Ocean Response for Typical Leftward-Biased Cold Wake Induced by Hurricane Jova (2005) in the Northeast Pacific

In the Northern Hemisphere, cold wakes induced by tropical cyclones (TCs) generally biases to the right of storm track. However, recent study found that a nonnegligible proportion of cold wakes is actually leftward-biased. To further reveal the underlying physical mechanisms, the three-dimensional dynamic processes for the typical leftward cold wake of Hurricane Jova (2005) are investigated through a sequence of numerical simulations. Results reveal that the vertical advection in response to Jova biases to the left of track in the upper layer. Cooperated with the heterogenous ambient oceanic fields, the rightward vertical mixing is suppressed while the leftward feature of vertical advection is further intensified, which effectively promote the formation of the leftward cold wake. Additionally, the currents induced by Jova drive colder (warmer) water to the left (right) when coupled with background horizontal temperature gradients, and then strengthen the leftward distribution of the temperature anomaly. These conclusions are substantiated by the control simulation, as the upper-layer temperature anomaly restores to rightward with the homogeneous initial thermal structures. Based on three groups of sensitivity experiments, the leftward pattern of upwelling is found inextricably accompanied with the curl of wind stress caused by the TCs movement. With the growth of translation speed from stationary state, the symmetric structure of vertical velocity gradually distorted to be leftward. Furthermore, the leftward bias distance of upwelling center in the upper layer positively correlates with the radius of maximum wind, indicating a significant effect of the wind structure on modulating the oceanic responses.