包含水分循环和海冰物理过程的气候模式及气候因子对海冰变化的影响

A CLIMATE MODEL WITH HYDROLOGICAL CYCLE AND SEA ICE PHYSICS AND THE EFFECT OF CLIMATE FACTORS ON VARIATION OF THE ARCTIC SEA ICE

鉴于水分循环和海冰过程是气候变化研究中两个比较薄弱的环节，而在以往的一些气候模式中往往简化甚至忽略了其中之一，给气候变化的研究带来了一定的不确定性。因此本文设计了一个包含详细水分循环和海冰物理过程的二维气候模式，在模拟出极地海冰面积和季节循环基础上，详细研究了存在大气、海洋、海冰以及水份循环中的各种气候因素对海冰季节循环的影响，得到了一些比较有意义的结论：（1）当大气中感热和潜热输送加强时，海冰面积减小，反之则增大。结合海冰面积增大有助于向极热量输送加强的结论，我们认为在北极地区存在着一种维持大气—海洋—极冰系统平衡的负反馈机制，即海冰面积增大，导致向极热量输送的增加，而向极热量输送的增加又有助于海冰面积的缩小。（2）当地表向大气输送的感热和潜热增大时，海冰的面积将增大，反之则减小。这一结论与海冰的隔热效应联系在一起，我们推测在冰线附近可能存在着一种周而复始，互为因果的时间自组织现象，即LE，HS↑→海冰面积于↑→LE、HS↓→海冰面积↓→LE、HS↑。通过这种时间自组织行为，海冰面积在一定程度上可以实现自我调节。（3）当边界层的垂直湍流交换系数减小时，海冰季节循环的振幅增大，即冬季海冰面积增大，夏季海冰面积减小；

A climate model including explicitly hydrological cycle and sea ice physics is presented,and is mainly used to study how the climate factors existing in atmosphere'ocean and sea ice affect the seasonal cycle of the sea ice area. It is shown that, firstly, there possibly exists a kind of negative feedback in the Arctic Region which keeps the atmosphere. ocean. sea ice system balance, that is, an increase of sea ice area results in the increasing of the poleward heat transport, but the increase of the poleward heat transport leads to the decreasing of the sea ice area again. Secondly, there exists a kind of time self-organization phenomenon between the sea ice and the upward heat flux from the surface to atmosphere, namely, LE, HS 4 ↑→sea ice area↑→LE, HS↓→sea ice area ↓→LE, HS↑,which takes a role of self-regulation to sea ice area and makes the sea ice not produce large change easily. Thirdly, the sea ice area is most sensitive to the vertical eddy diffusion coefficient KT in the boundary layer.The amplitude of the seasonal cycle of the sea ice area increases with decreasing of K. and decreases with increasing of KT. Fourthly, the ocean affects the sea ice more directly and effecti vely than the other factors. The amplitude of the seasonal cycle of sea ice area decreases with incereasing of depth of the ocean mixed layer, and the increase of the ocean's heat flux and the heat transport from ocean to sea ice will both reduce the sea ice area. Fifthly, sea ice physics also has great impact on the sea ice extent. The ice advection increases the amplitude of the seasonal cycle of sea ice F the increase of the upward conductive heat flux within the ice enlarges the sea ice extent; the parameterized surface albedo temperature dependence has the greatest effect on ice extent in summer but negligible effect in winter. In addition, thereare many other climate factors affecting the sea ice extent, for example, the sea ice area decreases when the CO2 content is doubled and the extent reduced is larger in summer than in winter;the sea ice area decreases with increasing of cloudiness and enhancement of the intensity of hydrological cycle.