Search Results

You are looking at 1 - 10 of 108 items for :

  • Optical properties x
  • Weather and Forecasting x
  • All content x
Clear All
Theodore W. Letcher, Sandra L. LeGrand, and Christopher Polashenski

incorporation of an explicit sublimation term which may limit this model’s accuracy under certain atmospheric conditions as sublimation will modify both the blowing snow mass concentration and optical properties. Finally, as part of this case study, we neglected to address the snow surface erodibility and u * t parameter in a physically meaningful way by treating it as uniform in time and space. While we argue that such a representation is acceptable for this case study due to the fact that the snow

Open access
Mana Inoue, Alexander D. Fraser, Neil Adams, Scott Carpentier, and Helen E. Phillips

-cloud-base height (hereinafter termed LCBH) observations, coupled with the cloud-base restrictions on flying, ensure that forecasting cloud properties in support of aviation remains a challenge. This study uses balloon-launched radiosonde data and surface observations from the three Australian East Antarctic coastal stations of Mawson, Davis, and Casey, along with near-coincident numerical weather prediction (NWP) forecasts, in order to determine the accuracy of the NWP relative humidity RH profile by comparing

Full access
Ming Liu, Jason E. Nachamkin, and Douglas L. Westphal

parameterization ( Harshvardhan 1987 , 1989 ) and an evaluation of a new advanced radiation parameterization in an effort to improve COAMPS. The standard model uses a two-stream scattering-absorption approximation for solar radiation, but neglects cloud scattering for thermal infrared (IR) radiation. The cloud optical property parameterization has no size dependence. This simplification increases the computational efficiency for weather forecasts and climate studies by speeding up flux calculations with a

Full access
Jörg Bendix, Boris Thies, Jan Cermak, and Thomas Nauß

microphysical properties is performed [liquid water path (LWP), effective radius]. This step is required for the determination of the geometrical thickness (step 3) of a cloud layer by specific approaches. Various algorithms for the retrieval of optical and microphysical properties based on NOAA AVHRR data have been successfully used in the past (e.g., Bendix 1995a ; Nakajima and Nakajima 1995 ; Bendix 2002 ) and have recently been adapted to the MODIS instrument ( Platnick et al. 2003 ; Nauß et al

Full access
Dan Bikos, Daniel T. Lindsey, Jason Otkin, Justin Sieglaff, Louie Grasso, Chris Siewert, James Correia Jr., Michael Coniglio, Robert Rabin, John S. Kain, and Scott Dembek

proportional to the ratio of the mass to the number concentration; consequently, the number concentration assignment leads to some uncertainty in the particle sizes for all five hydrometeor types. However, for the infrared bands currently being generated by CIRA, brightness temperatures are relatively insensitive to particle size, except possibly thin cirrus (discussed in section 3c ). Optical properties for all five hydrometeors are then combined with a number concentration weighting. This process yields

Full access
Ming Liu, Douglas L. Westphal, Annette L. Walker, Teddy R. Holt, Kim A. Richardson, and Steven D. Miller

of the inner-grid values. On the other hand, dust mass has no impact on the COAMPS dynamics. Dust is modeled as a monodispersed aerosol, that is, a single particle size, with a diameter of 2.0 μ m and a density of 2650 kg m −3 . This effective size of the particles was chosen because it provided the closest match to previous size-resolved simulations (10 size bins ranging from 0.05 to 35 μ m), both in terms of optical properties and sedimentation fluxes ( Liu et al. 2003 ). Applying Mie

Full access
Melanie A. Wetzel, Steven K. Chai, Marcin J. Szumowski, William T. Thompson, Tracy Haack, Gabor Vali, and Robert Kelly

conditions, covering all possible image pixel viewing angles and cloud types. Cloud optical properties were determined from a narrowband parameterization based on Mie theory using the gamma size distribution. Gas absorption coefficients using the exponential sum fitting technique were derived for water vapor, carbon dioxide, ozone, and oxygen ( Meier et al. 1997 ). The satellite channel filter functions for GOES-10 were applied in the model calculations of band radiances. The following equation ( Han

Full access
Caroline Jouan, Jason A. Milbrandt, Paul A. Vaillancourt, Frédérick Chosson, and Hugh Morrison

systems. For example, the Regional and Global Deterministic Prediction Systems (RDPS and GDPS, respectively) suffer from a systematic upwind displacement of precipitation (e.g., Mo et al. 2019 ), Sundqvist underpredicts ice water content (IWC) aloft ( Chosson et al. 2014 ), and a prescribed (constant) effective radius of ice crystals is used for the computation of cloud optical properties for the radiative transfer scheme. Thus, a more detailed condensation scheme—with a better representation of in

Open access
Oreste Reale, K. M. Lau, and Arlindo da Silva

) go back to the late 1970s (e.g., Carlson and Wendling 1977 ) but the possibilities of merging modern-era satellites with data such as those from the Moderate Resolution Imaging Spectroradiometer (MODIS) or Cloud-Aerosol lidar and Infrared Pathfinder Satellite Observation (CALIPSO) give us a much more accurate understanding of the aerosols’ optical properties (e.g., Remer et al. 2008 ; Omar et al. 2009 ). Among the various effects of dust over the tropical atmosphere, Dunion and Velden (2004

Full access
Caren Marzban and Scott Sandgathe

optical flow technique. Wea. Forecasting , 24 , 1297 – 1308 . 10.1175/2009WAF2222247.1 Lim, D-K. , and Ho Y-S. , 1998 : A fast block matching motion estimation algorithm based on statistical properties of object displacement. Proc. 2001 Int. Symp. on Intelligent Multimedia, Video and Speech Processing, Hong Kong, China, IEEE, 498–501 . Lucas, B. D. , and Kanade T. , 1981 : An iterative image registration technique with an application to stereo vision. Proc. Imaging Understanding

Full access