Verification of tropical cyclone heat potential for tropical cyclone intensity forecasting in the Western North Pacific

Tropical cyclone heat potential (TCHP) is a measurable metric calculated by the summation of ocean heat content from the surface down to the depth of the 26 A degrees C isotherm. TCHP calculated by the Meteorological Research Institute multivariate ocean variational estimation (MOVE) system is verified by using TCHP based on in situ observations by profiling floats during 2002-2012. After the verification, the threshold of MOVE-based TCHP before the passage of a tropical cyclone (TC) favorable for triggering TC deepening is determined by best-track central pressure drops for the nearest 6 hours from 1985 to 2012. The threshold is specified as the minimum range of TCHP when the ratio of the number of records for TC deepening to the total best-track number of records in a TCHP bin is significantly greater than the reference ratio determined for each domain at a significance level of 0.05. The threshold is relatively low (40-60 kJ cm(-2)) around 5-10A degrees N, west of 120A degrees E and east of 140A degrees E, whereas it is relatively high (80-100 kJ cm(-2)) around 15-20A degrees N. Around 5-10A degrees N, the ratio for each moving speed shows two peaks: with moving speeds of 3-5 and 7-9 m s(-1). The former case is exemplified by Typhoon Mike (1990) under relatively low TCHP (< 80 kJ cm(-2)), whereas the latter case is exemplified by Typhoon Haiyan (2013), which is more rapidly intensified and reaches a lower minimum central pressure under relatively high TCHP (> 120 kJ cm(-2)).