Preservation of the climatic signal in the old ice layers at Dome B area (Antarctica)

• Published in: Ice and Snow
• Main Authors: A. Ekaykin A., V. Lipenkov Ya., K. Tchikhatchev B., А. Екайкин А., В. Липенков Я., К. Чихачев Б.
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: IGRAS 2021
• Subjects: Antarctica; Dome B; old ice; paleoclimate; modeling; ice dynamics; stable water isotopes; diffusion; Антарктида; Купол В; древний лёд; палеоклимат; моделирование; динамика льда; стабильные изотопы воды; диффузия; Antarctic; Antarc*; ice core
• Online Access: https://ice-snow.igras.ru/jour/article/view/865; https://doi.org/10.31857/S2076673421010067

In this work we have presented the results of numerical modeling of the age and temperature distribution in ice layers at Dome B site (79,02° S, 93,69° E, altitude 3807 m a.s.l., ice thickness about 2.5 km), located 300 km to the west from Russian Antarctic station Vostok. Dome B is situated on the onset of the ice flow line passing through deep borehole 5G, and is considered as one of the most promising places to search for and to study the Easth’s oldest ice with the age of up to 1.5 Ma. According to our calculations, all realistic scenarios show the ice age at 60 m above the ice base to be considerably older than 1 Ma, and the glacier base temperature is well below the pressure melting point (−1.8 °С for pressure = 23 MPa). For the most likely scenario (accumulation rate 1.8 g/(cm2 year), effective ice surface temperature −64 °С and geothermal heat flux 60 mW/m2) the ice age is 1.4 Ma and the basal temperature is about −13 °С that is close to the earlier predictions from a 2D‑model. Maximum estimate of the «diffusion length» in the old ice (for the scenario in which the basal temperature reaches the melting point, and in which 30% of «excess diffusion» is taken into account) is 5.2 cm. In 1.4 Ma-old ice a 40-ka climatic cycle is squeezed into a 290-cm thick ice layer. For this ratio of wave length and diffusion length the climatic signal attenuation (ratio between the signal amplitude after and before the diffusive smoothing) is 0.6%. Thus, due to the relatively low ice temperature here we may expect a nearly undisturbed climatic curve in the old ice core that will be drilled one day at Dome B. At the same time shorter oscillations with the wavelengths of < 1500 years will be totally erased by diffusion. Представлены результаты моделирования возраста и температуры льда для Купола В (79,02° ю.ш., 93,69° в.д., высота 3807 м над ур. моря, толщина льда около 2,5 км) в Антарктиде. Для всех сценариев возраст льда на отметке 60 м выше ложа ледника составляет более 1 млн лет, а для наиболее вероятного сценария – ...