Global Wind Atlas v3

The Global Wind Atlas version 3 data-sets contain microscale wind information at approximately 250m grid point spacing.<br>The data is created by first dynamically down-scaling ERA5 reanalysis data from 2008-2017 to 3km resolution using the WRF mesoscale model.<br>The WRF results are then generalized using DTU's generalization methodology, and then down-scaled using the WAsP model to the final 250m resolution.<br>The data in this directory consist of the entire global tiff at the full 0.0025 degree resolution on the WGS84 map projection. These data also include four sets of overview pyramids to improve the viewing of the data at low resolution.<br>Most of the data are named as follows: gwa_{variable}_{height}.tif, where variable is one of<br>* <b>wind-speed</b> - The mean wind speed at the location for the 10 year period<br><br>* <b>power-density</b> - The mean power density of the wind, which is related to the cube of the wind speed, and can provide additional information about the strength of the wind not found in the mean wind speed alone.<br>* <b>combined-Weibull-A</b> and <b>combined-Weibull-k</b> - These are the all sector combined Weibull distribution parameters for the wind speed. They can be used to get an estimate of the wind speed and power density at a site. However, caution should be applied when using these in areas with wind speeds that come from multiple directions as the shapes of those individual distributions may be quite different than this combined distribution.<br>* <b>air-density</b> - The air density is found by interpolating the air density from the CFSR reanalysis to the elevation used in the global wind atlas following the approach described in WAsP 12.<br>* <b>RIX</b> - The RIX (Ruggedness IndeX) is a measure of how complex the terrain is. It provides the percent of the area within 10 km of the position that have slopes over 30-degrees. A RIX value greater than 5 suggests that you should use caution when interpreting the results.<br>The files which do not follow the naming convention above are the <b>capacity-factor</b> layers. The capacity factor layers were calculated for 3 distinct wind turbines, with 100m hub height and rotor diameters of 112, 126, and 136m, which fall into three IEC Classes (IEC1, IEC2, and IEC3). Capacity factors can be used to calculate a preliminary estimate of the energy yield of a wind turbine (in the MW range), when placed at a location. This can be done by multiplying the rated power of the wind turbine by the capacity factor for the location (and the number of hours in a year): <br><br>AEP = P_rated*CF*8760 hr/year, <br><br>where AEP is annual energy production, P_rated is rated power, and CF is capacity factor.<br>

全球风能地图集（Global Wind Atlas）第3版数据集包含间距约250米的网格点微尺度风能信息。
该数据集的制作流程如下：首先利用WRF中尺度模式，对2008-2017年的ERA5再分析数据进行动态降尺度处理，将分辨率细化至3千米；随后采用丹麦技术大学（DTU）的泛化方法对WRF输出结果进行泛化，再通过WAsP模型进一步降尺度，最终得到分辨率为250米的最终数据。
本目录下的数据包含采用WGS84地图投影、全分辨率为0.0025度的全球TIFF文件，同时附带四组概览金字塔图层，以提升低分辨率场景下的数据浏览体验。

多数数据文件遵循如下命名规则：gwa_{变量}_{高度}.tif，其中变量包含以下类型：
* **风速（wind-speed）**：该点位在10年研究周期内的平均风速；
* **功率密度（power-density）**：风能的平均功率密度，其数值与风速的三次方成正比，可提供仅通过平均风速无法获取的风能强度补充信息；
* **组合威布尔参数A（combined-Weibull-A）与组合威布尔参数k（combined-Weibull-k）**：为全扇区合并后的风速威布尔分布参数，可用于估算某点位的风速与功率密度。需注意：若区域内风速来自多个方向，各方向的风速分布形态可能与该合并分布存在显著差异，使用时需谨慎；
* **空气密度（air-density）**：按照WAsP 12中描述的方法，将CFSR再分析数据的空气密度插值至全球风能地图集所用的高程后得到的数值；
* **地形粗糙度指数（RIX，Ruggedness Index）**：用于表征地形复杂程度的指标，统计点位周边10千米范围内坡度超过30度的区域占比。当RIX值大于5时，建议对该区域的分析结果持谨慎态度。

不遵循上述命名规则的文件为**容量因子（capacity-factor）**图层。该图层针对3款不同的风力发电机组计算得到：轮毂高度均为100米，叶轮直径分别为112米、126米与136米，对应三类IEC风力发电机组等级（IEC1、IEC2与IEC3）。容量因子可用于估算某点位处兆瓦级风力发电机组的年发电量，计算方式为将风电机组额定功率、该点位的容量因子与年总小时数（8760小时）相乘：

AEP = P_rated × CF × 8760 小时/年

其中AEP为年发电量，P_rated为风电机组额定功率，CF为容量因子。