This is a very provisional quick look at some of the CLIMAT data from UK sites, chosen as probably fairly trustworthy over this time period in the light of the ongoing surface stations project.
I pulled out Tmax and Tmin, fed into the novel analysis software here to see what it makes of it. I’ve let it extrapolate.
The most obvious commonality is the above. It isn’t,large enough to notice to a human, half degree either way.
As expected Tmin is more problematic. I won’t go into the gory details but most of it makes sense in relation to site instabilities.
I expected Lerwick to be a reference so I was dismayed to note it only starts data in 2000. Very little is known about the site.
The inclusion of Lyneham is a hunch, slightly know the place and I suspect it has been fairly consistent without the “little war” panic changes near the met site. (aerodrome is closing end of this year so that dooms the meteorological site)
Manston is problematic but Tmax far less so than Tmin.
Most of remaining stations are active military bases or civil airports. If I do the other stations, needs automating, I have no idea if the above will hold up.
Quick web search, see if this period is known.
To my surprise there is recent work pointing at this period as a precursor to UK weather flows.
“Variability in the Global Equatorial Ocean (1000m) from Argo
Argo data show that 4.5-year Atlantic cycle associated with slowly propagating high-baroclinic mode waves is the dominant variability at depth”
– “Tropical Atlantic Climate Experiment Peter Brandt, IFM-GEOMAR, Kiel, Germany, 10M PDF from clivar.org
– PDF of abstract above EGU2011-4599 – CO Meeting Organizer
I’d be interested to see the phase of what they found.
The origin of 4.5y, I’d expect this to be related to earth plate positions, geometry of ocean and land with the excitation the annual orbit.
That will do for the moment, more if you search.
post by co-moderator
There must have been a climate station at Lerwick before 2000. See http://www.john-daly.com/stations/lerwick.gif
Here we are, won’t be the same processing but good enough.
(be lower noise because sig process methods are used)
tchannon.
Any chance this cycle was induced by insolation in the blue to Uvb spectra?
If so, there’s the possibility that it’s a forcing from solar influence (sunspot propensity).
Best regards, Ray.
tchannon.
In my last post, for clarity, I was referring to the paper and not the graph.
Best regards, Ray.
So you want a pretty blue background. Well, there was plenty of swearing.
I don’t know.
At this frequency I’d expect some interaction with lunar tidal modes. Is there any second order cyclicity of Tmax to be found in the longer record?
Nothing else is common looked at like that. I seem to be monosyllabic at the moment.
Tim,
1) What is your most precise estimate of the period? (Is it 4.5000000 years?)
2) What are the lengths of the records from which you derive your estimates?
Excluding Lerwick.
This will look confusing
Period_years | phase_radians (relative to start date) | amplitude (1/(2.sqrt(2)) for p-p)
4.62 4.99 0.44 Eskdalemuir
4.46 4.71 0.5 Lyneham
4.51 4.6 0.49 Manston
4.38 4.35 0.33 Camborne
One northern high wet inland, three across the south, Atlantic to SE coast.
Jan 1996 to Sept 2012 by month
“I’d be interested to see the phase of what they found.”
Maybe check directly
via visual inspection of the graphs included here
http://www.clivar.org/sites/default/files/imported/organization/atlantic/meetings/tropical_bias/talks/Brandt.pdf
or directly from Argo data.
Also note that they give geographic coordinates for surface expression (in equatorial Atlantic wind & SST). Maybe use KNMI Climate Explorer to see if other series record the cycle (and if so measure the phase).
Please update us with any new period estimates (needed to refine speculation about drivers) and with any further discoveries of non-equatorial-Atlantic expression.