scholarly journals Overview of Low-Level Wind Shear Characteristics over Chinese Mainland

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 628
Author(s):  
Caiyan Lin ◽  
Kaijun Zhang ◽  
Xintao Chen ◽  
Sheng Liang ◽  
Junjie Wu ◽  
...  
Keyword(s):  
Wind Shear ◽  
Weather Conditions ◽  
Chinese Mainland ◽  
Steady Increase ◽  
Low Level ◽  
Air Traffic Controllers ◽  
Shear Characteristics ◽  
Strong Winds ◽  
Almost All ◽  
The Impact

The characteristics of low-level wind shear (LLWS) over the Chinese mainland were investigated using reports from pilots, air traffic controllers and the number of arriving/departing flights from 2016 to 2020. A preliminary analysis of the impact of the flights on the LLWS reports was carried out, and the cause of LLWS was also investigated. LLWS reports from most airports indicate that LLWS is most likely to occur within 600 m AGL with a higher density below 300 m, but with some exceptions, as wind shear is reported at higher altitudes at some airports. Airports with a high frequency of LLWS reports are almost all located in or around regions with complex topography and in regions with prevailing weather conditions favorable to LLWS. The variation in overall LLWS reports displays a steady increase from 2016 to 2019 and a decrease from 2019 to 2020, consistent with the trend in the number of flights, but with no evidently similar trends for individual airports. Seasonal variations in LLWS reports are observed and demonstrate no notable impact caused by the number of flights, implying that the main cause is the monthly variation of weather conditions. Diurnal variation is also evident and largely associated with the variation in number of flights during the busy period in addition to weather conditions, such as common strong winds, in the afternoon.

Examining Terrain Effects on an Upstate New York Tornado Event Utilizing a High-Resolution Model Simulation

2021 ◽  
Author(s):  
Luke J. LeBel ◽  
Brian H. Tang ◽  
Ross A. Lazear
Keyword(s):  
New York ◽  
High Resolution ◽  
Wind Shear ◽  
Model Simulation ◽  
Wrf Model ◽  
Severe Weather ◽  
Streamwise Vorticity ◽  
Low Level ◽  
Severe Convection ◽  
The Impact

AbstractThe complex terrain at the intersection of the Mohawk and Hudson valleys of New York has an impact on the development and evolution of severe convection in the region. Specifically, previous research has concluded that terrain-channeled flow in the Mohawk and Hudson valleys likely contributes to increased low-level wind shear and instability in the valleys during severe weather events such as the historic 31 May 1998 event that produced a strong (F3) tornado in Mechanicville, New York.The goal of this study is to further examine the impact of terrain channeling on severe convection by analyzing a high-resolution WRF model simulation of the 31 May 1998 event. Results from the simulation suggest that terrain-channeled flow resulted in the localized formation of an enhanced low-level moisture gradient, resembling a dryline, at the intersection of the Mohawk and Hudson valleys. East of this boundary, the environment was characterized by stronger low-level wind shear and greater low-level moisture and instability, increasing tornadogenesis potential. A simulated supercell intensified after crossing the boundary, as the larger instability and streamwise vorticity of the low-level inflow was ingested into the supercell updraft. These results suggest that terrain can have a key role in producing mesoscale inhomogeneities that impact the evolution of severe convection. Recognition of these terrain-induced boundaries may help in anticipating where the risk of severe weather may be locally enhanced.

scholarly journals Low-Level Wind Shear Characteristics and Lidar-Based Alerting at Lanzhou Zhongchuan International Airport, China

2020 ◽  
Vol 34 (3) ◽  
pp. 633-645 ◽  
Author(s):  
Lanqian Li ◽  
Aimei Shao ◽  
Kaijun Zhang ◽  
Nan Ding ◽  
Pak-Wai Chan
Keyword(s):  
Wind Shear ◽  
Low Level ◽  
International Airport ◽  
Shear Characteristics

scholarly journals Impact of Lidar Data Assimilation on Low-Level Wind Shear Simulation at Lanzhou Zhongchuan International Airport, China: A Case Study

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1342
Author(s):  
Lanqian Li ◽  
Ningjing Xie ◽  
Longyan Fu ◽  
Kaijun Zhang ◽  
Aimei Shao ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Wind Shear ◽  
Three Dimensional ◽  
Wrf Model ◽  
Lidar Data ◽  
Positive Role ◽  
Low Level ◽  
Wind Lidar ◽  
The Impact ◽  
Doppler Wind Lidar

Doppler wind lidar has played an important role in alerting low-level wind shear (LLW). However, these high-resolution observations are underused in the model-based analysis and forecasting of LLW. In this regard, we employed the Weather Research and Forecasting (WRF) model and its three-dimensional variational (3D-VAR) system to investigate the impact of lidar data assimilation (DA) on LLW simulations. Eight experiments (including six assimilation experiments) were designed for an LLW process as reported by pilots, in which different assimilation intervals, assimilation timespans, and model vertical resolutions were examined. Verified against observations from Doppler wind lidar and an automated weather observing system (AWOS), the introduction of lidar data is helpful for describing the LLW event, which can represent the temporal and spatial features of LLW, whereas experiments without lidar DA have no ability to capture LLW. While lidar DA has an obviously positive role in simulating LLW in the 10–20 min after the assimilation time, this advantage cannot be maintained over a longer time. Therefore, a smaller assimilation interval is favorable for improving the simulated effect of LLW. In addition, increasing the vertical resolution does not evidently improve the experimental results, either with or without assimilation.

Sensitivity of a Simulated Midlatitude Squall Line to Parameterization of Raindrop Breakup

2012 ◽  
Vol 140 (8) ◽  
pp. 2437-2460 ◽  
Author(s):  
Hugh Morrison ◽  
Sarah A. Tessendorf ◽  
Kyoko Ikeda ◽  
Gregory Thompson
Keyword(s):  
Wind Shear ◽  
Squall Line ◽  
Cold Pool ◽  
Density Currents ◽  
Drop Breakup ◽  
Surface Precipitation ◽  
Low Level ◽  
Fall Speed ◽  
Storm Characteristics ◽  
The Impact

Abstract This paper describes idealized simulations of a squall line observed on 20 June 2007, in central Oklahoma. Results are compared with measurements from dual-polarization radar and surface disdrometer. The baseline model configuration qualitatively reproduces key storm features, but underpredicts precipitation rates and generally overpredicts median volume raindrop diameter. The sensitivity of model simulations to parameterization of raindrop breakup is tested under different low-level (0–2.5 km) environmental vertical wind shears. Storm characteristics exhibit considerable sensitivity to the parameterization of breakup, especially for moderate (0.0048 s−1) shear. Simulations with more efficient breakup tend to have higher domain-mean precipitation rates under both moderate and higher (0.0064 s−1) shear, despite the smaller mean drop size and hence lower mass-weighted fall speed and higher evaporation rate for a given rainwater content. In these runs, higher evaporation leads to stronger cold pools, faster propagation, larger storm size, greater updraft mass flux (but weaker convective updrafts at mid- and upper levels), and greater total condensation that compensates for the increased evaporation to give more surface precipitation. The impact of drop breakup on mass-weighted fall speed is also important and leads to a nonmonotonic response of storm characteristics (surface precipitation, cold pool strength, etc.) to changes in breakup efficiency under moderate wind shear. In contrast, the response is generally monotonic at higher wind shear. Interactions between drop breakup, convective dynamics, cold pool intensity, and low-level environmental wind shear are also described in the context of “Rotunno–Klemp–Weisman (RKW) theory,” which addresses how density currents evolve in sheared environments.

Recovery of the Marine Environment Following the Braer Spill, Shetland

1999 ◽  
Vol 1999 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Paul Kingston
Keyword(s):  
Benthic Communities ◽  
Weather Conditions ◽  
Human Consumption ◽  
Exclusion Zone ◽  
Surrounding Water ◽  
Background Levels ◽  
Show Evidence ◽  
Almost All ◽  
Fish And Shellfish ◽  
The Impact

ABSTRACT In January, 1993 on the southwest tip of Shetland the oil tanker Braer was wrecked, spilling 84,000 tonnes of crude oil and 1,500 tonnes of bunker oil into the sea. Heavy weather conditions dispersed almost all the oil into the surrounding water, producing oil-in-water concentrations near the wreck as high as 20,000 times background. Concentrations fell rapidly with time, regaining background values in 30–40 days. As surface slick formation was minimal and most seabirds were offshore at the time of the spill, seabird mortality was relatively light and seal and otter mortality was in single figures. Catching and marketing fish and shellfish for human consumption from the oil-contaminated area was prevented by the establishment of a Fishery Exclusion Zone. Oil concentrations in fish from this zone fell to background levels within 2 months of the spill. Shellfish were more severely affected, the most heavily contaminated regaining background levels within a year except for the sediment-dwelling Norway lobster, which still is contaminated. The impact on the intertidal habitat was minimal and most shores recovered within a year. Offshore benthic communities in contaminated sediments did not show evidence of being significantly stressed.

scholarly journals WIND SHEAR ASSOCIATED WITH MEDITERRANEAN CYCLONES ACTIVITY AND THE IMPACT ON FLIGHT SAFETY DURING WINTER OPERATIONS AT HENRI COANDA OTOPENI AND AUREL VLAICU BANEASA AIRPORTS

2021 ◽  
Vol 19 (1) ◽  
pp. 5-16
Author(s):  
Gica NAE ◽  
Keyword(s):  
Wind Shear ◽  
Weather Conditions ◽  
Flight Safety ◽  
Reference Period ◽  
Life And Death ◽  
Mediterranean Cyclones ◽  
Current Context ◽  
The Difference ◽  
And Behavior ◽  
The Impact

The regulated airspace in which aircraft flights take place is part of the Earth's atmosphere. At the same time, the same airspace is the seat of meteorological process and phenomena that have no borders and whose activity is not regulated, but whose evolution in time and behavior is governed by their own laws. This study presents, in a descriptive manner, low level dangerous weather conditions associated with wind shear also called the invisible killer. The phenomenon can occur locally, extremely rarely (3-4 times per year) during winter operations, mainly in January, under the activity of Mediterranean cyclones and its uniqueness consists in duration and intensity. To highlight the impact on flight safety in winter operations, especially in the current context of global warming, the reference and analysis periods applicable to this study are indissolubly reduced to days and minutes. When we talk about flight safety, the immediate application of corrective actions by pilots, the reference period is indissolubly reduced to seconds, those seconds that can make the difference between life and death

Impact of Lidar Data Assimilation on Analysis and Prediction of Low-level Wind Shears at Lanzhou Zhongchuan International Airport, China

2020 ◽  
Author(s):  
Lanqian Li ◽  
Aimei Shao
Keyword(s):  
Data Assimilation ◽  
Wind Shear ◽  
Weather Conditions ◽  
Experimental Results ◽  
Small Scale ◽  
Lidar Data ◽  
Low Level ◽  
International Airport ◽  
Rainy Weather ◽  
Lidar Observations

<p>Low-level wind shear could occur not only in rainy weather conditions but also in non-rainy weather conditions, which is dangerous to aircraft safety for its rapid changes in wind direction or velocity. Recently, dry wind shear occurred in non-rainy condition has drawn more and more attention. Rain-detecting Doppler radar has no capabilities in detecting dry wind shear occurred in non-rainy condition, while Doppler Lidar observations with higher spatial and temporal resolution provide valuable information for dry wind shear. For this, considering dry wind shear cases reported by pilots at Lanzhou Zhongchuan International Airport as study object, lidar observations (radial velocities) were assimilated along with surface data to improve the prediction skill of dry wind shear events.</p><p>All experiments were conducted with Weather Research and Forecasting (WRF) model and its three-dimensional variational (3D-VAR) system. Three-nested domains were employed with 1-km horizontal resolution in the innermost domain. The model was derived by the NCEP FNL data. Lidar data was processed and only assimilated in the innermost domain. Experimental results show that the low-level wind shear can not be found in the experimental results without lidar data assimilation, while lidar data assimilation experiment successfully represented wind shear small-scale characteristics and simulated radial wind pattern was close to lidar observation. In addition, assimilation cycles with short time intervals effectively improved simulation accuracy of wind shear events.</p>

Contemporary Qur'anic Studies in Iran and its Relationship with Qur'anic Studies in the West

2012 ◽  
Vol 14 (1) ◽  
pp. 45-72
Author(s):  
Morteza Karimi-Nia
Keyword(s):  
Islamic Law ◽  
Human Sciences ◽  
The West ◽  
Communications Technologies ◽  
Religious Learning ◽  
The Status ◽  
Islamic Republic Of Iran ◽  
Almost All ◽  
The Impact ◽  
The Relationship

The status of tafsīr and Qur'anic studies in the Islamic Republic of Iran has changed significantly during recent decades. The essay provides an overview of the state of Qur'anic studies in Iran today, aiming to examine the extent of the impact of studies by Western scholars on Iranian academic circles during the last three decades and the relationship between them. As in most Islamic countries, the major bulk of academic activity in Iran in this field used to be undertaken by the traditional ʿulamāʾ; however, since the beginning of the twentieth century and the establishment of universities and other academic institutions in the Islamic world, there has been increasing diversity and development. After the Islamic Revolution, many gradual changes in the structure and approach of centres of religious learning and universities have occurred. Contemporary advancements in modern sciences and communications technologies have gradually brought the institutions engaged in the study of human sciences to confront the new context. As a result, the traditional Shīʿī centres of learning, which until 50 years ago devoted themselves exclusively to the study of Islamic law and jurisprudence, today pay attention to the teaching of foreign languages, Qur'anic sciences and exegesis, including Western studies about the Qur'an, to a certain extent, and recognise the importance of almost all of the human sciences of the West.

Airborne infrared low level wind shear predictor

1984 ◽  
Author(s):  
P. KUHN ◽  
R. KURKOWSKI
Keyword(s):  
Wind Shear ◽  
Low Level

IFRS IMPLEMENTATION AS ONE OF THE FACTORS FOR IMPROVING THE INVESTMENT CLIMATE IN UKRAINE

2017 ◽  
Author(s):  
Kateryna Sova ◽  
◽  
Natalia Yatsenko ◽  
Denys Zagirniak ◽  
◽  
...  
Keyword(s):  
Financial Reporting ◽  
Direct Investment ◽  
Financial Statements ◽  
International Standards ◽  
Investment Climate ◽  
The European Union ◽  
Economic Activities ◽  
Financial Reporting Standards ◽  
Almost All ◽  
The Impact

The article is devoted to the study of the impact of the introduction of International Financial Reporting Standards (IFRS) on changes in the investment climate in Ukraine. The relevance of the topic is that improving the practice of applying IFRS as a tool for exchanging financial information is one of the key conditions for improving the investment climate in Ukraine. The authors have created the generalized scheme that illustrates the chronological list of enterprises that are required by law to prepare financial statements in accordance with IFRS. It was noted that in 2018, in accordance with Part 2 of Article 12 of the law on accounting and financial reporting in Ukraine and resolution of the Cabinet of Ministers of Ukraine No. 547 from 11.07.2018, the criteria of enterprises that are required to prepare financial statements in accordance with IFRS were updated. This step significantly increased the level of application of international standards due to the adoption of such a decision at the legislative level. The dynamics of the number of IFRS enterprises in Ukraine was analyzed. The analysis showed that over the past three years, the number of almost all enterprises that must apply international standards has been growing. The advantages of using IFRS for different users of financial statements were determined. It was determined that the priority users of IFRS financial statements are investors. At the same time, it was noted that the main advantage for other users of financial statements prepared in accordance with international standards is the improvement of the investment climate. The dynamics of the Investment Attractiveness Index of Ukraine based on the Likert scale in the period from 2016 to 2020 was analyzed. The direct investment receipts to Ukraine from the European Union countries were studied. The dynamics of direct investment in the Ukrainian economy was analyzed for two types of economic activities that should form financial statements in accordance with IFRS, namely, the extractive industry and quarrying, as well as financial and insurance activities.

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