Resolution Wind Fields Research Articles

Effect of Tropical Cyclone Wind Forcing on Improving Upper Ocean Simulation: An Idealized Study

We examined how wind forcing affects the upper ocean response under idealized tropical cyclone (TC) conditions. In this study, we constructed three parameterized wind fields with varying spatial and temporal resolutions for TCs of different intensities and translation speeds. The simulated surface and subsurface temperatures were cooler and deeper when using the blended wind fields owing to their higher wind speeds compared to those from coarse–resolution wind fields. Additionally, TC–induced currents were significantly stronger on the right side of the TC track, with notable differences in current velocities. Similar to the increase in ocean currents, the simulated turbulent kinetic energy driven by the blended winds is significantly higher than that simulated by the coarse-resolution wind fields. These findings suggest that using high-quality wind fields to drive ocean models can enhance the accuracy of the upper ocean response to TCs. The sensitivity of the upper ocean responses to wind forcing depends on the TC’s intensity and translation speed. Stronger and slower-moving TCs induce greater vertical shear and enhanced mixing. Therefore, accurate wind stress as a surface boundary condition is crucial for numerical ocean models.

Mesosphere/Lower Thermosphere 3‐Dimensional Spatially Resolved Winds Observed by Chinese Multistatic Meteor Radar Network Using the Newly Developed VVP Method

AbstractWe present the first continuous observations of three‐dimensional spatially resolved wind fields and atmospheric motions in the mesosphere and lower thermosphere in the mid‐latitudes of the Northern Hemisphere. Our observations were performed during a 19‐month campaign from January 2022 to July 2023 and exploited the composite data from the first multistatic meteor radar system in China and an adjacent monostatic meteor radar. To retrieve the atmospheric kinetic properties, we introduce an improved volume velocity processing method including coordinate transformations and non‐linear constraints to minimize errors. The vertical winds are estimated separately from the iteration of the horizontal divergence to avoid potential biases or contamination from the horizontal winds. The winds and air motions show annual/semiannual variation characteristics within certain altitudes, usually more variable around the equinoxes. The vertical winds are basically within the magnitude of 1 m/s and are upward as expected at the mesopause during the summer, which corresponds to the adiabatic cooling.

Remote Polar Boundary Layer Wind Profiling Using an All-Fiber Pulsed Coherent Doppler Lidar at Zhongshan Station, Antarctica

A compact all-fiber pulsed coherent Doppler lidar (PCDL) for boundary layer wind measurement was developed by the Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences). It has been deployed at Zhongshan Station (69.4° S, 76.4° E) during the 2020 austral summer season by the 36th Chinese National Antarctic Research Expedition (CHINARE) and started routine observation in January 2020. This system, based on the 1550 nm all-fiber components, employs a 100 mm telescope with a long focal length of 632.6 mm to emit and collect laser pulses. It provides the ability to measure vertically resolved wind fields with a spatial resolution of 30 m and a temporal resolution of 1 min; the maximum detection range is up to 1.5 km in Antarctica. Wind speed and direction inversion methods were introduced subsequently. Preliminary measurement results of wind profiles indicate that this Doppler lidar can be operated successfully in Antarctica. The synchronous observations between the lidar, anemometer, and radiosondes at Zhongshan station are presented and have good consistency with each other. The comparison results between the lidar and anemometer indicate a root mean square deviation (RMSD) of 0.98 m s−1 and 10.55° for wind speed and direction, respectively. The lidar continuous observations of wind profiles provide an opportunity to study the spatiotemporal variation of Antarctic wind with high resolutions, which is useful for further understanding of the atmosphere in Antarctic regions.

Column crossing and lateral transport in numerical weather models

AbstractTransport in numerical weather models is typically restricted to advection by the resolved wind field, and representation of other flow processes relies on forcing or coupling to other models. A discussion of non‐advective transport in numerical weather models is presented and illustrated using two examples. These are the sea breeze and surface water flow. Simple models of these phenomena are represented in an adapted version of the Met Office Unified Model (UM) by means of modifying the existing cold‐pool scheme in the UM. This approach of incorporating different transport processes in one framework could facilitate a better representation of the Earth system, by increasing interaction between meteorological, surface and subsurface processes.

Improving the estimation of ship emissions using the high‐spatiotemporal resolution wind fields simulated by the Weather Research and Forecast model: A case study in China

AbstractShips, sailing in favorable wind or obstructed by wind, will operate with different output power of the engines, and the exhaust emissions will be different even though the ships are sailing at the same ground speed. In this study, the influence of wind was taken into consideration; the ship emission inventory (0.025° × 0.025°) in China of a full year (2014) was reassessed. A speed modification model was employed to figure out the actual output speed of ships by integrating AIS data and the hourly wind. The Weather Research and Forecast (WRF) model was applied to predict the hourly real‐time wind field. The spatial and temporal changes in emissions between the results calculated by the proposed method and our previous study were presented. Overall, when considering the influence of wind, the total ship emissions for the year would increase. In this study, the total estimated emissions of SO2, NOx, PM10, PM2.5, HC, and CO in the area were 1.286 × 106, 2.583 × 106, 2.135× 105, 1.967 × 105, 1.522 × 105, and 3.053 × 105 t(metric tons) in 2014, respectively. Under the influence of wind, the proportion of the regions’ emissions to the total was close to that of the previous study. For SO2 and NOx, emissions presented significant monthly variations. On a monthly timescale, the difference in emissions was more obvious between the results considering and not considering the wind, relative to that on a yearly basis. This study adjusted the method of ship emission estimation, which modified the ship emission inventory over an hourly timescale.

Study of Coastal Effects Relevant for Offshore Wind Energy Using Spaceborne Synthetic Aperture Radar (SAR)

Coastal wind speed gradients relevant for offshore windfarming are analysed based on synthetic aperture radar (SAR) data. The study concentrates on situations with offshore wind directions in the German Bight using SAR scenes from the European satellites Sentinel-1A and Sentinel-1B. High resolution wind fields at 10 m height are derived from the satellite data set and respective horizontal wind speed gradients are investigated up to about 170 km offshore. The wind speed gradients are classified according to their general shape with about 60% of the cases showing an overall increase of wind speeds with growing distance from the coast. About half of the remaining cases show an overall wind speed decrease and the other half a decrease with a subsequent increase at larger distances from the coast. An empirical model is fitted to the horizontal wind speed gradients, which has three main parameters, namely, the wind speed over land, the equilibrium wind speed over sea far offshore, and a characteristic adjustment length scale. For the cases with overall wind speed increase, a mean absolute difference of about 2.6 m/s is found between wind speeds over land and wind speeds far offshore. The mean normalised wind speed increase with respect to the land conditions is estimated as 40%. In terms of wind power density at 10 m height this corresponds to an absolute average growth by 0.3 kW/m2 and a normalised increase by 160%. The distance over which the wind speed grows to 95% of the maximum wind speed shows large variations with maximum above 170 km and a mean of 67 km. The impact of the atmospheric boundary layer stability on horizontal wind speed gradients is investigated using additional information on air and sea temperature differences. The absolute SAR-derived wind speed increase offshore is usually higher in unstable situations and the respective adjustment distance is shorter. Furthermore, we have found atypical cases with a wind speed decrease offshore to be often connected to stable atmospheric conditions. A particular low-level jet (LLJ) situation is analysed in more detail using vertical wind speed profiles from a wind LIDAR system.

Wind‐Topo: Downscaling near‐surface wind fields to high‐resolution topography in highly complex terrain with deep learning

AbstractPredicting wind flow in highly complex terrain like the Alps is a challenge for all models. When physical processes need to be resolved in a spatially explicit manner, grids with high horizontal resolution of a few hundred meters are often required and drastically limit, in many cases, the extent and duration of the simulations. Many surface process models, like the simulation of heterogeneous snow cover across a season, however, need long time series on large domains as inputs. Statistical downscaling can provide the required data, but no model can reach the desired resolutions effectively and provide temporally resolved wind speed and direction on highly complex topography. The assessment of the potential for wind energy in the Alps, a promising player in the energy transition, is an example where the current shortcomings cause strong limitations. We present “Wind‐Topo”, a novel approach based on deep learning that discovers some of the interactions between high‐resolution topography and coarser‐resolution states of the atmosphere to generate near‐surface wind fields with a 50‐m resolution. In our test case, we use a large number of measurement stations in Switzerland to train the model and an operational weather prediction model (COSMO‐1) as predictor. Wind‐Topo employs a custom architecture that analyses the state of the atmosphere on various scales and associates it with high‐resolution topography. A dedicated loss function leads to good scoring metrics as well as accurate wind‐speed distributions at 60 independent stations used for a thorough validation. 50‐m resolution wind fields are generated efficiently and exhibit several expected orographic effects like ridge acceleration, sheltering, and deflection. Furthermore, the bias and mean absolute error from COSMO‐1 at the alpine validation stations, which are 0.72 and 1.77 ms respectively, are reduced to 0.07 and 1.21 ms.

Atmospheric Disturbance Modelling for a Piloted Flight Simulation Study of Airplane Safety Envelope over Complex Terrain

A concept of a new energy management system synthesizing meteorological and orographic influences on airplane safety envelope was developed and implemented at the ZHAW Centre for Aviation. A corresponding flight simulation environment was built in a Research and Didactics Simulator (ReDSim) to test the first implementation of the cockpit display system. A series of pilot-in-the-loop flight simulations were carried out with a group of pilots. A general aviation airplane model Piper PA-28 was modified for the study. The environment model in the ReDSim was modified to include a new ad hoc subsystem simulating atmospheric disturbance. In order to generate highly resolved wind fields in the ReDsim, a well-established large-eddy simulation model, the Parallelized Large-Eddy Simulation (PALM) framework, was used in the concept study, focusing on a small mountainous region in Switzerland, not far from Samedan. For a more realistic representation of specific meteorological situations, PALM was driven with boundary conditions extracted from the COSMO-1 reanalysis of MeteoSwiss. The essential variables (wind components, temperature, and pressure) were extracted from the PALM output and fed into the subsystem after interpolation to obtain the values at any instant and any aircraft position. Within this subsystem, it is also possible to generate statistical atmospheric turbulence based on the widely used Dryden turbulence model. The paper compares two ways of generating atmospheric turbulence, by combining the numerical method with the statistical model and introduces the flight test procedure with an emphasis on turbulence realism; it then presents the experiment results including a statistical assessment achieved by collecting pilot feedback on turbulence characteristics and turbulence/task combination.

Predicting origins of coherent air mass trajectories using a neural network—the case of dry intrusions

AbstractMid‐latitude cyclones are complex weather systems that are tightly related to surface weather impacts. Coherent air streams are known to be associated with such systems, in particular dry intrusions (DIs) in which dry air masses descend slantwise from the vicinity of the tropopause equatorward towards the surface. Often, DIs are associated with severe surface winds, heavy precipitation and frontogenesis. Currently, DIs can only be identified in hindsight by costly Lagrangian calculations using high resolution wind field data. Here, we use a novel method aiming to simplify the detection procedure of DI origins to allow their future identification in climate datasets, previously inaccessible for such diagnostic studies. A novel adaptation of a segmentation‐oriented neural network model is hereby presented as a successful tool to identify DI origins based solely on three ERA‐Interim reanalysis geopotential height fields, representing the state of the atmosphere. The model prediction skill is tested by calculating both the grid‐point and DI object based Matthews correlation coefficient. We find the model highly skilful in both reconstructing accurately the climatological distribution and predicting the vast majority of the individual DI origin objects. The skill decreases for relatively small objects and for objects occurring at locations where such cases are relatively less frequent. This indicates that geopotential height variability is related to the dynamic mechanisms involved in DI initiations. The results serve as a proof of concept for predicting DIs and other coherent air mass trajectories even when high resolution wind field data are not available, such as for model output for future climate projections.

Assessment of Wind Direction Estimation Methods from SAR Images

Wind information on SAR images are essential to characterize a marine environment in offshore or coastal area. More and more applications require high resolution wind field estimation. In this article, classical wind wave direction estimation methods are reviewed as the spectral or gradient approaches. In addition, a way to enhance the spectral method with the Radon transform is proposed. The aim of this document is to determine which method provides greatest results when the resolution grid is finer. Therefore, the methods accuracy, fidelity and uncertainty are compared through a simulation study, a section with RadarSAT2 data in coastal area and another one with Sentinel-1 measurements in offshore area.

High-fidelity simulations and field measurements for characterizing wind fields in a utility-scale wind farm

Characterizing wind farm flow fields at high temporal and spatial resolutions is critical prerequisite for the optimal design and operation of utility-scale wind farms and for reducing the levelized cost of energy. However, due to the large disparity of underlying scales, measurements or simulations alone cannot provide high resolution wind fields, which are informed by and account for the effect of both large scale (i.e. hour, day, month and year) and small scale (i.e. second and minute) site-specific variations in the atmosphere. We explore the feasibility of integrating field measurements and high-fidelity large-eddy simulation (LES) to characterize the wind field in a utility-scale wind farm while accounting for flow phenomena across multiple temporal scales. Specifically, we employ field measurements to characterize the monthly wind speed and wind direction distributions and investigate the wind characteristics in turbine wakes. It was found that the probability density function (PDF) of the wind speed in turbine wakes can be reasonably represented using the Weibull distribution but with shape factors smaller than those not in the wake. LES of the wind farm under statistically steady inflow is subsequently carried out for one wind direction. The LES predictions are compared with the measured data conditionally averaged based on the wind speed, wind direction and the root-mean-square of wind speed fluctuations over time intervals of 30 min. Good agreement is obtained for both mean wind speed and turbulence intensity. The present work shows the possibility of integrating field measurements and high-fidelity simulations for improved characterization of the site-specific wind fields in utility-scale wind farms.

PyDDA: A Pythonic Direct Data Assimilation Framework for Wind Retrievals

This software assimilates data from an arbitrary number of weather radars together with other spatial wind fields (eg numerical weather forecasting model data) in order to retrieve high resolution three dimensional wind fields. PyDDA uses NumPy and SciPy’s optimization techniques combined with the Python Atmospheric Radiation Measurement (ARM) Radar Toolkit (Py-ART) in order to create wind fields using the 3D variational technique (3DVAR). PyDDA is hosted and distributed on GitHub at https://github.com/openradar/PyDDA . PyDDA has the potential to be used by the atmospheric science community to develop high resolution wind retrievals from radar networks. These retrievals can be used for the evaluation of numerical weather forecasting models and plume modelling. This paper shows how wind fields from 2 NEXt generation RADar (NEXRAD) WSR-88D radars and the High Resolution Rapid Refresh can be assimilated together using PyDDA to create a high resolution wind field inside Hurricane Florence. Funding statement: The development of this software is supported by the Climate Model Development and Validation (CMDV) activity which is funded by the Office of Biological and Environmental Research in the US Department of Energy Office of Science.

Full scale rotor blade deformation measurements in comparison with aeroelastic simulations based on measured high-resolution wind fields

Aeroelasticity is one of the biggest challenges in wind turbine rotor design, as the length of rotor blades increases which comes along with a slenderer design. The knowledge of the aeroelastic turbine behavior is of great importance. A comparison to field measurements is of huge importance when validating aeroelastic tools. However, the measurement of deformation and torsion in the field is not trivial and the conduction of realistic post-test simulations is a challenge. One crucial factor for these simulations is the wind field, which needs to be captured in a high spatial and temporal resolution. In this paper, the results of deformation measurements conducted in the field with an optical measurement method called Digital Image Correlation (DIC) on one rotor blade will be shown and compared to aeroelastic post-test simulations using highly resolved wind fields measured with a SpinnerLidar.

Estimativa do campo de vento em alta resolução pelo Modelo Wind Ninja para estimativa em Energia Eólica

In this work it was proposed to predict high resolution wind fields in order to simulate the wind speed and direction variables in the Cerro Chato wind complex located in the city of Santana do Livramento / RS. For this, numerical weather forecasting techniques were used, using the \ textit {Weather Research and Forecasting} (WRF) model and a microscale mass and momentum conservation model, known as Windninja. In this study, the simulated data was compared with the observation data collected by the towers of the wind farm in question, using statistical procedures. The results presented by the Windninja simulation software were efficient, but not very effective.

Comparison of results from two 3D hydrodynamic models with field data: internal seiches and horizontal currents

ABSTRACTModel skills of two 3D hydrodynamic models, ELCOM and Delft3D, were assessed by simulating internal seiches and surface currents and comparing the results with field data in Upper Lake Constance, Germany. Both models were set up using the same horizontal and vertical discretisation and forced by a horizontally resolved wind field. Model simulations were carried out during a stable stratification period in summer. Oscillations of the simulated and the measured isotherms in Lake Überlingen (north basin of Upper Lake Constance) indicated the existence of a Kelvin-type wave with a period of 84 h. The major wave pattern in period and amplitude was consistent between the simulations and the measurements, whereas discrepancies appeared in the phase match. The measured and the simulated vertical velocity structure in the middle of the main basin of Upper Lake Constance showed occurrence of a Poincaré-type wave with a 14 h period. Major oscillations of the velocity structure were captured by both models, and the agreement between the simulations and the measurements was higher in deep layers than in near-surface layers. Model prediction of the near-surface velocities as well as the surface circulation pattern was more accurate under high current velocities during strong winds than under weak winds. This study concluded that both ELCOM and Delft3D were significantly skilled at simulating internal wave motions and surface currents, and there was no significant difference in reproducing the measured lake dynamics between ELCOM and Delft3D.

Using multiple-resolution data in an adaptive simulation for typhoon-induced waves in northwest Pacific Ocean

Due to the very large expanse of warm water in the northwest Pacific Ocean, typhoons are stronger and occur more frequently than hurricanes. In addition, there is usually a lack of unified high-resolution data of wind fields and bathymetry since multiple countries can be influenced by a typhoon. Therefore, we use multiple-resolution data in an adaptive simulation for typhoon-induced waves. Higher-resolution data are obtained from the government of Taiwan and are used for the area around Taiwan. In the other area, lower resolution data are adopted from the National Oceanic and Atmospheric Administration of the United States. An adaption criterion is implemented such that the highest resolution numerical grids move with the typhoon in a large-scale simulation. The numerical results obtained by the large-scale simulation with multiple-resolution wind fields are improved over those obtained by a smaller scale simulation with the higher resolution wind field at buoys near Taiwan. In addition, the large-scale simulation also provides results for buoys where the higher resolution wind field is not available. In addition, a speedup of fourfolds by the dynamic adaption model over the partially uniform grid one is demonstrated.

Retrieving horizontally resolved wind fields using multi-static meteor radar observations

Abstract. Recently, the MMARIA (Multi-static, Multi-frequency Agile Radar for Investigations of the Atmosphere) concept of a multi-static VHF meteor radar network to derive horizontally resolved wind fields in the mesosphere–lower thermosphere was introduced. Here we present preliminary results of the MMARIA network above Eastern Germany using two transmitters located at Juliusruh and Collm, and five receiving links: two monostatic and three multi-static. The observations are complemented during a one-week campaign, with a couple of addition continuous-wave coded transmitters, making a total of seven multi-static links. In order to access the kinematic properties of non-homogenous wind fields, we developed a wind retrieval algorithm that applies regularization to determine the non-linear wind field in the altitude range of 82–98 km. The potential of such observations and the new retrieval to investigate gravity waves with horizontal scales between 50–200 km is presented and discussed. In particular, it is demonstrated that horizonal wavelength spectra of gravity waves can be obtained from the new data set.

Complex behaviour in complex terrain - Modelling bird migration in a high resolution wind field across mountainous terrain to simulate observed patterns

Crossing of large ecological barriers, such as mountains, is in terms of energy considered to be a demanding and critical step during bird migration. Besides forming a geographical barrier, mountains have a profound impact on the resulting wind flow. We use a novel framework of mathematical models to investigate the influences of wind and topography on nocturnal passerine bird behaviour, and to assess the energy costs for different flight strategies for crossing the Jura Mountains. The mathematical models include three biological models of bird behaviour: i) wind drift compensation; ii) adaptation of flight height for favourable winds; and, iii) avoidance of obstacles (cross over and/or circumvention of an obstacle following a minimum energy expenditure strategy), which are assessed separately and in combination. Further, we use a mesoscale weather model for high-resolution predictions of the wind fields. We simulate the broad front nocturnal passerine migration for autumn nights with peak migration intensities. The bird densities retrieved from a weather radar are used as the initial intensities and to specify the vertical distributions of the simulated birds. It is shown that migration over complex terrain represents the most expensive flight option in terms of energy expenditure, and wind is seen to be the main factor that influences the energy expenditure in the bird's preferred flight direction. Further, the combined effects of wind and orography lead to a high concentration of migratory birds within the favourable wind conditions of the Swiss lowlands and north of the Jura Mountains.

South China Sea Wave Characteristics under Combined Wind Forcing of Typhoon and Winter Monsoon

Since monsoon winds prevail in South China Sea (SCS), SCS is unique for investigating wave characteristics during a typhoon’s passage in conjunction with steady monsoon wind forcing. This study investigated SCS wave characteristics using Wave Watch III, the third-generation wave model with winter typhoon forcing. The model was forced by a high resolution wind field from NASA’s Cross Calibrated Multi Platform (CCMP) ocean surface winds combined with the tropical cyclone wind model. The Wave Watch III model was evaluated using Jason-2 altimetry observations during the period of Typhoon Durian (2006).

Evaluation of wind induced currents modeling along the Southern Caspian Sea

To improve our understanding of the Caspian Sea hydrodynamics, its circulation is simulated with special focus on wind-driven currents of its southern basin. The hydrodynamic models are forced with a newly developed fine resolution wind field to increase the accuracy of current modeling. A 2D shallow water equation model and a 3D baroclinic model are applied separately to examine the performance of each model for specific applications in the Caspian Sea. The model results are validated against recent field measurements including AWAC and temperature observations in the southern continental shelf region. Results show that the 2D model is able to well predict the depth-averaged current speed in storm conditions in narrow area of southern coasts. This finding suggests physical oceanographers apply 2D modeling as a more affordable method for extreme current speed analysis at the continental shelf region. On the other hand the 3D model demonstrates a better performance in reproducing monthly mean circulation and hence is preferable for surface circulation of Caspian Sea. Monthly sea surface circulation fields of the southern basin reveal a dipole cyclonic-anticyclonic pattern, a dominant eastward current along the southern coasts which intensifies from May to November and a dominant southward current along the eastern coasts in all months except February when the flow is northward. Monthly mean wind fields exhibit two main patterns including a north-south pattern occurring at warm months and collision of two wind fronts especially in the cold months. This collision occurs on a narrow region at the southern continental shelf regions. Due to wind field complexities, it leads to a major source of uncertainty in predicting the wind-driven currents. However, this source of uncertainty is significantly alleviated by applying a fine resolution wind field.