Atmospheric boundary layer structure and drag coefficients over sea ice
Atmospheric boundary layer structure and drag coefficients over sea ice
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海冰上的大气边界层结构和阻力系数
DOI：
10.1029/jc090ic05p09029
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发表时间：
1985
影响因子：
--
通讯作者：
J. Overland
中科院分区：
文献类型：
--
作者：
J. Overland
本文估计的空气/海洋阻力系数的第一年的冰从最近的飞机测量和调和的范围内观察到的阻力系数（103 CD = 1.2-3.7参考10米）的所有海冰类型，根据冰的粗糙度和季节性气象。由于海冰在小于20 km的尺度上是不均匀的，为了进行海冰模拟，有必要定义一个有效的拖曳系数，它将区域应力与区域风联系起来。区域应力的影响分布的表面粗糙度，浮力通量从准周期性的铅，和外部大气条件，主要是逆温高度。103 CD对于光滑的冰是1.3-1.5，但对于非平坦表面要大得多。对于风速大于5 m/s和气温低于冰点的情况，对于几乎连续的浮冰，例如季节性冰区和北极盆地中部的第一年冰，有效103 CD为2.5-3.0。对于边缘冰区（MIZ）典型的离冰风不稳定边界层，103 CD值的范围为3.0-3.7，如果最近的风暴打破了冰，则甚至更大。在这些范围的下端的CD值与低反转高度相关联。这些系数由103 CD（2.9、2.5和3.1）证实，这些系数是根据边缘冰区试验期间NOAA P-3飞机在白令海内MIZ内部收集的阵风探测器数据计算的第一年海冰（MIZEX-West），根据1976年2月的北极冰动力学联合实验（AIDJEX）飞机数据计算出的北极103 CD为2.6。即使存在很小的海冰浓度，有效阻力系数也大于海洋值，如1984年6月MIZEX-84期间，根据NOAA P-3阵风探测器数据计算的103 CD为2.2，该数据在格陵兰海外MIZ的40 km轨道上的冰浓度为0.4。本文用一个湍流闭合大气边界层模式讨论了高纬度典型的浅逆温高度下地面风场和应力场与地转风场的关系。冬季北极的典型特征是低逆温（<100米），低地转阻力系数，大地转/地面风转向角，对地面粗糙度的功能依赖性低。季节性冰区的典型特征是逆温对边界层特性的影响较小。
This paper estimates the air/sea drag coefficient for first-year ice from recent aircraft measurements and reconciles the range of observed drag coefficients (103CD = 1.2–3.7 referenced to 10 m) for all sea ice types, based on ice roughness and seasonal meteorology. For the purpose of sea ice modeling, it is necessary to define an effective drag coefficient which relates regional stress to regional wind, because sea ice is heterogeneous on scales less than 20 km. Regional stress is influenced by the distribution of surface roughness, the buoyancy flux from quasi-periodic leads, and external atmospheric conditions, principally the inversion height. 103CD is 1.3–1.5 for smooth ice but is much greater for nonflat surfaces. For wind speeds greater than 5 m/s and air temperatures below freezing, the effective 103CD is 2.5–3.0 for nearly continuous pack ice, such as first-year ice in seasonal ice zones and central Arctic basin. The range of values of 103CD is 3.0–3.7 for unstable boundary layers typical of off-ice winds in the marginal ice zone (MIZ) or even greater if the ice has been broken by a recent storm. CD values at the lower end of these ranges are associated with low inversion heights. These coefficients are confirmed by 103CD of 2.9, 2.5, and 3.1 for first-year sea ice calculated from gust probe data collected by the NOAA P-3 aircraft, interior to the inner MIZ in the Bering Sea during the Marginal Ice Zone Experiment (MIZEX-West) in February 1983, and 103CD of 2.6 for the Arctic calculated from Arctic Ice Dynamics Joint Experiment (AIDJEX) aircraft data for February 1976. The effective drag coefficient with the presence of even a small concentration of sea ice is greater than the oceanic value as shown by a 103CD of 2.2 calculated from NOAA P-3 gust probe data over a 40-km track of 0.4 ice concentration in the outer MIZ of the Greenland Sea in June 1984 during MIZEX-84. The relation of surface wind and stress to the geostrophic wind for shallow inversion heights, typical of high latitudes, is reviewed with a turbulent closure atmospheric boundary layer model. The winter Arctic is typified by low inversions (<100 m), low geostrophic drag coefficients, and large geostrophic/surface wind turning angles, with low functional dependence on surface roughness. Seasonal ice zones are typified by a more modest influence of the inversion on boundary layer characteristics.