Examining the Relationship Between Tropical Jet Available Potential Energy (JAPE) and the Level of Extratropical Storm Activity During the Winter Season

Recently Hart (2011) presented evidence that the level of extratropical storm activity in the northern hemisphere over the winter season is correlated with the level of tropical cyclone activity of the previous summer and fall seasons. In this study, we attempt to show that the sum effect of the tropical activity can be quantified by the Jet Available Potential Energy (JAPE), which is trapped in the Upper Troposphere Lower Stratosphere (UTLS) of the tropics. The UTLS is a significant atmospheric layer because it lies above the level of zero net radiation loss and equatorward of strong inertial stability, which prevents large scale poleward exchange of the energy. In this paper, we will present calculations of JAPE over the past decade and show how it fluctuates with tropical and later extratropical activity. We will also show instances of explicit energy exchanges related to these fluctuations.