半干旱地区太阳光度计定标方法的研究

选用兰州大学半干旱气候与环境观测站2006年9月1日至2007年8月31日的光度计观测资料,以及同期的地面常规观测资料、卫星资料和探空资料,结合冗长绝对法对太阳光度计进行Langley定标。结果表明:选用某一天认为符合条件的观测日定标,其结果误差可能会较大;对各波段的多日定标值直接取平均,计算结果与真值的差别仍会较大;采用期望平均法和拟合平均法检验筛选后,日定标值的离散程度会显著减小,标准差减小了70%~90%;拟合平均法剔除偏离较大的散点后定标值的平均值更接近于真值。     

Early warning signals of abrupt temperature change in different regions of China over the past 50 years

In this paper, the early warning signals of abrupt temperature change in different regions of China are investigated. Seven regions are divided on the basis of different climate temperature patterns, obtained through the rotated empirical orthogonal function, and the signal-to-noise temperature ratios for each region are then calculated. Based on the concept of critical slowing down, the temperature data that contain noise in the different regions of China are preprocessed to study the early warning signals of abrupt climate change. First, the Mann-Kendall method is used to identify the instant of abrupt climate change in the temperature data. Second, autocorrelation coefficients that can identify critical slowing down are calculated. The results show that the critical slowing down phenomenon appeared in temperature data about 5-10 years before abrupt climate change occurred, which indicates that the critical slowing down phenomenon is a possible early warning signal for abrupt climate change, and that noise has less influence on the detection results of the early warning signals. Accordingly, this demonstrates that the model is reliable in identifying the early warning signals of abrupt climate change based on detecting the critical slowing down phenomenon, which provides an experimental basis for the actual application of the method.