ИСТИНА

The boreholes revealed the structure of the loess cover in four key sites along the line from East Azov to Terek-Kuma Lowland. In order to obtain the most preserved loess paleo-archives, the boreholes were located at near-horizontal flat interfluves, unimpaired by modern and relict erosion. The stratigraphic breakdown of sediments was carried out on the basis of a buried soils correlation with the loess-soil scheme, published by research fellows under guidance of A.A. Velichko [Velichko et al., 2006] and series of 15 OSL dates. 411 samples were investigated through granulometric analysis, loss on ignition, magnetic susceptibility. A gradual decrease in the thickness of the Upper Pleistocene and Holocene loess – paleosol sequence and particle size from east to west was found out. The results indicate that deserts of the Caspian lowland and possibly Central Asia were the source of material. The main direction of the aeolian transport during Late Pleistocene and Holocene were from east to west. Difference in loess and soils thickness and composition allowed revealing the intensity of aeolian processes for cold and warm stages. The intensity was higher during cold stages and lower during warm stages. The loess paleo-archives located in the east of Ciscaucasia have higher temporal resolution and more responsive paleoclimatic indicators than the western ones. They show regional climate changes better. In the west of Ciscaucasia the sedimentation conditions were more constant throughout the Upper Pleistocene and Holocene than in the east of the region. We used the climate model INMCM4.8 [Volodin E.M. et al., 2018] to study the relationships between climate conditions and loess formation in the past. We used PMIP4 boundary conditions for Mid-Holocene, Last Glacial Maximum and Last Interglacial for the paleoclimate simulations within the model INMCM4.8. The model INMCM4.8 contains the aerosol block. Types of vegetation prescribed and don’t change in the model, but vegetation “wither” or “blossom” depending on the climate conditions. The analysis of the model data show that during the cold period (LGM) the dust sources, the mass of the dust into the air are much higher than during the warm stages. The atmospheric circulation change analysis for this region in different climatic conditions is not complete yet. One of the possible reasons for such differences in loess accumulation can be link with Caspian Sea stage. There is no consensus about the periods, the range and the causes of its transgression and regression during the Late Pleistocene. In this work we used the available model data of the PMIP3 and PMIP4 projects (experiment LGM) to calculate the Caspian Sea (CS) water balance components around the Last Glacial Maximum (LGM). The “climatic” part of the river runoff was calculated as the difference between precipitation and evaporation in the CS watershed. In general, models demonstrated a decrease the “climatic” runoff of the Volga in the LGM compared to modern values. Also we evaluated the possible contribution of the meltwater of the Scandinavian ice sheet, which may have been a part of the Volga runoff. The meltwater flux was calculated for the various ice sheet reconstructions, which were used in PMIP3 and PMIP4 simulations: PMIP3, ICE-6G_C and GLAC-1D [Kageyama et al., 2017]. These data were compared with paleo-data for the upper Volga. We used coupled eddy-resolving ocean-sea ice general circulation model INMIO-CICE under control of the CMF compact modeling framework [Kalmykov et al., 2018] for the simulations of the Caspian Sea conditions. We used the results of the LGM simulation of the model INMCM4.8 as the climatic forcing for the Caspian Sea model. Now we start set of the experiments with different volume of the river runoff and sea level. This work is at the first stage now, we also plan to use the results of another models, which taken part into PMIP4. This work was supported by RSF grant 19-77-00103 (the study of Ciscaucasia upper Pleistocene loess) and RSF grant 19-17-00215 (the study of the Caspian Sea level fluctuations in the past). References Velichko A.A., Morozova T.D., Nechaev V.P. et al. (2006) Loess/paleosol/cryogenic formation and structure near the northernlimit of loess deposition, East European Plain, Russia. Quaternary International. V. 152–153. P. 14–30 E.M.Volodin, E.V. Mortikov, S.V. Kostrykin, V.Ya.Galin, V.N.Lykossov, A.S.Gritsun, N.A.Diansky, A.V.Gusev,N.G.Iakovlev, A.A.Shestakova, and S.V.Emelina. Simulation of the modern climate using the INM-CM48 climate model. J. Numer. Anal. Math. Modelling 2018; 33(6):367-374 (https://doi.org/10.1515/rnam-2018-0032) The PMIP4 contribution to CMIP6 – Part 4: Scientific objectives and experimental design of the PMIP4-CMIP6 Last Glacial Maximum experiments and PMIP4 sensitivity experiments, Kageyama, M., Albani, S., Braconnot, P., Harrison, S. P., Hopcroft, P. O., Ivanovic, R. F., Lambert, F., Marti, O., Peltier, W. R., Peterschmitt, J.-Y., Roche, D. M., Tarasov, L., Zhang, X., Brady, E. C., Haywood, A. M., LeGrande, A. N., Lunt, D. J., Mahowald, N. M., Mikolajewicz, U., Nisancioglu, K. H., Otto-Bliesner, B. L., Renssen, H., Tomas, R. A., Zhang, Q., Abe-Ouchi, A., Bartlein, P. J., Cao, J., Li, Q., Lohmann, G., Ohgaito, R., Shi, X., Volodin, E., Yoshida, K., Zhang, X., and Zheng, W., Geosci. Model Dev., 10, 4035-4055, doi:10.5194/gmd-10-4035-2017, 2017. Kalmykov V.V., Ibrayev R.A., Kaurkin M.N., Ushakov K.V. (2018) Compact Modeling Framework v3.0 for high-resolution global ocean–ice–atmosphere models. Geosci. Model Dev., 11, 3983-3997, https://doi.org/10.5194/gmd-11-3983-2018