Autumn atmospheric preconditioning for interannual variability of wintertime sea-ice in the Okhotsk Sea
详细信息 查看全文
- 作者：Yoshi N. Sasaki ; Yurika Katagiri ; Shoshiro Minobe and Ignatius G. Rigor
- 关键词：Okhotsk Sea ; sea ; ice variability ; autumn atmosphere ; prediction ; singular value decomposition analysis
- 刊名：Journal of Oceanography
- 出版年：2007
- 出版时间：April, 2007
- 年：2007
- 卷：63
- 期：2
- 页码：255-265
- 全文大小：687 KB
文摘
Relations in year-to-year variability between wintertime Sea-Ice Concentrations (SICs) in the Okhotsk Sea and atmospheric anomalies consisting of zonal and meridional 1000-hPa wind speeds and 850-hPa air temperatures are studied using a singular value decomposition analysis. It is revealed that the late autumn (October–November) atmospheric conditions strongly influence sea-ice variability from the same season (late autumn) through late winter (February—March), in which sea-ice extent is at its maximum. The autumn atmospheric conditions for the positive sea-ice anomalies exhibit cold air temperature anomalies over the Okhotsk Sea and wind anomalies blowing into the Okhotsk Sea from Siberia. These atmospheric conditions yield anomalous ocean-to-atmosphere heat fluxes and cold sea surface temperature anomalies in the Okhotsk Sea. Hence, these results suggest that the atmospheric conditions affect the sea-ice through heat anomalies stored in sea-ice and oceanic fields. The late autumn atmosphere conditions are related to large 700-hPa geopotential height anomalies over the Bering Sea and northern Eurasia, which are related to a stationary Rossby wave propagation over the North Pacific and that from the North Atlantic to Eurasia, respectively. In addition, the late autumn atmospheric preconditioning also plays an important role in the decreasing trend in the Okhotsk sea-ice extent observed from 1980 to the mid-1990s. Based on the lagged sea-ice response to the late autumn atmosphere, a simple seasonal prediction scheme is proposed for the February–March sea-ice extent using four-month leading atmospheric conditions. This scheme explains 45 % of the variance of the Okhotsk sea-ice extent.