Coastal Wind Research Articles

Frequency of Occurrence of the North Pacific Minke Whale <i>Balaenoptera acutorostrata scammoni</i> Deméré, 1986 off the North-Eastern Coast of Sakhalin Island in 2008–2021

The seasonal and interannual variability in the frequency of occurrence of the North Pacific common minke whale (Minke whale) Balaenoptera acutorostrata scammoni Deméré, 1986 off the north-eastern coast of Sakhalin Island (the Sea of Okhotsk) in 2008–2021 was studied. It has been shown that the occurrence of whales of this species in the study area has significant seasonal and interannual variability. The average frequency of occurrence in even years of observations was 1.6 times higher than in odd years and amounted to 7.1 and 4.4%, respectively. It has been suggested that the frequency of occurrence of minke whale in the study area is determined by the intensity of coastal wind upwelling off the eastern coast of Sakhalin Island.

Wintertime Synoptic Patterns of Midlatitude Boundary Layer Clouds Over the Western North Atlantic: Climatology and Insights From In Situ ACTIVATE Observations

AbstractThe winter synoptic evolution of the western North Atlantic and its influence on the atmospheric boundary layer is described by means of a regime classification based on Self‐Organizing Maps applied to 12 years of data (2009–2020). The regimes are classified into categories according to daily 600‐hPa geopotential height: dominant ridge, trough to ridge eastward transition (trough‐ridge), dominant trough, and ridge to trough eastward transition (ridge–trough). A fifth synoptic regime resembles the winter climatological mean. Coherent changes in sea‐level pressure and large‐scale winds are in concert with the synoptic regimes: (a) the ridge regime is associated with a well‐developed anticyclone; (b) the trough‐ridge gives rise to a low‐pressure center over the ocean, ascents, and northerly winds over the coastal zone; (c) trough is associated with the eastward displacement of a cyclone, coastal subsidence, and northerly winds, all representative characteristics of cold‐air outbreaks; and (d) the ridge–trough regime features the development of an anticyclone and weak coastal winds. Low clouds are characteristic of the trough regime, with both trough and trough–ridge featuring synoptic maxima in cloud droplet number concentration (Nd). The Nd increase is primarily observed near the coast, concomitant with strong surface heat fluxes exceeding by more than 400 W m−2 compared to fluxes further east. Five consecutive days of aircraft observations collected during the ACTIVATE campaign corroborates the climatological characterization, confirming the occurrence of high Nd for days identified as trough. This study emphasizes the role of boundary‐layer dynamics and aerosol activation and their roles in modulating cloud microphysics.

A new index for assessing the coastal wind disasters based on the HY-2 satellite data

Tropical cyclone disasters have a substantial impact on human activity in coastal zones. The traditional methods used to classify wind disasters include the Beaufort Scale, Saffir-Simpson Scale, and Chicago Mercantile Exchange Hurricane Index (CMEHI). This research established a new index, the Haiyang Cyclone Index (HYCI), which considers spatial distributions and sea level anomalies (SLA) using HY-2 satellite data. The HYCI of three mega coastal cities, Qingdao, Shanghai, and Guangzhou, was calculated. A brief analysis was then performed using Moving Average Convergence Divergence (MACD) and Long Short-Term Memory (LSTM). The proposed HYCI can accurately evaluate the impact of cyclone disasters, thereby confirming its financial application potential.

Offshore wind data assessment near the Iberian Peninsula over the last 25 years

Numerous processes affecting coastal ocean dynamics and water properties occur at the air-sea interface as a result of wind blowing on the ocean surface. In Earth system research, it is crucial to appropriately characterize the ocean surface wind (OSW) field because of its significance in many academic and economic activities. This study aimed to evaluate the accuracy of the most recent OSW datasets based on numerical modeling and remote sensing products in estimating in situ observations along the Atlantic coast of the Iberian Peninsula. The results are three-fold: (1) when high temporal resolutions are not necessary, remote sensing products are an excellent choice because they provide reliable OSW estimates; (2) for analyses that require high temporal resolution, numerical weather models are the best choice because they can statistically reproduce the main trend; (3) fifth generation of European ReAnalysis (ERA5) showed that, despite having a lower spatial resolution than the dynamically downscaled weather research and forecasting simulation, it captures the spatial and temporal dynamics and variability of coastal winds and may be used as forcing of the atmosphere-ocean interface modeling without compromising its accuracy.

Research on refined prediction of coastal wind power based on dynamic downscale and deep learning prediction

With the expansion of the installed capacity of offshore wind power, its impact on the safe operation of the power grid is increasingly obvious, and improving the prediction accuracy of offshore wind power power has become a key problem to be solved in the industry. The improvement of prediction accuracy, on the one hand, can facilitate the operation control of power grid, on the other hand, can also significantly improve the economic benefits of wind power plants. Based on power downscaling and deep learning methods, this paper carries out localized short-term and ultra-short-term power prediction modeling and optimization technologies for coastal offshore wind power. Comprehensive statistical prediction method, artificial intelligence prediction method, multi-model integration method and other combined prediction model, multi-source fusion information, to realize the refined prediction of Zhejiang offshore wind power, and improve the overall prediction accuracy. The research method is generally applicable and can guide the output prediction of the same type of offshore wind power.

Analysis and Research on Windproof Deviation of Coastal 500kV Transmission Line Jumpers

Based on the current situation of frequent wind deflection faults of 500 kV transmission line jumpers caused by typhoons in coastal areas, this paper proposes a new sectional wind deflection proof post insulator transformation measure by analyzing the advantages and disadvantages of conventional jumper wind deflection transformation measures, which effectively improves the anti typhoon and wind resistance of 500 kV transmission line jumpers. It can save the amount of steel for tower transformation and greatly shorten the transformation outage time. It provides a solution for future coastal transmission line construction and wind deflection prevention reconstruction.

Observations of Offshore Internal Boundary Layers

AbstractThe growth of the marine internal boundary layer (MIBL, height hi) with the shore‐normal distance x, is a topic of continuing interest because of its applications in coastal pollution dispersion, offshore wind farm siting, coastal air‐sea fluxes and in evaporative ducting. Available data on MIBL are scarce, given the difficulty of measuring the variability of coastal winds. During the Coupled Air‐Sea Processes and Electromagnetic Research campaigns, an array of instrumentation was deployed to measure offshore spatial variability and its effect on electromagnetic (EM) wave propagation. Meteorological sensors (flux towers and remote sensing) deployed along the coast of Point Mugu, California, on a research vessel and FLoating Instrument Platform provided surface layer and boundary layer observations. Measurements from multiple remote sensors such as synchronized triple Doppler lidars, small boat operations with tethered lifting system, and radiosondes provided a holistic view of the MIBL growth and its spatial variability in coastal areas. Convective and stable MIBL observed during two intensive operating period days showed distinct growth characteristics off the coast of Point‐Mugu. During stable stratified atmospheric conditions, an MIBL was observed to develop least as far as 47 km from the coast. The growth of MIBL within the nearshore adjustment zone was influenced by surrounding atmospheric, oceanographic, and topographic conditions. A parameterization scheme is developed based on advection‐diffusion balance equations, accounting for upstream turbulence, and compared with hi observations from a Doppler lidar and profiles taken from a small boat. An evaluation of existing IBL theories is also conducted.

Investigating the Diurnal Variation in Coastal Boundary Layer Winds on Hainan Island Using Three Tower Observations

This study analyzes wind structures up to 509 m in the atmospheric boundary layer in the coastal area of Hainan Island, using a dataset obtained from ultrasonic anemometers housed in three towers. The wind profile, consisting of the measurements from the three towers, followed logarithmic law. In a diurnal variation, the maximum wind speed occurred at night, with a greater component of northerly wind, while the minimum wind speed was observed at noon, with a greater component of easterly wind. The variation in wind speed suggests that the measurements were representative of the wind field in the upper part of the atmospheric boundary layer, and the variation in wind direction might be affected by sea and land breezes, which can be induced by the different thermal conditions of underlying surfaces. The diurnal variation in average wind speed ranged from 0.5 to 1.5 m s−1, and the diurnal variation in wind direction was 10–20 degrees. In our measurements, the diurnal trajectory of the wind vector was observed to be counterclockwise, which differs from previous studies conducted over uniform and flat underlying surfaces. This is partially due to the different thermodynamic conditions of the underlying land and sea surfaces. The impact of topographic relief on wind measurement is also discussed. The measurements suggest that wind speeds at altitudes above 50 m are less influenced by terrain. The height of the reversal layer, which is generated by the different diurnal variations in wind speed in the upper and lower parts of the boundary layer, was estimated to be around 300 m.

Recovering the urban forest: The role of trees, tree culture, and place attachment before and after Hurricane Harvey

Trees can be powerful symbols that contribute to the production and consumption of places. Disaster events, such as hurricanes, alter the physical landscape, causing tree damage and loss. In places with strong tree cultures, the reforestation of damaged landscapes becomes an implicit element of recovery plans; however, less is known about the implications of tree loss to community recovery. In 2017, Hurricane Harvey made landfall near the coastal communities of Rockport and Fulton, Texas. Rockport-Fulton, known for its beach tourism, is home to a remnant live oak (Quercus virginiana) forest shaped by coastal onshore winds. Many of Rockport-Fulton’s windswept oaks were damaged or lost along with native and non-native palm trees. Rockport-Fulton’s history is imbued with stories situated around its oak forest. Drawing from multiple sources and participant observations from repeated site visits, we analyzed references to Rockport-Fulton’s trees in news media, organizational communications, and public exhibits before and after Harvey to understand the area’s tree culture and its associated discourses. We also interviewed tourists, business owners, and community members nine months after Harvey to understand their perceptions of recovery efforts. Our findings show that tree narratives pre- and post-Harvey amplify social-ecological systems definitions of resilience and that tree loss was a dominant theme in the recovery process for all participants. Yet we also found that tourists discussed the damage to palm trees, whereas community members focused on the loss of live oaks. Despite these preferences, trees available through replanting efforts contained few live oak and palm species; furthermore, recovery plans did not amplify trees in recovery strategies. Overall, our findings highlight the importance of replanting trees during the disaster recovery process in a way that not only enhances local biodiversity but also reaffirms place characteristics to meet community members’ and visitors’ expectations.

Machine Learning-Based Prediction of Dynamic Responses of a Tower Crane under Strong Coastal Winds

With the rapid development of the construction industry, tower cranes are increasingly used in coastal engineering. However, due to the complexity of their operating environment, tower cranes are vulnerable to typhoons, thunderstorms, and other extreme natural disasters. Therefore, it is becoming increasingly important to carry out safety warnings for the tower crane structure under the action of strong winds. In this paper, a real-time monitoring system for tower responses based on the Internet of things (IoT), which realizes long-term monitoring of the whole process of tower crane operation, was built. Based on the long-term monitoring data and the machine learning algorithm, two tower response prediction models were established. During the transit of super typhoon In-fa, the maximum displacement of the tower structure was predicted in advance, based on the measured wind speed data at the site, which is in good agreement with the displacement data monitored by the IoT. The results show that under strong winds, the non-working tower has a response lag, resulting in the fact that its maximum displacement does not correspond to the maximum wind speed moment at the site. This is mainly due to the weathercock effect of the tower in the non-working condition. The prediction model proposed in this paper can provide timely and effective safety warnings for the tower structure. It also can provide useful engineering references and scientific structural safety warning suggestions for the same type of tower cranes that do not have IoT monitoring systems installed.

Projections of offshore wind energy and wave climate in Guangdong’s nearshore area using CMIP6 simulations

A good knowledge of future coastal wind and wave resources in the context of climate change is crucial for the construction of offshore wind farms. In this study, the dataset of the coupled model intercomparison project phase 6 (CMIP6) was used to evaluate the future wind resources and wave conditions in the nearshore area of Guangdong of China. The long short-term memory (LSTM) algorithm was used to develop a statistical downscaling method to render high spatial resolution data. The Copula function was used to construct the joint probability distribution function. The key findings were as follows. First, over the whole Guangdong coastal area, the projection of wind speed (<i>H</i>_s) shows a generally increasing trend, the wave height (<i>W</i>_s) remains almost unchanged, and the growth is particularly pronounced in the western area. Second, it is clear that the joint probability distribution is less spread in the late 21^st century; therefore, the distribution of wind energy will also be more suitable for the optimal operating of wind turbines. Third, the joint probability distribution results show that large wind and wave conditions possibly occur at the same time, which must be considered when determining worst-case conditions. Future work is required to use more models and scenarios from the ongoing CMIP6.

Cross-shore wind-induced changes to field-scale overturning wave shape

The shape of depth-limited breaking-wave overturns is important for turbulence injection, bubble entrainment and sediment suspension. Overturning wave shape depends on a nonlinearity parameter$H/h$, where$H$is the wave height, and$h$is the water depth. Cross-shore wind direction (offshore/onshore) and magnitude affect laboratory shoaling wave shape and breakpoint location$X_{{bp}}$, but wind effects on overturning wave shape are largely unstudied. We perform field-scale experiments at the Surf Ranch wave basin with fixed bathymetry and$\approx 2.25$m shoaling solitons with small height variations propagating at$C=6.7\ \mathrm {m}\ \mathrm {s}^{-1}$. Observed non-dimensional cross-wave wind$U_w$was onshore and offshore, varying realistically ($-1.2 &lt; U_{w}/C &lt; 0.7$). Georectified images, a wave staff, and lidar are used to estimate$X_{{bp}}$,$H/h$, overturn area$A$and aspect ratio for 22 waves. The non-dimensionalized$X_{{bp}}$was inversely related to$U_{w}/C$. The non-dimensional overturn area and aspect ratio also were inversely related to$U_{w}/C$, with smaller and narrower overturns for increasing onshore wind. No overturning shape dependence on the weakly varying$H/h$was seen. The overturning shape variation was as large as prior laboratory experiments with strong$H/h$variations without wind. An idealized potential air flow simulation on steep shoaling soliton shape has strong surface pressure variations, potentially inducing overturning shape changes. Through wave-overturning impacts on turbulence and sediment suspension, coastal wind variations could be relevant for near-shore morphology.

Tropical cyclone wind hazard assessment for Donghaitang wind farm (Zhejiang Province, China): Case study

Currently, offshore and coastal wind power resources are growing rapidly around the world, especially in China. However, systematic research on the hazard assessment of wind farms under tropical cyclone conditions remains lacking. This study simulated the wind field of tropical cyclones based on a parameterized tropical cyclone wind field model, and analyzed the characteristics of historical tropical cyclones in Donghaitang wind farm (Zhejiang, China). Four extreme tropical cyclone hazard factors including the maximum wind speed (Vmax), maximum duration of wind direction change (Tmax), maximum cumulative wind direction change (Δθmax) and maximum rate of change in wind direction (ΔDmax) were proposed and examined. Then a comprehensive hazard assessment model for wind farms based on the analytic hierarchy process was established, and the risk to the Donghaitang wind farm represented by tropical cyclones during 1949–2021 was evaluated. Results showed that the number and intensity of tropical cyclones made landfall near the coast of Donghaitang wind farm gradually increased with time, which results in a gradual increase in the composite tropical cyclone risk level of the Donghaitang wind farm with time. The numbers and risk levels of tropical cyclones traveling northwestward were much larger than those traveling northward or northeastward. Moreover, the average composite risk index for tropical cyclones passing to the left of the wind farm was 14.3% higher than that for tropical cyclones passing to the right. The large values of Vmax and ΔDmax are main reasons for the high risk of the wind farm, while the other two hazard factors (Tmax, Δθmax) proposed to account for the wind turbine backup power are also of great importance in the design, selection and operation stages of offshore wind turbines. The findings of this study could provide support for hazard assessment of offshore and coastal wind farms exposed to tropical cyclones, including macro site selection of wind farms and type selection of wind turbines.

Characterizing Coastal Wind Speed and Significant Wave Height Using Satellite Altimetry and Buoy Data

Wind speed and significant wave height are the most relevant metocean variables that support a wide range of engineering and economic activities. Their characterization through remote sensing estimations is required to compensate for the shortage of in situ observations. This study demonstrates the value of satellite altimetry to identify typical spatial patterns of wind speed and significant wave height in the northeastern region of the United States. Data from five altimetry satellite missions were evaluated against the available in situ observations with a 10 km sampling radius and a 30 min time window. An objective analysis of the collective altimeter dataset was performed to create aggregated composite maps of the wind speed and significant wave height. This asynchronous compositing of multi-mission altimeter data is introduced to compile a sufficient sampling of overpasses over the area of interest. The results of this approach allow for quantifying spatial patterns for the wind speed and significant wave height in the summer and winter seasons. The quality of altimeter estimations was assessed regarding the distance from the coast and the topography. It was found that while the altimeter data are highly accurate for the two variables, bias increases near the coast. The average minimum and maximum wind speed values detected in buoy stations less than 40 km from the coast were not matched by the aggregated altimeter time series. The method exposes the spatial and time gaps to be filled using data from future missions. The challenges of the objective analysis near the coast, especially in semi-enclosed areas, and the implications of the altimeter estimations due to the land contamination are explained. The results indicate that the combination of altimetry data from multiple satellite missions provides a significant complementary information resource for nearshore and coastal wind and wave regime estimations.

Uncertain future of sustainable fisheries environment in eastern boundary upwelling zones under climate change

Upwelling along ocean eastern boundaries is expected to intensify due to coastal wind strengthening driven by increasing land-sea contrast according to the Bakun hypothesis. Here, the latest high-resolution climate simulations that exhibit drastic improvements of upwelling processes reveal far more complex future upwelling changes. The Southern Hemisphere upwelling systems show a future strengthening in coastal winds with a rapid coastal warming, whereas the Northern Hemisphere coastal winds show a decrease with a comparable warming trend. The Bakun mechanism cannot explain these changes. Heat budget analysis indicates that temperature change in the upwelling region is not simply controlled by vertical Ekman upwelling, but also influenced by horizontal heat advection driven by strong near-coast wind stress curl that is neglected in the Bakun hypothesis and poorly represented by the low-resolution models in the Coupled Model Intercomparison Project. The high-resolution climate simulations also reveal a strong spatial variation in future upwelling changes, which is missing in the low-resolution simulations.

An Analysis of Policy Options Available to the International Maritime Organization to Protect the Costa Rica Thermal Dome: Building the Case for a Particularly Sensitive Sea Area

Intense maritime traffic threatens marine habitats globally. The Costa Rica Thermal Dome (CRTD) is a biologically productive ocean region that experiences a high volume of maritime traffic, and its location is dynamic, representing a governance challenge for this marine area. The CRTD is a high seas upwelling system influenced part of the year by coastal jet winds off the coast of Nicaragua and Costa Rica. During parts of the year, the CRTD moves into the jurisdictional waters of the adjacent countries (Costa Rica, Nicaragua, Guatemala, and El Salvador). Because there is currently no cross-sectoral coordination or capacity to address multiple threats in high seas areas such as the CRTD, regulation must be implemented on a sector-by-sector basis. This document analyzes tools under the International Maritime Organization (IMO) to reduce the threats from international shipping in the marine environment, with particular emphasis on the CRTD. The IMO has the authority to regulate shipping activity globally and implement precautionary measures to avoid threats such as hazardous and noxious substances, ship-whale strikes, or underwater noise pollution. The following IMO tools were included in the analysis: ship routing measures and speed reductions, a Special Area under the International Convention for the Prevention of Pollution from Ships (MARPOL), and a Particularly Sensitive Sea Area (PSSA). The results of the analysis concluded that the implementation of a PSSA within the CRTD is the best option to address threats from international shipping, since it can combine a range of Associated Protective Measures under its single administrative structure.

Black-tailed gulls alter their flight height and airspeed according to wind conditions during their coastal commuting trips

Seabirds are expected to increase their flight height in tailwind and to increase their airspeed in headwind during goal-oriented flight to minimize their cost of transport. To understand how flapping birds respond to variability in wind speed and direction experienced during their commuting flights between their breeding colony and foraging areas, we measured the flight height and speed of black-tailed gullsLarus crassirostrisusing GPS loggers. We analyzed the relationships between these flight parameters and local wind speed and direction. Over the course of the 2016 to 2018 breeding seasons, we tagged 105 birds at 2 colonies in northern Hokkaido, Japan. A total of 90 flight track-lines within a 500 m radius of 5 coastal meteorological stations were analyzed. The median flight height ranged from 0 to 153.8 m, and the median ground speed and airspeed were between 18.6-82.1 and 19.5-93.0 km h-1, respectively. Gulls flew higher with greater tailwind speed, supporting the hypothesis that birds utilize greater wind assistance at higher altitudes. Furthermore, gulls increased their airspeed under strong headwind conditions, suggesting they adjust airspeed to achieve the most cost-effective speed to reach their destination. Better understanding the drivers of seabird flight height is key to assessing the potential for collisions with wind turbines in coastal and offshore wind farms. These findings provide useful information to reduce collisions with coastal and offshore wind facilities.

High-Resolution Coastal Winds From the NOAA Near Real-Time ASCAT Processor

The NOAA near real-time operational ASCAT ocean surface wind vectors are produced at 12.5 and 25 km swath grid resolutions. To avoid land contamination due to the relatively large footprint size, the wind data in the inner most coastal regions (~15 - 25 km from the coast) are excluded from the final product. To obtain more retrievals in the coastal regions we utilize measurements containing up to 50% land contribution ratio and employ a combination of the enhanced resolution processing technique and a coastal normalized radar cross section correction method to achieve accurate wind retrievals to within ~1.0 - 2.5 km of the coast. The backscatter correction is implemented for each ASCAT coastal zone measurement. The mean and standard deviation of the land contribution for each measurement is determined, and then the land backscatter contribution is subtracted out from the actual measurement through an iteration method to estimate the ocean-only signal. An ocean calibration of the enhanced resolution backscatter was implemented before the wind retrieval step to improve the accuracy. Finally, a land contribution ratio ranking is implemented after the wind retrieval to further remove the remaining land contamination residuals. Additional quality control is also developed. The high-resolution coastal winds from ASCAT are validated against a variety of other independent wind measurements. The results are then presented and discussed.

Decadal Time‐Series Depletion of Dissolved Oxygen at Abyssal Depths in the Northeast Pacific

AbstractDissolved oxygen depletion in the global ocean is well documented over several decades from the surface ocean to abyssal depths. This decline is especially prevalent in the Northeast Pacific. A significant decline in dissolved oxygen has been measured over 30 years at 4,000–4,100 m depth (Station M) beneath the California Current off central California. Three principal hypotheses examined the relationship of declining oxygen with biological and physical factors over the 30‐year time series. Annual resolution revealed Ekman pumping, coastal upwelling, particulate matter flux, and sediment community oxygen consumption having significant correlations with bottom water dissolved oxygen concentration. Coastal upwelling accounted for 65% of the annual variation in bottom water oxygen concentration. Stepwise regression yielded descriptive models of bottom water dissolved oxygen using coastal upwelling, wind stress and primary production variables. Is continued oxygen depletion in the Northeast Pacific indicative of abyssal regions in the world ocean?

Reanalysis representation of low-level winds in the Antarctic near-coastal region

Abstract. Low-level easterly winds encircling Antarctica help drive coastal currents which modify transport of circumpolar deep water to ice shelves, and the formation and distribution of sea ice. Reanalysis datasets are especially important at high southern latitudes where observations are few. Here, we investigate the representation of the mean state and short-term variability of coastal easterlies in three recent reanalyses, ERA5, MERRA-2 and JRA-55. Reanalysed winds are compared with summertime marine near-surface wind observations from the Advanced Scatterometer (ASCAT) and surface and upper air measurements from coastal stations. Reanalysis coastal easterlies correlate highly with ASCAT (r= 0.91, 0.89 and 0.85 for ERA5, MERRA-2 and JRA-55, respectively) but notable wind speed biases are found close to the coastal margins, especially near complex orography and at high wind speeds. To characterise short-term variability, 12-hourly reanalysis and coastal station winds are composited using self-organising maps (SOMs), which cluster timesteps under similar synoptic and mesoscale influences. Reanalysis performance is sensitive to the flow configuration at stations near steep coastal slopes, where they fail to capture the magnitude of near-surface wind speed variability when synoptic forcing is weak and conditions favour katabatic forcing. ERA5 exhibits the best overall performance, has more realistic orography, and a more realistic jet structure and temperature profile. These results demonstrate the regime behaviour of Antarctica's coastal winds and indicate important features of the coastal winds which are not well characterised by reanalysis datasets.