Guest Post by Paul L. Vaughan, M.Sc.
Does the sun tweak the odds of busy Atlantic hurricane seasons on decadal timescales?
ACE = accumulated cyclone energy (based on duration, intensity, & number of storms)
SCL’ = rate of change of solar cycle length, calculated by applying a complex Morlet wavelet [at 4 different wavenumbers] to sunspot numbers:
Please read the cautionary notes regarding the early Atlantic hurricane record:
(Scroll down on that page for Atlantic hurricane data.)
Fotheringham & Rogerson (1993) assert that scale-dependency “[…] presents us with the challenge of reporting on the reliability of parameter estimates in the light of changes in scale […]”
Fotheringham, A.S.; & Rogerson, P.A. (1993). GIS and spatial analytical problems. International Journal of Geographic Information Systems 7(1), 3-19.
Alert statisticians may recognize the preceding as a cautionary note about “Simpson’s Paradox”.
AMO (Atlantic Multidecadal Oscillation) can be decomposed into a multidecadal wave and an interannual component, to arrive at the following:
[1a] indicates simple [i.e. boxcar-kernel] 1 year smoothing.
So another question arises:
Is the interannual variation simply ENSO (i.e. as many might suggest)?
Caution is advised with this notion, as follows:
a) Regional/hemispheric/interannual-scale spatiotemporal turbulence is constrained (by neighbouring pattern & process on a finite globe).
b) Interannual variations of various climate indices show intermittent nonrandom coherence with the highly regular QBO (quasi-biennial oscillation).
Bear in mind that as the solar cycle accelerates and solar cycle length shortens (SCL’ negative), beats of decadal-timescale component features (e.g. solar wind) with the terrestrial year & QBO lengthen on average – i.e. it takes longer, on average, for particular phase-alignments to recur. Conversely, as the solar cycle decelerates and SCL lengthens (SCL’ positive), beats with terrestrial temporal modes such as the year & QBO shorten – i.e. particular phase-alignments occur with higher frequency.
The near-stationary QBO is lunar-driven and solar cycle phase acceleration (or something confounded with it) regionally modulates terrestrial cloud, insolation (not to be confused with irradiance), pressure, circulation, & temperature patterns.
Earlier WUWT articles in this series:
In considering the preceding, the role of north-south & continental-maritime terrestrial asymmetry should not be underestimated.