Variations of latent heat flux during tropical cyclones over the South China Sea

Latent heat flux exchanges at the air-sea interface play important roles in the formation and development of tropical cyclones (TCs). Usually, the latent heat flux transferred from oceans to atmosphere increases during the intensification stages of the TCs. However, through analysing a number of TC cases over the South China Sea, it is found that the changes of latent heat flux exhibit different behaviours during the intensification stage of the TCs, depending upon their travelling pathways. The air-sea latent heat flux increases while the TCs are intensifying in open sea areas of the South China Sea. However, the latent heat flux decreases while the TCs are travelling over the narrow area between the Indo-China Peninsula and Hainan Island, even though the TCs are in their intensification stage. For the latter case, the decrease in latent heat flux F is accompanied by the decrease in surface winds due to the terrain frictions even though the upper troposphere winds are still increasing.