A Pressure-Based Analysis of the Historical Western North Pacific Tropical Cyclone Intensity Record

ThewesternNorthPacificOcean is themost active tropical cyclone (TC) basin.However, recent studies are not conclusive on whether the TC activity is increasing or decreasing, at least when calculations are based on max-imum sustained winds. For this study, TC minimum central pressure data are analyzed in an effort to better understand historical typhoons. Best-track pressure reports are compared with aircraft reconnaissance obser-vations; little bias is observed. An analysis of wind and pressure relationships suggests changes in data and practices at numerous agencies over the historical record. New estimates of maximum sustained winds are cal-culated using recent wind–pressure relationships and parameters from International Best Track Archive for Climate Stewardship (IBTrACS) data. The result suggests potential reclassification of numerous typhoons based on these pressure-based lifetimemaximum intensities. Historical documentation supports these new intensities in many cases. In short, wind reports in older best-track data are likely of low quality. The annual activity based on pressure estimates is found to be consistent with aircraft reconnaissance and between agencies; however, re-connaissance ended in thewestern Pacific in 1987. Since then, interagencydifferences inmaximumwind estimates noted here and by others also exist in theminimumcentral pressure reports. Reconciling these recent interagency differences is further exasperated by the lack of adequate ground truth. This study suggests efforts to intercali-brate the interagency intensity estimate methods. Conducting an independent and homogeneous reanalysis of past typhoon activity is likely necessary to resolve the remaining discrepancies in typhoon intensity records. 1