The Influence of the Upper-Level Environmental Flow on Tropical Cyclone Structure and Intensity Predictability

Features of the upper-level environmental flow, such as mid-latitude jets, troughs, and tropical upper-tropospheric troughs (TUTT), have long been thought to be important in regulating tropical cyclone (TC) intensity, although the exact physical processes are still to be clarified. This study uses idealized WRF simulations of TCs that interact with an upper-level trough (jet, and TUTT), to elucidate the mechanisms of their interactions and impact on TC structure and intensity. The TC outflow, which is the upper-part of the TC secondary circulation, mediates this interaction. We present a range of simulations where the simulated trough interacts with TCs at different stages (weak or strong), different characteristics (such as compact or big), and different distances. More specifically, the spatial distribution of the horizontal wind and convection is modulated by the enhanced asymmetric outflow, which is due to the trough-TC-interaction. The spatially asymmetric features will be highlighted in this study. Lastly, the potential role of TCs on regulating the state of upper-level environmental flow, such as the trough (jet) strength and phase, is explored.