Global Monitoring and Remote Sensing from Satellites

Abstract

Air monitoring. At present there is no existing technology for immediate satellite-borne monitoring of air pollutants. The instrumentation now being developed seems well adapted to use for ground observations or to be carried by aircraft. The very special conditions in the lower atmosphere indicate that in the near future this medium will not be monitored for information on the global environment, but the new techniques will be important for local monitoring. On the other hand the technology apparently exists for global monitoring of the upper atmosphere to follow large-scale climatic changes.

Water monitoring. Fresh water monitoring is mostly of local and regional interest and remote sensing from aircraft may be of future importance. The planned Earth resource satellites have too long intervals between observations to be really useful. In the future special ocean watching satellites, placed in Earth-synchronous equatorial orbit or in low polar orbits, could be used.

To follow the changes in the ocean ecosystems only a limited number of variables should be necessary. The most basic and important variable is primary production. Primary production is partly related to the number of green cells present — or the biomass. Since there is a. fairly constant relation between the amount of chlorophyll and the biomass, it might be possible to get an estimate of the biomass by measuring the chlorophyll from the air by aircraft or satellites. For development of instrumentation and for coordination of the global approach special international pilot projects have to be started.

Terrestrial monitoring. The existing methods offer great possibilities for the use of remote sensing to survey terrestrial ecosystems and to record changes. A recording of the vegetation changes in marginal areas as in deserts and tundras would be good variables for monitoring from satellites. The technology is available. Ground truth research has to be organized as pilot projects on an international level.