Very High-Resolution Gridded Climate Data for Djebel Aïssa National Park (SW Algeria) Derived via Downscaling of WorldClim v2.1 Using GAM and Random Forest

This dataset provides very high-resolution climatic data for Djebel Aïssa National Park, located in southwestern Algeria. It was produced by downscaling WorldClim version 2.1 data (1 km resolution) using a hybrid statistical approach that combines Generalised Additive Models (GAM) and Random Forests (RF) to enhance spatial resolution. The downscaling process integrates local topographic variables derived from the ALOS PALSAR Digital Elevation Model (12.5 m resolution) to improve the accuracy of precipitation estimates across complex terrain. To further improve reliability, bias correction was applied. Precipitation data were corrected using quantile mapping based on a gamma distribution, with reference values extrapolated from a lapse rate gradient to better capture altitudinal variability. Temperature data were corrected using a non-parametric quantile mapping approach, aligning the empirical distributions of modelled and extrapolated values. These corrections reduce systematic biases and improve consistency with observed local climate conditions, thereby enhancing the dataset’s suitability for fine-scale ecological, hydrological, and climate impact studies.All R scripts used to generate and process these data are provided in an accompanying R Markdown (.Rmd) file and compiled PDF report, ensuring full transparency and reproducibility of the workflow. Dataset details: Geographic coverage: Djebel Aissa National Park, SW-Algeria Data source: Downscaled WorldClim Version 2.1 Temporal resolution: 1970-2000. Spatial resolution: 12.5 m spatial resolution. Coordinate reference system: WGS 84 (EPSG: 4326) Format: GeoTIFF (.tif) files Usage: This data can be used for climatic modeling, ecological studies, and environmental monitoring, particularly for studies related to vegetation dynamics, hydrology, and climate change impacts within Djebel Aissa National Park. Precipitation Variables Monthly Precipitation Format: 12 rasters (.tif) Unit: millimetres (mm) Description: Total precipitation per month. Annual Precipitation Format: Single raster Calculation: Sum of all 12 monthly precipitation rasters. Temperature Variables Monthly Minimum Temperature (Tmin) Format: 12 rasters (tif) Unit: Degrees Celsius (°C) Description: Minimum temperature for each month. Monthly Maximum Temperature (Tmax) Format: 12 raster (tif) Unit: Degrees Celsius (°C) Description: Maximum temperature for each month. Monthly Average Temperature (Tavg) Format: 12 raster (tif) Calculation: (Tmax+Tmin)/2 Description: Average monthly temperature. Annual Mean Temperature Format: Single raster (tif) Calculation: Mean of monthly average temperatures本数据集为坐落于阿尔及利亚西南部的杰贝勒艾萨国家公园（Djebel Aïssa National Park）提供超高分辨率气候数据。该数据集通过结合广义加性模型（Generalised Additive Models, GAM）与随机森林（Random Forests, RF）的混合统计方法，对分辨率为1千米的WorldClim 2.1版（WorldClim Version 2.1）数据进行降尺度处理以提升空间分辨率。降尺度流程整合了来自ALOS PALSAR数字高程模型（Digital Elevation Model, DEM，分辨率12.5米）的局地地形变量，以提升复杂地形区域降水估算的精度。为进一步提升数据可靠性，研究施加了偏差校正步骤：降水数据基于伽马分布的分位数映射法进行校正，参考值通过气温递减率梯度外推得到，以更好地捕捉海拔变异性；气温数据则采用非参数分位数映射法进行校正，使模型模拟值与外推值的经验分布趋于一致。上述校正可降低系统性偏差，提升数据与局地实测气候条件的一致性，从而增强本数据集适用于精细尺度生态、水文及气候影响研究的潜力。用于生成和处理这些数据的全部R脚本均随附于配套的R Markdown（.Rmd）文件与编译完成的PDF报告中，确保研究流程完全透明且可复现。 ### 数据集详情 - 地理覆盖范围：阿尔及利亚西南部杰贝勒艾萨国家公园 - 数据源：降尺度处理后的WorldClim 2.1版数据 - 时间分辨率：1970-2000年 - 空间分辨率：12.5米 - 坐标参考系统：WGS 84（EPSG: 4326） - 数据格式：GeoTIFF（.tif）文件 - 应用场景：该数据可用于气候建模、生态研究与环境监测，尤其适用于杰贝勒艾萨国家公园内的植被动态、水文及气候变化影响相关研究。 ### 降水变量 #### 月度降水 - 格式：12个栅格（.tif）文件 - 单位：毫米（mm） - 描述：月度总降水量 #### 年度总降水 - 格式：单个栅格文件 - 计算方式：12个月度降水栅格的求和值 ### 气温变量 #### 月度最低气温（Tmin） - 格式：12个栅格（.tif）文件 - 单位：摄氏度（°C） - 描述：月度最低气温 #### 月度最高气温（Tmax） - 格式：12个栅格（.tif）文件 - 单位：摄氏度（°C） - 描述：月度最高气温 #### 月度平均气温（Tavg） - 格式：12个栅格（.tif）文件 - 计算方式：(Tmax + Tmin)/2 - 描述：月度平均气温 #### 年度平均气温 - 格式：单个栅格（.tif）文件 - 计算方式：月度平均气温的平均值