Assimilating satellite concentration data into an Arctic sea ice mass balance model, 1979–1985
Assimilating satellite concentration data into an Arctic sea ice mass balance model, 1979–1985
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将卫星浓度数据同化到北极海冰质量平衡模型中，1979-1985 年
DOI：
10.1029/96jc01690
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发表时间：
1996
影响因子：
--
通讯作者：
M. Steele
中科院分区：
文献类型：
--
作者：
D. R. Thomas;Seelye Martin;D. Rothrock;M. Steele
利用卫星冰浓度数据、观测浮标速度和冰的热力学增长模型，我们计算了四种冰类型的厚度分布的时间历史：水平冰和脊状一年冰，水平冰和脊状多年冰。这些历史是在1979年至1985年期间以10天的时间步长计算的覆盖北冰洋的7个区域。观测到的浮标运动和风驱动的自由漂移速度混合驱动模式的平流和隆起部分，而气候增长和融化速度决定了冰的厚度。该模型调整了厚度分布，使模拟的开放水域、第一年冰和多年冰的浓度与卫星无源微波观测的卡尔曼滤波得出的浓度相匹配。主要的调整是减少夏季，特别是周边海域的模拟冰浓度，以考虑未模拟的融化。该模型包括冰盐度参数化，该参数化与冰体积的变化一起给出了冰的盐或淡水通量。我们的结果表明，北极冰盖主要由多年冰组成，占面积的60%和体积的82%，而且大部分冰是脊状的。平均冰厚2.7 m，季节变化30%，年际变化10%。该研究还表明，对于每个细胞和整个北极来说，由生长减去融化引起的冰量变化大致平衡了由进口减去出口引起的变化。每年通过海峡的冰出口量从1100到3000立方千米不等，这主要是由于冰速度的变化。除楚科奇海外，所有地区都有净冰增长、净出口和净盐输入到海洋表面。净产冰向海面的年平均盐通量向下为7.3 kg m−2。沿极流的通量比其他地方大；南森盆地最大的下行通量为33 kg m−2 yr−1，这可归因于Fram海峡附近的强辐散。另一篇论文[Steele等人，本期]利用这些通量和冰速推导出北冰洋淡水平衡。
Using satellite ice concentration data, observed buoy velocities, and a thermodynamic ice growth model, we compute the time histories of the thickness distributions of four ice types: level and ridged first-year ice, and level and ridged multiyear ice. These histories are computed for seven regions covering the Arctic Ocean with a 10-day time step for 1979 through 1985. A blend of observed buoy motions and wind-driven, free-drift velocities drives the advective and ridging parts of the model, while climatological growth and melt rates determine the ice thickness. The model adjusts the thickness distributions so that the modeled concentrations of open water, first-year ice, and multiyear ice match the concentrations derived by Kalman filtering of satellite passive microwave observations. The major adjustment is to reduce modeled ice concentrations in summer and particularly in the peripheral seas to account for unmodeled melt. The model includes an ice salinity parameterization which, along with changes in ice volume, gives the salt or freshwater flux from the ice. Our results show that the Arctic ice cover consists primarily of multiyear ice, 60% by area and 82% by volume, and that most of this ice is ridged. The average ice thickness is 2.7 m with a seasonal variation of 30% and an interannual variation of 10%. The study also shows that for each cell and the Arctic as a whole, the changes in ice volume caused by growth minus melt approximately balance the changes caused by import minus export. The annual ice export through Fram Strait varies from 1100 to 3000 km3, primarily because of variations in ice velocity. All regions except the Chukchi Sea have a net ice growth, a net export, and a net salt input to the ocean surface. The annual mean salt flux to the ocean surface from net ice production is 7.3 kg m−2 downward. Fluxes along the transpolar drift stream are larger than elsewhere; the largest downward flux of 33 kg m−2 yr−1 in the Nansen Basin can be attributed to the strong divergence near Fram Strait. A companion paper [Steele et al., this issue] uses these fluxes and ice velocities to derive the Arctic Ocean freshwater balance.