typhoon_tip
(Meteorologist)
Tue Nov 22 2005 01:35 AM
Global Warming and weather events..

..The AMO is an SST index (Atlantic Multidecadal Oscillation) with a periodicity of 65-80 years, and a variance defined by an average value of about 1/2 a degree C. This is important because we have since 1990 been, as expected, on the curve toward the + side of neutral - meaning the warm phase has begun. The connection this normal and expected interval of warm SST has to the increase in hurricane frequency/intensities needs to be defined and parameterized first before any conclusions could possibly acquire veracity.

Clark is dead right when he intimates that you cannot assume the current apparent augmentation in both frequencies and intensities are due outrightly to Global Warming - though I have noticed that some media sources are taking more liberties with that assumption, as though it is becoming theory somehow by proxy or something....because for one reason among many, the current activity would likely have taken place in the absence of the last 30 years of Global numbers - or at least, the contrary has to be proven.

Further complicating the matters is that from a purely physical point of view, (and physical processes drive the atmosphere to begin with ) the gradients must be increased in coupled system to actually create the greater potential energy, and subsequent intensity, because potential energy is defined by dipolar gradient. If everyone is hot, that does not mean the gradients are sufficiently increased in the means, supplying storm intensities in general. If those gradients can be defined, this concern is compensated for, but I haven't really seen much evidence to support the gradients them selves being augmented through all of this... All the data that I have seen suggests that the Polar regions are warming just as smartly as the tropical regions, and therefore, the gradient is not any more sufficiently larger than a century ago, when both the tropics and the polar regions were cooler.. In other words, they're increasing in tandem (excuse the pun) in greater degree. Nor does there to appear to be an overwhelming gradient in the vertical in general - maybe some, but there's upper tropospheric indices as well....and around and around we go.

We turn on the television and radio every morning with our cup of joe and a donut and the first thing we hear is a Fox spun news story garnering hysteria over a 11 deaths from a freak November tornado outbreak... Fact of the matter is, there is a climatological precidents for a slight increase in tornado activity in the autumn, just prior to the seasonal flux. And....Holy Moly, a week later we have a +PNA pattern with a -6SD sub-polar vortex defining its core; it is no coincidence that we had these "freak" events last week because it was a super-duper transition period. There are other disasterous autumn twister events however, spanning decades...

Moreover, the hurricane frequency is entirely expected (intensity is an on-going debate), and fits nicely along expectation; which will likely also continue for ~ 1.5 decades (doesn't mean we're going to have 22 this or that every year...just that the atm is teleconnected to being conditioned for higher than normal activity. ) This periodicity in hurricane frequency has a time-span of about 20-30 years.

It is entirely possible that the intensity aspect of this expected frequency shift is because of compounding factors...If the AMO is increasing at its greatest rate during the next 3 decades, and in the first half of that 3 decades, we are also in the positive phase of hurricane frequencies, the latter may feed off the former... and it wouldn't have to be fore Global Warming. Just a supposition..

Now, having said all that...Yes, Global Warming is real.



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