Abstract
Over the past several years, progress in measurement and modeling of the oceanic response to hurricane forcing is given with a focus on the Gulf of Mexico basin for tropical cyclones (TCs). In terms of the upper ocean impacts on intensity, considerable attention has focused on the cold wake structure beginning just in back of the eye-wall of TCs. Cooling levels of more than 3°C often result in the negative feedback primarily due to vertical mixing at the base of the ocean mixed layer through wind-driven current shears.
This effect has been modeled extensively assuming that the basic state (or pre-TC condition) is at rest. However, the background oceanic state, and in particular in the western parts of the oceanic basins in the Northern Hemisphere the flows are energetic. The ensuing upper ocean thermal response tends to be considerably weaker (less surface cooling) to strong TC forcing where the warm layers extend to greater depth and currents transport warm water poleward (Loop Current, Florida Current, and Gulf Stream). Observed wind-driven shears do not develop that essentially keep sea surface temperatures (SSTs) and oceanic heat content levels high during TC passage. This less-negative feedback implies that a more sustained ocean-to-atmosphere heat and moisture flux to the TC and represents an important mechanism for observed deepening of recent severe TCs. Recently developed assimilation schemes for models and new measurement tools for oceanic observations are given, focusing on future avenues for basic and applied research in improving our understanding of these processes during TC passage.