Observations and analysis of the impact of annular eclipse on 10 MHz short-wave signal in Sanya area on June 21, 2020

The efficiency of virtual cross sections method and MELS (Magneto Elastic Layered Systems) hypotheses application is shown on model problem about distribution of wave field in thin surface layers of waveguide when plane wave signal is propagating in it. The impact of surface non-smoothness on characteristics of propagation of high-frequency horizontally polarized wave signal in isotropic elastic half-space is studied. It is shown that the non-smoothness leads to strong distortion of the wave signal over the waveguide thickness and along wave signal propagation direction as well. Â Numerical comparative analysis of change in amplitude and phase characteristics of obtained wave fields against roughness of weakly inhomogeneous surface of homogeneous elastic half-space surface is done by classical method and by proposed approach for different kind of non-smoothness.

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Performance Analysis of Cantilever Beam for Tunable Fabry Perot Filter

Sensor Letters ◽

10.1166/sl.2019.4140 ◽

2019 ◽

Vol 17 (9) ◽

pp. 739-745

Author(s):

M. Shanmugapriya ◽

T. Manimekalai ◽

C. V. Gayathri

Keyword(s):

Cantilever Beam ◽

Electrostatic Force ◽

Short Wave ◽

Cavity Surface ◽

Reflective Coating ◽

Fabry Perot ◽

Vertical Cavity Surface ◽

Surface Emitting Laser ◽

The Impact ◽

Long Wave Infrared

The design and simulation of the cantilever beam for tunable fabry perot filter is discussed in this paper. The fabry perot filter is tuned to operate in three frequency ranges namely short wave Infrared (SWIR), mid wave Infrared (MWIR) and long wave Infrared (LWIR) are operated in the frequency range of 1.6–2.5 μm, 3–5 μm and 8–12 μm respectively. The light that is emitted from the array of vertical cavity surface emitting laser (VCSEL) is tuned to the desired wavelength using this fabry perot filter. The fabry perot cavity length is varied using the MEMS cantilever. By applying the reflective coating to the arms of the cantilever, the fabry perot cavity is formed. The actuation given to the MEMS cantilever is electrostatic actuation. The potential difference between the two arms of the cantilever creates the electrostatic force, which attracts the free end of the cantilever. Due to the impact of the electrostatic force the arms get pulled in, as a result the separation between the mirrors varies, which in turn filters the desired wavelength. The array of cantilever is also simulated to get a desired pattern of the wavelength. The fabrication process flow for the simulated cantilever is explained. The fixed-free beam approach leads to the analysis of capacitance, stress, strain and displacement.

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Systematic satellite observations of the impact of aerosols from passive volcanic degassing on local cloud properties

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-10601-2014 ◽

2014 ◽

Vol 14 (19) ◽

pp. 10601-10618 ◽

Cited By ~ 18

Author(s):

S. K. Ebmeier ◽

A. M. Sayer ◽

R. G. Grainger ◽

T. A. Mather ◽

E. Carboni

Keyword(s):

Radiative Forcing ◽

Radiant Energy ◽

Cloud Droplet ◽

Energy System ◽

Short Wave ◽

Volcanic Emissions ◽

Aerosol Radiative Forcing ◽

Cloud Properties ◽

Wave Flux ◽

The Impact

Abstract. The impact of volcanic emissions, especially from passive degassing and minor explosions, is a source of uncertainty in estimations of aerosol indirect effects. Observations of the impact of volcanic aerosol on clouds contribute to our understanding of both present-day atmospheric properties and of the pre-industrial baseline necessary to assess aerosol radiative forcing. We present systematic measurements over several years at multiple active and inactive volcanic islands in regions of low present-day aerosol burden. The time-averaged indirect aerosol effects within 200 km downwind of island volcanoes are observed using Moderate Resolution Imaging Spectroradiometer (MODIS, 2002–2013) and Advanced Along-Track Scanning Radiometer (AATSR, 2002–2008) data. Retrievals of aerosol and cloud properties at Kīlauea (Hawai'i), Yasur (Vanuatu) and Piton de la Fournaise (la Réunion) are rotated about the volcanic vent to be parallel to wind direction, so that upwind and downwind retrievals can be compared. The emissions from all three volcanoes – including those from passive degassing, Strombolian activity and minor explosions – lead to measurably increased aerosol optical depth downwind of the active vent. Average cloud droplet effective radius is lower downwind of the volcano in all cases, with the peak difference ranging from 2–8 μm at the different volcanoes in different seasons. Estimations of the difference in Top of Atmosphere upward Short Wave flux upwind and downwind of the active volcanoes from NASA's Clouds and the Earth's Radiant Energy System (CERES) suggest a downwind elevation of between 10 and 45 Wm−2 at distances of 150–400 km from the volcano, with much greater local (< 80 km) effects. Comparison of these observations with cloud properties at isolated islands without degassing or erupting volcanoes suggests that these patterns are not purely orographic in origin. Our observations of unpolluted, isolated marine settings may capture processes similar to those in the pre-industrial marine atmosphere.

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Snow cover sensitivity to black carbon deposition in the Himalayas: from atmospheric and ice core measurements to regional climate simulations

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-4237-2014 ◽

2014 ◽

Vol 14 (8) ◽

pp. 4237-4249 ◽

Cited By ~ 54

Author(s):

M. Ménégoz ◽

G. Krinner ◽

Y. Balkanski ◽

O. Boucher ◽

A. Cozic ◽

...

Keyword(s):

Snow Cover ◽

Black Carbon ◽

Regional Climate ◽

Ice Core ◽

Ice Cores ◽

Short Wave ◽

Wave Radiation ◽

The Tibetan Plateau ◽

Snow Cover Duration ◽

The Impact

Abstract. We applied a climate-chemistry global model to evaluate the impact of black carbon (BC) deposition on the Himalayan snow cover from 1998 to 2008. Using a stretched grid with a resolution of 50 km over this complex topography, the model reproduces reasonably well the remotely sensed observations of the snow cover duration. Similar to observations, modelled atmospheric BC concentrations in the central Himalayas reach a minimum during the monsoon and a maximum during the post- and pre-monsoon periods. Comparing the simulated BC concentrations in the snow with observations is more challenging because of their high spatial variability and complex vertical distribution. We simulated spring BC concentrations in surface snow varying from tens to hundreds of μg kg−1, higher by one to two orders of magnitude than those observed in ice cores extracted from central Himalayan glaciers at high elevations (>6000 m a.s.l.), but typical for seasonal snow cover sampled in middle elevation regions (<6000 m a.s.l.). In these areas, we estimate that both wet and dry BC depositions affect the Himalayan snow cover reducing its annual duration by 1 to 8 days. In our simulations, the effect of anthropogenic BC deposition on snow is quite low over the Tibetan Plateau because this area is only sparsely snow covered. However, the impact becomes larger along the entire Hindu-Kush, Karakorum and Himalayan mountain ranges. In these regions, BC in snow induces an increase of the net short-wave radiation at the surface with an annual mean of 1 to 3 W m−2 leading to a localised warming between 0.05 and 0.3 °C.

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Cutoff low over the southeastern Pacific Ocean: a case study

Journal of Southern Hemisphere Earth System Science ◽

10.1071/es19051 ◽

2021 ◽

Vol 71 (1) ◽

pp. 17

Author(s):

Nelson Quispe-Gutiérrez ◽

Vannia Aliaga-Nestares ◽

Diego Rodríguez-Zimmermann ◽

Martí Bonshoms ◽

Raquel Loayza ◽

...

Keyword(s):

Extreme Rainfall ◽

Heavy Precipitation ◽

Short Wave ◽

Extreme Weather Events ◽

Reanalysis Dataset ◽

Peruvian Andes ◽

Wave Trough ◽

Southeastern Pacific ◽

Vorticity Equations ◽

The Impact

Cutoff lows (COLs) are infrequent events in the tropics that can cause extreme rainfall, flash flooding and landslides in arid areas, such as western South America. In this study, the life cycle of a COL in the southeastern Pacific at the beginning of April 2012 was analysed using the ERA-Interim reanalysis dataset. This paper examines: (1) the precursor flow evolution prior to the COL, its development and dissipation by applying the quasi-geostrophic and vorticity equations; and (2) the influence of the COL in the heavy precipitation events over the western Peruvian Andes. During April 2012, the highest amount of precipitation was recorded in Chosica (850 masl) with 37mm on 5 April. Days prior to the formation of the COL, a subtropical trough deepened by the amplification of a ridge over the tropical Pacific and the incursion of cold air from medium and low levels into the trough. The strong cyclonic vorticity advection was intensified by a short-wave trough embedded inside a long-wave one that strengthened the system on 5 April 2012. In the dissipation stage, warm vertical advection predominated, resulting in the reabsorption of the COL by a new trough. Understanding the behaviour COL systems is important for reducing the impact of these extreme weather events on lives and infrastructure in densely populated areas.

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The Impact of Rooftop Vegetation on the UHI Phenomenon in Housing Projects: Baghdad City as an Example

Journal of Recent Activities in Architectural Sciences ◽

10.46610/joraas.2020.v05i02.003 ◽

2020 ◽

Vol 5 (2) ◽

Keyword(s):

Short Wave ◽

Wave Radiation ◽

Climatic Parameters ◽

Short Wave Radiation ◽

Housing Projects ◽

High Rise ◽

Urban Heat ◽

Almost All ◽

Radiant Temperature ◽

The Impact

This research investigates the impact of rooftop vegetation on the phenomenon of urban heat island (UHI) in hot-aired microclimates with an emphasis on housing projects in the context of Baghdad city. The methodology of this research relies on ENVI-met Headquarter 4.4.5 to create models that simulate and comparatively analyze the effect of rooftop vegetation on reduction UHI within housing projects. The analysis encompassed models of low-rise, mid-rise, and high-rise buildings. The simulated climatic parameters included the Predicted Mean Vote (PMV), air temperature, mean radiant temperature (MRT), reflected short-wave radiation, and humidity. The findings of this research indicated that rooftop vegetation can participate in the reduction of UHI phenomenon in housing projects, the most significant for almost all climatic parameters results were in low-rise and mid-rise buildings as compared to high-rise buildings.

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The Developmental Effect of a New Political Anomaly on the Oldest ICT

Advances in Electronic Government, Digital Divide, and Regional Development - IT in the Public Sphere ◽

10.4018/978-1-4666-4719-0.ch008 ◽

2014 ◽

pp. 157-183 ◽

Cited By ~ 1

Author(s):

Sam Takavarasha Jr. ◽

Eldred V. Masunungure

Keyword(s):

Urban Economy ◽

Short Wave ◽

Coalition Government ◽

Amartya Sen ◽

Economic Stability ◽

Developmental Effect ◽

Rural Economies ◽

Political Freedoms ◽

The Impact

Economic growth in countries like China, whose democratic credentials and human rights records are unimpressive, compels us to question the democracy-development nexus articulated by eminent writers like Amartya Sen. Against this background, this chapter assesses the impact of pseudo-democratic politics on the use of ICTs for development. It is based on research done in Zimbabwe, an electoral autocracy that recovered from being the world's worst economy in 2008 to impressive economic stability post-2009 (i.e. after the formation of a coalition government that, however, did not usher in substantive improvements in political and civic freedoms and liberties). Sen's (1999) capability approach and Illich's (1973) concept of conviviality are used for analysing the banning of the use of short wave radios in Zimbabwe just before elections that will signal the termination of the coalition government before the end of 2013. The research investigates if and how political and civic freedoms affect development. It shows that in a dual political economy like Zimbabwe, the formal (urban) economy may stabilize without political freedoms yet enclaves of poverty may deepen in the informal and rural economies due to lack of human development. A framework for the effect of politics on the role of analogue radio in development is proposed.

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Fraternizing in the Ether, 1931–1933

Wireless Internationalism and Distant Listening ◽

10.1093/oso/9780198800231.003.0003 ◽

2020 ◽

pp. 50-83

Author(s):

Simon J. Potter

Keyword(s):

Short Wave ◽

League Of Nations ◽

English Speakers ◽

International Affairs ◽

International Broadcasting ◽

The Us ◽

Foreign Office ◽

World Economic ◽

Anglo American ◽

The Impact

During the early 1930s faith in a utopian form of wireless internationalism was shaken by the world economic crisis, the Japanese invasion of Manchuria, and the Nazi revolution in Germany. Radio still seemed a potential means to encourage international understanding and peace, but increasingly it also appeared to be a powerful tool of propaganda that might serve aggressive nationalist ends. As Europe’s broadcasting infrastructure became more formidable, broadcasters continued to work through the International Broadcasting Union to regulate the airwaves and combat interference and hostile propaganda. These measures were only partially effective and were ignored by a powerful new station broadcasting commercial programmes across Europe in several languages, Radio Luxembourg. The League of Nations also began to study the disruptive impact of radio on international affairs, and established its own broadcasting station, Radio Nations. Relay work continued, linking up the broadcasters of Europe and forging new connections across the Atlantic. The number of short-wave broadcasters increased significantly during this period, and the BBC established its own short-wave Empire Service, designed to reach out to white expatriate listeners in Britain’s colonies, and to English speakers in the ‘dominions’. Many in the US could also tune in, and British civil servants, notably at the Foreign Office, worried about the impact on Anglo-American relations.

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Historical ablation rates and their drivers in Greenland – assessing the potential of the Wegener expedition for modern glaciological research

10.5194/egusphere-egu2020-10032 ◽

2020 ◽

Author(s):

Jakob Abermann ◽

Wolfgang Schöner ◽

Robert Schjøtt Fausto

Keyword(s):

Air Temperature ◽

Grid Point ◽

Short Wave ◽

Ice Age ◽

Wave Radiation ◽

Climate Change Signal ◽

Horizontal Distance ◽

West Greenland ◽

Geometrical Change ◽

The Impact

<p>Alfred Wegener contributed extraordinarily to early days of scientific explorations in Greenland. Involved in three expeditions, we present unique historical data that is stored at Graz University, where Wegener filled his last academic position until his tragic death in Greenland in 1930. In this contribution we reevaluate data from his last expedition 1929-1931 acquired at the Qaamarujuup Glacier in West Greenland (71&#176;09'N; 51&#176;11'W). Sub-weekly ablation measurements along with air temperature, humidity, pressure, wind and short-wave radiation data exist for two full ablation seasons both near sea level and in 950 m a.s.l.. The 20<sup>th</sup> Century reanalysis product of the nearest grid-point performs well reproducing air temperature variability. Coincidentally, this expedition was carried out during a very warm period that was in fact comparable to recent years. We compare vertical ablation gradients from the years 1929/1930 obtained at Qaamarujuup in West Greenland with recent observations from the closest PROMICE automated weather station and discuss differences in a centennial perspective. Furthermore, we present a time-series of glacier stages from the little ice age (LIA) maximum up to present and quantify area and volume changes since. The glacier margin was in close proximity (<50 m distance) to the ocean during the LIA maximum, 660 m and almost 3 km horizontal distance from the ocean in 1930 and in 2019, respectively. Such a drastic geometrical change manifests in differing drivers of the glacier boundary layer with the impact of the cooling ocean during summer decreasing with time as the glacier margin&#8217;s distance to the ocean increases. We discuss the potential in using historical glacio-meteorological measurements along with a detailed glacier history in order to extract geometrical feedbacks from the climate change signal.</p>

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Impact of Lightning NOx Emissions on Atmospheric Composition and Meteorology in Africa and Europe

Atmosphere ◽

10.3390/atmos11101128 ◽

2020 ◽

Vol 11 (10) ◽

pp. 1128

Author(s):

Laurent Menut ◽

Bertrand Bessagnet ◽

Sylvain Mailler ◽

Romain Pennel ◽

Guillaume Siour

Keyword(s):

Surface Flux ◽

Short Wave ◽

Atmospheric Composition ◽

Wave Radiation ◽

Nox Emissions ◽

Large Area ◽

Convective Clouds ◽

Pollutant Concentrations ◽

The Impact ◽

Lightning Nox

NOx emissions from lightning have been added to the CHIMERE v2020r1 model using a parameterization based on convective clouds. In order to estimate the impact of these emissions on pollutant concentrations, two simulations, using the online coupled WRF-CHIMERE models with and without NOx emissions from lightning, have been carried out over the months of July and August 2013 and over a large area covering Europe and the northern part of Africa. The results show that these emissions modify the pollutant concentrations as well as the meteorology. The changes are most significant where the strongest emissions are located. Adding these emissions improves Aerosol Optical Depth in Africa but has a limited impact on the surface concentrations of pollutants in Europe. For the two-month average we find that the maximum changes are localized and may reach ±0.5 K for 2 m temperature, ±0.5 m s−1 for 10 m wind speed, 10 W m−2 for short wave radiation surface flux, and 50 and 2 μg m−3 for dust and sea salt surface concentrations, respectively. This leads to maximum changes of 1 μg m−3 for surface concentrations of PM2.5.

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