Earlier we noted that the number of hurricane-days in 1933 actually exceeded the number of hurricane-days in 2005. However, the 2005 PDI was significantly higher than 1933 PDI, which indicates fairly trivially that hurricane speeds in 2005 were estimated to be higher than 1933. So here is a histogram of 1933 compared to 2005 wind-speed counts in 5 knot increments – first a 1933 histogram, then a 2005 histogram and then the same data side-by-side. Obviously the 2005 distribution is skewed towards higher wind speeds. When you cube the wind speeds in a PDI calculation, this difference is exacerbated.
The shape of the 2005 histogram is actually a little odd – it’s got a bimodal look that surprises me. Does anyone know what is the explanation for this? There definitely seems to be a bias to measurement in even 10s that is more pronounced in the 2005 measurements and which seems surprising given that these are supposedly scientific measurements. The peak in the 110 knot tranche is also very remarkable in the 2005.
1933 was a notable year in other respects. As I recall, it is still the record year for U.S. temperature. It was the bottom of the Great Depression, with a dust bowl in the Prairies.