Shia R L, Yung Y L, Allen M, Zurek R W, Crisp D
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, USA.
J Geophys Res. 1989 Dec 20;94(D15):18467-84. doi: 10.1029/jd094id15p18467.
Using the California Institute of Technology/Jet Propulsion Laboratory two-dimensional transport model, with transport coefficients taken from Yang and Tung (1989), we study the time evolution of excess carbon 14 in the stratosphere and the troposphere from October, 1963 to December, 1966. The model provides a satisfactory simulation of the observed data. Due to the impulsive nature of its source, initial distributions of excess carbon 14 exhibit large spatial gradients. This permits important constraints on the range of transport coefficients in the lower stratosphere to be derived. The standard model uses the circulation and eddy diffusivity of the year 1980. Large deviations (by factor of 2) from this standard transport are ruled out by our model. A self-consistently derived Kyy which is small (approximately 10(9) cm2 s-1) in tropical regions, but is larger (approximately 10(10) cm2 s-1) at higher latitudes is preferred. A Kzz as large as 1 x 10(4) cm2 s-1 would be inconsistent with the data. Excess carbon 14 is removed from the atmosphere with surface deposition velocities vS = 3 x 10(-3) cm s-1 and vN = 5 x 10(-3) cm s-1 in the southern and northern hemispheres, respectively. The last result is contrary to the current understanding that the oceans are the dominant sink for excess 14C.
利用加州理工学院/喷气推进实验室的二维输运模型，并采用Yang和Tung（1989年）给出的输运系数，我们研究了1963年10月至1966年12月期间平流层和对流层中过剩碳14的时间演化。该模型对观测数据给出了令人满意的模拟。由于其源的脉冲性质，过剩碳14的初始分布呈现出较大的空间梯度。这使得我们能够对平流层下部输运系数的范围得出重要限制。标准模型采用1980年的环流和涡动扩散率。我们的模型排除了与该标准输运存在较大偏差（相差2倍）的情况。一个自洽推导得出的Kyy在热带地区较小（约为10(9) cm2 s-1），但在高纬度地区较大（约为10(10) cm2 s-1），这种情况更为可取。一个高达1×10(4) cm2 s-1的Kzz与数据不符。过剩碳14分别以vS = 3×10(-3) cm s-1和vN = 5×10(-3) cm s-1的地表沉积速度从大气中去除，在南半球和北半球分别如此。最后一个结果与目前认为海洋是过剩14C的主要汇的认识相反。
