Holocene dynamics in the Bering Strait inflow to the Arctic and the Beaufort Gyre circulation based on sedimentary records from the Chukchi Sea
Masanobu Yamamoto1,2, Seung Il Nam3, Leonid Polyak4, Daisuke Kobayashi2, Kenta Suzuki2, Tomohisa Irino1,2, and Koji Shimada51Faculty of Environmental Earth Science, Hokkaido University, Kita-10, Nishi-5, Kita-ku, Sapporo 060-0810, Japan 2Gradute School of Environmental Science, Hokkaido University, Kita-10, Nishi-5, Kita-ku, Sapporo 060-0810, Japan 3Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, Republic of Korea 4Byrd Polar and Climate Research Center, The Ohio State University, , Columbus, OH 43210, USA 5Tokyo University of Marine Science and Technology, 4-5-7, Konan, Minato-ku, Tokyo 108-8477, Japan
Received: 13 Oct 2016 – Accepted for review: 23 Oct 2016 – Discussion started: 31 Oct 2016
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.
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., doi:10.5194/cp-2016-105, in review, 2016.