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

Wind Energy ◽  
2016 ◽  
Vol 20 (6) ◽  
pp. 987-1002 ◽  
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

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

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.

scholarly journals Low-Level Wind Shear Identification along the Glide Path at BCIA by the Pulsed Coherent Doppler Lidar

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 50
Author(s):  
Hongwei Zhang ◽  
Xiaoying Liu ◽  
Qichao Wang ◽  
Jianjun Zhang ◽  
Zhiqiang He ◽  
...  
Keyword(s):  
Wind Shear ◽  
Vertical Direction ◽  
Small Scale ◽  
Observation Data ◽  
Doppler Lidar ◽  
Low Level ◽  
Glide Path ◽  
Coherent Doppler Lidar ◽  
Scanning Strategies ◽  
Meteorological Phenomenon

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.

scholarly journals Low Level Jet Wind Shear in the Sahel

2013 ◽  
Vol 11 ◽  
pp. 1-10
Author(s):  
Saïdou Madougou ◽  
Frederique Saïd ◽  
Bernard Campistron ◽  
Fadel Kebe Cheikh
Keyword(s):  
Wind Shear ◽  
Vertical Wind Shear ◽  
Shear Direction ◽  
Low Level ◽  
Aircraft Navigation ◽  
Time Period ◽  
Wind Profiler Radar ◽  
Low Level Jet ◽  
Wind Shears ◽  
Uhf Wind Profiler

In the Sahel, a vertical wind shear appears in the dry and in the wet seasons. In Niamey, Niger, during the dry season, the period of strong shears is clearly linked to the Nocturnal Low Level Jet (LLJ) since it occurs in a narrow time period around 06H00 UTC at 60% of the cases reach shears which require an alert to the pilots (higher than 4 ms-1 per 100 m). The majority of cases occur during the night with a wind shear direction between 90 and 150° per 100 m, which is shown that it is dangerous for aircraft. In Bamako, Mali, high wind shears represent (higher than 4 ms-1 per 100 m) only 16-22% of the cases and can occur at any time of the day. There are, however, 8% of the cases, the whole day long, when the wind shear can reach more than 6 ms-1 per 100 m. Most of the wind shear directions are also between 0 and 90° per 100 m during the night. This is why the Agency for the safety of aircraft navigation in Africa and Madagascar (ASECNA) has put in 2004 at Bamako airport an UHF wind profiler radar for monitoring nocturnal strong Low Level Jet wind shear which occur regularly in this airport.

The Response of Simulated Nocturnal Convective Systems to a Developing Low-Level Jet

2010 ◽  
Vol 67 (10) ◽  
pp. 3384-3408 ◽  
Author(s):  
Adam J. French ◽  
Matthew D. Parker
Keyword(s):  
Boundary Layer ◽  
Stable Boundary Layer ◽  
Wind Shear ◽  
Squall Line ◽  
Stable Boundary ◽  
Low Level ◽  
Convective Systems ◽  
Squall Lines ◽  
Central United States ◽  
Low Level Jet

Abstract Some recent numerical experiments have examined the dynamics of initially surface-based squall lines that encounter an increasingly stable boundary layer, akin to what occurs with the onset of nocturnal cooling. The present study builds on that work by investigating the added effect of a developing nocturnal low-level jet (LLJ) on the convective-scale dynamics of a simulated squall line. The characteristics of the simulated LLJ atop a simulated stable boundary layer are based on past climatological studies of the LLJ in the central United States. A variety of jet orientations are tested, and sensitivities to jet height and the presence of low-level cooling are explored. The primary impacts of adding the LLJ are that it alters the wind shear in the layers just above and below the jet and that it alters the magnitude of the storm-relative inflow in the jet layer. The changes to wind shear have an attendant impact on low-level lifting, in keeping with current theories for gust front lifting in squall lines. The changes to the system-relative inflow, in turn, impact total upward mass flux and precipitation output. Both are sensitive to the squall line–relative orientation of the LLJ. The variations in updraft intensity and system-relative inflow are modulated by the progression of the low-level cooling, which mimics the development of a nocturnal boundary layer. While the system remains surface-based, the below-jet shear has the largest impact on lifting, whereas the above-jet shear begins to play a larger role as the system becomes elevated. Similarly, as the system becomes elevated, larger changes to system-relative inflow are observed because of the layer of potentially buoyant inflowing parcels becoming confined to the layer of the LLJ.

Vergleiche von Profilen der turbulenten kinetischen Energie in der Atmosphärischen Grenzschicht auf der Basis von Doppler-Lidar-Messungen mit Simulationsergebnissen des NWV-Modells ICON 

2021 ◽  
Author(s):  
Claudia Becker ◽  
Eileen Päschke ◽  
Frank Beyrich
Keyword(s):  
Cold Pool ◽  
Doppler Lidar ◽  
Low Level ◽  
Statistische Analyse ◽  
Low Level Jet

<p>Bestandteil des Gleichungssystems im Wettervorhersage-Modell ICON des DWD ist neben den klassischen Gleichungen für die zeitliche Änderung der Temperatur, des Windes und des Wassergehaltes der Atmosphäre in allen drei Phasen auch eine prognostische Gleichung für die turbulente kinetische Energie (TKE). Hieraus ergibt sich zunehmend der Bedarf nach Messdaten zur Verifikation der Modellergebnisse auch für diese Variable. Operationelle Messungen der TKE werden in der Praxis nur an wenigen Standorten mittels 3D-Ultraschall-Anemometern durchgeführt und sind damit oft auf Höhen in Bodennähe, in Einzelfällen auf Mastmessungen bis etwa 200 m Höhe beschränkt.</p> <p>Am Meteorologischen Observatorium Lindenberg – Richard-Aßmann-Observatorium des DWD wurde in den letzten Jahren ein in der Literatur beschriebenes Verfahren zur Ableitung von Profilen der turbulenten kinetischen Energie (TKE) aus Doppler-Lidar-Messungen implementiert, getestet und anhand mehrmonatiger Datensätze bewertet (vgl. Beitrag von Päschke et al., diese Session). Im vorliegenden Beitrag werden die Ergebnisse dieser Messungen mit den Ergebnissen der operationellen Modellvorhersagen mit ICON verglichen.</p> <p>In einem ersten Schritt werden charakteristische Einzelfälle betrachtet (Cold-Pool-Event, nächtlicher Low-Level Jet, Strahlungstag). Im zweiten Schritt erfolgt eine statistische Analyse gemittelter Tagesgänge der TKE aus Messungen im Vergleich zu den Ergebnissen der NWV-Modelle ICON global, ICON-EU und ICON-D2 unter Berücksichtigung von Jahreszeit, Strahlungsbilanz, Stabilitätsverhältnissen und Windgeschwindigkeit. Besonderes Augenmerk wird dabei auf das seit Februar 2021 im operationellen Betrieb laufende Regionalmodell ICON-D2 gerichtet, das bei einer horizontalen Auflösung von 2.2 km die Auflösung von Konvektion erlaubt. </p>

scholarly journals Long-lived high-frequency gravity waves in the atmospheric boundary layer: observations and simulations

2019 ◽  
Vol 19 (24) ◽  
pp. 15431-15446 ◽  
Author(s):  
Mingjiao Jia ◽  
Jinlong Yuan ◽  
Chong Wang ◽  
Haiyun Xia ◽  
Yunbin Wu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Gravity Waves ◽  
Horizontal Wind ◽  
Doppler Lidar ◽  
Low Level ◽  
Coherent Doppler Lidar ◽  
Computational Fluid Dynamics Cfd ◽  
Phase Progression ◽  
Low Level Jet

Abstract. A long-lived gravity wave (GW) in the atmospheric boundary layer (ABL) is analysed during a field experiment in Anqing, China (30∘37′ N, 116∘58′ E). Persistent GWs with periods ranging from 10 to 30 min over 10 h in the ABL within a 2 km height are detected by a coherent Doppler lidar from 4 to 5 September 2018. The amplitudes of the vertical wind due to these GWs are approximately 0.15–0.2 m s−1. The lifetimes of these GWs are longer than 20 wave cycles. There is no apparent phase progression with altitude. The vertical and zonal perturbations in the GWs are 90∘ out of phase, with vertical perturbations generally leading to zonal ones. Based on experiments and simplified two-dimensional computational fluid dynamics (CFD) numerical simulations, a reasonable generation mechanism of this persistent wave is proposed. A westerly low-level jet of ∼5 m s−1 exists at an altitude of 1–2 km in the ABL. The wind shear around the low-level jet leads to wave generation under the condition of light horizontal wind. Furthermore, a combination of thermal and Doppler ducts occurs in the ABL. Thus, the ducted wave motions are trapped in the ABL and have long lifetimes.

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

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.

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

2016 ◽  
Vol 45 (1) ◽  
pp. 0106001 ◽  
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

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

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

scholarly journals Long-live High Frequency Gravity Wavesin Atmospheric Boundary Layer: Observations and Simulations

2019 ◽  
Author(s):  
Mingjiao Jia ◽  
Jinlong Yuan ◽  
Chong Wang ◽  
Haiyun Xia ◽  
Yunbin Wu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Horizontal Wind ◽  
Doppler Lidar ◽  
Low Level ◽  
Coherent Doppler Lidar ◽  
Long Lifetime ◽  
Computational Fluid Dynamics Cfd ◽  
Phase Progression ◽  
Low Level Jet

Abstract. A long-live gravity wave (GW) in atmospheric boundary layer (ABL) during a field experiment in Anqing, China (116°58′ E, 30°37′ N) is analysed. Persistent GWs over 10 hours with periods ranging from 10 to 30 min in the ABL within 2 km height are detected by a coherent Doppler lidar from 4 to 5 in September 2018. The amplitudes of the vertical wind due to these GWs are about 0.15~0.2 m s−1. The lifetime of the GWs is more than 20 wave cycles. There is no apparent phase progression with altitude. The vertical and zonal perturbations of the GWs are apparent quadrature with vertical perturbations generally leading ahead of zonal ones. Based on experiments and simplified 2-Dimensional Computational Fluid Dynamics (CFD) numerical simulations, a reasonable generation mechanism of this persistent wave is proposed. A westerly low-level jet of ~ 5 m s−1 exists at the altitude of 1~2 km in the ABL. The wind shear around the low-level jet lead to the wave generation in the condition of light horizontal wind. Furthermore, a combination of thermal and Doppler ducts occurs in the ABL. Thus, the ducted wave motions are trapped in the ABL with long lifetime.

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