VARIABILITY OF BIOGEOCHEMICAL PROCESSES IN THE WHITE SEA UNDER DIFFERENT CLIMATIC CONDITIONS: THE MODELING APPROACH

Abstract

The JASMINE numerical complex based on the FEMAO model of the Arctic Ocean and the BFM pelagic ecosystem model is used for integrated modeling of hydrodynamic, thermodynamic, and biogeochemical processes in the White Sea. The variation of the White Sea ecosystems under different climatic conditions, i. e., a warm, cold, and an average (close to multiannual average) year, is studied by numerical experiments. Several years are considered in detail: the warm 2013 and the cold 1994, including the surface layer and the water column temperature, the distribution of chlorophyll a, primary production. We reveal some regularities and explain the observed dependencies in the warm and the cold year. The phenomenon of warm, cold, and average years in the biogeochemical processes in the White Sea is influenced by global oscillations in the atmosphere, mainly the North Atlantic Oscillation (NAO). The events of the North Atlantic oscillation (both positive and negative) correspond to positive and negative deviations of the surface layer temperature of the White Sea. NAO is generated by the pressure difference between the Icelandic minimum and the Azores maximum, which, in turn, amplifies the Western transport in the Northern hemisphere, redistribution of heat and moisture. According to the numerical experiments, the key period of the year for the pelagic ecosystem dynamics is May. It is shown to be tightly connected to the later biogeochemical processes during the summer.

Keywords

• white sea
• pelagic ecosystem
• biogeochemistry
• modeling
• jasmine
• bfm.