A New High-resolution Passive Microwave Satellite for SST: The ESA STSE MICROWAT Mission Concept
Catherine, Prigent1; Aires, Filipe2; Frederic, Bernardo2; Orlhac, Jean-Claude3; Goutoule, Jean-Marc3; Atkinson, Karl4; Roquet, Herve5; Donlon, Craig6
1CNRS / Observatoire de Paris, FRANCE; 2Estellus, FRANCE; 3EADS / Astrium, FRANCE; 4EADS / Astrium, UNITED KINGDOM; 5CMS / Meteo-France, FRANCE; 6ESA / ESTEC, NETHERLANDS
The requirements of the user community for Sea Surface Temperature (SST) are very demanding, in terms of accuracy, spatial resolution, and revisiting time. A 10km spatial resolution, with an accuracy of 0.3K globally, under clear and cloudy conditions is desired. To satisfy these requirements, new satellite missions have to be designed.
The sensitivity of passive microwave observations to the SST is carefully analyzed, with the objective of designing an optimized satellite instrument, MICROWAT, dedicated to an 'all-weather' accurate estimation of the SST at high spatial resolution.
Our study stresses the importance of the low frequency observations around 6GHz for accurate SST retrieval. Compared to the 11GHz channel, the 6GHz channel provides more sensitivity to the low SSTs and offers lower instrument noise, thanks to possibly broader channel bandwidths. However, it requires much larger antenna size for a given spatial resolution. Two instrument concepts have been suggested, one using a classic real aperture antenna and the other one synthetic interferometric antennas. This first analysis shows that 2D interferometric systems would be very complex, and would not satisfy the user requirements in terms of SST accuracy. A 1D interferometric system could be proposed, but its development requires additional investigation. A dedicated conical scanner on board a satellite flying in train with Metop with a 6 m antenna and channels at 6.9 and 18.7GHz (both with V and H polarizations) can provide a SST accuracy of 0.3K with a 15km spatial resolution, with today's technology.