ПРИРОДНЫЕ ПОЖАРЫ: ДАННЫЕ НАБЛЮДЕНИЙ И МОДЕЛИРОВАНИЕ

Abstract

A review of the contemporary knowledge on natural fires (NF) and on contemporary approaches for their modelling is presented. The review is targeted to the implementation of NF models into the global Earth system models. In the last years, satellite retrievals are able to detect even small (with the size < 500 m) fires. Nonetheless, marked uncertainties of the estimates for the burned are and for the NF-associated release of different substances into the atmosphere still persist. For the most detailed satellite dataset GFED-4.1, the annual burned area is close to 5 mln km2 , including at least 2.9 Mkm2 due to NF themselves. This leads to the carbon release of ~2 PgC year into the atmosphere, mostly in the form of CO2.In the Russian territory, the annual burned area is close to 135 thnd km2 , and the annual carbon release into the atmosphere is equal to 0.12 PgC year. These estimates appear much larger the respective estimates reported in the Russian National Report for 1900-2015. NF Characteristics follow the interannual climate variability, including that in the El Niño years. Nevertheless, no significant trends are found at the global and subcontinental spatial scales based on the satellite data. Proxy data and modelling results exhibit a general increase of the NF activity during the preindustrial Holocene (including cold epochs) as well as an overall enhancement of this activity from cold stadials to warm interstadials in the Pleistocene. Currently the NF simulation modules are started to be implemented into the Earth system models. These modules take into account fire-affecting weather and/ or climate characteristics, the number of ignitions depending on lightning activity and population density (sometimes, depending on landuse type as well), fire suppression, amount and type of fuel for fires, and combustion completeness. A number of models is able to simulate even the simplified dynamics of individual fires. However, the limited contemporary knowledge on NF leads to the marked intermodel scatter even in the simulated climatology of the NF characteristics and in the simulated trend slopes of such characteristics. In particular, the intermodel differences in the 20th century variations in the simulated NF characteristics are mostly caused by the implemented assumptions on the landuse impact on NF dynamics. As a result, further development of the NF modules is needed.