Strong Updraft at a Sea-Breeze Front and Associated Vertical Transport of Near-Surface Dense Aerosol Observed by Doppler Lidar and Ceilometer

2011 ◽  
Vol 141 (1) ◽  
pp. 117-142 ◽  
Author(s):  
Hironori Iwai ◽  
Yasuhiro Murayama ◽  
Shoken Ishii ◽  
Kohei Mizutani ◽  
Yuichi Ohno ◽  
...  
Keyword(s):  
Sea Breeze ◽  
Vertical Transport ◽  
Doppler Lidar ◽  
Near Surface

scholarly journals Structure Analysis of the Sea Breeze Based on Doppler Lidar and Its Impact on Pollutants

2022 ◽  
Vol 14 (2) ◽  
pp. 324
Author(s):  
Jiaxin Liu ◽  
Xiaoquan Song ◽  
Wenrui Long ◽  
Yiyuan Fu ◽  
Long Yun ◽  
...  
Keyword(s):  
Dissipation Rate ◽  
Sea Breeze ◽  
Turbulent Intensity ◽  
Horizontal Wind ◽  
Land Breeze ◽  
Doppler Lidar ◽  
Helmholtz Instability ◽  
Spatiotemporal Resolution ◽  
Near Surface ◽  
Wind Profiles

The Doppler lidar system can accurately obtain wind profiles with high spatiotemporal resolution, which plays an increasingly important role in the research of atmospheric boundary layers and sea–land breeze. In September 2019, Doppler lidars were used to carry out observation experiments of the atmospheric wind field and pollutants in Shenzhen. Weather Research and Forecasting showed that the topography of Hongkong affected the sea breeze to produce the circumfluence flow at low altitudes. Two sea breezes from the Pearl River Estuary and the northeast of Hong Kong arrived at the observation site in succession, changing the wind direction from northeast to southeast. Based on the wind profiles, the structural and turbulent characteristics of the sea breeze were analyzed. The sea breeze front was accurately captured by the algorithm based on fuzzy logic, and its arrival time was 17:30 on 25 September. The boundary between the sea breeze and the return flow was separated by the edge enhancement algorithm. From this, the height of the sea breeze head (about 1100 m) and the thickness of the sea breeze layer (about 700 m) can be obtained. The fluctuated height of the boundary and the spiral airflow nearby revealed the Kelvin–Helmholtz instability. The influence of the Kelvin–Helmholtz instability could be delivered to the near-surface, which was verified by the spatiotemporal change of the horizontal wind speed and momentum flux. The intensity of the turbulence under the control of the sea breeze was significantly lower than that under the land breeze. The turbulent intensity was almost 0.1, and the dissipation rate was between 10−4 and 10−2 m2·s−3 under the land breeze. The turbulent intensity was below 0.05, and the dissipation rate was between 10−5 and 10−3 m2·s−3 under the sea breeze. The turbulent parameters showed peaks and large gradients at the boundary and the sea breeze front. The peak value of the turbulent intensity was around 0.3, and the dissipation rate was around 0.1 m2·s−3. The round-trip effect of sea–land breeze caused circulate pollutants. The recirculation factor was maintained at 0.5–0.6 at heights where the sea and land breeze alternately controlled (below 600 m), as well as increasing with a decreasing duration of the sea breeze. The factor exceeded 0.9 under the control of the high-altitude breeze (above 750 m). The convergence and rise of the airflow at the front led to collect pollutants, causing a sharp decrease in air quality when the sea breeze front passed.

scholarly journals Wind Energy Meteorology: Insight into Wind Properties in the Turbine-Rotor Layer of the Atmosphere from High-Resolution Doppler Lidar

2013 ◽  
Vol 94 (6) ◽  
pp. 883-902 ◽  
Author(s):  
Robert M. Banta ◽  
Yelena L. Pichugina ◽  
Neil D. Kelley ◽  
R. Michael Hardesty ◽  
W. Alan Brewer
Keyword(s):  
Wind Energy ◽  
Ground Level ◽  
Turbine Rotor ◽  
Energy Industry ◽  
Doppler Lidar ◽  
Near Surface ◽  
Surface Measurements ◽  
Wind Measurements ◽  
Upper Level ◽  
Insight Into

Addressing the need for high-quality wind information aloft in the layer occupied by turbine rotors (~30–150 m above ground level) is one of many significant challenges facing the wind energy industry. Without wind measurements at heights within the rotor sweep of the turbines, characteristics of the flow in this layer are unknown for wind energy and modeling purposes. Since flow in this layer is often decoupled from the surface, near-surface measurements are prone to errant extrapolation to these heights, and the behavior of the near-surface winds may not reflect that of the upper-level flow.

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.

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

<p>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.</p><p>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°, 5°, and 45° elevation angles and vertical cross-section (RHI) scans at 0°, 30°, 60, 90°, 120°, and 150° 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 – 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.</p><p>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).</p><p> </p><p>Branch, O., Behrendt, Andreas Alnayef, O., Späth, 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 “Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL)” in the United Arab Emirates: First results on Convection Initiation, J. Geophys. Res.  Atmos., 2021. In review (submitted 23.11.2020).</p>

Evolution of the Monterey Bay Sea-Breeze Layer As Observed by Pulsed Doppler Lidar

1993 ◽  
Vol 50 (24) ◽  
pp. 3959-3982 ◽  
Author(s):  
Robert M. Banta ◽  
Lisa D. Olivier ◽  
David H. Levinson
Keyword(s):  
Sea Breeze ◽  
Monterey Bay ◽  
Doppler Lidar ◽  
Pulsed Doppler

scholarly journals A numerical process study on the rapid transport of stratospheric air down to the surface over western North America and the Tibetan Plateau

2019 ◽  
Vol 19 (9) ◽  
pp. 6535-6549 ◽  
Author(s):  
Bojan Škerlak ◽  
Stephan Pfahl ◽  
Michael Sprenger ◽  
Heini Wernli
Keyword(s):  
Boundary Layer ◽  
Tibetan Plateau ◽  
Surface Ozone ◽  
Vertical Transport ◽  
The Tibetan Plateau ◽  
Near Surface ◽  
Air Mass ◽  
Ozone Concentrations ◽  
Rapid Transport ◽  
Upper Level

Abstract. Upper-level fronts are often associated with the rapid transport of stratospheric air along tilted isentropes to the middle or lower troposphere, where this air leads to significantly enhanced ozone concentrations. These plumes of originally stratospheric air can only occasionally be observed at the surface because (i) stable boundary layers prevent an efficient vertical transport down to the surface, and (ii) even if boundary layer turbulence were strong enough to enable this transport, the originally stratospheric air mass can be diluted by mixing, such that only a weak stratospheric signal can be recorded at the surface. Most documented examples of stratospheric air reaching the surface occurred in mountainous regions. This study investigates two such events, using a passive stratospheric air mass tracer in a mesoscale model to explore the processes that enable the transport down to the surface. The events occurred in early May 2006 in the Rocky Mountains and in mid-June 2006 on the Tibetan Plateau. In both cases, a tropopause fold associated with an upper-level front enabled stratospheric air to enter the troposphere. In our model simulation of the North American case, the strong frontal zone reaches down to 700 hPa and leads to a fairly direct vertical transport of the stratospheric tracer along the tilted isentropes to the surface. In the Tibetan Plateau case, however, no near-surface front exists and a reservoir of high stratospheric tracer concentrations initially forms at 300–400 hPa, without further isentropic descent. However, entrainment at the top of the very deep boundary layer (reaching to 300 hPa over the Tibetan Plateau) and turbulence within the boundary layer allows for downward transport of stratospheric air to the surface. Despite the strongly differing dynamical processes, stratospheric tracer concentrations at the surface reach peak values of 10 %–20 % of the imposed stratospheric value in both cases, corroborating the potential of deep stratosphere-to-troposphere transport events to significantly influence surface ozone concentrations in these regions.

Diurnal and Seasonal Lightning Variability over the Gulf Stream and the Gulf of Mexico

2015 ◽  
Vol 72 (7) ◽  
pp. 2657-2665 ◽  
Author(s):  
Katrina S. Virts ◽  
John M. Wallace ◽  
Michael L. Hutchins ◽  
Robert H. Holzworth
Keyword(s):  
Gulf Of Mexico ◽  
Diurnal Cycle ◽  
Gulf Stream ◽  
Land Surface ◽  
Southeastern United States ◽  
Surface Wind ◽  
Tropical Rainfall Measuring Mission ◽  
Sea Breeze ◽  
Near Surface ◽  
Early Evening

Recent observations from the World Wide Lightning Location Network (WWLLN) reveal a pronounced lightning maximum over the warm waters of the Gulf Stream that exhibits distinct diurnal and seasonal variability. Lightning is most frequent during summer (June–August). During afternoon and early evening, lightning is enhanced just onshore of the coast of the southeastern United States because of daytime heating of the land surface and the resulting sea-breeze circulations and convection. Near-surface wind observations from the Quick Scatterometer (QuikSCAT) satellite indicate divergence over the Gulf of Mexico and portions of the Gulf Stream at 1800 LT, at which time lightning activity is suppressed there. Lightning frequency exhibits a broad maximum over the Gulf Stream from evening through noon of the following day, and QuikSCAT wind observations at 0600 LT indicate low-level winds blowing away from the continent and converging over the Gulf Stream. Over the northern Gulf of Mexico, lightning is most frequent from around sunrise through late morning. During winter, lightning exhibits a weak diurnal cycle over the Gulf Stream, with most frequent lightning during the evening. Precipitation rates from a 3-hourly gridded dataset that incorporates observations from Tropical Rainfall Measuring Mission (TRMM), as well as other satellites, exhibit a diurnal cycle over the Gulf Stream that lags the lightning diurnal cycle by several hours.

scholarly journals Interannual Variability in the Large-Scale Dynamics of the South Asian Summer Monsoon

2015 ◽  
Vol 28 (9) ◽  
pp. 3731-3750 ◽  
Author(s):  
Jennifer M. Walker ◽  
Simona Bordoni ◽  
Tapio Schneider
Keyword(s):  
Interannual Variability ◽  
South Asian ◽  
Summer Monsoon ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Sea Breeze ◽  
South Asian Summer Monsoon ◽  
The South ◽  
Near Surface ◽  
Asian Summer

Abstract This study identifies coherent and robust large-scale atmospheric patterns of interannual variability of the South Asian summer monsoon (SASM) in observational data. A decomposition of the water vapor budget into dynamic and thermodynamic components shows that interannual variability of SASM net precipitation (P − E) is primarily caused by variations in winds rather than in moisture. Linear regression analyses reveal that strong monsoons are distinguished from weak monsoons by a northward expansion of the cross-equatorial monsoonal circulation, with increased precipitation in the ascending branch. Interestingly, and in disagreement with the view of monsoons as large-scale sea-breeze circulations, strong monsoons are associated with a decreased meridional gradient in the near-surface atmospheric temperature in the SASM region. Teleconnections exist from the SASM region to the Southern Hemisphere, whose midlatitude poleward eddy energy flux correlates with monsoon strength. Possible implications of these teleconnection patterns for understanding SASM interannual variability are discussed.

The Land/Sea Breeze Experiment (LASBEX)

1990 ◽  
Vol 71 (5) ◽  
pp. 656-664 ◽  
Author(s):  
J. M. Intrieri ◽  
C. G. Little ◽  
W. J. Shaw ◽  
R. M. Banta ◽  
P. A. Durkee ◽  
...  
Keyword(s):  
Vertical Structure ◽  
Sea Breeze ◽  
Triangular Array ◽  
Land Breeze ◽  
Doppler Lidar ◽  
Preliminary Results ◽  
Surface Weather ◽  
Weather Stations ◽  
Observing Systems

The Land/Sea Breeze Experiment (LASBEX) was conducted at Moss Landing, California, 15–30 September 1987. The experiment was designed to study the vertical structure and mesoscale variation of the land/sea breeze. A Doppler lidar, a triangular array of three sodars, two sounding systems (one deployed from land and one from a ship), and six surface weather stations (one shipborne) were sited around the Moss Landing area. Measurements obtained included ten sea-breeze and four land-breeze events. This paper describes the objectives and design of the experiment, as well as the observing systems that were used. Some preliminary results and selected observations are presented, called from the data collected, as well as the ensuing analysis plans.

Retrieving Winds in the Surface Layer over Land Using an Airborne Doppler Lidar

2012 ◽  
Vol 29 (4) ◽  
pp. 487-499 ◽  
Author(s):  
K. S. Godwin ◽  
S. F. J. De Wekker ◽  
G. D. Emmitt
Keyword(s):  
Surface Wind ◽  
Surface Wind Speed ◽  
Lower Atmosphere ◽  
Doppler Lidar ◽  
Near Surface ◽  
Wind Retrieval ◽  
Wind Speed Maximum ◽  
Salinas Valley ◽  
Wind Retrievals ◽  
Wind Profiles

Abstract Airborne Doppler wind lidars are increasingly being used to measure winds in the lower atmosphere at higher spatial resolution than ever before. However, wind retrieval in the range gates closest to the earth’s surface remains problematic. When a laser beam from a nadir-pointing airborne Doppler wind lidar intercepts the ground, the return signal from the ground mixes with the windblown aerosol signal. As a result, winds in a layer adjacent to the surface are often unreliable and removed from wind profiles. This paper describes the problem in detail and discusses a two-step approach to improve near-surface wind retrievals. The two-step approach involves removing high-intensity ground returns and identifying and tracking aerosol radial velocities in the layer affected by ground interference. Using this approach, it is shown that additional range gates closer to the surface can be obtained, thereby further enhancing the potential of airborne Doppler lidar in atmospheric applications. The benefits of the two-step approach are demonstrated using measurements acquired over the Salinas Valley in central California. The additional range gates reveal details of the wind field that were previously not quantified with the original approach, such as a pronounced near-surface wind speed maximum.

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