13. A BIOPHYSICAL PROCESS-BASED ESTIMATE OF GLOBAL
LAND SURFACE EVAPORATION USING SATELLITE AND
ANCILLARY DATA
125
significant determinant of the partitioning; transpiration decreases, while soil
evaporation increases systematically. The pattern of zonal variation of soil
evaporation fraction appears almost as a mirror image of transpiration
fraction.
While transpiration is clearly the dominant component in most of the
latitude bands (20 out of the 28 latitude bands in Fig. 3), interception
exceeds soil evaporation only in four of the 5° latitude bands (55°-60°N and
5°-10°S). Soil evaporation and interception fractions are equal for the
latitude band 10°-15°S. Thus, the rank ordering of the component
dominating total evaporation, when all bands are taken together, would be
transpiration, soil evaporation and interception. More specifically, the
partitioning of annual total evaporation over the global land area is
calculated to be 52% for transpiration, 28% for soil evaporation, and 20%
for interception. We are not aware of any previous attempt to quantify the
ranking of these components at regional or global scale based on spatially
representative observations for specific years.
4.
SUMMARY AND CONCLUSIONS
The present study has provided a framework for assessing land surface
evaporation, energy balance and carbon accumulation using spatially
representative data, several of which were derived from satellite
observations. Future sensors will improve both the accuracy and the spatial
resolution of these data, and are thus expected to improve the results.
5. ACKNOWLEDGEMENTS
Financial support for this work was provided by the NASA Earth
Observing Systems (EOS) Project under interdisciplinary science
investigations. Mr. N. DiGirolamo has provided computing assistance. This
work would not have been possible without the support and assistance of
Drs. J. Susskind, S. Gupta, and G. Asrar.
6. REFERENCES
Baumgartner, A., and Reichel, E. (1975) The World Water Balance, Elsevier, NY.
LAND SURFACE EVAPORATION USING SATELLITE AND
ANCILLARY DATA
125
significant determinant of the partitioning; transpiration decreases, while soil
evaporation increases systematically. The pattern of zonal variation of soil
evaporation fraction appears almost as a mirror image of transpiration
fraction.
While transpiration is clearly the dominant component in most of the
latitude bands (20 out of the 28 latitude bands in Fig. 3), interception
exceeds soil evaporation only in four of the 5° latitude bands (55°-60°N and
5°-10°S). Soil evaporation and interception fractions are equal for the
latitude band 10°-15°S. Thus, the rank ordering of the component
dominating total evaporation, when all bands are taken together, would be
transpiration, soil evaporation and interception. More specifically, the
partitioning of annual total evaporation over the global land area is
calculated to be 52% for transpiration, 28% for soil evaporation, and 20%
for interception. We are not aware of any previous attempt to quantify the
ranking of these components at regional or global scale based on spatially
representative observations for specific years.
4.
SUMMARY AND CONCLUSIONS
The present study has provided a framework for assessing land surface
evaporation, energy balance and carbon accumulation using spatially
representative data, several of which were derived from satellite
observations. Future sensors will improve both the accuracy and the spatial
resolution of these data, and are thus expected to improve the results.
5. ACKNOWLEDGEMENTS
Financial support for this work was provided by the NASA Earth
Observing Systems (EOS) Project under interdisciplinary science
investigations. Mr. N. DiGirolamo has provided computing assistance. This
work would not have been possible without the support and assistance of
Drs. J. Susskind, S. Gupta, and G. Asrar.
6. REFERENCES
Baumgartner, A., and Reichel, E. (1975) The World Water Balance, Elsevier, NY.