北半球500毫巴候平均图的波谱分析和预报

THE ZONAL HARMONIC OF PENTAD MEAN 500 MB HEIGHT CONTOURS OVER THE NORTHERN HEMISPHERE AND THEIR PREDICTION

中文摘要:

      本文应用谐波分析和功率谱分析方法,计算分析了1951-1970年北半球500毫巴多年候平均图和1975-1980年40°N、60°N 500毫巴逐候的候平均高度值.发现逐候的各谐波系数序列,除具有气候季节变化趋势外,还具有“指数循环”时间尺度及多种韵律活动准周期性振荡的特征.利用这一特征,设计了一个用周期外延叠加的预报方案.每次接连预报未来8个候的北半球500毫巴候平均高度.对1976-1980年60个月40°N和60°N两纬圈进行预报试验.效果检验表明,本预报方案有一定预报价值.它对纬圈偏差符号的预报准确率平均达ρ=0.22,对气候距平符号的预报准确率平均为ρ=0.08.

英文摘要:

      The power spectra of the zonal harmonic coefficients show that the quasiperiodic oscillations such as "Index Cycle",half-year rhythm and seasonal varialion are predominant.In terms of these quasi-periodic oscillations,a statistical forecast scheme has been designed,with which a set of eight successive pentad mean height forecast at 500 mb level over the Northern Hemisphere can be made.The results of sixty sets of forecasts for the period from 1976 throughout 1980 indicate that the mean forecast accuracy for the sign of deviations from the latitude average ρ=(n₊-n_-)/N is approximately 0.22,and for the sign of the sign of the anomalies from the climatic average gives ρ=0.08.