Global Soil Bioclimatic variables at 30 arc second resolution

Soil temperature layers were calculated by adding monthly soil temperature offsets to monthly air-temperature maps from CHELSA (date range 1979-2013) (Karger et al. 2017, Sci Data). These soil temperature layers were then used to calculate annual means, temperature ranges, standard deviation, warmest and coldest months and quarters. Wettest and driest quarters were identified for each pixel based on CHELSA monthly values. A quarter is a period of three months (1/4 of the year).

When using any of these layers, please cite: Lembrechts et al., Mismatches between soil and air temperature (2021). Global Change Biology. DOI: 10.1111/gcb.16060

For each Soil Bioclim layer, two depth intervals are available: 0 - 5 cm and 5 - 15 cm.

We have followed the generally accepted definitions of BIO 1 - BIO 11: 

• SBIO1 = Annual Mean Temperature
• SBIO2 = Mean Diurnal Range (Mean of monthly (max temp - min temp))
• SBIO3 = Isothermality (BIO2/BIO7) (×100)
• SBIO4 = Temperature Seasonality (standard deviation ×100)
• SBIO5 = Max Temperature of Warmest Month
• SBIO6 = Min Temperature of Coldest Month
• SBIO7 = Temperature Annual Range (BIO5-BIO6)
• SBIO8 = Mean Temperature of Wettest Quarter
• SBIO9 = Mean Temperature of Driest Quarter
• SBIO10 = Mean Temperature of Warmest Quarter
• SBIO11 = Mean Temperature of Coldest Quarter

These layers are also publicly available as Google Earth Engine assets. These are acessible via:

• https://code.earthengine.google.com/?asset=projects/crowtherlab/soil_bioclim/SBIO_v2_0_5cm
• https://code.earthengine.google.com/?asset=projects/crowtherlab/soil_bioclim/SBIO_v2_5_15cm

Also available are monthly maps of soil temperature, for two depth intervals (0-5 cm and 5-15 cm). For example, the soil temperature map for month 1 (January) at 0-5 cm is named soilT_1_0_5cm.tif'. 

To mask pixels by the proportion of extrapolation, the files 'PCA_int_ext_0_5cm.tif' and 'PCA_int_ext_5_15cm.tif' can be used.