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Thermal Regime of Submarine Permafrost in Kara Seaтезисы доклада
- Авторы: Vasiliev Alexander, Oblogov Gleb, Streletskaya Irina, Shirokov Roy
- Сборник: International Conference «Permafrost in XXI century: basic and applied researches» Pushchino, Moscow region, Russia, September 27 – October 1, 2015. Program and Conference materials
- Том: 1
- Тезисы
- Год издания: 2015
- Место издания: Pushchino
- Первая страница: 117
- Последняя страница: 117
- Аннотация: Distribution, structure, and thermal regime of submarine permafrost (SMP) in the Kara Sea region have been understudied. Thermal regime of SMP can be determined only on the base of direct measurements in boreholes or modeling, which provides only approximate estimations. Analysis of published and archived data on SMP temperatures suggests the occurrence of two types of SMP with different thermal regimes. The first type is represented by relic permafrost with ground temperatures close to phase-transition temperature, which depends on texture of soils and content of salts. This quasi-equilibrium temperature for the Kara Sea varies from –0.8 to –1.5оС. Similar quasi-equilibrium temperatures are also typical of stock-like permafrost massifs, which have formed due to stream degassing of methane originated from underneath of the permafrost stratum. The second type was determined during the drilling of boreholes in the mouth of Obskaya Guba, when SMP with the temperatures of –4.0 to –4.5 оС were encountered. The sea in this area was 13 to 15 m deep, and permafrost table was detected at depths of 25 to 30 m from the sea bottom. A temperature profile characterized by the abrupt decrease in permafrost temperatures with depth indicates rapid permafrost degradation. Presumably, such distribution of SMP temperature with depth is the evidence of recent submersion of this area. Thus, SMP of the Kara Sea shelf are divided according to their thermal regimes into two types: (1) relic and stock SMP with temperatures close to the phase-transition temperature, and (2) SMP within recently submerged areas with low temperatures and a temperature profile which indicates an active warming and thawing of the upper permafrost. An analysis of dynamics of the Kara Sea bottom temperature revealed that during the last 100 years permafrost temperature has increased by 0.3 to 2.2оС. The biggest increase in the near-bottom temperature was observed in the south-eastern part of the Kara Sea. This temperature increase has resulted in the rapid SMP degradation with the rates of 0.5 to 2.5 cm/year. The map of regions with the rapid SMP degradation is presented.
- Добавил в систему: Стрелецкая Ирина Дмитриевна