Thursday, February 18, 2010

Old Hurricanes

The record of past tropical cyclones provides an important means to evaluate the hurricane hazard. Historical chronologies are a source of information about tropical cyclones prior to the modern era. Chenoweth (2006) describes an archive of 383 tropical cyclones occurring during the eighteenth and nineteenth centuries, largely before the official hurricane record.

We demonstrate a novel way this archive can be used to articulate historical tropical cyclone activity across space. First, an event in the archive is assigned a series of latitude/longitude coordinates approximating the descriptive locations of the cyclone’s affect. Second, tropical cyclones from the modern record that approach these locations (modern analogs) are mapped. Third, a probable pathway and a realistic track of the archived event is created by averaging the modern analog tracks. As an example, the procedure is used to generate a map showing the tracks of the Atlantic tropical cyclones of 1766. Sensitivity of the methodology to changes in event location and event timing are considered.

Results show historical hurricane chronologies when combined with a history of cyclone tracks can provide new information about the older events not directly related to where the original information was gathered. When this new information is available for all cyclones it should help climatologists better understand long-term variations in tropical cyclone activity.

For more information see here.

2 comments:

Shawn_Lewers said...

Has there been any critique from the climatology community that taking the average of the analog storms from the modern era introduces undesired uncertainty into the ancient/historic record? The average track does provide a scenario/model for the ancient storm. But, it could also describe a scenario that did not happen for many possible reasons. Hence, using modeled or even predicted "values" (positions) as essentially observed data then applying that data in other models could lead to questions. I am not one of those who would make this argument for dismissive purposes, but given the politics of research and peer review I wondered if someone had?

James Elsner said...

Shawn,
This is an interesting observation. But, just as an average temperature does not mean that temperature is more likely than any other, an average track does not mean this is a likely track.
Jim