Observational Analysis of the Local Structure of the Wave Activity Flux Associated with Maintenances of the Arctic Oscillation Index

Abstract

In this study, we analyze the local structure of the wave activity flux associated with maintenances of the Arctic Oscillation (AO) index by separating it in quasi-stationary and transient components.For maintenances to the positive phase of the AO, it is found that the wave activity of the transient component plays an important role, supplementing that of the quasi-stationary component in the mid latitude upper troposphere. The local patterns of wave activity indicate a southeastward flux over North America from the transient waves and the Atlantic from the transient and quasi-stationary waves, strengthening the polar jet. Similarly, for maintenances to the negative phase, it is found that the transient component makes a more important contribution than the quasi-stationary component. It is shown that the local patterns of wave activity indicate a northeastward flux over the North Atlantic from the transient waves and the North Pacific from the quasi-stationary waves, enhancing the weaker polar jet. It is concluded that the positive feedback between wave activity flux and zonal mean flow is greatest over the two major storm track regions.