Autumn atmospheric preconditioning for interannual variability of wintertime sea-ice in the Okhotsk Sea

What determines the maximum sea ice extent in the Sea of Okhotsk? Importance of ocean thermal condition from the Pacific

“…The SST in the EKC and the upwind air temperature are related to the sea ice extent in the northeastern and center to southern parts of the Okhotsk Sea, respectively. Since the prediction scheme using only the T850 explains 50% of the total variance [ Sasaki et al , 2007], the skill of our prediction scheme with both the SST and T850 is 20% higher than that using only the T850. Thus, the SST in the EKC significantly improves the prediction skill of the MSIE.…”

“…This concern arises from the significant negative correlation between the MSIE and the SST over the western subarctic gyre all through the preceding November–March (Figures 2b–2f). These significant negative correlations may be partly related to the local atmospheric condition over the Okhotsk Sea in late autumn [ Sasaki et al , 2007] and winter [e.g., Kimura and Wakatsuchi , 1999] and the dominant atmospheric modes in the northern hemisphere of the Aleutian low strength [e.g., Tachibana et al , 1996], the North Atlantic Oscillation (NAO) [ Deser et al , 2000], and the Arctic Oscillation (AO) [ Ogi and Tachibana , 2006]. Therefore, we checked the possibility that these atmospheric variabilities determine both the SST in the EKC region and the MSIE.…”

“…As shown in section 3.2, it was found that the SST in the EKC is significantly correlated with the MSIE even if the contribution of the atmospheric conditions is excluded. Since the SST leads the MSIE by 2–3 months, use of the SST as well as T850 would permit the development of a more precise prediction scheme for the MSIE than that using only T850 data [ Sasaki et al , 2007]. Thus, we built a statistical prediction scheme for the MSIE based on the SST and T850 data by multiple linear regression as follows: where y represents the MSIE (× 10 6 km 2 ) in the Sea of Okhotsk, x 1 is the SST (°C) averaged in the EKC region in the preceding November–December, and x 2 is the T850 (°C) in the preceding October–November at 52.5°N, 135°E.…”

“…Therefore, it is expected that warm water advection from the Pacific is an important factor in determining the MSIE. Recently, it was suggested that the autumn atmospheric heat condition affects the MSIE through the ocean thermal persistence in the Sea of Okhotsk [ Sasaki et al , 2007]. However, the variation in the ocean temperature in itself has not been examined yet.…”

Summer-to-Winter Sea-Ice Linkage between the Arctic Ocean and the Okhotsk Sea through Atmospheric Circulation

“…It is also suggested that initializing the sea-ice variability may in turn enhance the predictability of atmospheric circulations in seasonal forecasts (Balmaseda et al 2010;Doblas-Reyes et al 2013). Sasaki et al (2007) showed that autumnal wind anomalies flowing from Siberia into the Okhotsk Sea bring cold air temperatures and heavy sea-ice conditions there. Their results show that the decrease of the Arctic sea-ice extent along the Siberian coast in September is associated with significant cold anomalies over the Far East and high pressure anomalies over Siberia in early winter.…”