First geophysical and shallow ice core investigation of the Kazbek plateau glacier,Caucasus Mountains

First-ever ice core drilling at Mt. Kazbek (Caucasus Mountains) took place in the summer of 2014. A shallow ice core (18 m) was extracted from a plateau at ~4500 m a.s.l. in the vicinity of the Mt. Kazbek summit (5033 m a.s.l.). A detailed radar survey showed that the maximum ice thickness at this location is ~250 m. Borehole temperature of ?7 °C was measured at 10 m depth. The ice core was analyzed for oxygen and deuterium isotopes and dust concentration. From the observed seasonal cycle, it was determined that the ice core covers the time interval of 2009–2014, with a mean annual snow accumulation rate of 1800 mm w. eq. Multiple melt layers have been detected. δ¹⁸O values vary from ?25 to ?5‰. The dust content was determined using a particle sizing and counting analyzer. The dust layers were investigated using scanning electron microscopy and X-ray diffraction analysis. Dust can be separated into two categories by its origin: local and distant. Samples reflecting predominantly local origin consisted mainly of magmatic rocks, while clay minerals were a characteristic of dust carried over large distances, from the deserts of the Middle East and Sahara. The calculated average dust flux over three years at Kazbek was of 1.3 mg/cm² a^?1. Neither δ¹⁸O nor dust records appear to have been affected by summer melting. Overall, the conditions on Kazbek plateau and the available data suggest that the area offers good prospects of future deep drilling in order to obtain a unique environmental record.     

Modeling of variations in river runoff on the East European Plain under different climates of the past

The results of modeling of the annual river runoff on the East European Plain, performed with the help of atmospheric general circulation models for the conditions of the present-day climate, the Atlantic Optimum of the Holocene, and the Cryochrone of the Late Pleistocene, are analyzed. The quality of modeling the present-day climate is assessed; the spatial scales, within which the model results are appropriate for using in hydrological calculations, are determined. The genesis of variations in the river runoff on the East European Plain in the epochs of the Holocene Optimum and Late-Pleistocene Cryochrone is investigated.     

Present-day variations and paleodynamics of the Caspian Sea level as a standard for climate modeling data verification

Long-term variations of the Caspian Sea level occur mainly due to river runoff variations (the variations of the Volga River runoff is of primary importance here). In this case, the observed and reconstructed variations of the Caspian Sea level can serve as a standard for assessing the quality of the model runoff simulated by climate models. To solve this problem, a number of detailed maps of the Caspian Sea are prepared for the series of regression and transgression stages. These data are used for verifying the results of some numerical experiments carried out within the framework of CMIP5/PMIP3. It is demonstrated that the model data can be verified depending on how well the models simulate the present-day (instrumentally observed) variations of the decadal scale reconstructed in recent 1000 years of variations: the transition from the Derbent regression to the New Caspian transgression (the 5th phase) with the insignificant sea level drop in the late 19th century and under conditions of large regression during the period of the late Pleistocene glaciation maximum.