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New trends in the development of meteorological satellites
Acta Astro~mttca VoL 5, pp. 607--6/M © Pmpmon Press, 1978. Prints! in G r i t Britain
0094-5765/0701-4}607/$02.00~
New t r e n d s in t h e development of m e t e o r o l o g i c a l satellites A. V I L L E V I E I L L E Director of Department of Science, MeteorologicNationale, Rue de S~vres, 92 Bologne, France (Received 15 October
1977)
M~.TEOROLOGY, as a p a n of applied sciences, deals with conventional aspects, such as numerical forecasting, but also with new missions, namely: --studies of climate ----climatic impact ---weather modification ---quality of air and pollution transport ---and, as a particular case of pollution, stratospheric pollution and monitoring. Both conventional and newly defined objectives in meteorology have to rely on the satellite as a major instrument for investigation, since it provides the following capabilities: •global coverage •permanent observation (at least for geostationary satellites) •homogeneous imaging •quick data dissemination. To take full advantage of these capabilities, one should not consider meterological satellites as separate units, hut as components of a global network, including low orbiting and geostationary satellites, working in close cooperation: such a system will be implemented by 1978-79 during the GARP First Global Experiment, sponsored by WMO and ICSU. It will involve a "belt" of 5 geostationary satellites, primarily for cloud imaging, and a set of multi-purpose low-orbiting satellites, whose main purpose will be vertical temperature sounding and service as data collection platforms. The answer to the question whether all meteorological requirements are fully met by current satellites and current satellite technology is definitely "no", since the scope of meteorology is very broad, covering an extremely wide range of time and space scales. Moreover there are still big voids unknown in our knowledge of the atmosphere. Smaller scale (mesoscale and microscale) events, including severe storms and tornadoes, need further investigation, both for science and operational early warning: satellites with high geographical resolution and new detectors (such as lightning detectors) will be most helpful in that field. On the opposite side, dealing with the largest time scales, climate studies will have a tremendous development in the next future. And we should pay attention 6o7
608
A. Villevieille
to the fact that these studies not only involve the atmospheric machinery itself, but also---and this has to be strongly underlinedwinvolve extraterrestrial factors such as the solar radiation (the so-called solar constant and energetic particles effects), and geophysical factors, such as snow and ice cover, volcanic dust dissemination, air-sea interactions, and the like. So that: solar monitoring, surface state mapping, both on sea and land, and aerosols detection, become new essential missions. Also, antropogenic minor constituents will play a role in the world climatic evolution: this is quite obvious when we contemplate the CO2 steady increase and the related dangers, possibly in the next century (snow melting and continental flooding). Specific sensing methods, using limb measurements as well as vertical soundings, will be devoted to the chemical composition of the atmosphere. What consequences can we infer from these considerations, in the technological field? Obviously, multispectral radiometry will have a continuous development, with some increasing overlap between meteorological and properly geophysical measurements. A great amount of research will be devoted to microwave technology, since the terrestrial emission in these wavelengths provide a valuable information on sea state, ground state, cloud water content and rain occurrence. Radar and lidar measurements from satellites will be used for the same purposes. Also, satellite on-board operations will be extended, as concerns sensors calibration and further data processing, in order to somewhat reduce the gigantic data output of satellites. Along with that, in order to improve the scientific interpretation of satellite data, some more "ground truth" experiments should be performed in various fields, such as radiative transfers and radiances inversion, wind determination etc. These are some new trends, and some new fields of development, in meteorological satellites technology. The aim of this development is not only a better scientific understanding of the atmospheric behaviour and a better efficiency in operational forecasting (or nowcasting), but also deals with matters which are vital for mankind: protection from outer space dangerous radiations, climate evolution, quality of air monitoring... Such essential objectives surely deserve a major involvement of scientists and engineers.
0094-5765/0701-4}607/$02.00~
New t r e n d s in t h e development of m e t e o r o l o g i c a l satellites A. V I L L E V I E I L L E Director of Department of Science, MeteorologicNationale, Rue de S~vres, 92 Bologne, France (Received 15 October
1977)
M~.TEOROLOGY, as a p a n of applied sciences, deals with conventional aspects, such as numerical forecasting, but also with new missions, namely: --studies of climate ----climatic impact ---weather modification ---quality of air and pollution transport ---and, as a particular case of pollution, stratospheric pollution and monitoring. Both conventional and newly defined objectives in meteorology have to rely on the satellite as a major instrument for investigation, since it provides the following capabilities: •global coverage •permanent observation (at least for geostationary satellites) •homogeneous imaging •quick data dissemination. To take full advantage of these capabilities, one should not consider meterological satellites as separate units, hut as components of a global network, including low orbiting and geostationary satellites, working in close cooperation: such a system will be implemented by 1978-79 during the GARP First Global Experiment, sponsored by WMO and ICSU. It will involve a "belt" of 5 geostationary satellites, primarily for cloud imaging, and a set of multi-purpose low-orbiting satellites, whose main purpose will be vertical temperature sounding and service as data collection platforms. The answer to the question whether all meteorological requirements are fully met by current satellites and current satellite technology is definitely "no", since the scope of meteorology is very broad, covering an extremely wide range of time and space scales. Moreover there are still big voids unknown in our knowledge of the atmosphere. Smaller scale (mesoscale and microscale) events, including severe storms and tornadoes, need further investigation, both for science and operational early warning: satellites with high geographical resolution and new detectors (such as lightning detectors) will be most helpful in that field. On the opposite side, dealing with the largest time scales, climate studies will have a tremendous development in the next future. And we should pay attention 6o7
608
A. Villevieille
to the fact that these studies not only involve the atmospheric machinery itself, but also---and this has to be strongly underlinedwinvolve extraterrestrial factors such as the solar radiation (the so-called solar constant and energetic particles effects), and geophysical factors, such as snow and ice cover, volcanic dust dissemination, air-sea interactions, and the like. So that: solar monitoring, surface state mapping, both on sea and land, and aerosols detection, become new essential missions. Also, antropogenic minor constituents will play a role in the world climatic evolution: this is quite obvious when we contemplate the CO2 steady increase and the related dangers, possibly in the next century (snow melting and continental flooding). Specific sensing methods, using limb measurements as well as vertical soundings, will be devoted to the chemical composition of the atmosphere. What consequences can we infer from these considerations, in the technological field? Obviously, multispectral radiometry will have a continuous development, with some increasing overlap between meteorological and properly geophysical measurements. A great amount of research will be devoted to microwave technology, since the terrestrial emission in these wavelengths provide a valuable information on sea state, ground state, cloud water content and rain occurrence. Radar and lidar measurements from satellites will be used for the same purposes. Also, satellite on-board operations will be extended, as concerns sensors calibration and further data processing, in order to somewhat reduce the gigantic data output of satellites. Along with that, in order to improve the scientific interpretation of satellite data, some more "ground truth" experiments should be performed in various fields, such as radiative transfers and radiances inversion, wind determination etc. These are some new trends, and some new fields of development, in meteorological satellites technology. The aim of this development is not only a better scientific understanding of the atmospheric behaviour and a better efficiency in operational forecasting (or nowcasting), but also deals with matters which are vital for mankind: protection from outer space dangerous radiations, climate evolution, quality of air monitoring... Such essential objectives surely deserve a major involvement of scientists and engineers.