The Statistical Relation between Tropical Cyclone Rapid Intensification and Ocean Heat Content in the Western North Pacific

In this study, rapid intensification (RI) of tropical cyclone in the western north Pacific is defined as an increase of at least 35 kt in the maximum sustained surface wind over a period of 24 h or less by the Joint Typhoon Warning Center (JTWC) best-track from 1998 to 2013. The Archiving, Validation and Interpretation of Satellite Oceanographic (AVISO) and the National Centers for Environmental Prediction (NCEP) FNL data are employed to examine the ocean and wind shear characteristics of RI, respectively. The statistical analysis show that the ocean heat content (OHC) and sea surface temperature (SST) of RI are higher than Non-RI cases, especially from the 20⁰ to 30⁰ latitude region. In addition, the OHC and SST near the TC center are weaker than the outer region of TC.

According the Oceanic Nino Index (ONI) from NOAA Center for Weather and Climate Prediction Climate Prediction Center, RI divided into 5 phase; the first phases are strong El Nino (ONI ≥ 1.0), weak El Nino (1.0 ≥ ONI ≥ 0.5), Neutral (0.5 ≥ ONI ≥ -0.5), weak La Nina (-0.5 ≥ ONI ≥ -1.0), and strong La Nina (ONI ≤ -1.0), respectively. It is shown that systematic difference for the onset, lifetime maximum intensity (LMI), and genesis locations of RI TC. When TC under the strong El Nino tend to form lower and more right region. However, the there is no significant difference in OHC and SST between these 5 phase.

For the vertical wind shear, statistically significant difference is examined between RI and Non-RI. RI events occur under weaker vertical wind shear environment than Non-RI events. The vertical wind shear at the LMI of RI cases also show consistent results. Meanwhile, the LMI of RI cases are more intense than the LMI of Non-RI case.