Doppler lidar alerting algorithm of low-level wind shear based on ramps detection

Low-level wind shear is usually to be a rapidly changing meteorological phenomenon that cannot be ignored in aviation security service by affecting the air speed of landing and take-off aircrafts. The lidar team in Ocean University of China (OUC) carried out the long term particular researches on the low-level wind shear identification and regional wind shear inducement search at Beijing Capital International Airport (BCIA) from 2015 to 2020 by operating several pulsed coherent Doppler lidar (PCDL) systems. On account of the improved glide path scanning strategy and virtual multiple wind anemometers based on the rang height indicator (RHI) modes, the small-scale meteorological phenomenon along the glide path and/or runway center line direction can be captured. In this paper, the device configuration, scanning strategies, and results of the observation data are proposed. The algorithms to identify the low-level wind shear based on the reconstructed headwind profiles data have been tested and proved based on the lidar data obtained from December 2018 to January 2019. High spatial resolution observation data at vertical direction are utilized to study the regional wind shear inducement at the 36L end of BCIA under strong northwest wind conditions.

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Mixed layer depths via Doppler lidar during low-level jet events

EPJ Web of Conferences ◽

10.1051/epjconf/201817606017 ◽

2018 ◽

Vol 176 ◽

pp. 06017

Author(s):

Brian Carroll ◽

Belay Demoz ◽

Timothy Bonin ◽

Ruben Delgado

Keyword(s):

Fuzzy Logic ◽

Wind Speed ◽

Mixed Layer ◽

Wind Shear ◽

Lower Troposphere ◽

Doppler Lidar ◽

High Wind ◽

Fuzzy Logic Algorithm ◽

Low Level ◽

Low Level Jet

A low-level jet (LLJ) is a prominent wind speed peak in the lower troposphere. Nocturnal LLJs have been shown to transport and mix atmospheric constituents from the residual layer down to the surface, breaching quiescent nocturnal conditions due to high wind shear. A new fuzzy logic algorithm combining turbulence and aerosol information from Doppler lidar scans can resolve the strength and depth of this mixing below the jet. Conclusions will be drawn about LLJ relations to turbulence and mixing.

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Properties of the offshore low level jet and rotor layer wind shear as measured by scanning Doppler Lidar

Wind Energy ◽

10.1002/we.2075 ◽

2016 ◽

Vol 20 (6) ◽

pp. 987-1002 ◽

Cited By ~ 13

Author(s):

Y. L. Pichugina ◽

W. A. Brewer ◽

R. M. Banta ◽

A. Choukulkar ◽

C. T. M. Clack ◽

...

Keyword(s):

Wind Shear ◽

Doppler Lidar ◽

Low Level ◽

Low Level Jet

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Airport low-level wind shear lidar observation at beijing capital international airport

EPJ Web of Conferences ◽

10.1051/epjconf/201817606013 ◽

2018 ◽

Vol 176 ◽

pp. 06013

Author(s):

Hongwei Zhang ◽

Songhua Wu ◽

Qichao Wang ◽

Bingyi Liu ◽

Xiaochun Zhai

Keyword(s):

Wind Shear ◽

Doppler Lidar ◽

Low Level ◽

Lidar Observation ◽

International Airport ◽

Glide Path ◽

Coherent Doppler Lidar

Ocean University of China lidar team operated a pulse coherent Doppler lidar (PCDL) for the low level wind shear monitoring at the Beijing Capital International Airport (BCIA) in 2015. The experiment configuration, observation modes is presented. A case study shows that the low level wind shear events at the southern end of 18R/36L runway were mainly caused by the trees and buildings along the glide path under strong northwest wind conditions.

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Doppler lidar alerting algorithm of low-level wind shear based on ramps detection

Infrared and Laser Engineering ◽

10.3788/m0001820164501.106001 ◽

2016 ◽

Vol 45 (1) ◽

pp. 106001

Author(s):

蒋立辉 Jiang Lihui ◽

闫妍 Yan Yan ◽

熊兴隆 Xiong Xinglong ◽

陈柏纬 Chen Bowei ◽

陈星 Chen Xing ◽

...

Keyword(s):

Wind Shear ◽

Doppler Lidar ◽

Low Level

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Airborne infrared low level wind shear predictor

10.2514/6.1984-356 ◽

1984 ◽

Author(s):

P. KUHN ◽

R. KURKOWSKI

Keyword(s):

Wind Shear ◽

Low Level

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Geographic Shift and Environment Change of U.S. Tornado Activities in a Warming Climate

Atmosphere ◽

10.3390/atmos12050567 ◽

2021 ◽

Vol 12 (5) ◽

pp. 567

Author(s):

Zuohao Cao ◽

Huaqing Cai ◽

Guang J. Zhang

Keyword(s):

Wind Shear ◽

Convective Available Potential Energy ◽

Geographic Location ◽

Reanalysis Data ◽

Cyclonic Circulation ◽

Upward Motion ◽

Environment Change ◽

Low Level ◽

High Event ◽

The U.S

Even with ever-increasing societal interest in tornado activities engendering catastrophes of loss of life and property damage, the long-term change in the geographic location and environment of tornado activity centers over the last six decades (1954–2018), and its relationship with climate warming in the U.S., is still unknown or not robustly proved scientifically. Utilizing discriminant analysis, we show a statistically significant geographic shift of U.S. tornado activity center (i.e., Tornado Alley) under warming conditions, and we identify five major areas of tornado activity in the new Tornado Alley that were not identified previously. By contrasting warm versus cold years, we demonstrate that the shift of relative warm centers is coupled with the shifts in low pressure and tornado activity centers. The warm and moist air carried by low-level flow from the Gulf of Mexico combined with upward motion acts to fuel convection over the tornado activity centers. Employing composite analyses using high resolution reanalysis data, we further demonstrate that high tornado activities in the U.S. are associated with stronger cyclonic circulation and baroclinicity than low tornado activities, and the high tornado activities are coupled with stronger low-level wind shear, stronger upward motion, and higher convective available potential energy (CAPE) than low tornado activities. The composite differences between high-event and low-event years of tornado activity are identified for the first time in terms of wind shear, upward motion, CAPE, cyclonic circulation and baroclinicity, although some of these environmental variables favorable for tornado development have been discussed in previous studies.

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An Observational Study of Mesoscale Convective Systems with Heavy Rainfall over the Korean Peninsula

Weather and Forecasting ◽

10.1175/waf912.1 ◽

2006 ◽

Vol 21 (2) ◽

pp. 125-148 ◽

Cited By ~ 33

Author(s):

Hyung Woo Kim ◽

Dong Kyou Lee

Keyword(s):

Observational Study ◽

Korean Peninsula ◽

Wind Shear ◽

Heavy Rainfall ◽

Vertical Wind Shear ◽

Vertical Wind ◽

Mesoscale Convective Systems ◽

Low Level ◽

Convective Systems ◽

Mesoscale Convective

Abstract A heavy rainfall event induced by mesoscale convective systems (MCSs) occurred over the middle Korean Peninsula from 25 to 27 July 1996. This heavy rainfall caused a large loss of life and property damage as a result of flash floods and landslides. An observational study was conducted using Weather Surveillance Radar-1988 Doppler (WSR-88D) data from 0930 UTC 26 July to 0303 UTC 27 July 1996. Dominant synoptic features in this case had many similarities to those in previous studies, such as the presence of a quasi-stationary frontal system, a weak upper-level trough, sufficient moisture transportation by a low-level jet from a tropical storm landfall, strong potential and convective instability, and strong vertical wind shear. The thermodynamic characteristics and wind shear presented favorable conditions for a heavy rainfall occurrence. The early convective cells in the MCSs initiated over the coastal area, facilitated by the mesoscale boundaries of the land–sea contrast, rain–no rain regions, saturated–unsaturated soils, and steep horizontal pressure and thermal gradients. Two MCSs passed through the heavy rainfall regions during the investigation period. The first MCS initiated at 1000 UTC 26 July and had the characteristics of a supercell storm with small amounts of precipitation, the appearance of a mesocyclone with tilting storm, a rear-inflow jet at the midlevel of the storm, and fast forward propagation. The second MCS initiated over the upstream area of the first MCS at 1800 UTC 26 July and had the characteristics of a multicell storm, such as a broken areal-type squall line, slow or quasi-stationary backward propagation, heavy rainfall in a concentrated area due to the merging of the convective storms, and a stagnated cluster system. These systems merged and stagnated because their movement was blocked by the Taebaek Mountain Range, and they continued to develop because of the vertical wind shear resulting from a low-level easterly inflow.

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

Weather and Forecasting ◽

10.1175/waf-d-21-0018.1 ◽

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.

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First Doppler lidar and cloud radar measurements of orographic convection initiation from a mountain observatory in the Al Hajar Mountains of the United Arab Emirates.

10.5194/egusphere-egu21-9715 ◽

2021 ◽

Author(s):

Oliver Branch ◽

Andreas Behrendt ◽

Osama Alnayef ◽

Florian Späth ◽

Thomas Schwitalla ◽

...

Keyword(s):

United Arab Emirates ◽

Sea Breeze ◽

Doppler Lidar ◽

Cloud Seeding ◽

Low Level ◽

Cloud Radar ◽

Orographic Convection ◽

Radar Measurements ◽

Convection Initiation ◽

Convective Cells

We present exciting Doppler lidar and cloud radar measurements from a high-vantage mountain observatory in the hyper-arid United Arab Emirates (UAE) - initiated as part of the UAE Research Program for Rain Enhancement Science (UAEREP). The observatory was designed to study the clear-air pre-convective environment and subsequent convective events in the arid Al Hajar Mountains, with the overarching goal of improving understanding and nowcasting of seedable orographic clouds. During summer in the Al Hajar Mountains (June to September), weather processes are often complex, with summer convection being initiated by several phenomena acting in concert, e.g., interaction between sea breeze and horizontal convective rolls. These interactions can combine to initiate sporadic convective storms and these can be intense enough to cause flash floods and erosion. Such events here are influenced by mesoscale phenomena like the low-level jet and local sea breeze, and are constrained by larger-scale synoptic conditions.The Doppler lidar and cloud radar were employed for approximately two years at a high vantage-point to capture valley wind flows and observe convective cells. The instruments were configured to run synchronized polar (PPI) scans at 0&#176;, 5&#176;, and 45&#176; elevation angles and vertical cross-section (RHI) scans at 0&#176;, 30&#176;, 60, 90&#176;, 120&#176;, and 150&#176; azimuth angles. Using this imagery, along with local C-band radar and satellite data, we were able to identify and analyze several convective cases. To illustrate our results, we have selected two cases under unstable conditions - the 5 and 6 September 2018. In both cases, we observed areas of low-level convergence/divergence, particularly associated with wind flow around a peak 2 km to the south-west of the observatory. The extension of these deformations are visible in the atmosphere to a height of 3 km above sea level. Subsequently, we observed convective cells developing at those approximate locations &#8211; apparently initiated because of these phenomena. The cloud radar images provided detailed observations of cloud structure, evolution, and precipitation. In both convective cases, pre-convective signatures were apparent before CI, in the form of convergence, wind shear structures, and updrafts.These results have demonstrated the value of synergetic observations for understanding orographic convection initiation, improvement of forecast models, and cloud seeding guidance. The manuscript based on these results is now the subject of a peer review (Branch et al., 2021).&#160;Branch, O., Behrendt, Andreas Alnayef, O., Sp&#228;th, F., Schwitalla, Thomas, Temimi, M., Weston, M., Farrah, S., Al Yazeedi, O., Tampi, S., Waal, K. de and Wulfmeyer, V.: The new Mountain Observatory of the Project &#8220;Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL)&#8221; in the United Arab Emirates: First results on Convection Initiation, J. Geophys. Res.&#160; Atmos., 2021. In review (submitted 23.11.2020).

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