北半球大气对春季北极海冰异常响应的数值模拟

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...

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 anomalies 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.