A5071141943- Atmospheric aerosols and clouds
- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Meteorological Phenomena and Simulations
- Cryospheric studies and observations
- Atmospheric and Environmental Gas Dynamics
- Thermal Radiation and Cooling Technologies
- Icing and De-icing Technologies
- Climate variability and models
- Precipitation Measurement and Analysis
- Planetary Science and Exploration
- Electromagnetic Scattering and Analysis
- Hydrology and Watershed Management Studies
- Space Science and Extraterrestrial Life
- Urban Heat Island Mitigation
- Space Exploration and Technology
- nanoparticles nucleation surface interactions
- Optical Polarization and Ellipsometry
- Calibration and Measurement Techniques
- Chemical Thermodynamics and Molecular Structure
- Teleoperation and Haptic Systems
- Advanced Machining and Optimization Techniques
- Aerospace Engineering and Energy Systems
- Satellite Communication Systems
- Lightning and Electromagnetic Phenomena
University of California, Los Angeles
2004-2023
Japan Aerospace Exploration Agency
2016
NOAA Oceanic and Atmospheric Research
2014
Sapporo Medical University
2009
University of California System
2006
University of Utah
1989-1999
University of Alaska Fairbanks
1985
Tohoku University
1980-1983
The National Aeronautics and Space Administration's Clouds the Earth's Radiant Energy System (CERES) Project was designed to improve our understanding of relationship between clouds solar longwave radiation. This is achieved using satellite broad-band instruments map top-of-atmosphere radiation fields with coincident data from narrow-band imagers employed retrieve properties associated those fields. paper documents CERES Edition-2 cloud property retrieval system used analyze Tropical...
We have developed an efficient light scattering and polarization program, based on a ray-tracing technique, for hexagonal ice crystals randomly horizontally oriented in space. Improvements been made the computations through proper treatment of δforward transmission by geometric rays incorporation effect birefringence ice. Using this phase matrix are from observed crystal size distributions four typical cirrus clouds. The results single-scattering parameters, including function, albedo,...
Abstract. A theoretical black carbon (BC) aging model is developed to account for three typical evolution stages, namely, freshly emitted aggregates, BC coated by soluble material, and particles undergoing further hygroscopic growth. The geometric-optics surface-wave (GOS) approach employed compute the single-scattering properties at each stage, which are subsequently compared with laboratory measurements. Theoretical calculations consistent measurements in extinction absorption cross...
The interpretation of satellite-observed radiances to derive cloud optical depth and effective particle size requires radiative transfer calculations relating these parameters the reflectance, transmittance, emittance cloud. Such computations can be extremely time consuming when used in an operational mode analyze routine satellite data. Adding–doubling (AD) models are here compute reflectance at wavelengths commonly by meteorological imagers for droplet radii ranging from 2 32 μm...
A new Monte Carlo/geometric ray-tracing method has been developed for the computation of scattering, absorption, and polarization properties ice crystals with various irregular structure, including hollow columns, bullet rosettes, dendrites, capped columns. The shapes these are defined by appropriate geometric models incident coordinate systems. photons traced a hit-and-miss Carlo followed reflection refraction on crystal boundary. Absorption accounted means stochastic procedures....
Abstract. The version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. top temperature, pressure, height effective fraction now reported at AIRS field-of-view (FOV) resolution. Significant improvements in assignment over 5 shown with FOV-scale comparisons to vertical structure observed by CloudSat 94 GHz radar Cloud-Aerosol LIdar Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid,...
A stochastic approach has been developed to model the positions of BC (black carbon)/dust internally mixed with two snow grain types: hexagonal plate/column (convex) and Koch snowflake (concave). Subsequently, light absorption scattering analysis can be followed by means an improved geometric-optics coupled Monte Carlo photon tracing determine BC/dust single-scattering properties. For a given shape (plate, snowflake, spheroid, or sphere), action internal mixing absorbs substantially more...
Abstract We quantify the effects of grain shape and multiple black carbon (BC)‐snow internal mixing on snow albedo by explicitly resolving structures. Nonspherical grains tend to have higher albedos than spheres with same effective sizes, while difference due increases size, up 0.013 0.055 for radii 1,000 μm at visible near‐infrared bands, respectively. BC‐snow reduces wavelengths < ~1.5 μm, negligible longer wavelengths. show less BC‐induced reductions sizes 0.06 ultraviolet bands....
Current techniques for deriving cirrus optical depth and altitude from visible (0.65 μm) infrared (11.5 satellite data use radiative transfer calculations based on scattering phase functions of spherical water droplets. This study examines the impact using droplets hexagonal ice crystals to analyze radiances cirrus. Adding-doubling are used compute different cloud thicknesses heights over various backgrounds. These develop parameterizations top-of-the-atmosphere reflectance emittance...
A new instrument, a cloud integrating nephelometer (CIN), was used on the University of Washington's CV-580 research aircraft to measure asymmetry parameter (g), volume scattering coefficient, and backscatter ratio in clouds situ visible spectrum during FIRE-ACE/SHEBA field project late spring summer 1998 Arctic. The principle behind operation CIN is described, error estimates for measurements are calculated. average value g measured with all Arctic 0.824, which slightly less than expected...
We have developed a theoretical framework for the computation of transfer solar radiation in an anisotropic medium with particular application to oriented ice crystals cirrus clouds. In development, adding principle radiative has been used modifications account anisotropy phase matrix. The single-scattering properties including function, albedo, and extinction cross section, randomly horizontally are then reflected transmitted intensifies, planetary polarization multiple scattering. There...
The scattering phase matrices for finite hexagonal cylinders oriented randomly in space were computed by superposing the scattered intensities of Fraunhofer diffracted rays and geometrical optics rays. However, effect interference is considered when optical path lengths two rays, split some obstacle same direction, are equal to each other. Single models (c/a = 2.5 0.4) a column plate, resembling corresponding crystals atmospheric clouds, used computations. Our results showed different values...
We develop a retrieval scheme by using advanced very-high-resolution radiometer (AVHRR) 3.7- and 10.9-μm data to compute simultaneously the temperature, optical depth, mean effective ice-crystal size for cirrus clouds. The methodology involves numerical solution of set nonlinear algebraic equations derived from theory radiative transfer. requires correlation emissivities two channels in terms extinction ratio. dependence this ratio on distribution is examined an adding-doubling transfer...
Abstract We develop a stochastic aerosol‐snow albedo model that explicitly resolves size distribution of aerosols internally mixed with various snow grains. use the to quantify black carbon (BC) effects on and optical properties for BC‐snow internal mixing. Results show BC‐induced single‐scattering coalbedo enhancement reduction decrease by factor 2–3 increasing BC effective radii from 0.05 0.25 μm, while polydisperse results in up 40% smaller visible compared monodisperse equivalent radii....
Abstract We extend a stochastic aerosol‐snow albedo model to explicitly simulate dust internally/externally mixed with snow grains of different shapes and for the first time quantify combined effects dust‐snow internal mixing nonsphericity on optical properties albedo. Dust‐snow internal/external significantly enhances single‐scattering coalbedo absorption at wavelengths <1.0 μm, stronger enhancements (relative external mixing) higher concentrations but very weak dependence size shape...
Using a model that combines single-scattering properties for spheroidal and hexagonal ice crystals, the thermal infrared radiative of cirrus clouds have been investigated. Infrared scattering absorption randomly oriented spheroids hexagons are parameterized based on anomalous diffraction theory geometric ray-tracing method, respectively. observed crystal size distributions, upwelling radiances at top cloudy atmospheres computed. Results show presence small crystals can produce significant...
Using the data obtained from Advanced Very High Resolution Radiometer (AVHRR) 3.7-µm and 10.9-µm channels, a retrieval scheme has been developed to simultaneously infer cirrus cloud optical depth mean effective ice crystal size based on theory of radiative transfer parameterizations. A numerical is further remove solar component in radiance for applications daytime satellite data. This correlation between (solar) 0.63-µm reflectances. Validation algorithm performed by using various datasets...
Abstract Previous modeling of snow albedo, a key climate feedback parameter, follows the independent scattering approximation (ISA) such that grains are considered as number separate units with distances longer than wavelengths. Here we develop new albedo model for widely observed close‐packed internally mixed black carbon (BC) and demonstrate simulations match closer to observations. Close packing results in stronger light absorption clean BC‐contaminated snow. Compared ISA, close reduces...
During the 1986 Project FIRE (First International Satellite Cloud Climatology Regional Experiment) field campaign, four 22° halo-producing cirrus clouds were studied jointly from a ground-based polarization lidar and an instrumented aircraft. The data show vertical cloud structure relative position of aircraft, which collected total 84 slides by impaction, preserving ice crystals for later microscopic examination. Although many particles too fragile to survive impaction intact, large...
Using the observed ice crystal size distribution in contrail cirrus from SUCCESS, we have carried out scattering and absorption calculations based on a unified theory for light by crystals covering all sizes shapes. We illustrate effects of surface roughness phase function features remote sensing applications. The extinction coefficient single‐scattering albedo exhibit minimum feature at 2.85 µm, referred to as Christiansen effect, which is particularly pronounced clouds consisting...
A dual-channel retrieval technique involving the water vapor band at 6.5 microns and window region 10.5 has been developed to infer temperature emissivity of tropical anvils. This applied data obtained from ER-2 narrow field-of-view radiometers during two flights in field observation Stratosphere-Troposphere Exchange Project near Darwin, Australia, January-February 1987. The retrieved cloud temperatures are between 190 240 K, while emissivities derived algorithm range about 0.2 1. Moreover,...