CHclim25 - minimum temperature (Tmin)

Minimum air temperature above 2m is derived from daily 1 km resolution gridded dataset from the Swiss federal agency for meteorology and climate (MeteoSwiss) using a downscaling procedure based on local regressions with a 25 m resolution elevation model. Monthly and yearly individual and current average (1981-2010) and future average (2020-2049, 2045-2074, and 2070-2099)<strong> </strong>geoTIFF layers can be downloaded from separate zip files. Future layers are based on the transient daily time series of gridded climate scenarios of temperature at 0.02°D (~2.2 km) provided by the CH2018 initiative. Anomalies between monthly temperature for 1981-2010 and monthly temperature for the future period at 2.2 km were downscaled at 25 m using bilinear interpolation. Anomalies were then added to 1981-2010 average monthly variables. We calculated future climatic layers for 4 GCMs (HADGEM, ECEARTH, MPIESM, and IPSL), 3 time slices (2020-2049, 2045-2074, and 2070-2099) and 3 representative concentration pathways (RCP 2.6, 4.5 and 8.5) The layer files are stored in compressed GeoTIFF format with the “deflate” algorithm with option “predictor2” from the GDAL. This format has a high compression ratio but allows direct import in most GIS softwares. All the maps are projected in the Swiss coordinate system CH 1903+ LV95 (epsg:2056) with a resolution of 25x25m using the extent of the digital height model DHM25 of the Swiss office for topography (swisstopo).2米高度以上的最低气温数据，源自瑞士联邦气象与气候局（MeteoSwiss）发布的逐日1公里分辨率格点数据集，通过基于25米分辨率高程模型的局地回归降尺度方法生成。逐月、逐年的单要素原始数据以及现状平均（1981-2010年）与未来平均（2020-2049、2045-2074及2070-2099年）的GeoTIFF（geoTIFF）图层，可通过独立压缩包下载。未来图层基于CH2018计划提供的0.02°（约2.2公里）分辨率的格点气温气候情景逐日动态时间序列构建。将2.2公里分辨率下1981-2010年月均气温与未来时段月均气温的距平，通过双线性插值法降尺度至25米分辨率。随后将该距平叠加至1981-2010年的月均气候变量中，以此计算得到4种全球气候模式（GCMs，即HADGEM、ECEARTH、MPIESM及IPSL）、3个时段（2020-2049、2045-2074与2070-2099）以及3种典型浓度路径（RCP 2.6、4.5和8.5）下的未来气候图层。图层文件采用GDAL（地理空间数据抽象库）的"deflate"压缩算法及"predictor2"选项，以压缩GeoTIFF格式存储。该格式压缩比高，且可直接导入绝大多数GIS软件中。所有地图均采用瑞士联邦地形局（swisstopo）的DHM25（数字高程模型25）范围，以瑞士坐标系CH 1903+ LV95（epsg:2056）进行投影，分辨率为25×25米。