DEFINITION OF AN UNCOOLED SUBMILLIMETER/TERAHERTZ LIMB SOUNDER FOR MEASURING MIDDLE ATMOSPHERIC WINDS.

摘要

Simulations from 100 GHz to 3 THz for assessing the potentialrnof spaceborne microwave spectrometer for observingrnwinds at the atmospheric limb have been performed.rnThe line-of-sight wind can be derived from 25 km tornmore than 90 km with a radiometer of moderate sensitivity.rnFor example, winds can be retrieved from 20 kmrnto more than 90 km from observations using a single sidebandrnradiometer with a system temperature of 1440 K atrn600 GHz. Such radiometer can be realized with a Schottkyrndiode cooled down to 100 K. A well established andrnreliable technology can be used for the cooler with lowrnpower, mass and costs, and without compromising thernmission life-time. In the sub- millimetre and terahertzrnranges, high quality retrievals are obtained from 40 kmrnto 65 km by choosing favourable spectral ranges containingrna cluster of strong O_3 lines. The vertical resolutionrnis better than 5 km and the precision is 2–3 ms~(-1). Betweenrn25 km and 35 km, the best retrievals are obtainedrnat 233 GHz and 352 GHz with a vertical resolution betterrnthan 8 km and a precision better than 15 ms~(-1). The spectralrnbands are similar to and compatible with the onesrnused for observing stratospheric trace-gases. Given thernlack of past and future wind measurements above 30 km,rnwinds should be regarded as one of the possible productsrnfor middle atmospheric trace-gases measurement missionrnand should be taken into account in the definition of thernmission.