Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling
26 December 2014

A Zonal Wave Number-3 Pattern of Northern Hemisphere Wintertime Planetary Wave Variability at High Latitudes


Low-frequency variability and the trend of the Northern Hemisphere (NH) wintertime large-scale circulation are often represented in terms of a NH annual mode (NAM), which mainly represents the zonal mean circulations. However the NH high latitudes exhibit strong wave structures. In a recent study, BER-funded scientists at the National Center for Atmospheric Research analyzed reanalysis data during the past 50 years or so and global coupled climate model simulations. They identified a prominent pattern of variability of the stationary waves defined by the second empirical orthogonal function of detrended December-February mean 300 hPa meridional wind and they named it the Wave3 Pattern. This pattern is worthy of attention because its structure is similar to the linear trend pattern as well as the leading pattern of multi-decadal variability of the planetary waves during the past half century. Climate models must represent it correctly if they are to accurately estimate the regional reaction to greenhouse gas increases.

H. Teng