All - Weather Hyperspectral Atmospheric Sounding

Remote measurements of Earth's atmospheric state using microwave and infrared wavelengths have been carried out for many years [1, 2]. Physical considerations involving the use of these spectral regions include the relatively high cloud-penetrating capability at microwave wavelengths and the relatively sharp weighting functions at infrared wavelengths, particularly in the shortwave region near 4 µm in which Planck nonlinearity further increases temperature sensitivity. Infrared spectrometer technology has advanced markedly over the last 15 years or so, leading to the simultaneous spectral sampling of thousands of bands spaced along narrow atmospheric absorption features [3]. These sensors, and similar sensors to be launched as part of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) and Meteorological Satellite (Meteo-sat) Third Generation systems, substantially improve atmospheric sounding through the use of hyperspectral measurements, which yield greater vertical resolution throughout the atmosphere [6]. Global simulation studies over ocean and land in clear and cloudy atmospheres use three different atmospheric profile databases to assess the temperature, moisture , and precipitation sounding capability of several notional hyperspectral microwave systems with channels sampled near the 50–60, 118.75, and 183.31 GHz absorption lines. These analyses demonstrate that hyperspec-Development of a new hyperspectral microwave (HM) remote sensing modality for all-weather atmospheric sounding has been enabled by recent advances in microwave device technology driven largely by the commercial communications sector. A spaceborne HM sounder would substantially improve weather forecasting by offering both cloud penetration and high vertical resolution.