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首页> 外文会议>NATO Advanced Research Workshop on the Freshwater Budget of the Arctic Ocean, Apr 27-May 1, 1998, Tallinn, Estonia >FRESH WATER FREEZING/MELTING CYCLE IN THE ARCTIC OCEAN
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FRESH WATER FREEZING/MELTING CYCLE IN THE ARCTIC OCEAN

机译：北极海洋的新鲜水冻结/融化循环

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摘要

In the upper layer of the Arctic Ocean fresh water transported with the polar branch of the global hydrological cycle accumulates at its surface with sea ice and its outflow to the North Atlantic is formed. Between these two processes in the Arctic Ocean, repeated phase "water-ice" transformations occur. They constitute the internal Arctic hydrological cycle changing the dynamic and thermodynamic properties of the upper layer, and the time of residence of freshwater and thus influence the formation of its outflow. The fresh water flows to the Arctic and its outflow from the Arctic Ocean comprise an active part of a full excess of fresh water in it resulting in the preservation of sea ice. The total content of the fresh water "excess" in the Arctic Ocean estimated relative to the salinity of 34.80 PSU is non-uniformly distributed over its area changing from year-to-year. The climatic FWC maximum is located in the Canadian Basin and is formed by the fresh water flows with precipitation, river runoff and Bering water. The active FWC portion is centered in the upper 50 m layer within the winter convective mixing depth in the Arctic Ocean. The interannual changes of the mean FWC over the area reach here 1.3 m of the equivalent layer of freshwater. A similar value of FWC changes was obtained from water salinity changes in the region of sources of the East Greenland Current north of Greenland. The interannual FWC changes are characterized by increased values up to the mid-1970s and decreased FWC after 1975. The differences between them are most noticeable at the periphery of the Arctic Ocean. The main cause of the significant interannual FWC changes is connected with the summer flows of fresh water to the Arctic Ocean. According to different estimates, they are within 6000 to 10000 km~3, which exceeds by several times the net annual inflow. The changes in the conditions of summer melting lead to a disturbed balance in the "freezing-melting" cycle and as a result to freshening or salination of the upper layer of the Arctic Ocean. The summer fresh water flows are formed due to snow melting (whose depth before melting is 36 cm, on average, for the Arctic Basin varying within 25 to 85 cm from data of observations at some drifting stations) and ice melting from the top and the bottom and lateral ice melting. The average value of ice melting determined from data of observations at the drifting stations for multiyear ice comprises 44 cm for melting from the top and 20 to 40 cm for melting from the bottom. A contribution from lateral ice melting is also significant. The volume of winter ice growth in the Arctic Basin was estimated from climatic data as 9677-9886 km~3 and the volume of summer melting as 6876-7086 km~3, which corresponds to the prescribed volume of the exported ice from the Arctic Ocean of 2800/2850 km~3. The excess of the winter ice formation over summer melting serves as the main source of heat released in the winter period from the surface of the Arctic Ocean to the atmosphere. The anomalous water freshening in the upper layer of the North Atlantic observed in the 1960s-early 1970s is primarily related to the increased flow of freshwater to the Arctic Ocean due to intense snow and ice melting in the Arctic, especially in 1958-1963 in the region of the Canadian archipelago, Baffin Bay and West Greenland. The increased summer air temperature in the Arctic, which began at the end of the 1980s can be an indication of the formation of a new impulse of freshening in the Arctic Ocean.
机译：在北冰洋的上层，随着全球水文循环的极分支运输的淡水在其表面积聚有海冰，并形成了向北大西洋的流出。在北冰洋的这两个过程之间，发生了重复的“水冰”相变。它们构成了北极内部的水文循环，改变了上层的动态和热力学性质，并改变了淡水的停留时间，从而影响了其流出的形成。淡水流向北极，其从北冰洋流出的水构成了其中全部过量淡水的活跃部分，从而保护了海冰。相对于34.80 PSU的盐度，估计的北冰洋“过量”淡水的总含量在其区域中不均匀地分布，并且每年都在变化。气候FWC最大值位于加拿大盆地，由淡水流量，降水，河流径流和白令水组成。活跃的FWC部分位于北冰洋冬季对流混合深度内的50 m高层。整个区域的平均FWC的年际变化在这里达到淡水当量层的1.3 m。从格陵兰以北的东格陵兰洋流源区的水盐度变化获得了FWC变化的相似值。年际FWC的变化特征是直到1970年代中期的值增加，而1975年之后的FWC减少。北冰洋边缘之间的差异最明显。每年FWC发生重大变化的主要原因与夏季流入北冰洋的淡水有关。根据不同的估计，它们在6000至10000 km〜3之内，是每年净流入量的几倍。夏季融化条件的变化导致“冰冻融化”周期的平衡紊乱，并导致北冰洋上层的新鲜或盐碱化。夏季的淡水流是由融雪形成的（融化之前，北极流域的融化深度平均为36厘米，与某些漂流站的观测数据相差25至85厘米），而顶部和底部则融化了冰。底部和侧面的冰融化。由多年冰的漂流站的观测数据确定的冰融化平均值包括：从顶部融化为44 cm，从底部融化为20至40 cm。横向冰融化的作用也很重要。根据气候数据估算，北极盆地冬季冰的生长量为9677-9886 km〜3，夏季融化量为6876-7086 km〜3，这与从北冰洋输出的冰的规定量相对应。 2800/2850公里〜3。在夏季融化期间，冬季冰层形成的过量部分是冬季从北冰洋表面释放到大气的主要热量来源。 1960年代至1970年代初在北大西洋上层观测到的异常水清新现象，主要与北极冰雪融化特别是1958-1963年北极冰雪融化导致流入北冰洋的淡水增加有关。加拿大群岛，巴芬湾和西格陵兰岛地区。始于1980年代末的北冰洋夏季气温上升，可能表明北冰洋出现了新的清新冲动。

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