Search Results

You are looking at 51 - 60 of 2,454 items for :

  • Aerosol optical thickness x
  • All content x
Clear All
Maria João Costa, Vincenzo Levizzani, and Ana Maria Silva

simulated spectral reflectances contained in lookup tables (LUTs). LUTs are derived for different aerosol climatological models ( Dubovik et al. 2002 ) and are refined through the variation of some of the size distribution parameters (fine-mode modal radius and fine-mode percentage density of particles), as well as the imaginary part of the refractive index in two spectral regions (0.35–0.50 and 0.70–0.86 μ m) and the aerosol optical thickness (AOT). The aerosol characterization that best fits the

Full access
D. D. Turner, R. A. Ferrare, L. A. Heilman Brasseur, W. F. Feltz, and T. P. Tooman

nitrogen data, and the extinction profile derived from the backscatter data using the smoothed S a data. The raw and smoothed extinction-to-backscatter ratio data for this case are shown in the lower-left panel of Fig. 4 . After extending the extinction profiles to the surface using the above technique, these profiles are then integrated from the surface to 7 km, or below cloud-base height, to provide aerosol optical thickness at 355 nm in the lower troposphere. Random error bars are shown on the 10

Full access
Friedrich Obleitner

of solar radiation at the earth's surface--elements of a model. Sol. Energy 20(2), 143 150.Leiterer, U., and K. Schulz, 1987: Experimental data and Aerosol optical thickness in Antarctica in summer 1984/85. Zeitschr. f Meteorol. 35, 315-321.--, and Sakunow, G., 1989: Messungen von aerosolpartikeln im Grrl3enbereich 0.2 bis 4.0 ~m in der Antarktis. Zeitschr. f Me teorol., 39, 309-316.Liljequist, G. H., t957: Energy exchange of an antarctic snowfield. Norwegian

Full access
Glenn E. Shaw

1254 JOURNAL OF APPLIED METEOROLOGYTransport of Asian Desert Aerosol to the Hawaiian Islands GLENN E, StIAWGeophysical Institute, University of Alaska, Fairbanks 99701(Manuscript received 30 March 1980, in final form 28 July 1980) ABSTRACT A cloud of aerosol with optical thickness - ~, 0.18 (500 nm wavelength), passed over the HawaiianIslands from late April to early May 1979. Vertical profiles, taken by evaluating the optical

Full access
A. A. Kokhanovsky

for the statistical ensemble of phase functions were calculated at effective radii of a ef = 0.1–1.5 μ m, a coefficient of variance of the particle size distribution (PSD) of Δ = 0.2–1.1, real part of the refractive index of n = 1.45–1.6, and imaginary part of the refractive index of k = 0.001–0.01. These calculations were made using Mie theory ( Shifrin 1968 ; van de Hulst 1981 ). The results obtained were applied to estimating the error of the aerosol optical thickness determination from

Full access
Mikhail V. Panchenko and Svetlana A. Terpugova

expensive tools, which limits the possibility of their routine use in practice of aerosol observations. It is clear that to develop a model for a wide wavelength range it is necessary to include the data on the spectral optical thickness and solar aureole measurements. With inclusion of the lidar data into the list of measured parameters, we had in mind the following ideas. The development of lidar facilities is aimed at obtaining a complete dataset on the vertical profiles of different atmospheric

Full access
J. Li and J. S. Dobbie

correctly reduce to the thin atmosphere approximation (single scattering approximation) as the optical thickness approaches zero. For this reason, the C–C model is widely used for radiative transfer involving optically thin layers and, especially, for aerosol radiative forcing studies ( Charlson et al. 1992 ) and clear-sky radiation calculations for general circulation models ( Barker and Li 1995 ). The C–C scheme is not very successful for describing the radiative properties of layers with larger

Full access
J. V. Dave and Norman Braslau

,basic layers with total opt/col thicknesses greater than 0.02 were subdivided so that total optical thickness ofno layer exceeded 0.02. Fluxes at all levels of such a model were calculated by using the direct solution ofthe spherical harmonics approximation to the basic transfer equation discussed by Dave and Canosa. Results will be presented for eight model atmospheres containing gases, aerosol of different concentrationan.d refractive index, and, in two models, a stratus cloud of water drops, showing

Full access
Eduardo Landulfo, Alexandros Papayannis, Ani Sobral Torres, Sandro Toshio Uehara, Lucila Maria Viola Pozzetti, Caio Alencar de Matos, Patricia Sawamura, Walter Morinobu Nakaema, and Wellington de Jesus

using the aerosols as passive tracers of the atmospheric dynamic processes. The sun photometer data are used to provide the aerosol optical thickness (AOT) values at selected wavelengths and thus, to derive the Ångström exponent (AE) values. The synergy of Cimel and lidar measurements also acts to minimize the uncertainties of the assumptions made, especially when inverting the lidar signal using Klett’s technique ( Klett 1985 ). In Brazil, a continent-sized country, there are only two operating

Full access
U. Dayan, J. Heffter, J. Miller, and G. Gutman

transport levels, airflow back trajectories were calculated usingthe Branching Atmospheric Trajectory (BAT) model for two layers (300-2000 and 1500-3000 m) in conjunctionwith the synoptic situations prevailing during these dust outbreak events. Aerosol mass loading and horizontalvisibility were derived for each of these seven cases from optical thickness values as analyzed by visible andnear infrared radiances measured with the NOAA-9 and NOAA- 11 satelliteborne radiometers. Optical thicknessis

Full access