Tropical cyclone (TC) observations are of critical importance in not only providing real-time data for operational needs, including assimilation into TC forecast models, but also in providing increased situational awareness of these catastrophic storms to forecasters and decision makers. Due to the intense nature of TCs, obtaining observations is incredibly challenging, particularly within the air-sea transition zone, which is inclusive of the upper ocean, air-sea interface, and the marine atmospheric boundary layer. In recent years, there have been great strides in the capability to observe TCs within this zone. This session places particular emphasis on the advancements and rising capabilities of observing techniques for the air-sea transition zone within TCs.