Evaluation of the Reliability of Tropical Cyclone Data Using ENSO

The understanding and prediction of tropical cyclones (TCs) in a changing climate have been active research topics. Over the past few decades, studies have found important relationships between TC activity and climate variability. However, the temporal heterogeneity of TC best track data due to changes in observational and analytical technology makes long-term analysis of the relationship difficult. In particular, it was difficult to quantify when TC data were reliable, which led to the use of different start years for the analysis and eventually hindered a consistent study. This study developed a new method to quantitatively evaluate the reliability of the data, specifically TC genesis frequency in the western North Pacific (WNP), using the relationship between TCs and the El Niño Southern Oscillation (ENSO). This is based on the fact that TC genesis extends east of 140°E in the WNP during El Niño but is limited to within the west of 140°E during La Niña. Using the relationship, this study proposes that the period with the most reliable TC data began in 1985. The analysis revealed that the unreliability during earlier periods was related primarily to the technical difficulties in detecting and classifying weak TCs, such as tropical depressions and tropical storms. These results will reduce the uncertainty in the TC data and will facilitate the detection of a more solid relationship between TCs and climate variability in future studies.