The fire danger rating on the vegetation land surface is based on the Soil Moisture Deficit Index of Fire Danger (SMDIFD), developed at NIMH. SMDIFD is a measure of vegetation susceptibility to fire ignition and spread, regarding the severity and duration of soil-vegetation system dryness.

The calculations and analyses are performed on the basis of data from synoptic stations and forecasts of meteorological elements from the global model of European Centre for Medium-Range Weather Forecasts (ECMWF). The calculative procedure is performed by the following methodology:

• Numerical description of site-scale biogeophysical cycling by 1D (vertical) meteorological ‘SVAT_bg’ model, developed at NIMH. The model quantifies the coupled energy and water transfer processes in soil-vegetation-atmosphere continuum, accounting for the specific soil and geophysical characteristics As model outputs, vegetated land surface water cycle characteristics (evapotranspiration and soil moisture along the root zone depth, among the others), etc. are derived.
• Based on soil moisture data derived by ‘SVAT_bg’, a threshold scheme for indicating the quantity of Soil Moisture Availability for the specific vegetation land cover type has been developed. The threshold scheme is applied to indicate the persistence and severity of ‘dry anomalies’ in soil-vegetation system and related soil moisture deficit.
• The levels of fire risk are presented by colour-coded maps in 6-level scale reflecting the land cover dryness (in the lower vegetation belt, up to 800 m altitude). Warnings are issued depending on the intensity and prolongation of the soil dryness.

SMDIFD is jointly used with other materials in the forecasting environment for issuing warnings and specialized forecasts by NIMH for fire risk at extreme conditions.

The development and operational implementation of ‘SVAT_bg’ model as well as analyses of land surface processes and related extreme states (drought, fire risk, overmoistening, etc) are performed at Remote sensing Division, Forecasting and Information Service Department of NIMH. These meteorological products are intended for exploiting by national institutions to ensure the safety of the population as well as for providing meteorological support to economic activities like agriculture, forestry, sustainable development of natural recourses.