Saturday, March 15, 2014

Adjustable plotting for multiscale global temperatures

This post relates to a challenge posed by Gavin at Real Climate, to better depict the long term history of temperature. Gavin linked to datasets ranging from instrumental (150 years) to Phanærozoic (540 M yrs). I have been experimenting with user-adjustable graphs (see also gallery). The big changes of scale are a challenge, but I thought it was worth a try. The current version is rough, but I'll put in more data, with selectable axes.

The graph initially shows the last 200 years or so, but with a temperature scale big enough to cover the whole period. You can adjust the scales as follows:
  • Translation - by mouse dragging in the plot space. However, zero time (before 2014) is fixed to the origin.
  • Temp scale - by dragging vertically in the space to the left of the y-axis.
  • Time scale - this is the critical one. You can make fine adjustments by dragging below the x-axis. But faster is to click in the region with <...>, blue, bottom left. < shrinks the scale (longer times), and the response is proportional to how far you click from the centre (about double per <).
The data sets given by Gavin were:
Period Reference Data download
0-600 Mya Veizer et al (2000), Royer et al (2004) (updated Royer (2014)) Veizer d180, Royer04 Temp, Royer14 CO2
0-65 Mya Zachos et al (2008), Hansen et al (2010) Zachos/Hansen
0-5.3 Mya Lisiecki and Raymo (2005) LR04 Stack
0-800 kya EPICA Dome C Temperature Reconstruction
0-125 kya NGRIP/Antarctic analog? NGRIP 50yr
0-12 kya Marcott et al (2013) MEA12 stack (xls)
0-2 kya Mann et al (2008), Ljungqvist (2010) MEA08 EIV, Ljungqvist10
1850-2013 CE HadCRUT4 HadCRUT4 Global annual average, Cowtan&Way (infilled)
1850-2013 CE Berkeley Earth Land+Ocean annual mean

I have currently done HadCRUT4, GISTEMP LOTI, Ljungqvist10, Marcott et al (2013), EPICA Dome C,Lisiecki and Raymo (2005), Zachos and Hansen, Veizer d180. L&R is d190O data, so I scaled to to match Z&H over the first 5 million years. Veizer is ocean bottom temperature, so I used a faint color - I'm currently just trying to get the scaling to work well. So here is the plot:
Update: As Gavin at RC noted, I had L&R upside (d18O). Fixed now.

Other imperfections

I haven't been careful with anomaly base - the data is as is. I tried adjusting sequentially by overlaps, but there is noise, and for the moment, I don't think it adds value.

I have smoothed and sampled opportunistically. Epica was smoothed by three boxcar filterings, length 5, and then sampling every fifth. Zachos was smoothed once and sampled every fifth. L&R was sampled. With smoothing, end regions were included unsmoothed.

I'll surely find more.


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