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Author(s):  
Shaobo Yang ◽  
Linyun Xiong ◽  
Sunhua Huang ◽  
Yalan He ◽  
Penghan Li ◽  
...  

2021 ◽  
Author(s):  
Bianca Zilker ◽  
Anne-Marlene Blechschmidt ◽  
Sora Seo ◽  
Ilias Bougoudis ◽  
Tim Bösch ◽  
...  

<p align="justify">Bromine Explosion Events (BEEs) have been observed since the late 1990s in the Arctic and Antarctic during polar spring and play an important role in tropospheric chemistry. In a heterogeneous, autocatalytic, chemical chain reaction cycle, inorganic bromine is released from the cryosphere into the troposphere and depletes ozone often to below detection limit. Ozone is a source of the most important tropospheric oxidizing agent OH and the oxidizing capacity and radiative forcing of the troposphere are thus being impacted. Bromine also reacts with gaseous mercury, thereby facilitating the deposition of toxic mercury, which has adverse environmental impacts. C<span lang="en-US">old saline surfaces, such as young sea ice, frost flowers, and snow are likely bromine sources </span><span lang="en-US">during BEEs. </span><span lang="en-US">D</span>ifferent meteorological conditions seem to favor the development of these events: on the one hand, low wind speeds and a stable boundary layer, where bromine can accumulate and deplete ozone, and on the other hand, high wind speeds above approximately 10 m/s with blowing snow and a higher unstable boundary layer. In high wind speed conditions – occurring for example along fronts of polar cyclones – recycling of bromine on snow and aerosol surfaces may take place aloft.</p> <p align="justify">To improve the understanding of weather conditions and bromine sources leading to the development of BEEs, case studies using high resolution S5P TROPOMI retrievals of tropospheric BrO together with meteorological simulations by the WRF model and Lagrangian transport simulations of BrO by FLEXPART-WRF are carried out. WRF simulations show, that high tropospheric BrO columns observed by TROPOMI often coincide with areas of high wind speeds. This probably points to release of bromine from blowing snow with cold temperatures favoring the bromine explosion reactions. However, some BrO plumes are observed over areas with very low wind speed and a stable low boundary layer. To monitor the amount of ozone depleted during a BEE, ozone sonde measurements from Ny-Ålesund are compared with MAX-DOAS BrO profiles. First evaluations show a drastic decrease in ozone, partly below the detection limit, while measuring enhanced BrO values at the same time. <span lang="en-US">In order to analyze </span><span lang="en-US">the possible origin</span><span lang="en-US"> of the BrO </span><span lang="en-US">plume </span><span lang="en-US">arriving in </span><span lang="en-US">Ny-</span><span lang="en-US">Å</span><span lang="en-US">lesund</span><span lang="en-US">, </span><span lang="en-US">and to investigate its transportation route, </span><span lang="en-US">FLEXPART-WRF runs are </span><span lang="en-US">executed </span><span lang="en-US">for the times of observed ozone depletion.</span></p> <p align="justify"> </p> <p align="justify"><em>This work was supported by the</em><em> DFG funded Transregio-project TR 172 “Arctic Amplification </em>(AC)<sup>3</sup><em>“.</em></p>


Author(s):  
Dina ElMaamoun ◽  
George Xydis

Wind Energy is occupying more and more space of the energy mix in most of the world. In this work, the challenges for distributed projects in communities and industrial areas are presented for Egypt and a comparison with the mass wind onshore and offshore deployment is unavoidable. In Egypt, there are plans to installed large-scale projects, but the development pace is slow. Furthermore, while the Egypt wind atlas provides ample information to properly plan and deploy wind farms, developers of distributed wind would probably have never analysed small scale sites, which may lead them to make mistakes while siting, and thus a project may end up losing money. Two use cases were selected for analysis: industrial & offshore sites and community/residential sites. It was revealed via a detailed spatial analysis that there are abundant wind resources and potential in high wind – high gain selected areas of almost 40 GW of onshore and offshore wind projects that could make Egypt a unique energy hub between Africa, Europe and the Middle East.


MAUSAM ◽  
2021 ◽  
Vol 61 (3) ◽  
pp. 361-368
Author(s):  
R. D. VASHISTHA ◽  
K. N. MOHAN ◽  
P. S. BIJU

The continuous and accurate monitoring of wind speed and direction is of utmost importance to weatherman, particularly during the cyclonic storms.  Wind monitoring also helps the meteorologists in tracking the cyclone accurately and estimating their devastating potential.  One major disadvantage of all the existing wind monitoring and storing systems is their huge consumption of power, and hence are not suitable during cyclonic storms due to mains power supply failure.  So an attempt has been made by the authors to design and develop a low cost, low power, more accurate and maintenance free High Wind Speed Recording (HWSR) System for the coastal meteorological observatories along the East and West Coasts of India. One such system after successful field trials have been installed at Meteorological Office, Puri in the Orissa coast, and 19 more stations are proposed along East and West Coasts of India. The system meets the operational accuracy requirements and vector averaging of wind data as recommended by the World Meteorological Organisation (WMO, 1992). The system design aspects and scope for expansion have been presented in this paper.


MAUSAM ◽  
2021 ◽  
Vol 60 (2) ◽  
pp. 197-210
Author(s):  
ARUN KUMAR ◽  
S. K. DASH ◽  
S. K. DHAKA

Hazards for a fossil fired power plant located at   coastal Gujarat in India have been assessed.  The trajectory and spread of the plume from tanks of fossil fired power plant were predicted using existing models named Carter, Mills, Briggs and Zonato during winter and summer seasons with low and high wind speeds observed in day and night hours. Results show that wide areas of habitation and human settlement to the northeast of the site may be potentially under hazards due to southwesterly and southerly winds during summer. Plume heights and widths are found high in the morning hours or late night when wind speeds are low. As wind speed increases around noon, low plume heights and widths are obtained.   Length scales become low at low wind speeds and vice-versa. Lethal doses of thermal radiation beyond radial distance of 70 m are within the tolerable limit under hazardous condition.


2021 ◽  
Vol 9 (11) ◽  
pp. 1248
Author(s):  
Jian Shi ◽  
Zhihao Feng ◽  
Yuan Sun ◽  
Xueyan Zhang ◽  
Wenjing Zhang ◽  
...  

The sea surface drag coefficient plays an important role in momentum transmission between the atmosphere and the ocean, which is affected by ocean waves. The total air–sea momentum flux consists of effective momentum flux and sea spray momentum flux. Sea spray momentum flux involves sea surface drag, which is largely affected by the ocean wave state. Under strong winds, the sea surface drag coefficient (CD) does not increase linearly with the increasing wind speed, namely, the increase of CD is inhibited by strong winds. In this study, a sea surface drag coefficient is constructed that can be applied to the calculation of the air–sea momentum flux under high wind speed. The sea surface drag coefficient also considers the influence of wave state and sea spray droplets generated by wave breaking. Specially, the wave-dependent sea spray generation function is employed to calculate sea spray momentum flux. This facilitates the analysis not only on the sensitivity of the sea spray momentum flux to wave age, but also on the effect of wave state on the effective CD (CD, eff) under strong winds. Our results indicate that wave age plays an important role in determining CD. When the wave age is >0.4, CD decreases with the wave age. However, when the wave age is ≤0.4, CD increases with the wave age at low and moderate wind speeds but tends to decrease with the wave age at high wind speeds.


2021 ◽  
Author(s):  
Helen Czerski ◽  
Ian M. Brooks ◽  
Steve Gunn ◽  
Robin Pascal ◽  
Adrian Matei ◽  
...  

Abstract. Bubbles formed by breaking waves in the open ocean influence many surface processes but are poorly understood. We report here on detailed bubble size distributions measured during the High Wind Speed Gas Exchange Study (HiWinGS) in the North Atlantic, during four separate storms with hourly averaged wind speeds from 10–27 m s−1. The measurements focus on the deeper plumes formed by advection downwards (at 2 m depth and below), rather than the initial surface distributions. Our results suggest that bubbles reaching a depth of 2 m have already evolved to form a heterogeneous but statistically stable population in the top 1–2 metres of the ocean. These shallow bubble populations are carried downwards by coherent near-surface circulations; bubble evolution at greater depths is consistent with control by local gas saturation, surfactant coatings and pressure. We find that at 2 m the maximum bubble radius observed has a very weak wind speed dependence and is too small to be explained by simple buoyancy arguments. For void fractions greater than 10−6, bubble size distributions at 2 m can be fitted by a two-slope power law (with slopes of −0.3 for bubbles of radius < 80 μm and −4.4 for larger sizes). If normalised by void fraction, these distributions collapse to a very narrow range, implying that the bubble population is relatively stable and the void fraction is determined by bubbles spreading out in space rather than changing their size over time. In regions with these relatively high void fractions we see no evidence for slow bubble dissolution. When void fractions are below 10−6, the peak volume of the bubble size distribution is more variable, and can change systematically across a plume at lower wind speeds, tracking the void fraction. Relatively large bubbles (80 μm in radius) are observed to persist for several hours in some cases, following periods of very high wind. Our results suggest that local gas supersaturation around the bubble plume may have a strong influence on bubble lifetime, but significantly, the deep plumes themselves cannot be responsible for this supersaturation. We propose that the supersaturation is predominately controlled by the dissolution of bubbles in the top metre of the ocean, and that this bulk water is then drawn downwards, surrounding the deep bubble plume and influencing its lifetime. In this scenario, oxygen uptake is associated with deep bubble plumes, but is not driven directly by them. We suggest that as bubbles move to depths greater than 2 m, sudden collapse may be more significant as a bubble destruction mechanism than slow dissolution, especially in regions of high void fraction. Finally, we present a proposal for the processes and timescales which form and control these deeper bubble plumes.


2021 ◽  
Author(s):  
Colin Manning ◽  
Elizabeth J. Kendon ◽  
Hayley J. Fowler ◽  
Nigel M. Roberts ◽  
Ségolène Berthou ◽  
...  

AbstractExtra-tropical windstorms are one of the costliest natural hazards affecting Europe, and windstorms that develop a sting jet are extremely damaging. A sting jet is a mesoscale core of very high wind speeds that occurs in Shapiro–Keyser type cyclones, and high-resolution models are required to adequately model sting jets. Here, we develop a low-cost methodology to automatically detect sting jets, using the characteristic warm seclusion of Shapiro–Keyser cyclones and the slantwise descent of high wind speeds, within pan-European 2.2 km convection-permitting climate model (CPM) simulations. The representation of wind gusts is improved with respect to ERA-Interim reanalysis data compared to observations; this is linked to better representation of cold conveyor belts and sting jets in the CPM. Our analysis indicates that Shapiro–Keyser cyclones, and those that develop sting jets, are the most damaging windstorms in present and future climates. The frequency of extreme windstorms is projected to increase by 2100 and a large contribution comes from sting jet storms. Furthermore, extreme wind speeds and their future changes are underestimated in the global climate model (GCM) compared to the CPM. We conclude that the CPM adds value in the representation of extreme winds and surface wind gusts and can provide improved input for impact models compared to coarser resolution models.


2021 ◽  
Vol 10 (10) ◽  
pp. 707
Author(s):  
Athanasios Koukofikis ◽  
Volker Coors

Moving into the third decade of the 21st century, smart cities are becoming a vital concept of advancement of the quality of life. Without any doubt, cities today can generate data of high velocity which can be used in plethora of applications. The wind flow inside a city is an area of several studies which span from pedestrian comfort and natural ventilation to wind energy yield. We propose a Visual Analytics platform based on a server-client web architecture capable of identifying areas with high wind energy potential by employing 3D technologies and Open Geospatial Consortium (OGC) standards. The assessment of a whole city or sub-regions will be supported by integrating Computational Fluid Dynamics (CFD) outcomes with historical wind sensor readings. The results, in 3D space, of such analysis could be used by a wide audience, including city planners and citizens, for locating installation points of small-scale horizontal or vertical axis wind turbines in an urban area. A case study in an urban quarter of Stuttgart is used to evaluate the interactiveness of the proposed workflow. The results show an adequate performance, although there is a lot of room for improvement in future work.


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