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Author: Jianyu Liang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Tropical weather systems such as the African Easterly Waves (AEWs), the African Easterly Jet (AEJ), and tropical cyclones usually interact with the Saharan Air Layer (SAL) and mineral dust aerosols embedded in the SAL. Previous studies have debates about the strength and even the direction of the impact from the dust and SAL on the development of the tropical systems. In this study, the sole impact from the dust on a hurricane is quantified using carefully designed numerical experiments. Hurricane Earl (2010) was originated from an AEW disturbance over Africa. It was influenced by the dusty SAL especially in its early development stage. We conduct numerical experiments using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to simulate Hurricane Earl (2010) starting from a weak disturbance. Experiments with 36-km resolution show that without moist convection, dust slightly weakens the low-pressure system in North Africa by cooling the atmosphere. This scenario mainly results from a reduction of the boundary layer heating during the daytime and from the enhancement of the outgoing longwave radiative cooling during the nighttime. The zonal mean of the AEJ is intensified slightly (less than 1m/s) in its southern part and weakened in its northern part when dust is included in the model. Adding dust weakens the AEWs at 850 hPa and 600 hPa levels and the tropical cyclone. High-resolution (4-km) cloud-resolving model experiments show that dust deepens the system slightly but does not affect the track. In the tropical low stage, dust increases the low-level cloud at 1-2 km height. It reduces rainfall in the outer edge of SAL region between 250 km to 350 km radii while it increases rainfall in the inner edge at around 200 km. The associated latent heat release shifts the updraft radially inward. The dynamical consequence is the acceleration of the tangential wind and the mid-level circulation. In the tropical depression stage, adding dust increases the number of cloud droplets in most of the regions and enhances the convection around the center, which generates more ice, snow, and rain. Overall, the impact of dust aerosols on Earl is small, the center minimum sea-level pressures only differ by less than 1 hPa at the end of the simulation. This suggests that pure meteorological model may be sufficiently accurate to forecast hurricanes if the dynamical and thermodynamical features of the SAL are properly described. In order to predict aerosols, one can use a simple chemistry model such as GOCART which only has aerosol direct effects. Using the Ensemble Kalman Filter (EnKF) to assimilate conventional observations and MODIS aerosol optical depth (AOD) data, both forecasts of the track of the storm and the aerosol can be improved.
Author: Jianyu Liang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Tropical weather systems such as the African Easterly Waves (AEWs), the African Easterly Jet (AEJ), and tropical cyclones usually interact with the Saharan Air Layer (SAL) and mineral dust aerosols embedded in the SAL. Previous studies have debates about the strength and even the direction of the impact from the dust and SAL on the development of the tropical systems. In this study, the sole impact from the dust on a hurricane is quantified using carefully designed numerical experiments. Hurricane Earl (2010) was originated from an AEW disturbance over Africa. It was influenced by the dusty SAL especially in its early development stage. We conduct numerical experiments using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to simulate Hurricane Earl (2010) starting from a weak disturbance. Experiments with 36-km resolution show that without moist convection, dust slightly weakens the low-pressure system in North Africa by cooling the atmosphere. This scenario mainly results from a reduction of the boundary layer heating during the daytime and from the enhancement of the outgoing longwave radiative cooling during the nighttime. The zonal mean of the AEJ is intensified slightly (less than 1m/s) in its southern part and weakened in its northern part when dust is included in the model. Adding dust weakens the AEWs at 850 hPa and 600 hPa levels and the tropical cyclone. High-resolution (4-km) cloud-resolving model experiments show that dust deepens the system slightly but does not affect the track. In the tropical low stage, dust increases the low-level cloud at 1-2 km height. It reduces rainfall in the outer edge of SAL region between 250 km to 350 km radii while it increases rainfall in the inner edge at around 200 km. The associated latent heat release shifts the updraft radially inward. The dynamical consequence is the acceleration of the tangential wind and the mid-level circulation. In the tropical depression stage, adding dust increases the number of cloud droplets in most of the regions and enhances the convection around the center, which generates more ice, snow, and rain. Overall, the impact of dust aerosols on Earl is small, the center minimum sea-level pressures only differ by less than 1 hPa at the end of the simulation. This suggests that pure meteorological model may be sufficiently accurate to forecast hurricanes if the dynamical and thermodynamical features of the SAL are properly described. In order to predict aerosols, one can use a simple chemistry model such as GOCART which only has aerosol direct effects. Using the Ensemble Kalman Filter (EnKF) to assimilate conventional observations and MODIS aerosol optical depth (AOD) data, both forecasts of the track of the storm and the aerosol can be improved.
Author: Guillaume A. D'Almeida
Publisher: A. Deepak Publishing
ISBN:
Category : Science
Languages : en
Pages : 592
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Book Description
Author: Peter Knippertz
Publisher: Springer
ISBN: 9401789789
Category : Science
Languages : en
Pages : 526
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Book Description
This volume presents state-of-the-art research about mineral dust, including results from field campaigns, satellite observations, laboratory studies, computer modelling and theoretical studies. Dust research is a new, dynamic and fast-growing area of science and due to its multiple roles in the Earth system, dust has become a fascinating topic for many scientific disciplines. Aspects of dust research covered in this book reach from timescales of minutes (as with dust devils, cloud processes and radiation) to millennia (as with loess formation and oceanic sediments), making dust both a player and recorder of environmental change. The book is structured in four main parts that explore characteristics of dust, the global dust cycle, impacts of dust on the Earth system, and dust as a climate indicator. The chapters in these parts provide a comprehensive, detailed overview of this highly interdisciplinary subject. The contributions presented here cover dust from source to sink and describe all the processes dust particles undergo while travelling through the atmosphere. Chapters explore how dust is lifted and transported, how it affects radiation, clouds, regional circulations, precipitation and chemical processes in the atmosphere and how it deteriorates air quality. The book explores how dust is removed from the atmosphere by gravitational settling, turbulence or precipitation, how iron contained in dust fertilizes terrestrial and marine ecosystems, and about the role that dust plays in human health. We learn how dust is observed, simulated using computer models and forecast. The book also details the role of dust deposits for climate reconstructions. Scientific observations and results are presented, along with numerous illustrations. This work has an interdisciplinary appeal and will engage scholars in geology, geography, chemistry, meteorology and physics, amongst others with an interest in the Earth system and environmental change. body>
Author: Laura Franziska Korte
Publisher:
ISBN: 9789402811315
Category :
Languages : en
Pages : 251
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Book Description
Author: Stefano Guerzoni
Publisher: Springer Science & Business Media
ISBN: 0792342941
Category : Science
Languages : en
Pages : 415
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Book Description
The atmosphere is an important pathway for the transport of continentally-derived material to the oceans. In this respect the Mediterranean Sea is of special importance because its atmosphere receives inputs of anthropogenic aerosols from the north and desert- derived Saharan dusts from the south. The dusts, much of which is transported in the form of seasonal `pulses', have important effects on climate, marine chemistry and sedimentation in the Mediterranean Sea. This volume brings together reviews and specific-topic papers on the following aspects of Saharan dust transport to the Mediterranean Sea: (i) the modelling of Saharan dust transport, (ii) the chemistry and mineralogy of the dusts and their effect on precipitation, (iii) the contribution of the dusts to marine sedimentation, (iv) the aerobiology of the dusts, and (v) climatic implications of Saharan dust transport. The volume is aimed at students and researchers with an interest in the climate, biogeochemistry and geology of the Mediterranean Sea.
Author: Intergovernmental Panel on Climate Change. Working Group II.
Publisher: Cambridge University Press
ISBN: 9780521634557
Category : Science
Languages : en
Pages : 532
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Book Description
Cambridge, UK : Cambridge University Press, 1998.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309133041
Category : Science
Languages : en
Pages : 252
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Book Description
The climate record for the past 100,000 years clearly indicates that the climate system has undergone periodic-and often extreme-shifts, sometimes in as little as a decade or less. The causes of abrupt climate changes have not been clearly established, but the triggering of events is likely to be the result of multiple natural processes. Abrupt climate changes of the magnitude seen in the past would have far-reaching implications for human society and ecosystems, including major impacts on energy consumption and water supply demands. Could such a change happen again? Are human activities exacerbating the likelihood of abrupt climate change? What are the potential societal consequences of such a change? Abrupt Climate Change: Inevitable Surprises looks at the current scientific evidence and theoretical understanding to describe what is currently known about abrupt climate change, including patterns and magnitudes, mechanisms, and probability of occurrence. It identifies critical knowledge gaps concerning the potential for future abrupt changes, including those aspects of change most important to society and economies, and outlines a research strategy to close those gaps. Based on the best and most current research available, this book surveys the history of climate change and makes a series of specific recommendations for the future.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309183359
Category : Science
Languages : en
Pages : 41
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Book Description
The warming of the Earth has been the subject of intense debate and concern for many scientists, policy-makers, and citizens for at least the past decade. Climate Change Science: An Analysis of Some Key Questions, a new report by a committee of the National Research Council, characterizes the global warming trend over the last 100 years, and examines what may be in store for the 21st century and the extent to which warming may be attributable to human activity.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309287766
Category : Science
Languages : en
Pages : 281
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Book Description
Climate is changing, forced out of the range of the past million years by levels of carbon dioxide and other greenhouse gases not seen in the Earth's atmosphere for a very, very long time. Lacking action by the world's nations, it is clear that the planet will be warmer, sea level will rise, and patterns of rainfall will change. But the future is also partly uncertain-there is considerable uncertainty about how we will arrive at that different climate. Will the changes be gradual, allowing natural systems and societal infrastructure to adjust in a timely fashion? Or will some of the changes be more abrupt, crossing some threshold or "tipping point" to change so fast that the time between when a problem is recognized and when action is required shrinks to the point where orderly adaptation is not possible? Abrupt Impacts of Climate Change is an updated look at the issue of abrupt climate change and its potential impacts. This study differs from previous treatments of abrupt changes by focusing on abrupt climate changes and also abrupt climate impacts that have the potential to severely affect the physical climate system, natural systems, or human systems, often affecting multiple interconnected areas of concern. The primary timescale of concern is years to decades. A key characteristic of these changes is that they can come faster than expected, planned, or budgeted for, forcing more reactive, rather than proactive, modes of behavior. Abrupt Impacts of Climate Change summarizes the state of our knowledge about potential abrupt changes and abrupt climate impacts and categorizes changes that are already occurring, have a high probability of occurrence, or are unlikely to occur. Because of the substantial risks to society and nature posed by abrupt changes, this report recommends the development of an Abrupt Change Early Warning System that would allow for the prediction and possible mitigation of such changes before their societal impacts are severe. Identifying key vulnerabilities can help guide efforts to increase resiliency and avoid large damages from abrupt change in the climate system, or in abrupt impacts of gradual changes in the climate system, and facilitate more informed decisions on the proper balance between mitigation and adaptation. Although there is still much to learn about abrupt climate change and abrupt climate impacts, to willfully ignore the threat of abrupt change could lead to more costs, loss of life, suffering, and environmental degradation. Abrupt Impacts of Climate Change makes the case that the time is here to be serious about the threat of tipping points so as to better anticipate and prepare ourselves for the inevitable surprises.
Author: United Nations Environment Programme
Publisher: Hodder Arnold
ISBN: 9780340691663
Category : Nature
Languages : en
Pages : 182
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Book Description
The World Atlas of Desertification summarises the state of scientific knowledge on the drylands of the globe. Representing in graphic form the current stage of our understanding of desertification, as well as its extent and possible solutions, it contains an extraordinary amount of information of value to students and experts alike. The Atlas clearly shows that desertification is one of the world's most pressing environmental problems, and that it is a truly global issue. Since the publication of the first edition in 1992, over 100 countries have ratified the United Nations Convention to Combat Desertification. This 2nd edition reflects major advances in our understanding of desertification over the past few years and has been thoroughly revised and expanded to almost twice its original size. Because combating desertification involves all aspects of environmental issues, this edition covers a broader range of topics, including concerns surrounding poverty, biodiversity, climate change and the availability of water. Social and economic conditions also have a major impact on the progress and control of desertification and this edition contains the latest information on population movements which result from, and lead to desertification. Desertification directly affects the livelihoods of more than one billion people who are directly dependent on the land for their survival. Using the latest updated digitised maps of desertification and fully referenced throughout, this Atlas is essential reading for everyone concerned with the drylands and their people.
