Methodology

Based on this mapping, grid cells were identified that are suitable for TSS systems. A map of cropland areas was used as a mask to limit this suitability to those grid cells that currently are under cultivation.

The following spatial databases were used in the analyses:

• Historical weather data are from the Climate Research Unit of the University of East Anglia. Here, we use the dataset CRU TS v. 3.23 which has a spatial resolution of 30x30 arc minutes, about 55x55 km near the equator, and a temporal resolution that covers each month in the period 1981 – 2010 (30 years). This dataset comprises monthly values of cloud cover, temperature, diurnal temperature range, vapour pressure, rainfall, and the number of rain days.
• Soil data are based on the Harmonized World Soil Database (HWSD v1.21) with a spatial resolution of about 1 km2 near the equator. Soil properties of the top soil (0-30 cm) were selected for the suitability analyses and comprise: (1) clay content, (2) pH and (3) soil organic carbon content. Soil organic matter content (SOM) was calculated by dividing soil organic carbon content by 0.58.
• Terrain slope class and elevation maps are used to assess suitability with respect to slope conditions and altitude (HWSD v1.21).
• A spatial cropland distribution map, i.e. cropland extent as fraction of grid cell area, is used to distinguish between arable and non-arable areas (Fritz et al, 2015).