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.

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.

scholarly journals Doppler lidar at Observatoire de Haute Provence for wind profiling up to 75 km altitude: performance evaluation and observations

2019 ◽  
Author(s):  
Sergey M. Khaykin ◽  
Alain Hauchecorne ◽  
Robin Wing ◽  
Philippe Keckhut ◽  
Sophie Godin-Beekmann ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Direct Detection ◽  
Horizontal Wind ◽  
Doppler Lidar ◽  
Qualitative Comparison ◽  
Horizontal Wind Speed ◽  
Early Validation ◽  
Wind Lidar ◽  
Wind Profiles ◽  
Hourly Observation

Abstract. A direct-detection Rayleigh-Mie Doppler lidar for measuring horizontal wind speed in the middle atmosphere has been deployed at Observatoire de Haute Provence (OHP) in southern France since 1993. After a recent upgrade, the instrument gained the capacity of wind profiling between 5 and 75 km altitude with high vertical and temporal resolution. The lidar comprises a monomode Nd:Yag laser emitting at 532 nm, three telescope assemblies, and a double-edge Fabry-Perot interferometer for detection of the Doppler shift in the backscattered light. In this article, we describe the instrument design, recap retrieval methodology and provide an updated error estimate for horizontal wind. The evaluation of the wind lidar performance is done using a series of twelve time-coordinated radiosoundings conducted at OHP. A point-by-point intercomparison shows a remarkably small average bias of 0.1 m/s between the lidar and the radiosonde wind profiles with a standard deviation of 2.2 m/s. We report examples of a weekly and an hourly observation series, reflecting various dynamical events in the middle atmosphere, such as a Sudden Stratospheric Warming event in January 2019 and an occurrence of a stationary gravity wave, generated by the flow over the Alps. A qualitative comparison between the wind profiles from the lidar and the ECMWF Integrated Forecast System is also discussed. Finally, we present an example of early validation of the ESA Aeolus space-borne wind lidar using its ground-based predecessor.

scholarly journals Doppler lidar at Observatoire de Haute-Provence for wind profiling up to 75 km altitude: performance evaluation and observations

2020 ◽  
Vol 13 (3) ◽  
pp. 1501-1516 ◽  
Author(s):  
Sergey M. Khaykin ◽  
Alain Hauchecorne ◽  
Robin Wing ◽  
Philippe Keckhut ◽  
Sophie Godin-Beekmann ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Direct Detection ◽  
European Space Agency ◽  
Horizontal Wind ◽  
Doppler Lidar ◽  
Qualitative Comparison ◽  
Horizontal Wind Speed ◽  
Wind Lidar ◽  
Wind Profiles ◽  
Hourly Observation

Abstract. A direct-detection Rayleigh–Mie Doppler lidar for measuring horizontal wind speed in the middle atmosphere (10 to 50 km altitude) has been deployed at Observatoire de Haute-Provence (OHP) in southern France starting from 1993. After a recent upgrade, the instrument gained the capacity of wind profiling between 5 and 75 km altitude with vertical resolution up to 115 m and temporal resolution up to 5 min. The lidar comprises a monomode Nd:Yag laser emitting at 532 nm, three telescope assemblies and a double-edge Fabry–Pérot interferometer for detection of the Doppler shift in the backscattered light. In this article, we describe the instrument design, recap retrieval methodology and provide an updated error estimate for horizontal wind. The evaluation of the wind lidar performance is done using a series of 12 time-coordinated radiosoundings conducted at OHP. A point-by-point intercomparison shows a remarkably small average bias of 0.1 m s−1 between the lidar and the radiosonde wind profiles with a standard deviation of 2.3 m s−1. We report examples of a weekly and an hourly observation series, reflecting various dynamical events in the middle atmosphere, such as a sudden stratospheric warming event in January 2019 and an occurrence of a stationary gravity wave, generated by the flow over the Alps. A qualitative comparison between the wind profiles from the lidar and the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System is also discussed. Finally, we present an example of early validation of the European Space Agency (ESA) Aeolus space-borne wind lidar using its ground-based predecessor.

A Simple Technique for Creating Regional Composites of Sea Surface Temperature from MODIS for Use in Operational Mesoscale NWP

2010 ◽  
Vol 49 (11) ◽  
pp. 2267-2284 ◽  
Author(s):  
Jason C. Knievel ◽  
Daran L. Rife ◽  
Joseph A. Grim ◽  
Andrea N. Hahmann ◽  
Joshua P. Hacker ◽  
...  
Keyword(s):  
High Resolution ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Real Time ◽  
Simple Technique ◽  
Weather Prediction ◽  
Sea Breeze ◽  
Sea Surface ◽  
Horizontal Wind ◽  
Near Surface

Abstract This paper describes a simple technique for creating regional, high-resolution, daytime and nighttime composites of sea surface temperature (SST) for use in operational numerical weather prediction (NWP). The composites are based on observations from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua and Terra. The data used typically are available nearly in real time, are applicable anywhere on the globe, and are capable of roughly representing the diurnal cycle in SST. The composites’ resolution is much higher than that of many other standard SST products used for operational NWP, including the low- and high-resolution Real-Time Global (RTG) analyses. The difference in resolution is key because several studies have shown that highly resolved SSTs are important for driving the air–sea interactions that shape patterns of static stability, vertical and horizontal wind shear, and divergence in the planetary boundary layer. The MODIS-based composites are compared to in situ observations from buoys and other platforms operated by the National Data Buoy Center (NDBC) off the coasts of New England, the mid-Atlantic, and Florida. Mean differences, mean absolute differences, and root-mean-square differences between the composites and the NDBC observations are all within tenths of a degree of those calculated between RTG analyses and the NDBC observations. This is true whether or not one accounts for the mean offset between the skin temperatures of the MODIS dataset and the bulk temperatures of the NDBC observations and RTG analyses. Near the coast, the MODIS-based composites tend to agree more with NDBC observations than do the RTG analyses. The opposite is true away from the coast. All of these differences in point-wise comparisons among the SST datasets are small compared to the ±1.0°C accuracy of the NDBC SST sensors. Because skin-temperature variations from land to water so strongly affect the development and life cycle of the sea breeze, this phenomenon was chosen for demonstrating the use of the MODIS-based composite in an NWP model. A simulated sea breeze in the vicinity of New York City and Long Island shows a small, net, but far from universal improvement when MODIS-based composites are used in place of RTG analyses. The timing of the sea breeze’s arrival is more accurate at some stations, and the near-surface temperature, wind, and humidity within the breeze are more realistic.

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

Observed and Modeled Urban Heat Island and Sea Breeze Circulation Interactions: a Shanghai Case Study

2021 ◽  
Keyword(s):  
Urban Heat Island ◽  
Time Scales ◽  
Single Layer ◽  
Sea Breeze ◽  
Accurate Estimation ◽  
Land Breeze ◽  
Heat Island ◽  
Near Surface ◽  
Low Level ◽  
Urban Heat

Abstract Urban heat island (UHI) and sea-land breeze systems are well-known and important characteristics of the climate of coastal cities. To model these, the accurate estimation of the surface energy balance (SEB) is a key factor needed to improve local scale simulations of thermodynamic and dynamic boundary circulations. The Weather Research and Forecasting model with a single layer urban model (WRF/SLUCM), with parameters derived from MODIS and local GIS information, is used to investigate the UHI and sea breeze circulations (SBC) in the megacity of Shanghai. The WRF/SLUCM can reproduce observed urban radiation and SEB fluxes, near-surface meteorological variables, and the evolution of the UHI and SBC. Simulations for an August period show the maximum UHI tends to drift northwest in the afternoon, driven by the prevailing southeast wind. The sea breeze lasts for about 4-h and is strongest between 1200 and 1400 Local Time (UTC+8 h). The interaction between UHI and SBC is evident with low-level convergence, upward motion and moisture transport from the sea and urban breezes simulated. An urban circulation (horizontal/vertical/time scales: ∼20-km/ ∼1.5-km/ ∼3-h) with thermal vertical motions (∼1.5 m s−1) above the urban area and a SBC (horizontal/vertical/time scales: 6 - 7 km/ ∼1 km/ 2 - 3-h) above the northern coastal suburb occur. Combined the sea breeze and southerly winds form a low-level wind shear (convergence zone) ∼5 km from the coast that penetrates ∼20 km inland to the urban center. Using the WRF/SLUCM simulations we improve understanding of the complex spatial dynamics of summer-time urban heating in coastal megacities, such as Shanghai.

scholarly journals Influence of winds on temporally varying short and long period gravity waves in the near shore regions of the eastern Arabian Sea

Ocean Science ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 343-353 ◽  
Author(s):  
J. Glejin ◽  
V. Sanil Kumar ◽  
T. M. Balakrishnan Nair ◽  
J. Singh
Keyword(s):  
Southern Ocean ◽  
Wave Height ◽  
Arabian Sea ◽  
Sea Breeze ◽  
Land Breeze ◽  
Wind System ◽  
Near Surface ◽  
Maximum Wave Height ◽  
Long Period ◽  
Wave Data

Abstract. Wave data collected off Ratnagiri, west coast of India, during 1 May 2010 to 30 April 2012 are used in this study. Seasonal and annual variations in wave data controlled by the local wind system such as sea breeze and land breeze, and remote wind generated long period waves are also studied. The role of sea breeze on the sea state during pre- and postmonsoon seasons is studied and it is found that the maximum wave height is observed at 15:00 UTC during the premonsoon season, with an estimated difference in time lag of 1–2 h in maximum wave height between premonsoon and postmonsoon seasons. Observed waves are classified in to (i) short waves (Tp < 8 s), (ii) intermediate waves (8 < Tp < 13 s), and (iii) long waves (Tp> 13 s) based on peak period (Tp) and the percentages of occurrence of each category are estimated. Long period waves are observed mainly during the pre- and the postmonsoon seasons. During the southwest monsoon period, the waves with period > 13 s are a minimum. An event during 2011 is identified as swells propagated from the Southern Ocean with an estimated travelling time of 5–6 days. The swells reaching the Arabian Sea from the south Indian Ocean and Southern Ocean, due to storms during the pre- and postmonsoon periods, modify the near surface winds due to higher phase wave celerity than the wind speed. Estimation of inverse wave age using large-scale winds such as NCEP (National Centers for Environmental Prediction) reflects the presence of cyclonic activity during pre- and postmonsoon seasons but not the effect of the local sea breeze/land breeze wind system.

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

&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;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&amp;#176;, 5&amp;#176;, and 45&amp;#176; elevation angles and vertical cross-section (RHI) scans at 0&amp;#176;, 30&amp;#176;, 60, 90&amp;#176;, 120&amp;#176;, and 150&amp;#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 &amp;#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.&lt;/p&gt;&lt;p&gt;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).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Branch, O., Behrendt, Andreas Alnayef, O., Sp&amp;#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 &amp;#8220;Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL)&amp;#8221; in the United Arab Emirates: First results on Convection Initiation, J. Geophys. Res.&amp;#160; Atmos., 2021. In review (submitted 23.11.2020).&lt;/p&gt;

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