Energy and Water Cycles in the Climate System ...
25
It is hoped, that these deficits for the soil moisture can be overcome by multispectral SARmeasurements in the X- and L-bands at 3 cm and 15 cm wavelength, respectively, where the
reflection is strongly effected by the water content of soil. But we need to control the model
results steadily. This may only be possible installing instrumentally "controlled" areas of the
size of one or several grid element of an operational weather forecast model, where steady and
quality-controlled measurements are performed. One of them is now in development at the
Meteorological Observatory of the German Weather Service, near Lindenberg (about 50 km
south-east of Berlin).
1.8 Runoff
The runoff in rivers cannot be directly monitored with instruments onboard of satellites. But
satellites can very efficiently be used as relay stations from many automatic river gauges. Such
networks are now in preparation for the major river systems in developing countries and may
become even more common to centralize such data streams and control their quality from the
beginning, since they are of global interest.
Occasional observations of flooded river beds have been reported (and illustrated with often
fine color images) using the imaging data of earth resources satellites, such as Landsat or the
European ERS-l, which are made in the visible and microwave portions of the spectrum (e.g.
Gunley and King, 1995). They provided immediate and areal informations for the management
of such disasters.
1.9 Some Conclusive Remarks
This brief overview on our present knowledge on the various radiation and water flows in our climate system, which are components of energy and water cycles, and on the present possibilities
of spaceborne observations has shown that despite of the already advanced developments of such
techniques the backbone of such observations may in some case still remain with surface-based
and also airborne direct measurements.
As a consequence, ground-based networks must be maintained and kept at highest technological
levels to provide best data quality. It will remain to the data assimilation techniques, which have
successfully been developed and applied for several purposes in meteorology and oceanography
(see contribution by Courtier in this volume), to combine the various data streams into a useful
frame. On the other side many operational ground-based networks begin to erode often due to
the false belief, that they can (in part) be replaced by space-borne observations.
Furthermore, the need for a steady control of quantities, such as the precipitation or radiation
budget over the vast ocean areas has in most publications on these quantities been overlooked,
due to the fact that related measurement techniques need to be developed and installed onboard
ships of opportunity. And one also may not overlook the more political fact, that the space
engineers and politicians neglected for many reasons the fact that the development of space
technology requires also adequate investments into the scientific background and ground-based
networks.
1.10 References
Andre J-C et al. (1989) Evaporation over land-surfaces: First results from the HAPEXMOBILHY special observing period. Ann Geophys 6: 477-492
25
It is hoped, that these deficits for the soil moisture can be overcome by multispectral SARmeasurements in the X- and L-bands at 3 cm and 15 cm wavelength, respectively, where the
reflection is strongly effected by the water content of soil. But we need to control the model
results steadily. This may only be possible installing instrumentally "controlled" areas of the
size of one or several grid element of an operational weather forecast model, where steady and
quality-controlled measurements are performed. One of them is now in development at the
Meteorological Observatory of the German Weather Service, near Lindenberg (about 50 km
south-east of Berlin).
1.8 Runoff
The runoff in rivers cannot be directly monitored with instruments onboard of satellites. But
satellites can very efficiently be used as relay stations from many automatic river gauges. Such
networks are now in preparation for the major river systems in developing countries and may
become even more common to centralize such data streams and control their quality from the
beginning, since they are of global interest.
Occasional observations of flooded river beds have been reported (and illustrated with often
fine color images) using the imaging data of earth resources satellites, such as Landsat or the
European ERS-l, which are made in the visible and microwave portions of the spectrum (e.g.
Gunley and King, 1995). They provided immediate and areal informations for the management
of such disasters.
1.9 Some Conclusive Remarks
This brief overview on our present knowledge on the various radiation and water flows in our climate system, which are components of energy and water cycles, and on the present possibilities
of spaceborne observations has shown that despite of the already advanced developments of such
techniques the backbone of such observations may in some case still remain with surface-based
and also airborne direct measurements.
As a consequence, ground-based networks must be maintained and kept at highest technological
levels to provide best data quality. It will remain to the data assimilation techniques, which have
successfully been developed and applied for several purposes in meteorology and oceanography
(see contribution by Courtier in this volume), to combine the various data streams into a useful
frame. On the other side many operational ground-based networks begin to erode often due to
the false belief, that they can (in part) be replaced by space-borne observations.
Furthermore, the need for a steady control of quantities, such as the precipitation or radiation
budget over the vast ocean areas has in most publications on these quantities been overlooked,
due to the fact that related measurement techniques need to be developed and installed onboard
ships of opportunity. And one also may not overlook the more political fact, that the space
engineers and politicians neglected for many reasons the fact that the development of space
technology requires also adequate investments into the scientific background and ground-based
networks.
1.10 References
Andre J-C et al. (1989) Evaporation over land-surfaces: First results from the HAPEXMOBILHY special observing period. Ann Geophys 6: 477-492