HR: 08:30h
AN: A11D-02    [Abstracts]
TI: Lidar Measurements from Space: New Global Results on Cloud and Aerosol Distribution and Overlap, PBL Height and Elevated Aerosol
AU: * Spinhirne, J D
EM: james.spinhirne@nasa.gov
AF: NASA Goddard SFC, GSFC 613.1, Greenbelt, MD 20771 United States
AU: Palm, S P
EM: spp@agnes.gsfc.nasa.gov
AF: SSAI, NASA Goddard SFC MC 613.1, Greenbelt, MD 20771
AU: Hlavka, D
EM: sgdlh@virl.gsfc.nasa.gov
AF: SSAI, NASA Goddard SFC MC 613.1, Greenbelt, MD 20771
AU: Hart, W D
EM: billhart@virl.gsfc.nasa.gov
AF: SSAI, NASA Goddard SFC MC 613.1, Greenbelt, MD 20771
AB: Space borne observations by a high performance polar orbiting lidar, the Geoscience Laser Altimeter System (GLAS), have provided fundamentally new results on the global distribution of clouds and aerosol. The primary advance from the active optical sensing is an unambiguously accurate, and highly resolved, measurement of the vertical distribution for atmospheric scattering layers. In addition the lidar data provides an extremely sensitive detection of the thinnest aerosol and cloud layers and their optical thickness. The initial analyzed results for GLAS from fall 2003 show the total global cloud cover is 69% and cloud overlap, defined as the detection of a second cloud layer before full optical attenuation, is found to be present in 40% of cloudy areas globally. The global pattern of retrieved cloud altitude is significantly different than results from passive sensors. The measured penetration height of cirrus clouds in the tropics is observed to be a significant factor for stratosphere/troposphere exchange. The optical depth frequency distribution of cirrus is found to peak at 0.02. For atmospheric aerosol, regions of heavy loading - North Africa, the Indian Ocean, Asia and biomass burning - with elevated aerosol layers above and overlapping clouds are a normal occurrence. Defining clear as aerosol and cloud optical depths of less than 0.01, we find 20% of the global atmosphere as clear. From interpretation of the aerosol height distribution a unique global data product of PBL height has been produced. The PBL height data have been applied as a new validation for the ECMWF and other global circulation models. The GLAS data are limited to eight months, but demonstrate the value of active optical remote sensing that is to continue with three additional instruments to be launched by NASA and ESA in the next seven years.
UR: http://glo.gsfc.nasa.gov
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0321 Cloud/radiation interaction
DE: 3311 Clouds and aerosols
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005