Surge in North Atlantic hurricanes due to better detectors, not climate change

[Derecho!]

A spate of research has indicated there may be a link between climate change and the prevalence of North Atlantic tropical cyclones. Upon closer inspection, however, researchers have noted that the prominent upswing in tropical cyclone detections beginning in the mid twentieth century is attributable predominantly to the detection of "shorties," tropical cyclones with durations of less than 2 days. That the apparent surge in cyclone activity could be attributable to changes in the quality and quantity of detections has gained ground as a potential alternative explanation.

Using a database of hurricane observations stretching back to 1878, Villarini et al. try to tease out any detectable climate signal from the records. The authors note that between 1878 and 1943 there were 0.58 shorty detections per year, and between 1944 and 2008 there were 2.58 shorty detections per year. This increase in shorties, which the authors propose may be related to the end of World War II and the dawn of air-based reconnaissance and weather tracking, was not mirrored by an increase in tropical cyclone activity for storms longer than 2 days.

The authors compare the rate of shorty detections against a variety of climate parameters, including North Atlantic sea surface temperature, mean tropical sea surface temperature, the North Atlantic Oscillation, and the Southern Oscillation Index. The authors find that North Atlantic sea surface temperatures were related to tropical cyclones of longer than 2 days' duration but were not related to the rate of short detections. Additionally, for every decade after 1950s the occurrence of shorties seems to be related to a different climate parameter. Both of these findings are highly suggestive of data quality problems for the shorties record. The researchers note that their finding does not rule out the possibility of a climate-driven increase in shorties over the twentieth century. Rather, any existing trend will be imperceptible, as it is masked by data quality issues.

Source: Journal of Geophysical Research-Atmospheres, doi:10.1029/2010JD015493, 2011

http://dx.doi.org/10.1029/2010JD015493

Title: Is the recorded increase in short-duration North Atlantic tropical storms spurious?

Authors:

Gabriele Villarini: Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey, USA; and Willis Research Network, London, UK;

James A. Smith: Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey, USA;

Gabriel A. Vecchi and Thomas R. Knutson: Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, Princeton, New Jersey, USA.

[Clifford]

Interesting article.

Here is the full text version.

http://www.gfdl.noaa.gov/cms-filesystem-action?file=user_files/gav/publications/vvks_10_shorties.pdf

This mirrors other studies indicating that increasing tornado detections may be due to better detection of the weakest F0 & F1 tornadoes.