N. N. Filatov

Mathematical modeling of the ecosystem functioning conditions in the Chupa Estuary of the White Sea: Transformation of organogenic substances and bioproductivity of the marine environment

The use of a mathematical model, describing the transformations of organic and mineral compounds of C, Si, N, and P for the generalization of hydrological, hydrochemical, and hydrobiological data on nine regions in the White Sea is demonstrated. The regions examined include the head of Kandalaksha Gulf, Dvina Gulf, Mezen Gulf, Onega Bay, the Solovetskie Islands’ area, the central, deep-water part (or Basin), Gorlo, Voronka, and the Chupa Estuary. The results of modeling the transformations of biogenic substances in the water areas of the Chupa Estuary, and other gulfs and bays in the White Sea are compared and analyzed. Calculated variations in the concentrations of biogenic substances and detritus, microorganism biomasses, characteristics of their activity (specific growth rates and biomass turnover times) within a year are presented and discussed. The estimated characteristics are shown to agree with observational data. Particular attention is paid to estimating the organic matter production rates by phytoplankton and calculating balances of biogenic compounds in the Chupa Estuary.

Ecosystem modeling of freshwater lakes (review): 2. Models of freshwater lake’s ecosystem

Mathematical models of ecosystems are considered, including models formulated as systems of differential equations and using up-to-date numerical methods for their implementation and models formulated and implemented using fuzzy logic and methods of artifical intellect. Logical-linguistic and cognitive models, which largely give qualitative description of ecological systems, are also considered.

Response of lakes in Eastern Fennoscandia and Eastern Antarctica to climate changes

752 This communication is dedicated to regional cli mate changes and their impact on lakes of different sizes, configurations, and geneses located in different physicogeographic settings. Lakes of eastern Fennos candia subjected to relatively strong anthropogenic impact and Eastern Antarctica, where the influence of such factors is insignificant, were selected for analysis (Fig. 1). The response of the hydrological regime in these lakes and their biota to climate changes was investigated.

Karelian Lakes Expert System: 1. Ordinal and Nominal Characteristics of Lakes

An expert system is proposed for the assessment of characteristic and the trophic status of lakes for which little or no direct observational data are available. The system is based on the mathematical apparatus of fuzzy logic and applied to the best studied in Russia Karelian lake region. The created database on the morphometry, hydrology, hydrochemistry, and hydrobiology for 100 best studied lakes is described. The lakes are classified by methods of multidimensional statistics, factor, cluster, and logical-information analysis with the use of multidimensional scaling technique. Serious drawbacks of different classifications are demonstrated, in particular, because of the lack of a constructive algorithm for the recovery of unknown characteristics of a lake once it is referred to a certain class. In such cases, the mathematical apparatus of fuzzy sets and fussy logic should be used.

Ecosystem modeling of freshwater lakes (Review): 1. Hydrodynamics of lakes

The development and use of lake ecosystem models are discussed as an essential part of integrated studies of lake ecosystem, the processes of eutrophication and matter transport and transformation for solving the problems of rational use of the natural resources of a water body, preservation of high water quality, prediction of the further development of lake ecosystems under the effect of anthropogenic and climate factors. Description is given to models that can be formulated as boundary value problems for systems of one-, two-, or three-dimensional transport differential equations for both reactive and nonreactive solutes in water. Those equations include nonlinear operators, describing the transformation of living and dead organic matter (phytoplankton, zooplankton, benthos, detritus) and dissolved biogenic substances (carbon, nitrogen, phosphorus, and silicon). The possibility to construct models including fish, macrophytes, and dissolved oxygen and its exchange with the atmosphere through water surface is discussed. Modern numerical methods are used to implement the models formulated as systems of differential equations. The need to introduce stochasticity is demonstrated. Additionally, models, whose formulation and implementation involves methods of fuzzy sets, artificial intellect, as well as logical-linguistic and cognitive models are described.

“Karelian lakes” expert system: 2. Classification of lakes

Construction algorithms of the expert system are given. The results of expert system application to the assessment of the trophic status of Karelian lakes are presented. The system was tested against independent data on well-known lakes. The lakes were classified with the use of fuzzy logic apparatus.

Intrasecular variability in the level of the largest lakes of Russia

The features of the intrasecular changes in the level of the largest lakes of Russia (Baikal, Ladoga, Onego, and the inland Caspian Sea) are jointly considered for the first time on the basis of the long-term data measured in the 20th–21st centuries. The influence of climate and anthropogenic factors is considered to improve the forecast of the level of lakes.

Modeling climatic circulation of Onega Lake

The results of numerical modeling of Onega Lake climatic circulation are presented. The model used in this study was developed earlier and successfully applied to the reproduction of large-scale hydrodynamical processes in Ladoga Lake. The obtained results are of importance for the development of both models of nonreactive pollutant transport and ecosystem models of the water body. The developed model can be used to calculate currents and temperature fields for individual scenarios of external impacts on the water body, and the results of calculation of the climatic circulation can serve as initial approximations for scenario-based calculations.

Many-year level variations in the Great Lakes of Eurasia and North America

Regularities in the secular variations of water level in the Great Lakes of Eurasia and North America under natural climate and anthropogenic impacts are studied.

Water resources of the Northern Economic Region of Russia: The state and use

The issues of water availability and water resources use in the Northern Economic Region are considered for the region as a whole and for the RF constituent entities it embraces.