Desirability and Feasibility of a Global Reanalysis of Tropical Cyclones

Accurate records of historical tropical cyclones are invaluable for scientific research and risk quantification. Yet most tropical cyclone data were collected in aid of operational forecasting with mixed attention to its use as a climate archive. To remedy this, as far as possible, a comprehensive reanalysis of Atlantic tropical cyclones was undertaken and is enjoying widespread use. To explore the feasibility of undertaking a similar effort for the rest of the globe, covering about 88% of all tropical cyclones, a workshop was convened, involving 12 scientists from around the world, including researchers, data analysts and forecasters.

The North Atlantic “best-track” hurricane database (HURDAT2; Landsea and Franklin 2013) has profited enormously from detailed reanalyses (Landsea et al 2012) that applies modern knowledge and newly discovered measurements to historical tropical cyclone events to arrive at best estimates of the history of each storm in the record. Relative to other ocean basins, the North Atlantic region lends itself to a relatively robust cyclone record, thanks to its comparatively small size, dense shipping, and the availability of aircraft reconnaissance going back to the mid-1940s. Analyses of historical events in other regions have suffered from a paucity of in situ measurements, changing standards of analysis, and the absence of a single agency that takes full responsibility for the data and oversees its quality. Thus there have been few, if any, attempts to revisit the records and produce reanalyses that take advantage of contemporary practices and/or which add newly discovered data sources. Yet risk modeling and insurance rates depend on historical data in these regions as much as they do in the North Atlantic.

For these reasons, we convened a workshop in Asheville, NC, on May 22-23 2017, to explore the feasibility of performing a global reanalysis of tropical cyclones and to lay the foundations for a set of standards for future observations. The workshop was funded by the Bermuda Institute of Ocean Sciences’ Risk Prediction Initiative (RPI), a non-profit organization supported by the risk transfer industry and focused on questions surrounding the quantification of catastrophic risk. The meeting consisted of a series of 30-minute presentations and discussion about 36 desired outcomes and possible paths forward. Here we summarize those discussions for the benefit of the broader meteorological community.

Emanuel, K., P. Caroff, S. Delgado, C. Guard, M. Guishard, C. Hennon, J. Knaff, K. Knapp, J. Kossin, C. Schreck, C. Velden, and J. Vigh, 2017: Desirability and Feasibility of a Global Reanalysis of Tropical Cyclones. Bull. Amer. Meteor. Soc. doi:10.1175/BAMS-D-17-0226.1, in press.