北冰洋中心区海冰漂流与大气过程

Sea ice drifting and atmospheric processes over the central Arctic Ocean

利用北冰洋中心区漂流自动气象站(DAWS)2012年9月—2013年2月的观测数据,分析了北极点周围海冰漂流轨迹和速度及相关大气过程。结果显示,北冰洋中心区海冰具有不稳定漂流过程。2012年9月1日—2013年1月6日,DAWS所在海冰从西向西北方向漂流,2013年1月6日以后稳定地向东南方向漂流,平均移速为0.06m/s,最大达到0.4m/s。海冰漂流方向的突变和加速与穿极气旋和急流的影响有关。净辐射常出现短期突变过程,导致海冰从大气吸收能量,减缓了海冰的辐射冷却。爆发性增温过程的最大幅度达到30℃,是由强穿极气旋和伴随的暖湿气流向北极中心区输送引起,这种现象在中低纬度十分罕见。增温过程的作用是高空大气向冰面输送热量,导致海冰破裂,海冰硬度的脆变,减缓海冰厚度的增长,这种过程可能是北极海冰面积和厚度减少重要过程。

Based on the data observed by drifting automatic weather station（DAWS）from August 2012 to February2013and NOAA re-analyzing data over the Arctic Centre,the track,movement velocity of drifting sea ice and the evolution of temperature,humidity,radiation of drifting sea ice,atmospheric processes,including the evolvement of flow pattern and temperature field and its relative dynamic and thermodynamic processes over the Arctic troposphere in 500 and 1 000 hPa during period of autumn and winter around north polar are analyzed.The results show that,before 6January 2013,sea ice moves mainly from the east to the northwest,and appearing the unstable trajectory of roundabout and turning process,then drifting towards to the south east.Its average drift velocity is 0.06m/s,the maximum speed up to 0.4m/s.The mutation and accelerated in the direction of polar sea ice drifting is associated with the activities of across the polar cyclone and jet stream in polar troposphere.Sea ice surface net radiation repeated short-term mutation process,resulting in the ice surface to absorb energy from the air,reduced the radiation cooling of sea ice in the Arctic area.In the autumn and winter it emerges sudden warming process in many time with the maximum increased of temperature reaches 30℃,caused conveying the warm and wet air flow.This kind of phenomenon is very rare in area of low and middle latitude.In the warming process it transports heat to the ice surface from the middle or up layer atmosphere may lead to ice floe rupture,fragile sea ice hardness,thickness of the slow growth of sea ice to accelerate the movement of the channel.This process may be one of the important mechanisms of the Arctic sea ice area and thickness reduction.