{"title":"A Model for Low-Frequency, Anisotropic Wind Fluctuations and Coherences in the Marine Atmosphere","authors":"Abdul Haseeb Syed, Jakob Mann","doi":"10.1007/s10546-023-00850-w","DOIUrl":"https://doi.org/10.1007/s10546-023-00850-w","url":null,"abstract":"<p>To assess dynamic loads, large offshore wind turbines need detailed and reliable statistical information on the inflow turbulence. We present a model that includes low frequencies down to <span>(sim 1)</span> hr<span>(^{-1})</span> using the observed <span>(S(f) propto f^{-5/3})</span> in that range. The presented model contains a parameter representing the anisotropy of the two-dimensional, incompressible turbulence, and it assumes the low-frequency fluctuations to be homogeneous in the vertical direction. Combined with a three-dimensional model for the smaller scales, the model can predict correlations between different points. We have validated the model against two offshore wind data sets: a nacelle-mounted, forward-looking Doppler lidar with four beams at the Hywind Scotland offshore wind farm and sonic anemometer measurements at the FINO1 research platform in the North Sea. One-point auto spectra and two-point cross spectra were calculated after splitting the data into different atmospheric stability classes. The relative strength of the 2D low-frequency fluctuations to the 3D fluctuations was higher under stable conditions. The combined 2D+3D model was able to fit the measured spectra with good accuracy and could then predict the two-point cross spectra, co-coherences, and phase angles between wind fluctuations at different lateral and vertical separations. Good agreement was found between the measured and predicted values, albeit with exceptions. The model can generate stochastic wind fields for investigating wake meandering in wind farms or dynamic loads on floating wind turbines.</p>","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"30 1","pages":""},"PeriodicalIF":4.3,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139421832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laura Mack, Terje Koren Berntsen, Nikki Vercauteren, Norbert Pirk
{"title":"Transfer Efficiency and Organization in Turbulent Transport over Alpine Tundra.","authors":"Laura Mack, Terje Koren Berntsen, Nikki Vercauteren, Norbert Pirk","doi":"10.1007/s10546-024-00879-5","DOIUrl":"10.1007/s10546-024-00879-5","url":null,"abstract":"<p><p>The exchange of momentum, heat and trace gases between atmosphere and surface is mainly controlled by turbulent fluxes. Turbulent mixing is usually parametrized using Monin-Obukhov similarity theory (MOST), which was derived for steady turbulence over homogeneous and flat surfaces, but is nevertheless routinely applied to unsteady turbulence over non-homogeneous surfaces. We study four years of eddy-covariance measurements at a highly heterogeneous alpine valley site in Finse, Norway, to gain insights into the validity of MOST, the turbulent transport mechanisms and the contributing coherent structures. The site exhibits a bimodal topography-following flux footprint, with the two dominant wind sectors characterized by organized and strongly negative momentum flux, but different anisotropy and contributions of submeso-scale motions, leading to a failure of eddy-diffusivity closures and different transfer efficiencies for different scalars. The quadrant analysis of the momentum flux reveals that under stable conditions sweeps transport more momentum than the more frequently occurring ejections, while the opposite is observed under unstable stratification. From quadrant analysis, we derive the ratio of the amount of disorganized to organized structures, that we refer to as organization ratio (OR). We find an invertible relation between transfer efficiency and corresponding organization ratio with an algebraic sigmoid function. The organization ratio further explains the scatter around scaling functions used in MOST and thus indicates that coherent structures modify MOST. Our results highlight the critical role of coherent structures in turbulent transport in heterogeneous tundra environments and may help to find new parametrizations for numerical weather prediction or climate models.</p>","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"190 9","pages":"38"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11358334/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142104270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sergi González-Herrero, Armin Sigmund, Michael Haugeneder, Océane Hames, Hendrik Huwald, Joel Fiddes, Michael Lehning
{"title":"Using the Sensible Heat Flux Eddy Covariance-Based Exchange Coefficient to Calculate Latent Heat Flux from Moisture Mean Gradients Over Snow.","authors":"Sergi González-Herrero, Armin Sigmund, Michael Haugeneder, Océane Hames, Hendrik Huwald, Joel Fiddes, Michael Lehning","doi":"10.1007/s10546-024-00864-y","DOIUrl":"https://doi.org/10.1007/s10546-024-00864-y","url":null,"abstract":"<p><p>In absence of the high-frequency measurements of wind components, sonic temperature and water vapour required by the eddy covariance (EC) method, Monin-Obukhov similarity theory (MOST) is often used to calculate heat fluxes. However, MOST requires assumptions of stability corrections and roughness lengths. In most environments and weather situations, roughness length and stability corrections have high uncertainty. Here, we revisit the modified Bowen-ratio method, which we call C-method, to calculate the latent heat flux over snow. In the absence of high-frequency water vapour measurements, we use sonic anemometer data, which have become much more standard. This method uses the exchange coefficient for sensible heat flux to estimate latent-heat flux. Theory predicts the two exchange coefficients to be equal and the method avoids assuming roughness lengths and stability corrections. We apply this method to two datasets from high mountain (Alps) and polar (Antarctica) environments and compare it with MOST and the three-layer model (3LM). We show that roughness length has a great impact on heat fluxes calculated using MOST and that different calculation methods over snow lead to very different results. Instead, the 3LM leads to good results, in part due to the fact that it avoids roughness length assumptions to calculate heat fluxes. The C-method presented performs overall better or comparable to established MOST with different stability corrections and provides results comparable to the direct EC method. An application of this method is provided for a new station installed in the Pamir mountains.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1007/s10546-024-00864-y.</p>","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"190 5","pages":"24"},"PeriodicalIF":4.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11068579/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140853132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Matthias Henkies, Knut Vilhelm Høyland, Aleksey Shestov, Christiane Duscha, Anna Sjöblom
{"title":"The Arctic Fjord Breeze: Characteristics of a Combined Sea Breeze and Valley Wind in a Svalbard Fjord Valley","authors":"Matthias Henkies, Knut Vilhelm Høyland, Aleksey Shestov, Christiane Duscha, Anna Sjöblom","doi":"10.1007/s10546-023-00840-y","DOIUrl":"https://doi.org/10.1007/s10546-023-00840-y","url":null,"abstract":"<p>Thermally-driven circulations are a frequent meteorological phenomenon in complex Arctic terrain, but the Arctic fjord breeze, a combined sea-breeze and up-valley wind, has received little attention. A field campaign was conducted in the valley Adventdalen in Svalbard in summer 2022 using a Scanning Doppler Lidar and automatic weather stations. It is shown that a local up-valley circulation occurred frequently in this valley, and that it was driven by the temperature and pressure gradient between valley and fjord, i.e., a fjord breeze. The fjord breeze existed in both large-scale up-valley and down-valley winds. Its strength, extent and depth varied due to the diurnal cycle of solar irradiation as well as the interaction with large-scale winds. In contrast to typical lower-latitude breezes, the Arctic fjord breeze could persist over several days. The breeze was found to be relatively strong even under small horizontal temperature contrasts and opposing large-scale winds, possibly due to an increase in the thermal pressure gradient by the surrounding topography.\u0000</p>","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"5 1","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138556880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Surface Energy Budget of a Wheat Crop: Estimates of Storage","authors":"J. R. Garratt","doi":"10.1007/s10546-023-00834-w","DOIUrl":"https://doi.org/10.1007/s10546-023-00834-w","url":null,"abstract":"<p>The residual found by Garratt and Pearman (2020, Boundary-Layer Meteorology 177: 613–641) in the surface energy budget of a winter wheat crop is the result of combining seven separately measured or estimated individual fluxes, each with its own uncertainty. We show that the mean hourly residual as it varies through the day is closely correlated with the rate-of-change of radiative surface temperature. Using the latter as a basis for estimating the hourly storage closes the budget to within 5% of the incident broadband shortwave irradiance, down from 10% when storage is excluded. The storage so calculated both agrees with estimates for a maize crop (Hicks et al. 2020, Agricultural and Forest Meteorology 290: 108035) and with theoretical considerations. However, for storage calculations in the field, soil and canopy temperatures are preferable to surface temperature.</p>","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"85 1","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138524488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Performance of GRAMM-SCI and WRF in Simulating the Surface-Energy Budget and Thermally Driven Winds in an Alpine Valley","authors":"Gaspard Simonet, Dietmar Oettl, Manuela Lehner","doi":"10.1007/s10546-023-00835-9","DOIUrl":"https://doi.org/10.1007/s10546-023-00835-9","url":null,"abstract":"Abstract Using WRF as a benchmark, GRAMM-SCI simulations are performed for a case study of thermally driven valley- and slope winds in the Inn Valley, Austria. A clear-sky, synoptically undisturbed day was selected when large spatial heterogeneities occur in the components of the surface-energy budget driven by local terrain and land-use characteristics. The models are evaluated mainly against observations from four eddy-covariance stations in the valley. While both models are able to capture the main characteristics of the surface-energy budget and the locally driven wind field, a few overall deficiencies are identified: (i) Since the surface-energy budget is closed in the models, whereas large residuals are observed, the models generally tend to overestimate the daytime sensible and latent heat fluxes. (ii) The partitioning of the available energy into sensible and latent heat fluxes remains relatively constant in the simulations, whereas the observed Bowen ratio decreases continuously throughout the day because of a temporal shift between the maxima in sensible and latent heat fluxes, which is not captured by the models. (iii) The comparison between model results and observations is hampered by differences between the real land use and the vegetation type in the model. Recent modifications of the land-surface scheme in GRAMM-SCI improve the representation of nighttime katabatic winds over forested areas, reducing the modeled wind speeds to more realistic values.","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"17 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135092366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Investigation of a Geometric Parameter Corresponding to the Turbulent Length Scale Within an Urban Canopy Layer","authors":"Takuto Sato, Hiroyuki Kusaka","doi":"10.1007/s10546-023-00832-y","DOIUrl":"https://doi.org/10.1007/s10546-023-00832-y","url":null,"abstract":"","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136102628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Matthew Coburn, Christina Vanderwel, Steven Herring, Zheng-Tong Xie
{"title":"Impact of Local Terrain Features on Urban Airflow","authors":"Matthew Coburn, Christina Vanderwel, Steven Herring, Zheng-Tong Xie","doi":"10.1007/s10546-023-00831-z","DOIUrl":"https://doi.org/10.1007/s10546-023-00831-z","url":null,"abstract":"Abstract Past work has shown that coupling can exist between atmospheric air flows at street scale (O(0.1 km)) and city scale (O(10 km)). It is generally impractical at present to develop high-fidelity urban simulations capable of capturing such effects. This limitation imposes a need to develop better parameterisations for meso-scale models but an information gap exists in that past work has generally focused on simplified urban geometries and assumed the buildings to be on flat ground. This study aimed to begin to address this gap in a systematic way by using the large eddy simulation method with synthetic turbulence inflow boundary conditions to simulate atmospheric air flows over the University of Southampton campus. Both flat and realistic terrains were simulated, including significant local terrain features, such as two valleys with a width about 50 m and a depth about average building height, and a step change of urban roughness height. The numerical data were processed to obtain averaged vertical profiles of time-averaged velocities and second order turbulence statistics. The flat terrain simulation was validated against high resolution particle image velocimetry data, and the impact of uncertainty in defining the turbulence intensity in the synthetic inflow method was assessed. The ratio between realistic and flat terrains of time-mean streamwise velocity at the same ground level height over a terrain crest location can be >2, while over a valley trough it can be <0.5. Further data analysis conclusively showed that the realistic terrain can have a considerable effect on global quantities, such as the depth of the spanwise-averaged internal boundary layer and spatially-averaged turbulent kinetic energy. These highlight the potential impact that local terrain features (O(0.1 km)) may have on near-field dispersion and the urban micro-climate.","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135853106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abhishek Mishra, Marco Placidi, Matteo Carpentieri, Alan Robins
{"title":"Wake Characterization of Building Clusters Immersed in Deep Boundary Layers","authors":"Abhishek Mishra, Marco Placidi, Matteo Carpentieri, Alan Robins","doi":"10.1007/s10546-023-00830-0","DOIUrl":"https://doi.org/10.1007/s10546-023-00830-0","url":null,"abstract":"Abstract Wind tunnel experiments were conducted to understand the effect of building array size ( N ), aspect ratio ( AR ), and the spacing between buildings ( $$W_S$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>S</mml:mi> </mml:msub> </mml:math> ) on the mean structure and decay of their wakes. Arrays of size 3 $$times $$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mo>×</mml:mo> </mml:math> 3, 4 $$times $$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mo>×</mml:mo> </mml:math> 4,and 5 $$times $$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mo>×</mml:mo> </mml:math> 5, AR = 4, 6, and 8, and $$W_S$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>S</mml:mi> </mml:msub> </mml:math> = 0.5 $$W_B$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>B</mml:mi> </mml:msub> </mml:math> , 1 $$W_B$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>B</mml:mi> </mml:msub> </mml:math> , 2 $$W_B$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>B</mml:mi> </mml:msub> </mml:math> and 4 $$W_B$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>B</mml:mi> </mml:msub> </mml:math> (where $$W_B$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>B</mml:mi> </mml:msub> </mml:math> is the building width) were considered. Three different wake regimes behind the building clusters were identified: near-, transition-, and far-wake regimes. The results suggest that the spatial extent of these wake regimes is governed by the overall array width ( $$W_A$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>A</mml:mi> </mml:msub> </mml:math> ). The effects of individual buildings are observed to be dominant in the near-wake regime ( $$0<x/W_A< {0.45}$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:mn>0</mml:mn> <mml:mo><</mml:mo> <mml:mi>x</mml:mi> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>A</mml:mi> </mml:msub> <mml:mo><</mml:mo> <mml:mrow> <mml:mn>0.45</mml:mn> </mml:mrow> </mml:mrow> </mml:math> ) where individual wakes appear behind each building. These wakes are observed to merge in the transition-wake region ( $${0.45}< x/W_A < 1.5$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:mrow> <mml:mn>0.45</mml:mn> </mml:mrow> <mml:mo><</mml:mo> <mml:mi>x</mml:mi> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>W</mml:mi> <mml:mi>A</mml:mi> </mml:msub> <mml:mo><</mml:mo> <mml:mn>1.5</mml:mn> </mml:mrow> </mml:math> ), forming a combined wake in which the individual contributions are no longer apparent. In the far-wake regime ( $$x/W_A > 1.5$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML","PeriodicalId":9153,"journal":{"name":"Boundary-Layer Meteorology","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135592233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}