冬季低纬度热源异常在北半球对流层大气环流异常中的作用

本文首先从理论上讨论了北半球冬季低纬度强迫源与中纬度强迫源强迫所产生的准定常行星波在实际基本气流中传播路径及其振幅分布的差异,指出冬季低纬度热源异常将对北半球中、高纬度对流层大气环流的异常起很大影响,而中纬度热源异常将对平流层环流异常起很大作用。 本文应用一个包括Rayleigh摩擦、Newton冷却及水平涡旋热力扩散准地转34层球坐标模式分别计算了冬季低纬度热源异常与中纬度热源异常所造成北半球扰动系统的异常情况,计算结果表明了冬季低纬度热源异常将对中、高纬度对流层大气环流异常起很大作用,热带太平洋上空热源异常将产生PNA型环流异常。

THE EFFECT OF HEATING ANOMALY OVER LOW LATITUDES ON THE CIRCULATION ANOMALIES IN THE NORTHERN HEMISPHERE WINTER TROPOSPHERE

First, the differences between the propagating path and amplitude distribution of quasi-stationary planetary waves forced by a forcing source over middle latitudes and those forced by a forcing source over low latitudes in a winter basic current are theoretically discussed. It is pointed out that the anomaly of heat source over low latitudes may largely influence the anomalies in the tropo- spheric circulations over middle and high latitudes, while the anomaly of heat source over middle latitudes may play an important role for the stratospheric circulation anomalies. A quasi-geostrophic, 34-level spherical coordinate model with Rayleigh friction, Newtonian cooling and horizontal eddy thermal diffusivity is used to compute the disturbance patterns responding to an anomaly of heat source over middle latitudes and over low latitudes, respectivily. The computed results show that the anomaly of heat source over low latitudes may largely influence on the winter circulation anomalies over middle and high latitudes, and the anomaly of heat source over the tropical Pacific Ocean may cause the PNA (the Pacific/North America) pattern anomalies.