New paper on global cyclone activity - Phil Klotzbach

[x-y-no]

Klotzbach has a new paper in press with Geophysical Research Letters which can be downloaded HERE. (pdf)

I've only had a chance to skim it, so I'll defer comment (I'll post in this thread tomorrow, probably).

He looks at the period 1986 - 2005 and compares the earlier decade with the later, finding essentially no change in either ACE (accumulated cyclone energy) or number of intense (cat 4 and 5) storms globally.

There's a remarkably clear inverse relationship between the Atlantic and the East Pacific (a relationship I was pointing out in one of the GW threads last week). See his tables 1 and 2.


Interesting paper - like I said I'll read it carefully and comment soon.

Jan

[Aslkahuna]

Two separate conclusions from the same sets of data-hmmmm, either that data needs to be reanalyzed or somebody's wrong.

Steve

[x-y-no]

Two separate conclusions from the same sets of data-hmmmm, either that data needs to be reanalyzed or somebody's wrong.

Steve

Not exactly the same dataset. Klotzbach only looks at 1986 - 2005, Emanuel goes back to 1970.

The dispute, of course, is over the reliability of the pre-1980 data.

I've read the Klotzbach paper in more detail now. The methodology looks good. There's some argument to be made both ways for the premise that if the trend is real one would neccesarily expect the same trend in the shorter dataset as the longer one. Klotzbach clearly interprets this as more evidence that the early data is bad. Emanuel quite likely still disagrees. Perhaps more reanalysis is possible to resolve this, or maybe it can't be resolved with the information we have.

[MGC]

Klotzbach concludes that "This study indicated that, based on data over the last twenty years, no significant increasing trend is evident in global ACE or in Category 4-5 hurricanes."

According to Klotzbach, from 1986 to 1995, globally there were 164 Cat 4-5 hurricanes compared to 96-05 there were 180 Cat 4-5 hurricanes world wide.

Draw your own conclusion, but I agree with Klotzbach that the increase was not significant........MGC

[Aslkahuna]

Well in the 1986-1995 time period the Atlantic was in a lower level of activity and although EPAC tends to be more active when the ATL is down, it is not historically a hotbed for intense storms. The question then would be is a difference of 16 storms over a ten year period between the two periods outside the realm of natural variability given the uptick in ATL activity or not. Or to put it another way, in order to really prove that there's an increase we have to compare periods with the same activity characteristics, which, given the the length of complete datasets is not possible. In other words, you need to compare global intensity trends for successive equal periods when the ATL is either high or low. I don't see at this time that we've proven anything one way or another when I look at the other basins besides the Atlantic.

Steve