Impact of barrier layer on typhoon-induced sea surface cooling

Abstract

Both Argo measurements and satellite sea surface temperature (SST) data revealed that there was less-than-usual surface cooling during the passage of typhoons Kaemi and Cimaron in the tropical Northwest Pacific. In the present study, it is found that SST cooling induced by typhoon can be greatly suppressed by a barrier layer with a thickness of 5–15 m. Such a barrier layer could reduce the entrainment cooling by 0.4–0.8 °C/d during typhoon passage, according to a diagnostic mixed layer model. The pre-existing barrier layer leads to a reduction in typhoon-induced surface cooling, and favors typhoon development. The average SST anomaly under barrier layer condition is 0.4–0.8 °C less than that under no-barrier-layer condition. Due to the reduced cooling, the available maximum potential intensity (MPI) under barrier layer condition are higher 6 and 9.34 m/s than those under no-barrier-layer condition according to SST-dependent MPI formulation for Kaemi and Cimaron. In addition, the results from Price–Weller–Pinkel (PWP) model indicate that stratification due to salinity may significantly influence both entrainment and the upper ocean heat content during typhoon passage in the tropical Northwest Pacific.