Chapter 8
Remote Sensing of Atmospheric
Water Vapor
William B. Rossow
NASA Goddard Institute for Space Studies
New York, NY 10025
USA
8.1 Water Vapor in the Climate System
Many of the unique features of Earth's surface environment result from the presence of large
amounts of water, mostly in liquid phase. However, key to many feedback processes in the
climate system is the fact that some water is also present in both vapor and solid phase:
exchanges between the different reservoirs of water in its different forms, mediated by the
circulation of the atmosphere, make the behavior of the whole system much more complicated.
Current concern with how sensitive the climate is to changes made by humans and how sensitive
human societies are to changes in climate motivates interest in water in all its forms; however,
the focus of this paper is on the roles played by water vapor in determining the energy content
and circulation of the troposphere.
Earth's surface is divided into two very different regimes, solid land including glaciers, and
liquid oceans; about 2.5% of all water resides on land, about 2% in the glaciers and about 0.5%
as near-surface or surface water (Peixoto and Oort, 1992). The latter small amount of water
is crucial to the survival of humans, directly for drinking and indirectly for food derived from
the land biosphere. Moreover, "developed" society depends on many other uses of water that
support an improved standard of living. This particularly important reservoir is maintained
by a balance between supply by rain and snow fall over land, more than 60% of which reevaporates, and loss by river runoff back into the ocean. Thus, our supply of water depends on
the processes in the atmosphere by which water vapor is transported from the oceans to the
land and converted into precipitation there.
The global atmosphere holds only 10- 5 of the amount of water in the oceans and the net
transport of water from the ocean surface, through the atmosphere, and onto the land surface
is equivalent to about 1% of this water vapor transferred per day (Peixoto and Oort, 1992).
Essentially, this transfer is a mixing process where the circulation of the atmosphere mixes
water from areas of higher abundance over the ocean source to areas of lower abundance over
NATO AS] Series, Vol. ] 45
Radiation and Water in the Climate System:
Remote Measurements
Edited by Ehrhard Raschke
© Springer- Verlag Berlin Heidelberg 1996
Remote Sensing of Atmospheric
Water Vapor
William B. Rossow
NASA Goddard Institute for Space Studies
New York, NY 10025
USA
8.1 Water Vapor in the Climate System
Many of the unique features of Earth's surface environment result from the presence of large
amounts of water, mostly in liquid phase. However, key to many feedback processes in the
climate system is the fact that some water is also present in both vapor and solid phase:
exchanges between the different reservoirs of water in its different forms, mediated by the
circulation of the atmosphere, make the behavior of the whole system much more complicated.
Current concern with how sensitive the climate is to changes made by humans and how sensitive
human societies are to changes in climate motivates interest in water in all its forms; however,
the focus of this paper is on the roles played by water vapor in determining the energy content
and circulation of the troposphere.
Earth's surface is divided into two very different regimes, solid land including glaciers, and
liquid oceans; about 2.5% of all water resides on land, about 2% in the glaciers and about 0.5%
as near-surface or surface water (Peixoto and Oort, 1992). The latter small amount of water
is crucial to the survival of humans, directly for drinking and indirectly for food derived from
the land biosphere. Moreover, "developed" society depends on many other uses of water that
support an improved standard of living. This particularly important reservoir is maintained
by a balance between supply by rain and snow fall over land, more than 60% of which reevaporates, and loss by river runoff back into the ocean. Thus, our supply of water depends on
the processes in the atmosphere by which water vapor is transported from the oceans to the
land and converted into precipitation there.
The global atmosphere holds only 10- 5 of the amount of water in the oceans and the net
transport of water from the ocean surface, through the atmosphere, and onto the land surface
is equivalent to about 1% of this water vapor transferred per day (Peixoto and Oort, 1992).
Essentially, this transfer is a mixing process where the circulation of the atmosphere mixes
water from areas of higher abundance over the ocean source to areas of lower abundance over
NATO AS] Series, Vol. ] 45
Radiation and Water in the Climate System:
Remote Measurements
Edited by Ehrhard Raschke
© Springer- Verlag Berlin Heidelberg 1996