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Author: Joannès Berque
Publisher:
ISBN:
Category : Atmosphere
Languages : en
Pages : 436
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Book Description
A radiative transfer model of the Antarctic snow-atmosphere system was developed, as radiometric contrast between clouds and the snow hinders remote sensing of clouds and surface properties over the high ice sheets. The radiative effect of clouds at the top of the atmosphere was evaluated over the South Pole with ground-based lidar observations and data from NASA's Terra satellite.
Author: Joannès Berque
Publisher:
ISBN:
Category : Atmosphere
Languages : en
Pages : 436
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Book Description
A radiative transfer model of the Antarctic snow-atmosphere system was developed, as radiometric contrast between clouds and the snow hinders remote sensing of clouds and surface properties over the high ice sheets. The radiative effect of clouds at the top of the atmosphere was evaluated over the South Pole with ground-based lidar observations and data from NASA's Terra satellite.
Author: Jeffrey R. Key
Publisher:
ISBN:
Category : Clouds
Languages : en
Pages : 10
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Book Description
Author: Jeffrey R. Key
Publisher:
ISBN:
Category : Clouds
Languages : en
Pages : 12
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Book Description
Author: Constantin Andronache
Publisher: Elsevier
ISBN: 012810550X
Category : Science
Languages : en
Pages : 302
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Book Description
Mixed-Phase Clouds: Observations and Modeling presents advanced research topics on mixed-phase clouds. As the societal impacts of extreme weather and its forecasting grow, there is a continuous need to refine atmospheric observations, techniques and numerical models. Understanding the role of clouds in the atmosphere is increasingly vital for current applications, such as prediction and prevention of aircraft icing, weather modification, and the assessment of the effects of cloud phase partition in climate models. This book provides the essential information needed to address these problems with a focus on current observations, simulations and applications. - Provides in-depth knowledge and simulation of mixed-phase clouds over many regions of Earth, explaining their role in weather and climate - Features current research examples and case studies, including those on advanced research methods from authors with experience in both academia and the industry - Discusses the latest advances in this subject area, providing the reader with access to best practices for remote sensing and numerical modeling
Author: Allison McComiskey Payton
Publisher:
ISBN:
Category :
Languages : en
Pages : 412
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Book Description
Author: Loknath Adhikari
Publisher:
ISBN: 9781267820068
Category : Antarctica
Languages : en
Pages : 146
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Book Description
Clouds in the polar regions play an important roles in the hydrologic cycle, the local radiative balance, and polar sea ice. However, harsh climatic conditions and perennial snow and ice cover limits the collection of cloud data from the surface as well as the effectiveness of cloud detection with satellite passive sensors. Therefore, there is a lack of reliable data on polar clouds and their properties. This study combines active and passive measurements from the NASA A-Train satellites to overcome these shortcomings and to provide a novel approach to study on polar clouds. Multi-year CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are used to investigate the characteristics of tropospheric clouds and precipitation systems, and their effect on the occurrence and microphysical properties of polar stratospheric clouds in the Antarctic region, south of 60 °S. The lidar and radar data are collocated to derive a combined cloud mask to improve detection of cloud vertical structure. Polar stratospheric clouds were detected using CALIPSO attenuated lidar scattering ratios (ALSR) at a horizontal resolution of 20 km to achieve good signal-to-noise ratios to allow the detection of tenuous PSCs. Clouds in the Antarctic region exhibit distinct land-sea and seasonal variabilities. The mean annual cloud occurrence is ~ 50 % over the continent and ~ 85 % over the ocean. Over the ocean the mean occurrence is higher in summer (90 %) than in winter (70 %). Low-level clouds contribute to more than 60 % of the total clouds. However, due to the extensive snow cover and cold surfaces in winter these low-level cloud occurrences are smaller in winter (50 %) than in summer (65 %). For ice clouds, both the effective radius and ice water content are larger in summer than in winter. High-level and deep tropospheric clouds strongly affect polar stratospheric cloud (PSC) occurrence and their microphysical properties by providing additional cooling of the lower stratosphere, especially during late winter and early spring. 70 % of all PSCs and 80 % of ice PSCs are formed in connection with tropospheric cloud systems during September and October. Similarly, PSCs associated with tropospheric cloud systems have higher particle number concentration than PSCs not associated with tropospheric cloud systems. A novel stratiform mixed-phase cloud retrieval algorithm has been developed by combining CloudSat, CALIPSO and Moderate Resolution Imaging Spectroradiometer (MODIS) measurements to address the large positive biases of the MODIS operational algorithm, which assumes a single liquid- or ice-phase in its retrieval for mixed-phase clouds. The algorithm is validated using collocated MODIS and ground-based measurements at the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) North Slope Alaska (NSA) site. Results indicate that the new mixed-phase algorithm reduces the positive LWP biases of the operational MODIS algorithm from 35 % and 68 % to 10 % and 22 % over the temperature ranges of -5 to -10 °C and -10 to -20 °C, respectively.
Author: Ryan Scott
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
West Antarctica is experiencing rapid ice loss and complex regional climate change. This dissertation investigates how cloud properties and the large-scale atmospheric circulation influence surface heat exchange and melting on West Antarctic ice shelves and ice sheet margins using field measurements, satellite observations, and atmospheric reanalysis data. Surface-based shortwave spectral irradiance measurements and satellite data reveal strong orographic controls on West Antarctic cloud formation and ice-phase microphysics. Orographically-forced updrafts and waves favor rapid conversion of supercooled liquid water into ice, which efficiently attenuates incoming solar near-infrared energy. Frequent intrusions of marine air from the Amundsen Sea anchor a semipermanent cloud band over the West Antarctic Ice Sheet (WAIS) that continues downstream along the Transantarctic Mountain range. Cloud systems sampled downstream at Ross Island tend to be optically thin and radiatively dominated by ice water. In contrast, direct onshore flows of marine air from the Southern Ocean bring low clouds with enhanced liquid-phase spectral signatures. Radiative transfer calculations using vertically-resolved cloud data indicate that, owing to a dominance of longwave effects, clouds radiatively warm the surface of the WAIS in every month of the year. On annual average, cloud cover is estimated to warm the grounded ice-sheet by 34 Watts per square-meter. Thin low-level liquid-bearing clouds, which favor strong radiative heat input to the snow surface, are common during the summer melt season. Summer atmospheric warming in West Antarctica is favored by blocking activity over the Amundsen Sea and a negative phase of the Southern Annular Mode, which both correlate with El Niño conditions in the tropical Pacific Ocean. Extensive melt events on the Ross and Pacific-sector coastal ice shelves are linked to persistent, intense Amundsen Sea anticyclones, which force intrusions of marine air over the ice-sheet. Surface melting is driven by enhanced downwelling longwave radiation from clouds and a warm, moist atmosphere and by downward turbulent mixing of sensible heat by föhn winds. Since the late 1990s, concurrent with accelerating ocean-driven WAIS mass loss, summer surface melt occurrence has increased from the Pine Island and Thwaites Glacier systems to the eastern Ross Ice Shelf, linked to increasing anticyclonic marine influence and regional sea-ice loss.
Author: Michael J. Pavolonis
Publisher:
ISBN:
Category :
Languages : en
Pages : 296
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Book Description
Author: Kris Scarci
Publisher:
ISBN:
Category :
Languages : en
Pages : 78
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Book Description
Understanding the effect of clouds on atmospheric radiative processes affecting downwelling radiation is critical in discerning the causal nature of large-scale melt events in Antarctica. The influence of varying cloud types on solar and terrestrial radiation presents itself as a multifarious problem interwoven within many hierarchical orders of physical interactions across a range of spatial scales. In this work we show how large-scale meteorology leads to advection of moisture over varying terrain, influencing the microphysical properties of clouds and their effect on shortwave and longwave radiation at the Antarctic surface. Synoptic circulation patterns over West Antarctica (WA) were grouped and categorized by Scott et al. 2018 into four recurring meteorological regimes using k-means cluster analysis of daily 700 hPa geopotential height fields. Regime 1 is representative of warm surface air temperature, and moist marine air advection over WA with liquid-bearing and classical liquiddominated mixed-phase clouds. Regime 2 is characterized by large-scale subsidence, outflow of continental polar air, and anomalously clear skies. Regime 3 is of smaller sample size, and produces similar surface radiative flux levels to those of Regime 1. Regime 4 is distinguished by an orographic influence upstream of Ross Island, resulting in the formation of geometrically thick, mixed-phase clouds. This study focuses on the radiative differences in downwelling shortwave and longwave irradiance by comparing prevailing meteorological regimes and cloud properties therein. The influence of supplemental ice absorption on downwelling shortwave flux is highlighted when comparing cloud optical depth properties of Regime 4 to that of Regime 1 and 2. The influence of cloud base temperature on downwelling longwave flux is noted when comparing cloud optical depth properties of Regime 2 to that of Regime 1.
Author: Beau Riffenburgh
Publisher: Taylor & Francis
ISBN: 0415970245
Category : History
Languages : en
Pages : 1274
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