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The Atmosphere over Mountainous Regions

Authors: --- --- --- --- et al.
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889450169 Year: Pages: 160 DOI: 10.3389/978-2-88945-016-9 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Geography
Added to DOAB on : 2018-02-27 16:16:44
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Abstract

Mountainous regions occupy a significant fraction of the Earth’s continents and are characterized by specific meteorological phenomena operating on a wide range of scales. Being a home to large human populations, the impact of mountains on weather and hydrology has significant practical consequences. Mountains modulate the climate and create micro-climates, induce different types of thermally and dynamically driven circulations, generate atmospheric waves of various scales (known as mountain waves), and affect the boundary layer characteristics and the dispersion of pollutants. At the local scale, strong downslope winds linked with mountain waves (such as the Foehn and Bora) can cause severe damage. Mountain wave breaking in the high atmosphere is a source of Clear Air Turbulence, and lee wave rotors are a major near-surface aviation hazard. Mountains also act to block strongly-stratified air layers, leading to the formation of valley cold-air pools (with implications for road safety, pollution, crop damage, etc.) and gap flows. Presently, neither the fine-scale structure of orographic precipitation nor the initiation of deep convection by mountainous terrain can be resolved adequately by regional-to global-scale models, requiring appropriate downscaling or parameterization. Additionally, the shortest mountain waves need to be parameterized in global weather and climate prediction models, because they exert a drag on the atmosphere. This drag not only decelerates the global atmospheric circulation, but also affects temperatures in the polar stratosphere, which control ozone depletion. It is likely that both mountain wave drag and orographic precipitation lead to non-trivial feedbacks in climate change scenarios. Measurement campaigns such as MAP, T-REX, Materhorn, COLPEX and i-Box provided a wealth of mountain meteorology field data, which is only starting to be explored. Recent advances in computing power allow numerical simulations of unprecedented resolution, e.g. LES modelling of rotors, mountain wave turbulence, and boundary layers in mountainous regions. This will lead to important advances in understanding these phenomena, as well as mixing and pollutant dispersion over complex terrain, or the onset and breakdown of cold-air pools. On the other hand, recent analyses of global circulation biases point towards missing drag, especially in the southern hemisphere, which may be due to processes currently neglected in parameterizations. A better understanding of flow over orography is also crucial for a better management of wind power and a more effective use of data assimilation over complex terrain. This Research Topic includes contributions that aim to shed light on a number of these issues, using theory, numerical modelling, field measurements, and laboratory experiments.

Asymmetric Planetary Nebulae VII

Authors: ---
ISBN: 9783038976400 Year: Pages: 204 DOI: 10.3390/books978-3-03897-641-7 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Physics (General) --- Astronomy (General)
Added to DOAB on : 2019-03-21 14:08:22
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This book contains the best and most up-to-date contributions in the field of late stage stellar evolution, as presented at the APNVII conference in Hong Kong in December 2017. A total of 60 scientists from 20 countries gathered to present, listen, interact and discuss the most current issues and problems in planetary nebulae and related objects research. The emphasis of this influential series of meetings, which was the seventh occasion over the last 20 years, has always been on the hypothesized and observed physical shaping mechanisms of the ejected nebulae that have such wonderful and intriguing forms. This special Galaxies conference issue of fully refereed contributions brings together a representative compilation of the meeting presentations in paper form. It captures the current “snap shot” status of this research field in some real sense. Such proceedings are well received and can be used as a reference material by both participants and all others working in the field for years to come.

Keywords

planetary systems --- planetary nebulae --- stars: binaries --- stars: AGB and post-AGB --- stars: variables: general --- stars: abundances --- stars: AGB and post-AGB --- stars: atmospheres --- stars: individual: WD 0044–121 --- stars: individual: WD 2134+25 --- stars: individual: WD 1751+106 --- planetary nebulae --- asymptotic giant branch stars --- mass loss --- infra-red --- planetary nebulae --- integral field spectroscopy --- stellar evolution --- binarity --- planetary nebulae --- stellar mass loss --- stellar evolution --- planetary nebulae --- circumstellar dust --- planetary nebulae --- mass-loss --- stellar evolution --- X-rays --- stellar evolution --- late stage stellar evolution --- binarity: transients: planetary nebulae --- planetary nebulae --- stars: AGB and post-AGB --- late stage stellar evolution --- planetary nebulae --- stars: binaries --- central stars of planetary nebulae --- proto-planetary nebulae --- binaries: spectroscopic --- stars: atmospheres --- stars: abundances --- supernovae --- late stage stellar evolution --- planetary nebulae --- binarity --- stellar evolution --- AGB and post-AGB stars --- circumstellar matter --- winds and outflows --- mass-loss --- jets --- binaries: close --- stars: AGB and post-AGB --- stars: winds, outflows --- ISM: jets and outflows --- binary stars --- post-AGB --- discs --- planetary nebula --- X-ray --- stellar evolution --- AGB stars --- post-AGB stars --- planetary nebulae --- planetary nebulae --- fullerenes --- planetary nebulae --- AGB and post-AGB stars --- binarity --- accretion disks --- jets --- mass-loss --- circumstellar matter --- (sub)millimeter interferometry --- ultraviolet radiation, X-rays --- infrared interferometry --- AGB stars --- stellar evolution --- observations --- aperture masking --- planetary nebulae --- binarity --- abundances --- stellar evolution --- post-AGB stars --- pre-PN hydrodynamic models --- planetary nebulae: Common Envelope --- planetary nebulae: individual (OH231+8+04.2) --- astrochemistry --- planetary nebulae --- UIE bands --- normal modes --- displacement vectors --- late-stage stellar evolution --- planetary nebulae --- multi-wavelength photometry --- radial velocity --- stellar evolution --- pulsation --- shock wave --- late stage stellar evolution --- planetary nebulae --- theory and observation --- planetary nebulae --- AGB and post-AGB --- interstellar medium --- radio continuum --- winds --- outflows --- dust --- extinction --- ISM: abundances --- planetary nebulae: individual (NGC 6781)

Cosmic Plasmas and Electromagnetic Phenomena

Authors: --- ---
ISBN: 9783039214655 9783039214662 Year: Pages: 264 DOI: 10.3390/books978-3-03921-466-2 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Physics (General) --- Astronomy (General)
Added to DOAB on : 2019-12-09 11:49:16
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During the past few decades, plasma science has witnessed a great growth in laboratory studies, in simulations, and in space. Plasma is the most common phase of ordinary matter in the universe. It is a state in which ionized matter (even as low as 1%) becomes highly electrically conductive. As such, long-range electric and magnetic fields dominate its behavior. Cosmic plasmas are mostly associated with stars, supernovae, pulsars and neutron stars, quasars and active galaxies at the vicinities of black holes (i.e., their jets and accretion disks). Cosmic plasma phenomena can be studied with different methods, such as laboratory experiments, astrophysical observations, and theoretical/computational approaches (i.e., MHD, particle-in-cell simulations, etc.). They exhibit a multitude of complex magnetohydrodynamic behaviors, acceleration, radiation, turbulence, and various instability phenomena. This Special Issue addresses the growing need of the plasma science principles in astrophysics and presents our current understanding of the physics of astrophysical plasmas, their electromagnetic behaviors and properties (e.g., shocks, waves, turbulence, instabilities, collimation, acceleration and radiation), both microscopically and macroscopically. This Special Issue provides a series of state-of-the-art reviews from international experts in the field of cosmic plasmas and electromagnetic phenomena using theoretical approaches, astrophysical observations, laboratory experiments, and state-of-the-art simulation studies.

Sea Surface Roughness Observed by High Resolution Radar

Authors: --- --- ---
ISBN: 9783039217465 9783039217472 Year: Pages: 202 DOI: 10.3390/books978-3-03921-747-2 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Oceanography
Added to DOAB on : 2019-12-09 11:49:16
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Changes in sea surface roughness are usually associated with a change in the sea surface wind field. This interaction has been exploited to measure sea surface wind speed by scatterometry. A number of features on the sea surface associated with changes in roughness can be observed by synthetic aperture radar (SAR) because of the change in Bragg backscatter of the radar signal by damping of the resonant ocean capillary waves. With various radar frequencies, resolutions, and modes of polarization, sea surface features have been analyzed in numerous campaigns, bringing various datasets together, thus allowing for new insights into small-scale processes at a larger areal coverage. This Special Issue aims at investigating sea surface features detected by high spatial resolution radar systems, such as SAR.

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