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Satellite Gravity and the Geosphere Contributions to the Study of the Solid Earth and Its Fluid Envelopes (1997) / Chapter Skim
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6 WATER CYCLING
Pages 59-66

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From page 59...
... , understanding temporal and spatial variations in water exchange on land is of critical and world wide environmental and economic unportance. Measurements of changes in land-based water exchange are of use in long-term weather prediction, global climate modeling, assessment of the health of agricultural lands, and major groundwater supplies.
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From page 60...
... Over spatial scales of several hundred thousand square kilometers, measurements of seasonal changes in water mass with a resolution of 10-30 mm in thickness would be useful for weather forecasting, climate modeling, and soil moisture and aquifer assessments. Measurements of water mass changes at this resolution and spatial scale should be possible with either an SST or SSI mission.
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From page 61...
... In theory, a five-year SST mission at an altitude of 400 km should allow us to resolve annual changes in water mass in the subsurface equivalent to a 1-mm column of water for an area of 1,500,000 km2 and annual changes equivalent to a 10-mm column of water for an area of 250,000 km~ (Figure B.2~. For the nominal SSI mission, the 1-mm error could be achieved over about 125,000 km2, and a 10-mm error for an area of about 80,000 km2.
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From page 62...
... 62 SATELLITE GRAVITYAND THE GEOS'PHERE _.. __ __ ~ n 7 1 -1 FIGURE 6.3 The annually-varying contributions to the geoid from changes in continental water storage, as estimated from the soil moisture data set for 1987-1991.
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From page 63...
... Yearly projections of agricultural production would be greatly improved by measurements of soil moisture on a semiannual basis. Such infonnation would be highly valuable to commodity futures markets and to those world wide agencies that assess food availability, particularly if we can provide seasonal measurements with a resolution of 10-30 mm over an area of a few hundred thousand square kilometers (Figures 4.5 and 4.6)
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From page 64...
... Future growth in the agricultural use of arid and semi-arid lands partly fueled by population growth and partly influenced by a desire for self-sufficiency of agriculture and economic diversification will further increase the overdrafting of aquifers world wide. For example, in the near future Libya plans to irrigate some 200,000 hectares with water drawn from aquifers Hat receive little recharge.
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From page 65...
... Gravity measurements of changes in water storage are important to hydrologists for making the connection between hydrological processes at traditional hydrological length scales (tens of kilometers and less) and those of longer scales useful for estimating global water and energy balances.
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Key Terms

  • water mass
  • land surface
  • ssi mission
  • sst mission
  • gravity measurements

  • mass changes
  • groundwater levels
  • spatial resolution
  • hydrological processes
  • agricultural lands

  • seasonal changes
  • satellite gravity
  • spatial scales
  • seasonal variations
  • water exchange

  • water storage
  • atmospheric pressure
  • square kilometers
  • climate modeling
  • measurement error

  • climate models
  • agricultural production
  • hydrologic cycle
  • annual changes
  • provide seasonal

  • surface water
  • gravity mission
  • hundred thousand
  • snow melt
  • mississippi river


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