Turbulent surface fluxes and air–ice coupling in the Baltic Air–Sea–Ice Study (BASIS)
Turbulent surface fluxes and air–ice coupling in the Baltic Air–Sea–Ice Study (BASIS)
复制标题
波罗的海海冰研究（BASIS）中的湍流表面通量和空气-冰耦合
作者：
J. Launiainen;B. Cheng;J. Uotila;T. Vihma
摘要利用1998年3月在波罗的海海冰上的观测资料研究了海面湍流通量。用声速风速仪测量了动量通量和感热通量，并与风速和气温剖面的通量进行了比较。中性10 m阻力系数对风速没有明显的依赖性（在2-20 m s-1范围内），光滑冰雪的平均值为1.0 × 10 - 3，变形冰的平均值为1.5 × 10 - 3。总体平均值为1.28 × 10-3。温度粗糙度长度对风速的依赖性更强，低风速粗糙度略大于气动粗糙度，中高风速粗糙度反之。我们给出了一个经验表达式，预测标量粗糙度如何依赖于气动粗糙度（阻力系数）和风速。梯度法结果与涡流通量结果的一致性支持了莫宁-奥布霍夫相似理论的有效性。用气-冰-海耦合模式模拟的通量与涡旋通量法和梯度法模拟的通量比较好。三种方法估算的表面温度也很一致。试验和灵敏度分析强调，对于梯度法，需要特别精确的传感器校准和严格的传感器高度信息。
Abstract Turbulent surface fluxes were studied using observations taken over sea ice in the Baltic Sea in March 1998. The fluxes of momentum and sensible heat were measured by a sonic anemometer and compared with fluxes derived from wind velocity and air-temperature profiles. The neutral 10 m drag coefficient showed no apparent dependence on wind speed (in the range 2–20 m s–1), resulting in a mean value of 1.0 × 10–3 for smooth snow-covered ice and 1.5 × 10−3 for deformed ice. The overall mean value was 1.28 × 10–3. The roughness length for temperature revealed a greater apparent dependence on wind speed and was slightly larger than the aerodynamic roughness for low wind speeds, and vice versa for moderate and high winds. We give an empirical expression that predicts how the scalar roughness depends on the aerodynamic roughness (drag coefficient) and wind speed. Agreement of the gradient-method results with the eddy-flux results supports the validity of the Monin-Obukhov similarity theory. Fluxes modelled by a coupled air-ice-sea model compared well with the eddy-flux and gradient methods. Surface temperature estimates by the three methods also agreed well. Tests and sensitivity analysis emphasize the need for especially accurate sensor calibration and strict information about the sensor heights for the gradient method.