Generating Sounder Products at Imager Resolution

Polar-orbiting weather satellite platforms generally include an imager and a sounder. With a data fusion method, we demonstrate the ability to construct infrared (IR) absorption narrowband radiances as well as derived products at imager spatial resolution. Fusion results for IR radiances at 4.52 µm (CO₂), 6.72 µm (H₂O) and 13.94 µm (CO₂) have been obtained where MODIS measured radiances and fusion radiances constructed using AIRS are compared; the radiance differences are found to be fairly low and unbiased. This paper demonstrates another advance in which the fusion approach is applied directly to sounder derived products, omitting the interim step wherein radiances are constructed via fusion. We present MODIS Total Column Precipitable Water Vapor (TPW) results obtained at imager resolution in three ways: from MODIS measured radiances, from fusion constructed radiances (using AIRS radiances), and from fusion constructed TPW (using AIRS TPW). More generally, our example of TPW can be retrieved from hyperspectral sounder (AIRS, IASI, CrIS) measurements and provided at the imager’s (MODIS, AVHRR, VIIRS) high spatial resolution. With this approach, it will be possible to improve continuity in derived products (cloud properties, clear sky temperature and moisture layers, atmospheric stability) over the generations of weather satellite sensors, and continue applications that require IR absorption bands. The implications of these fusion results on the design and spectral selection of future imager/sounder pairs on research and operational instruments will be considered.