scholarly journals Wind climate of the Melbourne metropolitan area

2021 ◽  
Vol 133 (2) ◽  
pp. 82
Author(s):  
J. D. Holmes
Keyword(s):  
Surface Roughness ◽  
Metropolitan Area ◽  
Roughness Length ◽  
Probability Distributions ◽  
Open Water ◽  
Wind Data ◽  
Surface Roughness Length ◽  
Average Wind ◽  
Mean Wind Speed ◽  
Wind Climate

This paper describes a probabilistic analysis of data recorded by the Bureau of Meteorology (BoM) for the wind climate of the Melbourne metropolitan area. It is based on 10-minute average wind data from four automatic weather stations (AWS) ‒ at Melbourne and Essendon airports, Fawkner Beacon in Port Phillip Bay, and Moorabbin Airport. Corrections to the data were made to adjust to standard terrain conditions and height. For the land stations, these were based on estimates of the surface roughness length at each site as a function of wind direction, making use of recorded gust factors. For the Fawkner Beacon, which is completely surrounded by open water, the surface roughness length is a function of mean wind speed, and the Charnock relationship was used in determining the corrections. For each station the terrain-corrected wind data were fitted with Weibull probability distributions, as an all-direction group and for sixteen direction sectors. Directional probabilities were also determined. The parameters of the all-direction Weibull distributions are very similar for all four stations, but there are differences in directional probabilities for some directions, with a geographic trend from north to south in the region being apparent. Some possible explanations based on the general topography are given.

scholarly journals The making of the New European Wind Atlas – Part 1: Model sensitivity

2020 ◽  
Vol 13 (10) ◽  
pp. 5053-5078 ◽  
Author(s):  
Andrea N. Hahmann ◽  
Tija Sīle ◽  
Björn Witha ◽  
Neil N. Davis ◽  
Martin Dörenkämper ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Wind Speed ◽  
Planetary Boundary Layer ◽  
Roughness Length ◽  
Wrf Model ◽  
Model Sensitivity ◽  
Surface Roughness Length ◽  
Wind Climate ◽  
Physical Parameterizations

Abstract. This is the first of two papers that document the creation of the New European Wind Atlas (NEWA). It describes the sensitivity analysis and evaluation procedures that formed the basis for choosing the final setup of the mesoscale model simulations of the wind atlas. The suitable combination of model setup and parameterizations, bound by practical constraints, was found for simulating the climatology of the wind field at turbine-relevant heights with the Weather Research and Forecasting (WRF) model. Initial WRF model sensitivity experiments compared the wind climate generated by using two commonly used planetary boundary layer schemes and were carried out over several regions in Europe. They confirmed that the most significant differences in annual mean wind speed at 100 m a.g.l. (above ground level) mostly coincide with areas of high surface roughness length and not with the location of the domains or maximum wind speed. Then an ensemble of more than 50 simulations with different setups for a single year was carried out for one domain covering northern Europe for which tall mast observations were available. We varied many different parameters across the simulations, e.g. model version, forcing data, various physical parameterizations, and the size of the model domain. These simulations showed that although virtually every parameter change affects the results in some way, significant changes in the wind climate in the boundary layer are mostly due to using different physical parameterizations, especially the planetary boundary layer scheme, the representation of the land surface, and the prescribed surface roughness length. Also, the setup of the simulations, such as the integration length and the domain size, can considerably influence the results. We assessed the degree of similarity between winds simulated by the WRF ensemble members and the observations using a suite of metrics, including the Earth Mover's Distance (EMD), a statistic that measures the distance between two probability distributions. The EMD was used to diagnose the performance of each ensemble member using the full wind speed and direction distribution, which is essential for wind resource assessment. We identified the most realistic ensemble members to determine the most suitable configuration to be used in the final production run, which is fully described and evaluated in the second part of this study (Dörenkämper et al., 2020).

scholarly journals The Making of the New European Wind Atlas, Part 1: Model Sensitivity

2020 ◽  
Author(s):  
Andrea N. Hahmann ◽  
Tija Sile ◽  
Björn Witha ◽  
Neil N. Davis ◽  
Martin Dörenkämper ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Wind Speed ◽  
Planetary Boundary Layer ◽  
Land Surface ◽  
Roughness Length ◽  
Wrf Model ◽  
Model Sensitivity ◽  
Surface Roughness Length ◽  
Wind Climate

Abstract. This is the first of two papers that documents the creation of the New European Wind Atlas (NEWA). It describes the sensitivity analysis and evaluation procedures that formed the basis for choosing the final setup of the mesoscale model simulations of the wind atlas. An optimal combination of model setup and parameterisations was found for simulating the climatology of the wind field at turbine-relevant heights with the Weather Research and Forecasting (WRF) model. Initial WRF model sensitivity experiments compared the wind climate generated by using two commonly used planetary boundary layer schemes and were carried out over several regions in Europe. They confirmed that the largest differences in annual mean wind speed at 100 m above ground level mostly coincide with areas of high surface roughness length and not with the location of the domains or maximum wind speed. Then an ensemble of more than 50 simulations with different setups for a single year was carried out for one domain covering Northern Europe, for which tall mast observations were available. Many different parameters were varied across the simulations, for example, model version, forcing data, various physical parameterisations and the size of the model domain. These simulations showed that although virtually every parameter change affects the results in some way, significant changes on the wind climate in the boundary layer are mostly due to using different physical parameterisations, especially the planetary boundary layer scheme, the representation of the land surface, and the prescribed surface roughness length. Also, the setup of the simulations, such as the integration length and the domain size can considerably influence the results. The degree of similarity between winds simulated by the WRF ensemble members and the observations was assessed using a suite of metrics, including the Earth Mover's Distance (EMD), a statistic that measures the distance between two probability distributions. The EMD was used to diagnose the performance of each ensemble member using the full wind speed distribution, which is important for wind resource assessment. The most realistic ensemble members were identified to determine the most suitable configuration to be used in the final production run, which is fully described and evaluated in the second part of this study.

The Role of Sublimation on the Surface Mass Balance of the Interior Greenland Ice Sheet

2021 ◽  
Author(s):  
Laura Dietrich ◽  
Hans Christian Steen-Larsen ◽  
Cécile Agosta ◽  
Xavier Fettweis ◽  
Anne-Katrine Faber ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Roughness Length ◽  
Ice Core ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Climate Signal ◽  
Surface Mass ◽  
Surface Roughness Length ◽  
Surface Snow ◽  
Precipitation Events

<p>Precipitation along with sublimation and deposition are the main contributors to the surface mass balance (SMB) in the accumulation area of the Greenland Ice Sheet (GrIS). However, precipitation events are rare and intermittent. In between precipitation events the surface snow continuously undergoes sublimation and deposition. Recent studies imply that these surface exchange processes influence the isotopic composition of the surface snow which is later archived as a climate record in ice cores. In order to understand the possible implications on the recorded climate signal, sublimation needs to be quantified on a local scale.</p><p>Here we present simulated SMB components for eight ice core drilling sites on the GrIS using the regional climate model MAR (Modèle Atmosphérique Régional). We validated MAR against in-situ flux observations at the East Greenland Ice Core Project site and found a high sensitivity of sublimation to the downward long wave flux and to the parameterization of the surface roughness length. We propose a surface roughness length optimized for the interior of the GrIS which is supported by our observations.</p><p>Our results show that in the GrIS accumulation area the mass turnover via sublimation and deposition can reach the same order of magnitude as precipitation. This highlights the importance of a better understanding of how the climate signal is imprinted in the surface snow isotopic composition.</p>

Surface roughness length dynamic over several different surfaces and its effects on modeling fluxes

2006 ◽  
Vol 49 (S2) ◽  
pp. 262-272 ◽  
Author(s):  
Yanlian Zhou ◽  
Xiaomin Sun ◽  
Zhilin Zhu ◽  
Renhua Zhang ◽  
Jing Tian ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Roughness Length ◽  
Surface Roughness Length

CORRECTION OF WIND SPEED DATA ACCORDING TO THE OPEN TERRAIN CONDITIONS

2019 ◽  
pp. 131-139
Author(s):  
D.O. Oshurok ◽  
O.Y. Skrynyk
Keyword(s):  
Surface Roughness ◽  
Wind Speed ◽  
Roughness Length ◽  
Pearson Correlation ◽  
Aerodynamic Characteristics ◽  
Google Earth ◽  
Homogeneous Distribution ◽  
Heterogeneous Structure ◽  
Wind Speed Data ◽  
Surface Roughness Length

Wind speed spatial distribution over the territory of Ukraine built based on weather stations measurements has been analyzed. Interpolated field of wind speed averaged over 1981-2010 indicated fairly heterogeneous structure with a number of artificial spots of larger/smaller values compared to surrounding areas. The main reason of such heterogeneity might be associated with representativeness of observation site regarding the landscape zone. It is well known that surrounding obstacles have a great impact on wind flow in horizontal direction. In order to solve this problem we have corrected sub-daily wind speed data measured at 207 meteorological stations of Ukraine for the period of 1981-2010 according to the open terrain conditions and the standard height (10 m). Generally, aerodynamic characteristics (e.g. surface roughness length) of measurement sites are needed in order to perform such adjustment. However, the only usable parameter available at a climatological reference book is horizon closure degree. The research revealed significant relationship between this characteristic and wind speed records (Pearson correlation coefficient equals -0.58). Given that horizon closure degree could not be used in correction procedure directly, surface roughness length has been calculated for 10 stations and statistical relationship has been determined between these two parameters. Based on the obtained relation and additional information we have found roughness length for all 207 stations at eight directions. Supplementary materials for analysis included observation sites description and Google Earth snapshots as well. In the final step, there has been applied a correction formula derived from the neutral logarithmic profile of wind speed in the atmospheric surface layer. The output of the research is new database of corrected wind speed measurements for the multiyear period. These results have been compared with observations. Mean 30-yr corrected speeds are featured by more homogeneous distribution over Ukraine and mostly higher values (with positive mean spatial bias ~0.35 m/s). The applied method allowed us to remove uncertainties related to differences in vertical level of measurements and considerably eliminate influence of the micro-scale terrain inhomogeneity. Obtained datasets may facilitate to perform spatial interpolation and further development of Ukrainian Wind Atlas.

scholarly journals Land Cover Change Effects on the Climate of the La Plata Basin

2012 ◽  
Vol 13 (1) ◽  
pp. 84-102 ◽  
Author(s):  
Seung-Jae Lee ◽  
Ernesto Hugo Berbery
Keyword(s):  
Surface Roughness ◽  
Land Cover ◽  
Surface Temperature ◽  
River Basin ◽  
Land Surface ◽  
Roughness Length ◽  
Sensible Heat Flux ◽  
Near Surface ◽  
La Plata ◽  
Surface Roughness Length

Abstract Deforestation and replacement of natural pastures by agriculture have become a common practice in the La Plata River basin in South America. The changes in land cover imply changes in the biophysical properties of the land surface, with possible impacts on the basin’s hydroclimate. To help understand to what extent the climate could be affected, and through which processes, ensembles of seasonal simulations were prepared using the Weather Research and Forecasting Model for a control case and a scenario assuming an expansion of the agricultural activities to cover the entire basin. The La Plata River basin shows different climate responses to the land cover changes depending on the region. The northern part of the basin, where forests and savanna were replaced by crops, experiences an overall increase in albedo that leads to a reduction of sensible heat flux and near-surface temperature. A reduction of surface roughness length leads to stronger low-level winds that, in turn, favor a larger amount of moisture being advected out of the northern part of the basin. The result is a reduction of the vertically integrated moisture flux convergence (VIMFC) and, consequently, in precipitation. In the southern part of the basin, changes from grasslands to crops reduce the albedo and thus increase the near-surface temperature. The reduction in surface roughness length is not as large as in the northern sector, reducing the northerly moisture fluxes and resulting in a net increase of VIMFC and, thus, in precipitation. Notably, advective processes modify the downstream circulation and precipitation patterns over the South Atlantic Ocean.

scholarly journals Impact of Urban Surface Roughness Length Parameterization Scheme on Urban Atmospheric Environment Simulation

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Meichun Cao ◽  
Zhaohui Lin
Keyword(s):  
Surface Roughness ◽  
Roughness Length ◽  
Urban Morphology ◽  
Atmospheric Environment ◽  
Urban Surface ◽  
Parameterization Scheme ◽  
Roughness Parameters ◽  
Surface Roughness Length ◽  
Environment Simulation ◽  
The Impact

In this paper, the impact of urban surface roughness lengthz0parameterization scheme on the atmospheric environment simulation over Beijing has been investigated through two sets of numerical experiments using the Weather Research and Forecasting model coupled with the Urban Canopy Model. For the control experiment (CTL), the urban surfacez0parameterization scheme used in UCM is the model default one. For another experiment (EXP), a newly developed urban surfacez0parameterization scheme is adopted, which takes into account the comprehensive effects of urban morphology. The comparison of the two sets of simulation results shows that all the roughness parameters computed from the EXP run are larger than those in the CTL run. The increased roughness parameters in the EXP run result in strengthened drag and blocking effects exerted by buildings, which lead to enhanced friction velocity, weakened wind speed in daytime, and boosted turbulent kinetic energy after sunset. Thermal variables (sensible heat flux and temperature) are much less sensitive toz0variations. In contrast with the CTL run, the EXP run reasonably simulates the observed nocturnal low-level jet. Besides, the EXP run-simulated land surface-atmosphere momentum and heat exchanges are also in better agreement with the observation.

scholarly journals Sensitivity Analysis of the High-Resolution WISE-WRF Model with the Use of Surface Roughness Length in Seoul Metropolitan Areas

Atmosphere ◽  
2016 ◽  
Vol 26 (1) ◽  
pp. 111-126 ◽  
Author(s):  
Joon-Bum Jee ◽  
Min Jang ◽  
Chaeyeon Yi ◽  
Il-Sung Zo ◽  
Bu-Yo Kim ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Surface Roughness ◽  
High Resolution ◽  
Roughness Length ◽  
Metropolitan Areas ◽  
Wrf Model ◽  
Surface Roughness Length
Sign in / Sign up

Export Citation Format

Share Document