首页|北半球大气对春季北极海冰异常响应的数值模拟

北半球大气对春季北极海冰异常响应的数值模拟

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在CAM3.0模式中,通过设计一系列数值模拟试验来研究北半球大气环流对北极海冰密集度(Sea Ice Concentration,简称SIC)强迫的响应.将海冰密集度EOF第二模态(EOF2)的时间系数回归到原场,并把这个空间异常场逐月的加到SIC春季气候态上,作为敏感性试验的外强迫.试验结果表明:在季节尺度上,大气环流由春季逐渐向夏季演变,春季SIC异常与春、夏季北半球大气环流、地表温度以及降水异常有显著关系,尤其是对春季中国东部降水负异常,夏季东北部、东南沿海降水正异常有很大贡献.在逐日和逐周时间尺度瞬态演变上,局地高、低层大气环流对海冰强迫的响应呈现斜压结构,两周之后大气由斜压结构逐渐转变为正压结构,强迫响应可以通过遥相关波列传播到北极以外地区,到了第6周大气的响应基本达到正压平衡状态.这种遥相关的产生与极区热通量异常所激发的波活动通量有关:北极SIC异常首先通过直接热力强迫过程来改变表层热通量空间分布,这种表面热通量异常通过与大气环流的相互作用可以激发出大尺度罗斯贝波.在初始斜压区的低层有波动能量向上传播,并在对流层中高层向南传播,最后通过直接热力强迫和大气内部动力学相互作用引发的遥相关过程将能量频散到东亚地区,进而影响东亚地区的天气和气候.
The Northern Hemisphere Atmospheric Response to Spring Arctic Sea Ice Anomalies in CAM3.0 Model
The influence of Arctic Sea Ice Concentration (SIC) anomalies on the atmospheric general circulation during spring and summer is investigated with version 3. 0 of the NCAR Community Atmosphere Model (CAM3. 0). Regress the second EOF mode of ICE to observed ICE, and then added to climatic ICE as the external force of test The results show that on the intraseasonal time scale, the atmospheric circulation anomalies evolved from spring to summer, and the spring Arctic SIC anomalies were thermally and dynamically consistent with atmospheric circulation, surface temperature, and rainfall anomalies in spring and summer, especially contributing to less spring rainfall in eastern China and more summer rainfall in northeastern and central China. While on short time scales, the initial adjustment of the atmospheric circulation is characterized by relationship of out of phase in geopotential height anom-alies in the lower and upper troposphere locally, and after two weeks, the out of phase turned progressively to more barotropic with the responses propagating to remote areas, at last, the quasi-equilibrium stage of adjustment is reached in the sixth week. The remote responses are regarded as a stationary Rossby wave generated thermally and dynamically through an anomalous turbulent heat fluxes and atmospheric circulation internal varieties. At first, the surface heat fluxes were changed by anomalies in the Arctic SIC, and then a large scale stationary Rossby wave was triggered through the interaction with atmospheric circulation. The lower tropospheric response is baroclinic and thus favors upward emanation of wave activity flux in the negative height anomaly area; while, in upper levels, the energy is dispersed to East Asia through teleconnection, the internal varieties keeping the energy, and then affects the climate in this area.

sea ice, sea ice concentration, summer rainfall, sensitivity test, control test, transient process, wave activity flux

张若楠、武炳义

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中国气象科学研究院,北京100081

海冰 海冰密集度 夏季降水 敏感性试验 控制试验 瞬变过程 波活动通量

公益性行业(气象)科研专项公益性行业(气象)科研专项国家自然科学基金国家自然科学基金中国气象科学研究院资助项目

GYHY200906017GYHY2007060054087505240921003

2011

大气科学
中国科学院大气物理研究所

大气科学

CSTPCDCSCD北大核心
影响因子：2.11
ISSN：1006-9895
年,卷(期)：2011.35(5)
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