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344 results on '"Timokhov, L. A."'

3. Dynamics and History of the Laptev Sea and its Continental Hinterland: A Summary

Author

Scientific Party, Thiede, J., Timokhov, L., Bauch, H. A., Bolshiyanov, D. Y., Dmitrenko, I., Eicken, H., Fahl, K., Gukov, A., Hölemann, J., Hubberten, H.-W., Juterzenka, K. V., Kassens, H., Melles, M., Petryashov, Y., Pivovarov, S., Priamikov, S., Rachold, V., Schmid, M., Siegert, C., Spindler, M., Stein, R., Kassens, Heidemarie, editor, Bauch, Henning A., editor, Dmitrenko, Igor A., editor, Eicken, Hajo, editor, Hubberten, Hans-Wolfgang, editor, Melles, Martin, editor, Thiede, Jörn, editor, and Timokhov, Leonid A., editor

Published
1999
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11. The Laptev Sea system since the last glacial

Author

Kassens, H., primary, Thiede, J., additional, Bauch, H.A., additional, Hoelemann, J.A., additional, Dmitrenko, I., additional, Pivovarov, S., additional, Priamikov, S., additional, Timokhov, L., additional, and Wegner, C., additional

Published
2007
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13. Role of hydrometeorological factors and solar activity in interannual variability of ice extent in the East Siberian Sea (in Russian)

Author

Timokhov, L. A., Borodachev, V. E., Borodachev, I. V., Vyazigina, N. A., Mironov, E. U., Janout, M., Timokhov, L. A., Borodachev, V. E., Borodachev, I. V., Vyazigina, N. A., Mironov, E. U., and Janout, M.

Abstract

Interannual changes of the summer ice coverage were investigated, and the role of hydrometeorological factors and solar activity in long-period fluctuations of the ice area in the East Siberian Sea was determined. Multivariate statistical analysis of time series of the ice cover, hydrometeorological elements, and the solar activity (SA), was performed for the period from 1950 to 2012 with regard for the cross-correlations of the analyzed variables that made possible to develop the equations of interannual fluctuations of the ice coverage in the East Siberian Sea in August and September. The equations include the following variables: air temperature in June–August of the current year TVI‑VIII; the atmospheric circulation presented by indices of Arctic oscillation (Arctic Oscillation, AO), Arctic dipole (Arctic Dipole, AD), Pacific North American oscillation (Pacific North American Oscillation, PNA); average annual runoff of river waters into the Laptev and East Siberian seas (RivLES) with a time shift of one and two years; average annual index of the North Atlantic thermal state (AMO) with a time lag of eight years; solar activity SA, presented by the average annual Wolf number with advancing of one year. Diagnostic calculations of the ice area by the obtained equations using the actual values of the indices did show a good agreement between the actual and calculated values in August and September from 1950 to 2012. These equations were used to calculate contribution of each factor to the general dispersion of fluctuations of the ice coverage. The most important factors influencing the ice cover of the Sea in August and September are: the air temperature; the atmospheric circulation, presented by the Arctic Oscillation at the end of winter; and Atlantic waters which are characterized by AMO with a time lag of eight years. The role of other factors, i.e. summer atmospheric circulation, river runoff into the above seas, and 11-year cycle of solar activity were found to

Published
2019
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14. Atlantic Water in the Arctic Circulation Transpolar System

Author

Ivanov, V. V., Timokhov, L. A., Ivanov, V. V., and Timokhov, L. A.

Abstract

The water of Atlantic origin (Atlantic water) is of special importance for the formation of the hydrological regime of the Arctic Ocean and provides a “building material” for the main water masses in the surface and intermediate layers. Atlantic water are structurally included to the Arctic Transpolar System (ATS); it is a multicomponent physical object whose state defines the role of the Arctic Ocean in the planetary climate. The recent advances in the Atlantic water research are discussed, in particular, the role of Atlantic water in the Arctic sea ice reduction. Particular attention is paid to the possible activation of feedbacks in ATS that may result in an accelerated Arctic sea ice loss recorded after 2007.

Published
2019
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30. Sediment entrainment into sea ice and transport in the Transpolar Drift: a case study from the Laptev Sea (Winter 2011/12)

Author

Wegner, Carolyn, Wittbrodt, K., Hölemann, Jens, Janout, M., Krumpen, T., Selyuzhenok, V., Novikhin, A., Polyakova, Y., Kryukova, I., Kassens, Heidemarie, Timokhov, L. A., Wegner, Carolyn, Wittbrodt, K., Hölemann, Jens, Janout, M., Krumpen, T., Selyuzhenok, V., Novikhin, A., Polyakova, Y., Kryukova, I., Kassens, Heidemarie, and Timokhov, L. A.

Abstract

Highlights • Observations show that formation of sediment-laden sea ice occurs in coastal polynyas in winter. • Sea ice rafted sediments are a significant component of the Laptev Sea’s sediment budget. • No observational evidence for sediment entrainment into sea ice in mid-shelf polynyas at water depth greater than 20 m. Abstract Sea ice is an important vehicle for sediment transport in the Arctic Ocean. On the Laptev Sea shelf (Siberian Arctic) large volumes of sediment-laden sea ice are formed during freeze-up in autumn, then exported and transported across the Arctic Ocean into Fram Strait where it partly melts. The incorporated sediments are released, settle on the sea floor, and serve as a proxy for ice-transport in the Arctic Ocean on geological time scales. However, the formation process of sediment-laden ice in the source area has been scarcely observed. Sediment-laden ice was sampled during a helicopter-based expedition to the Laptev Sea in March/April 2012. Sedimentological, biogeochemical and biological studies on the ice core as well as in the water column give insights into the formation process and, in combination with oceanographic process studies, on matter fluxes beneath the sea ice. Based on satellite images and ice drift back-trajectories the sediments were likely incorporated into the sea ice during a mid-winter coastal polynya near one of the main outlets of the Lena River, which is supported by the presence of abundant freshwater diatoms typical for the Lena River phytoplankton, and subsequently transported about 80 km northwards onto the shelf. Assuming ice growth of 12 to 19 cm during this period and mean suspended matter content in the newly formed ice of 91.9 mg l-1 suggests that a minimum sediment load of 8.4x104 t might have been incorporated into sea ice. Extrapolating these sediment loads for the entire Lena Delta region suggests that at least 65% of the estimated sediment loads which are incorporated during freeze-up, and up to 10% of

Published
2017
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49. Transpolar matter fluxes

Author

Wegner, Carolyn, Hölemann, Jens, Janout, M., Bauch, Dorothea, Laukert, Georgi, Frank, Martin, Krumpen, T., Selyuzhenok, V., Novikhin, A., Polyakova, Y., Kryukova, I., Kassens, Heidemarie, Timokhov, L. A., Wegner, Carolyn, Hölemann, Jens, Janout, M., Bauch, Dorothea, Laukert, Georgi, Frank, Martin, Krumpen, T., Selyuzhenok, V., Novikhin, A., Polyakova, Y., Kryukova, I., Kassens, Heidemarie, and Timokhov, L. A.

Published
2016

50. Surface salinity fields in the Arctic Ocean and statistical approaches to predicting anomalies and patterns

Author

Chernyavskaya, E., Sudakov, I., Golden, K. M., and Timokhov, L. A.

Abstract

Significant salinity anomalies have been observed in the Arctic Ocean surface layer during the last decade. Using gridded data of winter salinity in the upper 50 m layer of the Arctic Ocean for the period 1950-1993 and 2007-2012, we investigated the inter-annual variability of the salinity fields, attempted to identify patterns and anomalies, and developed a statistical model for the prediction of surface layer salinity. The statistical model is based on linear regression equations linking the principal components with environmental factors, such as atmospheric circulation, river runoff, ice processes, and water exchange with neighboring oceans. Using this model, we obtained prognostic fields of the surface layer salinity for the winter period 2013-2014. The prognostic fields demonstrated the same tendencies of surface layer freshening that were observed previously. A phase portrait analysis involving the first two principal components exhibits a dramatic shift in behavior of the 2007-2012 data in comparison to earlier observations.

Published
2014

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