Aerosol Impacts on Cirrus Clouds and High-Power Laser Transmission: A Combined Satellite Observation and Modeling Approach PDF Download
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
The objective of this basic research effort is to provide the theoretical foundations for modeling/simulating the interaction of aerosols and ice at high altitudes (near and above the tropopause). The AF, together with the ABL SPO (through the MDA), anticipate that aerosols/ice will impact the efficacy of the ABL and the ability to predict possible impacts is of great value. The PI and his colleagues will interrogate a number of conceptual schemes which incorporate cloud microphysics (with 6 classes of moisture species together with actual ice concentrations). Particular attention will be paid to ice nucleation scenarios.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
The objective of this basic research effort is to provide the theoretical foundations for modeling/simulating the interaction of aerosols and ice at high altitudes (near and above the tropopause). The AF, together with the ABL SPO (through the MDA), anticipate that aerosols/ice will impact the efficacy of the ABL and the ability to predict possible impacts is of great value. The PI and his colleagues will interrogate a number of conceptual schemes which incorporate cloud microphysics (with 6 classes of moisture species together with actual ice concentrations). Particular attention will be paid to ice nucleation scenarios.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
A three-dimensional (3-D) model has been developed for the transmission and backscattering of a high-energy laser beam through inhomogeneous high-level clouds in plane-parallel and spherical geometries. The formulations of laser transmission and backscattering are based on the successive-order-of scattering approach in which multiple scattering by cloud and aerosol particles can be effectively accounted for. Effects of the cloud inhomogeneity on 3-D laser transmission and backscattering have been examined by using 3-D cirrus cloud fields inferred from a combination of satellite data and a parameterization of the vertical cloud profile involving temperature from sounding and /or analysis. The model simulation results for 3D direct transmission, forward-scattered transmission, and backscattering differ substantially from those for the 2-D model developed previously. The Earth's curvature effect becomes increasingly significant for laser transmission as the distance between the aircraft and the target increases. The 3-D laser transmission and backscattering model can be directly linked to cloud data derived from satellite remote sensing and numerical forecasting models for tactical application.
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Category :
Languages : en
Pages : 16
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Future high-altitude laser systems may be affected by cirrus clouds. Laser transmission models were applied to measured and retrieved cirrus properties to determine cirrus impact on power incident on a target or receiver. A major goal was to see how well radiosondes and geostationary satellite imagery could specify the required properties. Based on the use of ground-based radar and lidar measurements as a reference, errors in cirrus-top and cirrus-base height estimates from radiosonde observations were 20%- 25% of geostationary satellite retrieval errors. Radiosondes had a perfect cirrus detection rate as compared with 80% for satellite detection. Ice water path and effective particle size were obtained with a published radar-lidar retrieval algorithm and a documented satellite algorithm. Radar-lidar particle size and ice water path were 1.5 and 3 times the satellite retrievals, respectively. Radar-lidar-based laser extinction coefficients were 55% greater than satellite values. Measured radar-lidar cirrus thickness was consistently greater than satellite-retrieved thickness, but radar-lidar microphysical retrieval required detection by both sensors at each range gate, which limited the retrievals' vertical extent. Greater radar-lidar extinction and greater satellite-based cirrus thickness yielded comparable optical depths for the two independent retrievals. Laser extinction-transmission models applied to radiosonde-retrieved cirrus heights and satellite-retrieved microphysical properties revealed a significant power loss by all models as the laser beam transits the cirrus layer. This suggests that cirrus location is more important than microphysics in high-altitude laser test support. Geostationary satellite imagery may be insufficient in cirrus detection and retrieval accuracy. Humidity-sensitive radiosondes are a potential proxy for ground-based remote sensors in cirrus detection and altitude determination.
Author: David K. Lynch
Publisher: Oxford University Press
ISBN: 0195351398
Category : Science
Languages : en
Pages : 499
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Book Description
Cirrus clouds are high, thin, tropospheric clouds composed predominately of ice. In the last ten years, considerable work has shown that cirrus is widespread--more common than previously believed--and has a significant impact on climate and global change. As the next generation weather satellites are being designed, the impact of cirrus on remote sensing and the global energy budget must be recognized and accommodated. This book, the first to be devoted entirely to cirrus clouds, captures the state of knowledge of cirrus and serves as a practical handbook as well. Each chapter is based on an invited review talk presented at Cirrus, a meeting hosted by the Optical Society of America and co-sponsored by the American Geophysical Union and the American Meteorological Society. All aspects of cirrus clouds are covered, an approach that reaches into diverse fields. Topics include: the definition of cirrus, cirrus climatologies, nucleation, evolution and dissipation, mixed-phase thermodynamics, crystallinity, orientation mechanisms, dynamics, scattering, radiative transfer, in situ sampling, processes that produce or influence cirrus (and vice versa), contrails, and the influence of cirrus on climate.
Author: Ila L. Kolb
Publisher:
ISBN: 9781423524779
Category : Atmosphere
Languages : en
Pages : 88
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Book Description
Since approximately 20% of the globe is covered with cirrus clouds at any given time, it is clear that any airborne or spaceborne system using a laser will intercept cirrus clouds at some point. Cirrus clouds contain a very complex microphysical structure that will affect laser power by scattering and reflecting it away from the intended target, thus reducing efficiency and possibly even making it ineffective. Using two thin cirrus laser transmission models, a single homogeneous cloud layer model and a multiple cloud layer model, laser transmission profiles are generated from a simulated cirrus cloud case created by the RAMS model. Sensitivity studies are performed on the laser transmission model to examine the effects of aerosols and water vapor, ice crystal orientation, multiple scattering contributions, and the differences between the single and multiple layer models. Different parts of the RAMS simulated cloud are examined as well as the development of a particular cloud feature. The two different laser transmission models are compared against each other for a variety of different cirrus cloud conditions within the simulated case. Optical depth is a cloud variable that is fairly well measured using remote sensing techniques and airborne lidar. Average optical depth is examined as a viable parameter to indicate the likely transmission through a cloud.
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Publisher:
ISBN:
Category :
Languages : en
Pages : 5
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Book Description
Laser transmission model development. We developed a number of 2D radiative transfer models based on the successive-order-of-scattering approach for the computation of airborne high-energy laser transmission and backscattering through homogeneous and inhomogeneous thin cirrus clouds in both plane-parallel and spherical geometries. These models took into account the relative positions of aircraft, target, and cirrus clouds in the atmospheres. We investigated the sensitivity of laser transmission and backscattering on variation of the cloud optical depth, particle size, and cloud-base height, as well as the positions of aircraft and target. We also evaluated the effects of the earth's sphericity on laser transmission and backscattering. A paper describing our detailed research findings has been published in Applied Optics (Ou, et al. 2002). Our present research involves the theoretical formulation of a three-dimensional direct and first-order transmission-backscattering model for thin cirrus.
Author: George Geoffrey Koenig
Publisher:
ISBN:
Category : Cirrus clouds
Languages : en
Pages : 30
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Author: Jiang Zhu
Publisher:
ISBN:
Category : Cirrus clouds
Languages : en
Pages : 406
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Book Description
Understanding and describing the role of clouds in the climate system need intensive and extensive research on cloud properties. The albedo and greenhouse effects of clouds and their relations with the physical properties of clouds are analyzed. Cloud-top height and ice water content are key factors in impacting the longwave and shortwave radiation, respectively. Lidar and infrared radiometer measurement technologies are introduced. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) level I Lidar profile, level 2 cloud layer, and level 2 Lidar/IIR track products are briefly reviewed. The algorithms for identification of cirrus clouds, Linear Depolarization Ratio (LDR), and effective diameter are presented. An average LDR profile is calculated by using the sum of total attenuated backscattering profiles and the sum of perpendicular attenuated backscattering profiles. A weight-average method is applied to calculate the average LDR. A split-window method is applied to estimate the effective diameters of clouds. A set of bulk ice crystal models and a radiative transfer model are applied to produce a look-up table that includes the radiative transfer simulation results. The macro-physical properties of cirrus clouds are analyzed. The frequency of occurrence of cirrus clouds varies with latitude, and strongly relates to the atmospheric circulation. Cirrus clouds are few in high-pressure zones and abundant where seasonal monsoonal circulation occurs. Cloud-top height decreases with increasing latitude. Cloud-top temperature is lower in the tropical regions than in the midlatutude and the polar regions. The measured cloud thickness shows a great diurnal variation. CALIPSO lidar detects more cirrus clouds than satellite-based passive measurement. LDR values of cirrus clouds vary with latitude and location, and are higher during nighttime than during daytime. The 0.32 and 0.37 annual average LDRs derived by nadir and off-nadir measurements, respectively, indicate that substantial amounts of horizontal orientated ice crystals exist in cirrus clouds. The global distribution of effective diameter of cirrus clouds varies with latitude and season, and the effective diameter has relationship with the LDR.
Author: Alexander A. Kokhanovsky
Publisher: Springer
ISBN: 9783540865513
Category : Science
Languages : en
Pages : 388
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Book Description
Aerosols have a significant influence on the Earth's radiation budget, but there is considerable uncertainty about the magnitude of their effect on the Earth's climate. Currently, satellite remote sensing is being increasingly utilized to improve our understanding of the effect of atmospheric aerosols on the climate system. Satellite Aerosol Remote Sensing Over Land is the only book that brings together in one volume the most up-to-date research and advances in this discipline. As well as describing the current academic theory, the book presents practical applications, utilizing state-of-the-art instrumentation, invaluable to the work of environmental scientists. With contributions by an international group of experts and leaders of correspondent aerosol retrieval groups, the book is an essential tool for all those working in the field of climate change.
Author: George Geoffrey Koenig
Publisher:
ISBN:
Category : Cirrus clouds
Languages : en
Pages : 0
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