Tuesday, 16 December 2014: 11:35 AM
Hiroyuki Enomoto1,2, Nuerasimuguli Alimasi1,3, Yasuhiro Tanaka3, Kazutaka Tateyama3 and Takao Kameda3, (1)NIPR National Institute of Polar Research, Tokyo, Japan, (2)SOKENDAI Graduate University for Advanced Studies, Kanagawa, Japan, (3)Kitami Institute of Technology, Department of Civil Engineering, Kitami, Japan
Seasonal cycle is a principal march of sea ice change and has been studied for basic understanding of sea ice study. Recently many satellite data became available and strong interannual variation has been reported. In the seasonal cycle, Arctic summer sea ice minimum is strong concern. This shows largest interannual variations in the annual cycle. In May and November, Arctic sea ice shows least interannual variations. There are some important turning points of ice conditions in the annual cycle.

Summer Arctic sea decreasing and summer minimum has the largest interannual variability. Satellite data focuses summer ice reduction and the minimum area is strong concern. Although Arctic summer sea ice minimum is strong concern, other important timing or inflections are in the other season has been not well evaluated. Figure 1 shows seasonal cycle of sea ice area in the northern hemisphere. Arctic and sub-Arctic Sea ice area are indicated here. Winter sea ice shows also large variability, however this is due to sea ice variability in the sub-Arctic sea. Sea ice fluctuation in the Sea of Okhotsk influences winter sea ice variation in the sea ice variation in the northern hemisphere, and produces the decreasing trend in winter maximum of sea ice area. There are two timing of small deviations, appearing as tie points. These timings appear in May and November. Although winter and summer standard deviations are large, the standard deviations in these two timings are small. This indicates strong control of sea ice extent in these seasons.

Recent studies focused sea ice decrease in summer minimum in September. However, the summer surface melting is already ended in August and atmosphere and ice surface shifted to the freezing process in the end of August. Surface sea ice melt in the Arctic Ocean starts in June in the lower latitudes.

We tried to summaries resent understanding and unsolved problems, and discussed again the fundamental seasonal cycle. This study describes seasonal sea ice variation in the Arctic, then discusses with sea ice variation in the other ice covered regions.