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Study of the impact of atmospheric forcing and river discharge on the Laptev Seav summer hydrography and submarine permafrost state E.Golubeva, G.Platov, V.Malakhova, D.Iakshina and M.Krayneva

Russian Academy of Sciences Novosibirsk Scientific Centre Institute of Computational Mathematics and Mathematical Geophysics SB RAS ENVIROMIS – 2016 Tomsk, July , 11-16

Plan of presentation

• Region of East Siberian Arctic Shelf. Motivation
• f investigation
• Observational data and analysis results
• Method of numerical modeling
• Numerical results
• One of the important unresolved problems
• Conclusion

The Eastern Siberian Arctic Shelf (ESAS), including the Laptev and East Siberian Seas is the shallowest (20-30m average depth) and broadest (400-8000 km from shoreline) shelf region of the World Ocean

rivers The vast Siberian Shelf regions cover more than one third of the total Arctic Ocean area, and receive freshwater from several large rivers, with 394 km3 yr_1 from the Ob River (RosHydromet gauge data at Salekhard, from 1930to 1999) and 580 km3 yr_1 from the Yenisey River (RosHydromet gauge data at Igarka, from 1936 to 1999) in the Kara Sea, and about 541 km3 yr_1 from the Lena River (RosHydromet gauge data at Kusur, from 1985 to 2007) in the Laptev Sea (Fig. 1). (RosHydromet gauge data are accessible at http://www.r-Arcticnet.sr.unh.edu through the Regional, Eletronic Hydrographic Data Network for the Arctic Region.)

Satellite data reveal how the new record low Arctic sea ice extent, from Sept. 16, 2012, compares to the average minimum extent over the past 30 years (in yellow). Sea ice extent maps are derived from data captured by the Scanning Multichannel Microwave Radiometer aboard NASA's Nimbus-7 satellite and the Special Sensor Microwave Imager on multiple satellites from the Defense Meteorological Satellite

• Program. Credit: NASA/Goddard Scientific Visualization Studio

The Northern Sea Route comprises all routes from the Barents

to the Chukchi Sea and the Bering Strait suitable for shipping and includes Arctic seas and part of the Arctic Ocean limited by Russian economic zone

http://rusinform.net/severnyj-morskoj-put

East Siberian sector of the Arctic shelf -is the region where climatic changes of recent decades are the most pronounced.

Photo by M.Grigoriev Time series of annual atmosphere temperature anomaly

Recently it was reported about increasing coastal erosion rates

Dissolved methane in the Laptev Sea ans East-Siberian Sea. Observational data

2003 2004 2005 Distribution of dissolved methane in the surface layer (a), and bottom layer (b) (Shakhova and Semiletov, 2006). The essential increasing of the dissolved methane concentration during 2003-2005 years. Surface layer maximum: 2003 - 30nM, 2004 - 115 nM, 2005 - 500nM Bottom layer: 2003 - 87nM, 2004 - 154 nM, 2005

• 220nM

The extreme methane anomalies in plume areas indicate the presence of both surface and bottom methane sources, which might reflect unique geological, hydrological and climatic factors

Dmitrenko, I. A., S. A. Kirillov, L. B. Tremblay, H. Kassens, O. A. Anisimov,

• S. A. Lavrov, S. O. Razumov, and M. N. Grigoriev (2011), J. Geophys. Res., 116, C10027,

doi:10.1029/2011JC007218.

The data coverage of the interpolated field (percentage from the entire subregionarea) within subregions 1–7 for (b) winter (February–April) and (c) summer (July–September)

• J. Geophys. Res., 116, C10027, doi:10.1029/2011JC007218.

Weingartner T.J., Sasaki Y., Pavlov V.K. and Kulakov M.Yu. The Siberian Coastal Current: A wind and buoyancy-forced Arctic coastal current // J. of Geoph. Res.

• 1999. Vol. 104, C12. P. 29,697–29,713.

Figure 1. Temperature and salinity data on sections along 130E for summers (a) 1994 and (b) 1999. Schematic drawings indicate the supposed water circulation during years with ‘‘onshore’’ and ‘‘offshore’’ atmospheric forcing. The flow of the river plume is from west to east in 1994 as indicated by the arrow;

• D. Bauch,1 I. A. Dmitrenko,1 C. Wegner,1 J. Ho¨ lemann,2 S. A.

Kirillov,3L. A. Timokhov,3 and H. Kassens1 JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 114, C05008, doi:10.1029/2008JC005062, 2009

Anticyclinic mode Cyclonic mode

Two main circulation modes in the Arctic Ocean

Comparison between our normalized trajectory index calculated from model results with 3% (light green) and 7% (dark green) atmospheric wind forcing and the vorticity index (red line; inverted values)..

In Bauch et al.,2011 it was found that the third EOF pattern represents the relevant mode of variability, which determines local wind and SLP fields, and thus the distribution

• f river water on the Laptev

Shelf, whereas the first and second EOFs are only of minor importance. The vorticity index defined by Walsh et al. (1996) has been used to characterize the atmospheric forcing on the Laptev Sea surface waters basin (Dmitrenko et

• al. 2005). Another index based on the simple Ekman trajectory model for surface

Lagrangian particles has been used in (Bauch et al 2011) to investigate the effect

• f near surface winds on the river water summer distribution.

Citation: Polar Research 2011, 30: 5858 - DOI: 10.3402/polar.v30i0.5858

Dorothea Bauch1, Matthias Gro¨ ger2, Igor Dmitrenko1, Jens Ho¨ lemann3, Sergey Kirillov4,Andreas Mackensen3, Ekatarina Taldenkova5 & Nils Andersen6

Sea level pressure (NCEP/NCAR data), EOF and PC, summer (jja)

Numerical Modeling

Coupled Ice-Ocean Model

3D Ocean Circulation Model of ICMMG based

• n

z-level vertical coordinate approach

(Kuzin1982, Golubeva at al.,1992, Golubeva,[2001,2008], Golubeva and Platov,[2007])

• Conservation laws for heat, salt and momentum with

Boussinesq, hydrostatic and ‘rigid lid’ approximations

• Separation of the external and internal mode in

momentum equations

• Barotropic momentum equations are expressed in term
• f stream function
• QUICKEST (Leonard,[1992]) is used in the latest model

version for the T-S advection.

• Two versions of mixed layer parameterization:
• Vertical adjustment based on the Richardson

number

• Vertical diffusion coefficient based on the stable

solution of turbulent energy equation

Ice model-CICE 3.0 (elastic-viscous-plastic) W.D.Hibler ,1979, E.C.Hunke, J.K.Dukowicz,1997, G.A.Maykut 1971 C.M.Bitz, W.H.Lipscomb 1999,J.K.Dukowicz, J.R.Baumgardner 2000, W.H.Lipscomb, E.C.Hunke 2004

14-19км 38 vertical levels

Platov G.A. et al., Bulletin ICMMG,2015

The results of the 3D modeling present the spatial-temporal variability of the summer hydrological fields on the Siberian shelf

The eastward flow is steadily presented during the cyclonic atmospheric circulation. The salinity front develops in surface waters and spreads along the coast of the Laptev and East Siberian Seas. During the anticyclonic circulation the salinity front is oriented according to the prevailing wind field, and can shift to the north-east or north-west. An intensive northward flow in the central part of the sea provides a fresh water transport towards the edge of the shelf zone.

• ffshore
• nshore

• ffshore
• nshore

In contrast to the studies of the salinity distribution in the Arctic shelf waters, due to the influence of the river runoff, minor attention has been paid to the issue associated with the study of the role of the heat coming from the river waters.

Ice thickness difference caused by Lena River heat flux in numerical experiment

June July

The primary effect from the river heat flux could be seen in the state of the sea

• ice. The most important difference between the two experiments was obtained

in the region of the Lena River Delta. The results simulated show a decrease in the ice thickness caused by river heat in the vicinity of the Lena River Delta in spring and in summer. In June, the heat coming with the river water results in the ice melting in the immediate vicinity of the river.

Averaged temperature anomalies . Run2 (rivers heat flux) - Run1 (no river heat flux)

Nested Laptev Sea Regional Model

► POM, Laptev Sea region,nested into

ICMMG AO-NA model

► Horizotnal grid 200м-20км, ► Modeling period- up to 1 year

27

Model temperature

Salinity Temperature

• nshore
• ffshore
• nshore
• ffshore

2007 2008 2007 2008

June July Aug Sept

In contrast to Region I and Region II, the temperature anomaly in Region III has some

• peculiarities. Almost regularly the surface layer has two small local maxima, the first maximum

is observed in June and the second - in August. The first maximum is defined by the Yana River heat flux, and the second one is resulted from the Lena River water reaching Region III.

Transgressions and regressions of the ocean, which occurred in the past, have affected the development of permafrost on the Arctic shelf. The duration of the transgression/regression cycle, air temperature, the ocean bottom water temperature, the geothermal heat flux are some

• f the most important factors affecting the subsea permafrost distribution

Simulated present-day permafrost (in m) for a heat flow of 60 mW/m2 : (a) the permafrost thickness in the ESAS, (b) simulated locations of permafrost upper boundary in the ESAS for 2012, (c) deepening of a permafrost upper boundary from 1948 to 2012 in the ESAS a b

32

Sea Bottom Temperature on the Laptev Sea in numerical run with Lena River Heat flux and without it. Top boundary of subsea permafrost near the Delta region

Important question-how to get rivers T?

*Long-term open-water season stream temperature variations and changes

• ver Lena River Basin in Siberia,

Baozhong Liua ,2005et al., 2005

Alfred-Wegener-Institute, Helmholtz-Center for Polar and Marine Research German Federal Ministry of Education and Research 'Die Entwicklung von numerischen Modulen für die Lena Delta Region“

Рис. 2. (Григорьев М.Н.) Геоморфологическая схема дельты р. Лены: 1 – долина р. Лены; 2 – пойма и первая терраса - Q4 (абсолютная высота 1-12 м); 3 – вторая песчаная терраса - Q3-4 (абсолютная высота 20-25 м); 4 – третья терраса (ледовый комплекс) - Q3 (абсолютная высота 30-55 м); 5 – низкогорный и предгорный рельеф (Mz); 6 – останцы: галечники, конгломераты - Q1-N3; 7 – скальные останцы – Pz; 8 – выдвигающиеся современные прибрежно-дельтовые образования.

Creating a relief map

Each point contains information:

• 1. Longitude, Latitude
• 2. Velocity
• 3. Width of channel
• 4. Water level

Processing Soviet maps with a resolution of 2 km

• We have simulated the influence of the Lena River heat and

fresh water flux on the Laptev Sea shelf water state based on the coupled regional ocean-ice model and the subsea permafrost model.

• The numerical results show the variability of the summer

hydrological fields on the shelf caused by the atmosphere dynamics variability. We have obtained the eastward spreading of the Lena River water and a negative salinity anomaly to the east of the Lena Delta during the cyclonic regime and northward freshwater advection from the Lena Delta during the anticyclonic regime.

• The heat flux caused by the summer river run-off increases

the bottom water temperature in the Laptev Sea shelf and can affect the submarine permafrost state.

Thank you!