Drought and aridity hazard data for the National Climate Risk Assessment

Drought and aridity hazard regional change summaries for the National Climate Risk Assessment (NCRA). The drought and aridity hazards have been summarised for boundaries relating to assessments of freshwater and terrestrial natural environments.

Australian Climate Service (ACS) drought and aridity hazard datasets (https://github.com/AusClimateService/hazards-drought)
1. AI - Aridity index
2. SPI3 - Standardised precipitation index 3

Each hazard dataset includes an ensemble of climate models for four global warming levels (GWLs), 1.2, 1.5, 2.0 and 3.0 degrees Celsius, above a pre-industrial mean for 1850 to 1900.

Either the absolute change (difference to GWL1.2) or the relative change (difference to GWL1.2 divided by GWL1.2) was calculated for each of the higher GWLs compared to GWL1.2.

Regions of interest boundaries
1. Australia
2. NCRA regions
3. Aggregate Ecological Groups (AEGs)
4. Combined NCRA regions and AEGs
5. Level 2 drainage basins from the Australian Hydrological Geospatial Fabric (AHGF)
6. Spatially combined AHGF Level 2 drainage basins and hazard dataset grid cells which intersect with perennial drainage lines from the AHGF Network Streams
7. Spatially combined AHGF Level 2 drainage basins and hazard dataset grid cells which intersect with ephemeral drainage lines from AHGF Network Streams

For each hazard/GWL-change combination, a set of statistics (the mean, 10th percentile, 50th percentile, 90th percentile and standard deviation) was calculated for each climate model in the ensemble over the regions of interest areas. From these, the median of each statistic from all the models in the ensemble was calculated.

Collection data files
The outputs are tabular data in comma-separated value (csv) files with one file per hazard/GWL-change combination. The columns are ID and region name that link to the regions of interest boundary datasets for visualising in GIS software, and the medians of the statistics. Rows are the individual region of interest polygons.

本数据集为国家气候风险评估（National Climate Risk Assessment, NCRA）编制的干旱与干旱化灾害区域变化汇总成果。针对淡水与陆地自然环境评估相关的边界范围，已完成干旱与干旱化灾害相关内容的汇总整理。

澳大利亚气候服务局（Australian Climate Service, ACS）干旱与干旱化灾害数据集（https://github.com/AusClimateService/hazards-drought）包含以下两类数据集：
1. AI（Aridity index，干旱指数）
2. SPI3（Standardised precipitation index 3，标准化降水指数3）

各灾害数据集均包含针对4个全球升温阈值（Global Warming Levels, GWLs）的多模式集合气候模型数据集，分别对应较1850-1900年工业化前平均水平升温1.2℃、1.5℃、2.0℃及3.0℃的情景。

针对各较高升温阈值情景，均以升温1.2℃情景为基准，分别计算其绝对变化量（与GWL1.2的差值）与相对变化量（与GWL1.2的差值除以GWL1.2的数值）。

关注区域边界包括：
1. 澳大利亚全境
2. NCRA评估区域
3. 综合生态群（Aggregate Ecological Groups, AEGs）
4. NCRA评估区域与AEGs的叠加范围
5. 澳大利亚水文地理空间结构（Australian Hydrological Geospatial Fabric, AHGF）二级流域
6. 与AHGF网络溪流中的常年径流河道相交的AHGF二级流域与灾害数据集格点的空间叠加范围
7. 与AHGF网络溪流中的季节性径流河道相交的AHGF二级流域与灾害数据集格点的空间叠加范围

针对每一种灾害/升温阈值-变化量组合，针对研究区内的集合气候模型，计算其统计量（均值、10分位数、50分位数、90分位数及标准差）。基于上述计算结果，进一步求取集合内所有模型的各统计量的中位数。

数据集输出文件说明：
输出成果为逗号分隔值（comma-separated value, CSV）格式的表格数据，每一种灾害/升温阈值-变化量组合对应一个单独文件。表格列包含用于关联研究区边界数据集以在地理信息系统（GIS）软件中可视化的ID与区域名称字段，以及各统计量的中位数。表格每一行对应一个研究区多边形。