Faculty of Environmental Earth Science, Hokkaido University, Kita-10, Nishi-5, Kita-ku, Sapporo 060-0810, Japan
Gradute School of Environmental Science, Hokkaido University, Kita-10, Nishi-5, Kita-ku, Sapporo 060-0810, Japan
Tokyo University of Marine Science and Technology, 4-5-7, Konan, Minato-ku, Tokyo 108-8477, Japan
Abstract. The Beaufort Gyre (BG) and the Bering Strait inflow (BSI) are important elements of the Arctic Ocean circulation system and major controls on the distribution of Arctic sea ice. We report records of the quartz/feldspar and chlorite/illite ratios in two sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the BG circulation and the BSI during the Holocene. The quartz/feldspar ratio, a proxy of the BG strength, gradually decreased during the Holocene, suggesting a long-term decline in the BG strength, consistent with orbitally-controlled decrease in summer insolation. We suppose that the BG rotation weakened as a result of increasing stability of sea-ice cover at the margins of the Canada Basin, driven by decreasing insolation. Millennial to multi-centennial variability in the quartz/feldspar ratio (the BG circulation) is consistent with fluctuations in solar irradiance, suggesting that solar activity affected the BG strength on these timescales. The BSI, approximated by the chlorite/illite record, shows intensified flow from the Bering Sea to the Arctic during the middle Holocene, which is attributed primarily to the effect of an overall weaker Aleutian Low. This middle Holocene strengthening of the BSI was coeval with intense subpolar gyre circulation in the North Atlantic. We propose that the BSI is linked with the North Atlantic circulation via an atmospheric teleconnection between the Aleutian and Icelandic Lows. A correspondence between the Holocene variability of the BSI and North Atlantic Drift suggests that this connection is involved in a mechanism muting salinity changes in the North Atlantic, and thereby stabilizing the Atlantic Meridional Overturning Circulation.
How to cite. Yamamoto, M., Nam, S. I., Polyak, L., Kobayashi, D., Suzuki, K., Irino, T., and Shimada, K.: Holocene dynamics in the Bering Strait inflow to the Arctic and the Beaufort Gyre circulation based on sedimentary records from the Chukchi Sea, Clim. Past Discuss. [preprint], https://doi.org/10.5194/cp-2016-105, 2016.
Received: 13 Oct 2016 – Discussion started: 31 Oct 2016
We report mineral records in two sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the Arctic currents during the Holocene. We found a long-term decline in the BG strength, consistent with decrease in summer insolation. The millennial to multi-centennial variability is consistent with fluctuations in solar irradiance. The BSI shows intensification during the middle Holocene, which is attributed to a weak Aleutian Low.
We report mineral records in two sediment cores from the northern Chukchi Sea providing insights...