iser system were related
RS-1 SAR) data proved
icrowave could be used
addressed many of the
mate energy and water
tion between remotely-
tt resulted in a mixed
i and calculated surface
1 Kohsiek et al. (1993))
be linked to differences
from Monsoon’90 and
ssistance term), reliable
s for both sparsely- and
ensed data with a storm
mited to the catchment
sized the importance of
step is to exploit the
and interstorm models
’ the satellite data with
:sponding maps of air
data layers, it will be
s at the regional scale,
and Pielke, 1989) with
based spectral images,
opographically diverse
an and accuracy. Once
eady for application to
logic processes,
imental data sets, have
semiarid rangelands.
., but also in providing
climates, biomes, and
1 for a future study to
gional-scale processes,
and WG’92 results to
igraphy on hydrologic
LAND-SURFACE
regions of the world,
enhanced precipitation,
as. Nonetheless, many
te effects of local and
itively flat terrain. In
aroposed for execution
iraphy on hydrological
ughly 12,000 km 2 in
:o 2800 m in the upper
ea. The major biome
ah Chaparral, Pinyon-
Juniper, and Coniferous Forest; all of which are traversed in a horizontal distance as short as 20 km. The
topographically-induced gradients in biome types and the associated spatial variations in fluxes of moisture,
energy and carbon in the Upper San Pedro basin provide a unique opportunity for investigating bio-hydro-
atmospheric interactions in a relatively compact area. The site also offers the opportunity to investigate
anthropogenic impacts on the water and energy balance due to significant cross-border surface characteristics
resulting from widely disparate land use in Mexico and the United States (Bryant et al., 1990).
4.1. SALSA-MEX Objectives.
An experiment such as SALSA-MEX would provide the opportunity to determine the symbiotic links between
remote sensing and modeling that will advance the application of both at the regional scale. The site of SALSA-
MEX is most conducive to this research due to the generally clear sky conditions, the monsoon storm patterns
(in time and space), and the distinct, elevation-related vegetation communities. The following initial experimental
research objectives are proposed for SALSA-MEX. Observation over a range of scale and subsequent analysis
of scaling relationships is implied in all of the objectives:
1. Quantify hydrologic fluxes and identify the dominant hydrologic processes as a function of time-space scales
in regions with high topographic relief with particular emphasis on surface-ground water interactions in the
San Pedro riparian area and the role of near surface soil moisture in infiltration and runoff generation.
2. Evaluate evapotranspiration and its relationship to the water balance in topographically rough terrain over a
range of canopy-soil-understory conditions represented by the biome types in the San Pedro.
3. Assess the utility of remotely sensed data for regional land surface characterization and for incorporation into
hydrologic and energy balance models utilized for Obj. 1 and 2.
4. Test the ability of mesoscale models to realistically simulate a broad range of land-atmosphere interactions
in heterogeneous domain with significant topographic relief.
5. Determine the spatial and temporal patterns of carbon uptake and release by the vegetation-soil continuum.
In addition to seasonal trends, the effects of water availability, particularly those resulting from precipitation
events, on these fluxes will be evaluated.
SALSA-MEX is presented here as a conceptualization for an interdisciplinary, regional-scale, semiarid
mountain experiment. Greater detail and elaboration of the project will be forthcoming if sufficient interest is
expressed by the scientific community.
5-CONCLUDING REMARKS
The Monsoon’90 and WG’92 Experiments (and potentially SALSA-MEX) have provided the opportunity to make
substantial progress on the five components of the modeling strategy presented in Figure 1. The goal is still the
synthesis of these interdisciplinary results toward an integrated storm/interstonn hydrologic model. Such a
model, combined with the distributed, surface information provided by remotely-sensed data, will lead to a better
understanding of the processes that cause changes in regional hydrologic storages and fluxes. In this way, we
may better assess the role of the hydrologic cycle in a global context and predict the effects of natural or
anthropogenic changes on the climate. As we advance toward this goal, results from well-planned, regional-scale
experiments will not only provide more information about the surface-atmosphere system, but may well suggest
changes in the strategy itself. One of the goals of the future study described here could well be to evaluate and
modify the approach presented in Figure 1.
6 - ACKNOWLEDGEMENTS
The NASA Eos proposal from which Figure 1 was extracted was a joint research effort of French (LERTS,
fNRA, IRAT, CEMAGREF, LITS-GSTS and CMS-ORSTROM) and U.S. (Univ. Ariz., USDA-ARS and NWS-
HRL) research agencies and universities. Though Monsoon’90 was primarily organized by ARS Hydrology Lab.
and ARS Southwest Watershed Research Center, the participation of many agencies and institutions greatly
broadened the scope of the study. They include: Utah State Univ., USGS-Water Resources Division (Denver
and Carson City), ARS U.S. Water Conservation Lab., ARS Remote Sensing Research Lab., ARS Subtropical
Agricultural Research Lab., Los Alamos National Lab., Jet Propulsion Lab., LERTS-France, CEMAGREF-
ENGREF-France, IRE-Russia, University of Arizona (Dept, of Hydrology and Water Resources, Soil and Water
989
