Global soil type dataset for WRF-ARW model, based on HWSD version 2

Global soil type dataset, based on HWSD ("Harmonized World Soil Database", version 2.0), suitable for meteorological model WRF-ARW.

spatial resolution: 30 arc seconds by 30 arc seconds (about 1km)

original data (HWSD 2.0)

https://s3.eu-west-1.amazonaws.com/data.gaezdev.aws.fao.org/HWSD/HWSD2_RASTER.zip

https://s3.eu-west-1.amazonaws.com/data.gaezdev.aws.fao.org/HWSD/HWSD2_DB.zip

https://gaez.fao.org/pages/hwsd

documentation: Nachtergaele, Freddy, et al. Harmonized world soil database version 2.0. Food and Agriculture Organization of the United Nations, 2023. https://www.fao.org/3/cc3823en/cc3823en.pdf

the original 7 soil layers (0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm, 80–100 cm, 100–150 cm and 150–200 cm) have been remapped to the 2 layers required by WRF (topsoil 0-30 cm, botsoil 30-200 cm)

the original Soil Mapping Units (SMU) have been remapped to the 16 soil categories used by WRF:

the depth-weighted averages of the content of clay, silt and sand lead to 12 texture-based categories (Sand, Loamy sand, Sandy loam, Silt loam, Silt, Loam, Sandy clay loam, Silty clay loam, Clay loam, Sandy clay, Silty clay, Clay), as defined by USDA;

category "Organic material" is assigned where the average content of organic carbon exceeds the threshold of 25%;

where the content of clay, silt and sand is not defined, HWSD special categories are mapped to the WRF last 3 categories, as follows:

"Water bodies" to "Water", 

"Rock outcrops" and "Rocky sublayers" to "Bedrock", 

"Land ice and glaciers", "Dunes/shifting sands", "Salt flats", and "Other" to "Other"

The dataset is provided in two ways:

two global files (SoilType_depth<T>to<B>cm.tif), one for each layer;

16 tiles, 8 for each layer, each covering 90 degrees by 90 degrees (SoilType_depth<T>to<B>cm_lon<W>to<E>deg_lat<S>to<N>deg.tif).

The format of the files is GeoTIFF, compatible with convert_geotiff, a commandline utility for converting data from GeoTIFF to geogrid format used by WRF.

Soil categories are coded as follows

code
category

1
sand

2
loamy sand

3
sandy loam

4
silt loam

5
silt

6
loam

7
sandy clay loam

8
silty clay loam

9
clay loam

10
sandy clay

11
silty clay

12
clay

13
organic material

14
water

15
bedrock

16
other

本数据集为全球土壤类型数据集，基于世界土壤协调数据库（Harmonized World Soil Database, HWSD）2.0版本构建，适配气象模式WRF-ARW。
空间分辨率为30角秒×30角秒（约1km）。

原始数据（HWSD 2.0）
下载地址：
https://s3.eu-west-1.amazonaws.com/data.gaezdev.aws.fao.org/HWSD/HWSD2_RASTER.zip
https://s3.eu-west-1.amazonaws.com/data.gaezdev.aws.fao.org/HWSD/HWSD2_DB.zip
官方站点：https://gaez.fao.org/pages/hwsd
相关文献：Nachtergaele, Freddy, 等. 世界土壤协调数据库2.0版本[R]. 联合国粮食及农业组织, 2023. https://www.fao.org/3/cc3823en/cc3823en.pdf

数据预处理说明
原始数据集包含7层土壤（0–20 cm、20–40 cm、40–60 cm、60–80 cm、80–100 cm、100–150 cm及150–200 cm），已被重映射为WRF所需的2层土壤：表层土（0–30 cm）与底层土（30–200 cm）。
原始土壤制图单元（Soil Mapping Units, SMU）已被重映射为WRF采用的16类土壤分类，具体规则如下：
1. 基于美国农业部（United States Department of Agriculture, USDA）定义的土壤质地分类标准，通过深度加权平均计算黏粒、粉粒及砂粒含量，得到12类基于质地的土壤类别：砂质土、壤质砂土、砂质壤土、粉砂质壤土、粉砂土、壤土、砂质黏壤土、粉砂质黏壤土、黏壤土、砂质黏土、粉砂质黏土、黏土；
2. 当有机碳平均含量超过25%阈值时，将其归类为"有机物质"类别；
3. 对于未定义黏粒、粉粒及砂粒含量的HWSD特殊类别，按如下规则映射为WRF的最后3类土壤：
- "水体"映射为"水体"；
- "岩石露头"与"岩石亚层"映射为"基岩"；
- "陆地冰与冰川""沙丘/流动砂""盐沼"及"其他"映射为"其他"。

数据分发形式
数据集提供两种分发方式：
1. 两份全球范围文件（命名格式为`SoilType_depth<T>to<B>cm.tif`），分别对应两层土壤；
2. 16幅分幅文件，每层8幅，每幅覆盖90°×90°范围（命名格式为`SoilType_depth<T>to<B>cm_lon<W>to<E>deg_lat<S>to<N>deg.tif`）。

文件格式为GeoTIFF，可兼容WRF所用的GeoTIFF转地理网格格式命令行工具`convert_geotiff`。

土壤类别编码表
| 编码 | 土壤类别 |
|------|--------------|
| 1 | 砂质土 |
| 2 | 壤质砂土 |
| 3 | 砂质壤土 |
| 4 | 粉砂质壤土 |
| 5 | 粉砂土 |
| 6 | 壤土 |
| 7 | 砂质黏壤土 |
| 8 | 粉砂质黏壤土 |
| 9 | 黏壤土 |
| 10 | 砂质黏土 |
| 11 | 粉砂质黏土 |
| 12 | 黏土 |
| 13 | 有机物质 |
| 14 | 水体 |
| 15 | 基岩 |
| 16 | 其他 |