Search Results
(as inferred from clouds below 2 km on the left-hand side in Fig. 3a ) appears to decay at the SAL boundary (∼12°N near 1455 UTC), suggesting that some aspect of the dry, dusty SAL air mass suppresses vertical transport. Aerosol optical thickness values obtained by integrating LASE-derived, aerosol extinction profiles over the altitude of the SAL (1.2 to 7 km; black line plot in Fig. 7a ) ranged from 0.05 to 0.4. A thin cloud layer is seen at 1540 UTC at 7-km altitude. Attenuation of the lidar
(as inferred from clouds below 2 km on the left-hand side in Fig. 3a ) appears to decay at the SAL boundary (∼12°N near 1455 UTC), suggesting that some aspect of the dry, dusty SAL air mass suppresses vertical transport. Aerosol optical thickness values obtained by integrating LASE-derived, aerosol extinction profiles over the altitude of the SAL (1.2 to 7 km; black line plot in Fig. 7a ) ranged from 0.05 to 0.4. A thin cloud layer is seen at 1540 UTC at 7-km altitude. Attenuation of the lidar
algorithm from the GOES-8 imager. Using Mie and discrete ordinate radiative transfer (DISORT) calculations, smoke aerosol optical thickness (AOT) is retrieved from the GOES-8 visible channel reflectances. The GOES retrieved AOT is compared against ground-based sun photometer AOT values. These GOES-8 AOT values are then used in a four-stream broadband radiative transfer model to estimate the SW flux at the TOA for biomass burning aerosols. The SW flux in biomass burning regions from model
algorithm from the GOES-8 imager. Using Mie and discrete ordinate radiative transfer (DISORT) calculations, smoke aerosol optical thickness (AOT) is retrieved from the GOES-8 visible channel reflectances. The GOES retrieved AOT is compared against ground-based sun photometer AOT values. These GOES-8 AOT values are then used in a four-stream broadband radiative transfer model to estimate the SW flux at the TOA for biomass burning aerosols. The SW flux in biomass burning regions from model
. Kobayashi , T. , and K. Masuda , 2008 : Effects of precipitation on the relationships between cloud optical thickness and drop size derived from space-borne measurements. Geophys. Res. Lett. , 35 , L24809 . doi:10.1029/2008GL036140 . Lebsock , M. D. , G. L. Stephens , and C. Kummerow , 2008 : Multisensor satellite observations of aerosol effects on warm clouds. J. Geophys. Res. , 113 , D15205 . doi:10.1029/2008JD009876 . Lohmann , U. , G. Tselioudis , and C. Tyler , 2000
. Kobayashi , T. , and K. Masuda , 2008 : Effects of precipitation on the relationships between cloud optical thickness and drop size derived from space-borne measurements. Geophys. Res. Lett. , 35 , L24809 . doi:10.1029/2008GL036140 . Lebsock , M. D. , G. L. Stephens , and C. Kummerow , 2008 : Multisensor satellite observations of aerosol effects on warm clouds. J. Geophys. Res. , 113 , D15205 . doi:10.1029/2008JD009876 . Lohmann , U. , G. Tselioudis , and C. Tyler , 2000
compared to the preinjection, or unperturbed, aerosol. The peak scattering ratio of ouraverage 1975 profile was 1.7, and the vertically integrated particulate backscattering was 3.6X10-4 sr-~(both at X= 694 nm). The mean midvisible particulate optical thickness, derived from measured backscattering and realistic optical models, was about 0.03, approximately six times the mean value in theyear before the Fuego eruption, but not as large as values observed for some years after the 1963 Agungeruption
compared to the preinjection, or unperturbed, aerosol. The peak scattering ratio of ouraverage 1975 profile was 1.7, and the vertically integrated particulate backscattering was 3.6X10-4 sr-~(both at X= 694 nm). The mean midvisible particulate optical thickness, derived from measured backscattering and realistic optical models, was about 0.03, approximately six times the mean value in theyear before the Fuego eruption, but not as large as values observed for some years after the 1963 Agungeruption
dust is inconsistent with theobservations, as shown in Fig. 20a; it produces amuch larger limb-darkening than obs, erved at largek. Scattering aerosols, on the other hand, are consistent with the observations'for some optical thickness which depends upon the assumed verticaldistribution (Figs. 20b-E0e). The observed WL/CMis similar for the NEB (not illustrated), and thusbasically similar constraints on (o and - are obtained for that region. Several caveats must be attached to interpretation of
dust is inconsistent with theobservations, as shown in Fig. 20a; it produces amuch larger limb-darkening than obs, erved at largek. Scattering aerosols, on the other hand, are consistent with the observations'for some optical thickness which depends upon the assumed verticaldistribution (Figs. 20b-E0e). The observed WL/CMis similar for the NEB (not illustrated), and thusbasically similar constraints on (o and - are obtained for that region. Several caveats must be attached to interpretation of
11, the aerosol optical thickness, and the viewing geometry. 4. Sensitivity studies To determine the sensitivity of MERIS measurements to the individual influencing quantities, radiative transfer calculations were performed, again using the radiative transfer model MOMO. The simulations were analyzed with respect to the influence of surface pressure and other geophysical parameters, like aerosol optical thickness and scale height, surface albedo, and the temperature profile. Additionally, the
11, the aerosol optical thickness, and the viewing geometry. 4. Sensitivity studies To determine the sensitivity of MERIS measurements to the individual influencing quantities, radiative transfer calculations were performed, again using the radiative transfer model MOMO. The simulations were analyzed with respect to the influence of surface pressure and other geophysical parameters, like aerosol optical thickness and scale height, surface albedo, and the temperature profile. Additionally, the
superstructure itself or its shadow. Details on the SeaPRISM sea-viewing measurement sequence were already given elsewhere ( Zibordi et al. 2004 ). However, a summary is also provided here for the benefit of completeness. Each SeaPRISM sea-viewing measurement sequence, which is executed every 30 min within ±4 h of 1200 LT, comprises the following: (i) A series of direct sun measurements E ( λ , θ 0 , ϕ 0 ) acquired at all channels for the determination of the aerosol optical thickness τ a ( λ ), a
superstructure itself or its shadow. Details on the SeaPRISM sea-viewing measurement sequence were already given elsewhere ( Zibordi et al. 2004 ). However, a summary is also provided here for the benefit of completeness. Each SeaPRISM sea-viewing measurement sequence, which is executed every 30 min within ±4 h of 1200 LT, comprises the following: (i) A series of direct sun measurements E ( λ , θ 0 , ϕ 0 ) acquired at all channels for the determination of the aerosol optical thickness τ a ( λ ), a
or aerosol which defines the O 2 optical depth above the scattering layer, (iii) the surface albedo, (iv) the scattering phase function, and (v) the pressure thickness of the scattering layer or, more precisely, the optical depth of oxygen in this layer. The relevant conclusions that can be drawn from this study are the following. Crucial to any retrieval scheme that uses input measurables in the form of either I ν and s ν is the sensitivity of these measurables to changes in these five
or aerosol which defines the O 2 optical depth above the scattering layer, (iii) the surface albedo, (iv) the scattering phase function, and (v) the pressure thickness of the scattering layer or, more precisely, the optical depth of oxygen in this layer. The relevant conclusions that can be drawn from this study are the following. Crucial to any retrieval scheme that uses input measurables in the form of either I ν and s ν is the sensitivity of these measurables to changes in these five
.19 and0.35, and 0.6 x 10-3 and 1.4 x 10-3 (km sr)-~, respectively. It is estimated that the zenith-subvisual cirruscontained ice crystals of 25 ~m effective diameter at a mean concentration of 25 L-~ and ice mass content of0.2 mg m-3. The threshold cloud optical thickness for visual-versus-invisible cirrus, derived from both broadbandshortwave flux and 0.694 ~m lidar data, is found to be rc ~ 0.03. Such ~ values are comparable to those of 510 km deep stratospheric aerosol clouds of volcanic origin
.19 and0.35, and 0.6 x 10-3 and 1.4 x 10-3 (km sr)-~, respectively. It is estimated that the zenith-subvisual cirruscontained ice crystals of 25 ~m effective diameter at a mean concentration of 25 L-~ and ice mass content of0.2 mg m-3. The threshold cloud optical thickness for visual-versus-invisible cirrus, derived from both broadbandshortwave flux and 0.694 ~m lidar data, is found to be rc ~ 0.03. Such ~ values are comparable to those of 510 km deep stratospheric aerosol clouds of volcanic origin
influence of the sulfate aerosol on opticalproperties of the atmosphere. The measurements ofthe optical thickness of the aerosol layer following theMt. Pinatubo eruption were reported by Stowe et al.(1992) and Valero and Pilewskie (1992). The equivalent information could also be derived with some additional assumptions from the sulfate aerosol concentration calculated by the dynamic model with thechemistry terms. The formula used for this purpose isgiven simply by the vertical integral of the
influence of the sulfate aerosol on opticalproperties of the atmosphere. The measurements ofthe optical thickness of the aerosol layer following theMt. Pinatubo eruption were reported by Stowe et al.(1992) and Valero and Pilewskie (1992). The equivalent information could also be derived with some additional assumptions from the sulfate aerosol concentration calculated by the dynamic model with thechemistry terms. The formula used for this purpose isgiven simply by the vertical integral of the
