NUMERICAL MODELLING OF SUBMARINE PERMAFROST ON THE EURASIAN ARCTIC SHELF CONSIDERING MODERN CLIMATE ZONALITY
Yu.Yu. Smirnov1,2, T.V. Matveeva1, N.A. Shchur1,3, A.A. Shchur1, A.V. Bochkarev1
1Federal State Budgetary Institution "Academician I. S. GRAMBERG All-Russia Scientific Research Institute for Geology and Mineral Resources of the Ocean", St. Petersburg, Russia
2Russian State Hydrometeorological University, St. Petersburg, Russia
3Peter the Great Sankt-Petersburg Polytechnic University, St. Petersburg, Russia
Keywords: Eurasian Arctic shelf, submarine permafrost, Python, Julia, numerical permafrost modelling, forecast submarine permafrost mapping
Abstract
The study and prediction of subsea permafrost conditions hold profound significance in the context of global climate change, the formation of gas hydrates, and the assessment of natural hazards arising from the permafrost thawing. This study presents a forecast of relict subsea permafrost distribution across the Eurasian Arctic shelf through the resolution of a one-dimensional, non-stationary Stefan problem using finite difference methods, facilitated by contemporary software tools and libraries. The mathematical description of the model is presented. Particular attention is paid to the boundary conditions of the model and their synthesis. Calculations take into account the climate clustering of the expansive Eurasian shelf, considering zonal variations in both near-surface air temperature and the temperature and salinity of subsea waters. For the first time, model estimates of the position of the upper boundary of subsea permafrost are presented, and its position is compared with drilling data. Analysis of the influence of boundary conditions on the simulation results and comparison of our results with seismoacoustic and drilling data confirm the good quality of the model. The evolution of subsea relict permafrost in time is represented by a set of three maps for the Late Pleistocene-Holocene time spans. As a result, a high-resolution global two-dimensional map of the thickness of underwater permafrost on the Eurasian shelf was created. Detailed modelling and forecast mapping of the distribution of permafrost table was carried out in well-studied areas. According to our forecasts, a wide distribution of subsea relict permafrost is predicted throughout the Eurasian Arctic shelf. The greatest thickness of relict frozen deposits is confined to the littoral zone of the Laptev and East Siberian seas, as well as the offshore of the New Siberian Islands. In the Pechora and Chukchi seas, mostly poorly developed, close to complete degradation, relict subsea permafrost is predicted.
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