Meteomatics Soil Moisture Index (SMI)
The soil moisture index indicates the wetness of the soil. This index is computed using the permanent wilting point and the field capacity, which both depend on the geographical location (soil type).
We calculate our soil moisture index by using data from ECMWF’s atmospheric model, which brings a number of benefits, including a high spatial resolution (10km), the frequency of data updates, with high temporal resolution; four model runs with hourly timesteps. Plus, the advanced soil type scheme derived from the root zone data (30-100 cm below the surface) of the FAO/UNESCO Digital Soil Map of the World, DSMW (FAO, 2003), which exists at a resolution of 5' X 5' (about 10 km).
The SMI can be very helpful in several situations, such as estimating the drought risk, so an extensive history of soil moisture conditions in the upper soil layers is essential. Plus it can also be used in hydrological applications such as flooding and runoff forecasts, where a detailed knowledge of both upper and lower soil layers is indispensable.
Meteomatics soil moisture index includes four discrete layers (-150cm / -50cm / -15cm / -5cm below ground level) based on the model data within ECMWF atmospheric model.
The index is 0 if the permanent wilting point is reached and 1 at field capacity. Note that the index can exceed 1 after rainfall events. The soil moisture index is available for 4 depth levels.
Soil Moisture Deficit (SMD)
This parameter computes the difference between the actual water content of the soil and the possible water content that the soil can hold in mm. The amount of water that can be held is called field capacity. The calculation of the SMD is mainly based on soil water information in several depths as well as other meteorological parameters. SMD is a useful tool in order to assess prevailing soil conditions like droughts. The SMD also depends on the soil type.
The SMD capability is available globally and we already ingest observations from partners to create a localised forecast, particularly across the UK and Switzerland.
Please get in contact if you need any further information or would to access a free trial account, to experience the simplicity and power of Meteomatics weather API.