Mixed-phase Clouds, Thin Cirrus Clouds, and OLR Over the Tropics PDF Download
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Author: Joonsuk Lee
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The tropics is a very important region in terms of earth0́9s radiation budget because the net radiative heating is largest in the tropics and that surplus energy is redistributed by the circulations of oceans and atmospheres. Moreover, a large number of clouds are formed by deep convection and convergence of water vapor. Thus, it is very important to understand the radiative energy balance of the tropics and the effect of clouds on the radiation field. For mixed-phase clouds, error analyses pertaining to the inference of effective particle sizes and optical thicknesses are performed. Errors are calculated with respect to the assumption of a cloud containing solely liquid or ice phase particles. The analyses suggest that the effective particle size inferred for a mixed-phase cloud can be underestimated (or overestimated) if a pure liquid phase (or pure ice phase) is assumed for the cloud, whereas the corresponding cloud optical thickness can be overestimated (or underestimated). The analyses of optical depth and fraction of occurrence for thin cirrus clouds showed that about 40% of pixels flagged as clear-sky contain detectible thin cirrus clouds. The regions of high occurrence and large optical depth located around deep convection showed seasonal variations. The thin cirrus clouds occur more frequently with larger optical depth in the northern (southern) hemisphere during spring and summer (autumn and winter). The net cloud radiative forcing by thin cirrus clouds is positive at the top of atmosphere and is negative at the bottom of atmosphere. The difference in OLR between measurement and model is 4.2 Wm-2 for September 2005. The difference is smaller in moist regions and larger in drier regions. OLR increases with increasing surface temperatures up to 300 K but decreases at surface temperatures larger than 300 K due to the strong absorption of increased water vapor. In summary, if the surface temperature is lower than the threshold of convection (300 K), temperature is a dominant factor in OLR and if the surface temperature is larger than 300 K, OLR is strongly influenced by water vapor.
Author: Joonsuk Lee
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The tropics is a very important region in terms of earth0́9s radiation budget because the net radiative heating is largest in the tropics and that surplus energy is redistributed by the circulations of oceans and atmospheres. Moreover, a large number of clouds are formed by deep convection and convergence of water vapor. Thus, it is very important to understand the radiative energy balance of the tropics and the effect of clouds on the radiation field. For mixed-phase clouds, error analyses pertaining to the inference of effective particle sizes and optical thicknesses are performed. Errors are calculated with respect to the assumption of a cloud containing solely liquid or ice phase particles. The analyses suggest that the effective particle size inferred for a mixed-phase cloud can be underestimated (or overestimated) if a pure liquid phase (or pure ice phase) is assumed for the cloud, whereas the corresponding cloud optical thickness can be overestimated (or underestimated). The analyses of optical depth and fraction of occurrence for thin cirrus clouds showed that about 40% of pixels flagged as clear-sky contain detectible thin cirrus clouds. The regions of high occurrence and large optical depth located around deep convection showed seasonal variations. The thin cirrus clouds occur more frequently with larger optical depth in the northern (southern) hemisphere during spring and summer (autumn and winter). The net cloud radiative forcing by thin cirrus clouds is positive at the top of atmosphere and is negative at the bottom of atmosphere. The difference in OLR between measurement and model is 4.2 Wm-2 for September 2005. The difference is smaller in moist regions and larger in drier regions. OLR increases with increasing surface temperatures up to 300 K but decreases at surface temperatures larger than 300 K due to the strong absorption of increased water vapor. In summary, if the surface temperature is lower than the threshold of convection (300 K), temperature is a dominant factor in OLR and if the surface temperature is larger than 300 K, OLR is strongly influenced by water vapor.
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: 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: Allison Leanne Cardona
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Thin cirrus clouds play an important radiative role in the earth's atmosphere and climate system, yet are one of the least understood components of the climate system. With the use of data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), thin cirrus and thick cloud distributions in the tropics are analyzed at 121, 100, and 82 hPa. Observations obtained between December 2006 and November 2007 show that thin cirrus between 30°ʻN and 30°S occur in close proximity to regions of intense convection and are positively correlated with low values of outgoing longwave radiation (OLR). In conjunction with the CALIPSO data, water vapor data from the Earth Observing System (EOS) Microwave Limb Sounder (MLS), OLR data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.cdc.noaa.gov/, and linearly interpolated NCEP reanalysis temperature data were used. These data were used to examine how thick and thin cirrus cloud fractions at 121-hPa and 100-hPa are related to relative humidity with respect to ice (RHI), temperature, and OLR. Our observations show that both RHI and convection play important roles in the development and maintenance of thick and thin cirrus clouds at the pressure levels of interest. The highest fractions of clouds are almost always seen within OLR values representative of convection and at relatively high values of RHI. However, when peaks in cloud fraction are found above the convective threshold, higher RHI values are needed than are needed when convection is responsible for the formation and maintenance of these clouds.
Author: Kuo-Nan Liou
Publisher: Cambridge University Press
ISBN: 0521889162
Category : Science
Languages : en
Pages : 461
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Book Description
This volume outlines the fundamentals and applications of light scattering, absorption and polarization processes involving ice crystals.
Author: Ken S. Carslaw
Publisher: Elsevier
ISBN: 0128231726
Category : Science
Languages : en
Pages : 856
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Book Description
The ever-diversifying field of aerosol effects on climate is comprehensively presented here, describing the strong connection between fundamental research and model applications in a way that will allow both experienced researchers and those new to the field to gain an understanding of a wide range of topics. The material is consistently presented at three levels for each topic: (i) an accessible "quick read" of the essentials, (ii) a more detailed description, and (iii) a section dedicated to how the processes are handled in models. The modelling section in each chapter summarizes the current level of knowledge and what the gaps in this understanding mean for the effects of aerosols on climate, enabling readers to quickly understand how new research fits into established knowledge. Definitions, case studies, reference data, and examples are included throughout. Aerosols and Climate is a vital resource for graduate students, postdoctoral researchers, senior researchers, and lecturers in departments of atmospheric science, meteorology, engineering, and environment. It will also be of interest to those working in operational centers and policy-facing organizations, providing strong reference material on the current state of knowledge. - Includes a section in each chapter that focuses on the treatment of relevant aerosol processes in climate models - Provides clear exposition of the challenges in understanding and reducing persistent gaps in knowledge and uncertainties in the field of aerosol-climate interaction, going beyond the fundamentals and existing knowledge - Authored by experts in modeling and aerosol processes, analysis or observations to ensure accessibility and balance
Author: Robert M. Haberle
Publisher: Cambridge University Press
ISBN: 110817938X
Category : Science
Languages : en
Pages : 613
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Book Description
Humanity has long been fascinated by the planet Mars. Was its climate ever conducive to life? What is the atmosphere like today and why did it change so dramatically over time? Eleven spacecraft have successfully flown to Mars since the Viking mission of the 1970s and early 1980s. These orbiters, landers and rovers have generated vast amounts of data that now span a Martian decade (roughly eighteen years). This new volume brings together the many new ideas about the atmosphere and climate system that have emerged, including the complex interplay of the volatile and dust cycles, the atmosphere-surface interactions that connect them over time, and the diversity of the planet's environment and its complex history. Including tutorials and explanations of complicated ideas, students, researchers and non-specialists alike are able to use this resource to gain a thorough and up-to-date understanding of this most Earth-like of planetary neighbours.
Author: Maria Mudd Ruth
Publisher: Mountaineers Books
ISBN: 168051119X
Category : Nature
Languages : en
Pages : 224
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Book Description
• Written by a critically-acclaimed natural-history author • Shares author’s fun journey to understanding clouds • Written for the curious—but non-science—minded Author Maria Mudd Ruth fell in love with clouds the same way she stumbles into most passions: madly and unexpectedly. A Sideways Look at Clouds is the story of her quite accidental infatuation with and education about the clouds above. When she moved to the soggy Northwest a decade ago, Maria assumed that locals would know everything there was to know about clouds, in the same way they talk about salmon, tides, and the Seahawks. Yet in her first two years of living in Olympia, Washington, she never heard anyone talk about clouds—only the rain. Puzzled by this lack of cloud savvy, she decided to create a 10-question online survey and sent it to everyone she knew. Her sample size of 67 people included men and women, new friends in Olympia, family on the East Coast, outdoorsy and indoorsy types, professional scientists, and liberal arts majors like herself. The results showed that while people knew a little bit about clouds, most were like her—they had a hard time identifying clouds or remembering their names. As adults, they had lost their curiosity and sense of wonder about clouds and were, essentially, not in the habit of looking up. A Sideways Look at Clouds acknowledges the challenges of understanding clouds and so uses a very steep and bumpy learning curve—the author’s—as its plot line. The book is structured around the ten words used in most definitions of a cloud: “a visible mass of water droplets or ice crystals suspended in the atmosphere above the earth.” A captivating story teller, Maria blends science, wonder, and humor to take the scenic route through the clouds and encourages readers to chart their own rambling, idiosyncratic course.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 13
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Book Description
To understand the radiative impact of tropical thin cirrus clouds, the frequency of occurrence and optical depths of these clouds have been derived. "Thin" cirrus clouds are defined here as being those that are not detected by the operational Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask, corresponding to an optical depth value of approximately 0.3 or smaller, but that are detectable in terms of the cirrus reflectance product based on the MODIS 1.375-micron channel. With such a definition, thin cirrus clouds were present in more than 40% of the pixels flagged as "clear sky" by the operational MODIS cloud mask algorithm. It is shown that these thin cirrus clouds are frequently observed in deep convective regions in the western Pacific. Thin cirrus optical depths were derived from the cirrus reflectance product. Regions of significant cloud fraction and large optical depths were observed in the Northern Hemisphere during the boreal spring and summer and moved southward during the boreal autumn and winter. The radiative effects of tropical thin cirrus clouds were studied on the basis of the retrieved cirrus optical depths, the atmospheric profiles derived from the Atmospheric Infrared Sounder (AIRS) observations, and a radiative transfer model in conjunction with a parameterization of ice cloud spectral optical properties. To understand how these clouds regulate the radiation field in the atmosphere, the instantaneous net fluxes at the top of the atmosphere (TOA) and at the surface were calculated. The present study shows positive and negative net forcings at the TOA and at the surface, respectively. The positive (negative) net forcing at the TOA (surface) is due to the dominance of longwave (shortwave) forcing. Both the TOA and surface forcings are in a range of 0-20 W/sq m, depending on the optical depths of thin cirrus clouds.
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781729223628
Category : Science
Languages : en
Pages : 46
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Book Description
Over the convectively active tropical ocean regions, the measurement made from space in the IR and visible spectrum have revealed the presence of optically thin cirrus clouds, which are quite transparent in the visible and nearly opaque in the IR. The Nimbus-4 IR Interferometer Spectrometer (IRIS), which has a field of view (FOV) of approximately 100 km, was utilized to examine the IR optical characteristics of these cirrus clouds. From the IRIS data, it was observed that these optically thin cirrus clouds prevail extensively over the warm pool region of the equatorial western Pacific, surrounding Indonesia. It is found that the seasonal cloud cover caused by these thin cirrus clouds exceeds 50 percent near the central regions of the warm pool. For most of these clouds, the optical thickness in the IR is less than or = 2. It is deduced that the dense cold anvil clouds associated with deep convection spread extensively and are responsible for the formation of the thin cirrus clouds. This is supported by the observation that the coverage of the dense anvil clouds is an order of magnitude less than that of the thin cirrus clouds. From these observations, together with a simple radiative-convective model, it is inferred that the optically thin cirrus can provide a greenhouse effect, which can be a significant factor in maintaining the warm pool. In the absence of fluid transports, it is found that these cirrus clouds could lead to a runaway greenhouse effect. The presence of fluid transport processes, however, act to moderate this effect. Thus, if a modest 20 W/sq m energy input is considered to be available to warm the ocean, then it is found that the ocean mixed-layer of a 50-m depth will be heated by approximately 1 C in 100 days. Prabhakara, C. and Yoo, J.-M. and Dalu, G. and Kratz, P. Goddard Space Flight Center ...
