water in a 2 meter column that would be available for plant growth.
- General: by Winnipeg Climate Center, Canadian Dept. of Environment
- Specific:
Improving Global Climate Models
- General: Water is transported by a variety of processes.
Try to identify the fluxes (movements) and reservoirs (storages)
in this diagram.
- Specific:
- General: Soil Moisture data is useful to initialize and validate
general circulation models (GCM's). Even if our data is not wide-spread,
we can compare local concentrations of measurements with model output
at that location.
- Specific: This schematic diagram illustrates the processes
scientists try to model at the land-surface and couple to atmospheric
transfers of energy and mass. What GLOBE observations will you be making
and where do they fit in to the big picture?
UA/GLOBE Science;
Last updated: 7/30/97;
Comments? globe@hwr.arizona.edu