The urgent need for a re-analysis of western North Pacific tropical cyclones

The U.S. Hurricane Research Division (HRD) is well underway in a project to revise the Atlantic basin hurricane database (or HURDAT). HURDAT is the official record of tropical storms and hurricanes for the Atlantic Ocean, Gulf of Mexico and Caribbean Sea, including those that have made landfall in the United States. This database is utilized for a wide variety of purposes: setting of appropriate building codes for coastal zones, risk assessment for emergency managers, analysis of potential losses for insurance and business interests, intensity forecasting techniques, verification of official and model predictions of track and intensity, seasonal forecasting, and climatic change studies. There are many reasons why a re-analysis of the HURDAT dataset was both needed and timely. HURDAT contained many systematic and random errors that needed correction. Additionally, as our understanding or tropical cyclones developed, analysis techniques at the National Hurricane Center changed over the years, and led to biases in the historical database. Recent efforts led by the late Jose Fernandez-Partagas uncovered previously undocumented historical tropical cyclones in the mid-1800's to early 1900's. In the the western North Pacific, there are several institutions that archive statistics of the tropical cyclones. The Joint Typhoon Warning Center (now located in Pearl Harbor, Hawaii) has nearly 50-year record of tropical storms and typhoons for the western North Pacific Basin. The Tokyo Typhoon Center is the Regional Specialized Meteorological Center (RSMC) for the analysis, tracking and forecasting of western North Pacific tropical cyclones within the framework of the World Weather Watch Programme of the World Meteorological Organization (WMO). The Tokyo Typhoon Center was established at the Headquarters of the Japan Meteorological Agency (JMA) in July 1989, following the designation by the WMO Executive Council at its 40th session held in Geneva in June 1988. It has a record of tropical storms and typhoons in western North Pacific that extends back to 1951. This paper examines differences in the best track archives of these two institutions and documents the many substantial differences in the locations, intensities, and wind distributions of tropical cyclones. Intensities are sometimes found to vary by two Saffir-Simpson Categories. The archived distribution of gales and typhoon-force winds can vary by hundreds of kilometers. The objective of the work reported in this paper is to examine and summarize the differences that are found in the best track archives, and to attempt to explain some of them. The ultimate goal is to establish a working group of tropical cyclone experts to undertake a project similar to the HRD Hurricane Re-Analysis Project for the historical record of the tropical cyclones of the western North Pacific. The historical record of tropical cyclones has become important in the scientific and political challenges of climate change, and the risks of the ever increasing human habitation in cyclone-prone regions. It seems of the utmost importance to make the record as accurate as possible.