HR: 1340h
AN: A43B-0081    [Abstracts]
TI: Nighttime Measurements of Aerosol Optical Thickness with the VIIRS Day-Night Band
AU: * Shettle, E P
EM: shettle@nrl.navy.mil
AF: Naval Research Laboratory, Code 7227, Remote Sensing Division, Washington, DC 20375-5351 United States
AU: Halthore, R N
EM: halthore@nrl.navy.mil
AF: Naval Research Laboratory, Code 7228, Remote Sensing Division, Washington, DC 20375-5351 United States
AB: Currently the planned measurements of Aerosol Optical Thickness (AOT) from the National Polar-orbiting Operational Satellite System (NPOESS) will be limited to daytime, since they use reflected solar radiation. The primary aerosol instruments are the Visible/Infrared Imager/Radiometer Suite (VIIRS) and the Aerosol Polarimeter Sensor (APS). The VIIRS instrument also includes a Daytime/Nighttime Visible Imagery band or the Day-Night Band (DNB) which is a broad band channel covering from about 500 to 900 nm, with sufficient dynamic range to provide calibrated cloud imagery from quarter moon to full sunlight. We have used MODTRAN to simulate the lunar radiances scattered by the atmosphere under different conditions. Preliminary simulations indicate that there is sufficient signal-to-noise to measure the AOT with an uncertainty of ñ0.05 for lunar phase angle of 60 deg., near nadir with the uncertainty increasing towards the edge of the across-track scan. This would provide improved temporal information on the aerosol transport or other transient phenomena (such as Land/Sea breeze), due to the twice-a-day revisit frequency, instead of once. These retrievals of AOT would be limited to over the ocean where the surface albedo is small and well known. They could not be extended over vegetated surfaces using the "dark pixel" method, because the DNB includes much of the high reflectance in the near-IR of vegetation. This means the uncertainties in the contribution of radiances reflected by the surface could be greater than the backscattered radiances from the atmospheric aerosols.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0360 Radiation: transmission and scattering
DE: 1640 Remote sensing (1855)
DE: 3311 Clouds and aerosols
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005