benny wrote:MWatkins wrote:x-y-no wrote:I'm going to try and be there for the Wednesday show at least.
Looking forward to the discussion, Mike.
Jan
Me too Jan.
I have reread the Kerry Emanual Nature paper as well today and will (hopefully) address that tomorrow night too.
He makes a very compelling argument, but there is a methodology piece that I am digging through right now...it may or may not make a difference in the study. I haven't figured that out yet.
Interested to hear your thoughts as well...and hmmm...not to change the subject...but there appears to be an increase in subsurface warming in the Pacific.
MW
One of the bigger problems with the Kerry Emanuel paper is that it uses the wind speed cubed... which emphasizes the strongest winds. However the technologies have really improved over the years to measure the highest winds... we fly recon more than we ever do, satellite pictures have a better and better resolution... I'd argue that 30 years ago we could have missed the max intensity of Wilma. Heck if the plane that was scheduled to go down to Wilma late that fateful night of 882 mb had a mechanical problem... we would have missed it in this day and age. Back in the day... even when recon started flying some in the 40s & 50s.. you needed a ship of opportunity.. and back then the ships rarely reported about Beaufort Force 12. Something else to think about... perhaps more reasoning against the increase seen only in the strongest hurricanes (plus the global utilization of the Dvorak only since about 1980 or so)
Yep...and although I understand he's trying to account for the amount of energy released by very intense hurricanes, the cubing introduces positive (negative) biases in the post (pre) 1970 dataset for precicely the reason you note...hurricanes with small eyes dectable on todays improved equipment that would have been completely missed even 10 years ago, like Wilma's add to the problem, and there's another.
I have this question in to someone who knows a lot about this stuff and I hope to hear back soon. But there is a supplemental note to the paper which explains treatment of pre 1970 storms in the dataset.
Emanuel applied a finding by Landesa in this 1993 paper:
http://www.aoml.noaa.gov/hrd/Landsea/climo/
As you probably know, Landsea believed that windspeeds in pre 1970 hurricanes, especially intense hurricanes, were overstated due to a gap between the average MSLP reported in those storms and satellite classifications of those same hurricanes categorizied as intense.
While I would rather leave some of this discussion for tonight, I suppose I'll throw this out there.
He applied the same reduction to all cyclones worldwide prior to 1970, and there I think are all sorts of problems with that methodology.
1. Landsea applied the filter to account for classification between intense and non-intense hurricanes. Emanuels application of the reduction will reflect in the data for all storms, including known cat 5 hurricanes that get reduced downward, compounding the impact of the PDI calculation.
2. Landsea's findings apply to the Atlantic Basin only. We know pressure backgrounds and monitoring equipment, and methodologies are vastly different as you go across basins.
3. Without a recon punch and using GOES1 for example, we may not have seen Wilma's eye until much later, making it (probably) a cat 2 using conventional Dvorak estimates.
MW
