The Genesis of the ACE+ Anti-Rotating Satellites Concept
The lack of data over the oceans and other remote regions contributes greatly to the uncertainties in the initial state of global weather-prediction models, which, in turn, limits their forecast capabilities. It appeared, that the agreement of the GPS/MET data with NWP was noticeably better over data-dense (U.S., Europe) versus data-sparse (Pacific Ocean) regions. These studies suggest that the GPS radio occultation data are likely to have a significant positive impact on global climate analyses and global weather prediction. As a result of this, several systems proposed to take advantage of a constellation to provide a better repartition of GPS measurements all over the world. The main improvement of WATS1 or ACE+ missions2 lies in the introduction of a LEO-LEO link, besides of classical LEO-GNSS measurements, which will provide a spaceborne capacity to discriminate water vapour from temperature profiles (classical methods use radiosondes). The ALCATEL mission analysis group, in association with the system architecture department, conduced several studies to propose constellation concepts coping with all scientific mission requirements, instrument technological limitations, and mission analysis intrinsic constraints. The proposed paper makes therefore a review of the ALCATEL constellation studies and associated trade-off, including the evolution from the initial constellation concepts (based on classical Walker constellation types, on which many system such as GPS are based) up to the innovative approach of anti-rotating satellites (satellites on polar orbits with an opposite direction of rotation) that was finally selected in the WATS concept and re-used in the ACE+ mission. The work presented in this paper has been done in the frame of self-funded R&D activities, and in the frame of an ESA contract. Responsibility for the contents resides on the authors.
KeywordsEurope Assimilation Hunt Azimuth Tempo
Unable to display preview. Download preview PDF.
- Abbondanza S, WATS Final Mission Analysis, ALCATEL internal documentGoogle Scholar
- Anthes A, Rocken C, Kuo YH (March 2000) Applications of COSMIC to Meteorology and Climate Richard. Terrestrial, Atmospheric and Oceanic SciencesGoogle Scholar
- Eyre JR, English SJ, Butterworth P, Renshaw RJ, Ridley JK and Ringer MA (2000) 2000 Recent progress in the use of satellite data in NWP. UK Met Office, NWP Technical Report No. 296Google Scholar
- Mimoun D, WATS Mission Architecture Outline,ALCATEL internal document.Google Scholar
- Larson WJ, Wertz JR (1993) Space Mission Analysis and Design, Kluwer Academic Publisher, second editionGoogle Scholar
- Rocken C, Kuo YH, Schreiner W, Hunt D, Sokolovskiy S COSMIC System Description University Corporation for Atmospheric Research -COSMIC Project OfficeGoogle Scholar
- Walker, JG (1971) Some Circular Orbit Patterns Providing Continuous Whole Earth Coverage. Journal of the British Interplanetary Society, Vol. 24: 369–384Google Scholar
- WATS: report for assessment, ESA SP-l257(3)Google Scholar
- Johsen KP, Rockel B Comparison of GPS Water Vapour Estimates with a NWP Model and with Radiosonde AscentsGoogle Scholar