Gennady N. Panin

Correlations between the changes in the climate of the Caspian Sea region and in its level and the variations in the North Atlantic climate are studied. The indices of North Atlantic oscillation (NAO), Atlantic multidecadal oscillation (AMO), the intensity of Atlantic thermohaline circulation (ATHC), and the air humidity above the North Atlantic are used as basic indicators of climatic variations that influence the Caspian Sea. Results of an experiment for reproducing the World Ocean circulation and the parameterization of cyclic climate peculiarities made it possible to reveal their impact on the formation of Eurasian climatic variability and on the level regime of the Caspian Sea. This impact is studied through the variability of ATHC, the NAO index, and a composite index of moisture transport (CIMT) that is proposed as a result of the studies.

Reasons for the nonclosure of the heat balance in the atmospheric boundary layers over natural land surfaces are analyzed. Results of measuring the heat-balance components over different land surfaces are used. The Cabauw (Netherlands) data (obtained throughout 1996 over a grass surface with intermittent shrubs and single trees) and the data from the Anchor station in Germany (measured over coniferous forest in 2000–2001) are analyzed. In all, the analysis involves about fifty thousand independent values of the heat-balance components measured in the experiments, which should be indicative of the reliability of the results obtained in the paper. The data have shown that the heat balance is not closed and the imbalance is 50–250 W/m². The sum of the latent and sensible heat fluxes λE + H = STF is found to be systematically smaller than the difference between the net radiation and the heat flux into the ground R _n − G. It is shown that the main cause of a systematic heat imbalance in the atmospheric boundary layers over inhomogeneous land surfaces is that the methods of surface-flux measurement and estimation are based on the theory that requires the hypothesis of stationarity and horizontal homogeneity. Direct data analysis has shown that the heat imbalance increases with landscape inhomogeneity. In the paper, a parametrization of the heat imbalance is carried out and the coefficient k _f (z ₀ ^ef /L ^ef ) is introduced as a measure of inhomogeneity. For this, data from the experiments FIFE, KUREX, TARTEX, SADE, etc., are also used. Empirical formulas are presented to refine the results of direct measurements and calculations of surface fluxes over natural (inhomogeneous) land surfaces from profile and standard (using bulk parametrizations) data. These formulas can also be used to determine surface fluxes over inhomogeneous underlying land surfaces in order to take into account so-called subgrid-scale effects in constructing prediction models.

Results are rported from experimental and theoretical studies of the energy and mass exchange of a body of water with the atmosphere. A new parametric model has been developed on the basis of experimental data that takes into account the influence of the depth of the basin on evaporation, its heat exchange with the atmosphere, and the water-surface friction at different wind speeds. Comparison of the model with measurements during the LITFASS-98 and LITFASS-2003 experiments (Germany) shows good consistency. The results indicate, on the one hand, that the depth of the basin has a large effect on the intensity of energy exchange under natural conditions. On the other hand, the examples shown in the paper illustrate good agreement of the model calculations with experimental data. On the basis of the experimental data on the influence of the basin depth on the intensity of the interaction between the basin and the atmosphere, a balance model of the energy exchange in the coastal zone has been developed. The balance model calculates the momentum, heat, and moisture fluxes at different distances from the shore. Results of using the new model to estimate the intensification of evaporation and the heat exchange of the northern Caspian and the Kara-Bogaz Gol are discussed.

We performed special experimental and theoretical research concerning the energy--mass exchange process in shallow waters, which took into account the influence of the basin depth on the evaporation and sensible heat exchange. Data was obtained from deep water basins, as well as from shallow waters, at an open sea, as well as in its coastal zone. A new parameterization model of evaporation and friction velocity from shallow water surfaces under different wind velocities was investigated. Results of models and measurements of the energy/mass exchange intensity of a small shallow lake (LITFASS-experiments) were compared. The validation of these models with the eddy-covariance measurements of the LITFASS-98 and LITFASS-2003 experiments showed good results for the wind sector, with good fetch conditions. Therefore, the models examined may be used for calculating the evaporation of lakes where a standard data set of wind velocity, air and water temperature, air moisture and the depth of the lake is available. It should be remembered that in a coastal zone the roughness of the water surface is transformed and therefore there are additional calculation difficulties for the intensity of the energy–mass exchange. Based on our experimental data of the basin depth influence on the water–atmosphere exchange, a new model for the calculation of the energy–mass exchange in a coastal zone was developed. Our new model in combination with the empirical dependence for the calculation of the energy–mass exchange in a coastal zone allows calculation of the momentum, heat and humidity fluxes values at different distances from a shore.