Since Dave Burton was kind enough to remind us how great the danger of sea level rise is, I’m enjoying the recent focus on the topic. I’d like to apply my new alignment technique (including variable station weights) to several regions of eastern North America, to see how they differ and what they have in common in their sea level history.
I’ll even form a composite mean for all eastern North America based on the five regional means, which is a little bit like area weighting — the regions aren’t really right for that, but at least we’ll be able to compensate to some degree for the concentration of stations in a few regions.
Here are the resulting time series for each region, and I’ve offset them so they don’t plot on top of each other:
In region 2, sea level is rising faster than the others. I note that both regions 3 and 4 show a spike in sea level in 1948 which is not present in the other regions.
A glance at the map above shows that region 2 also has a large number of stations. This means that when forming a composite average, the fast-rising region can be over-represented. This can be confirmed by comparing the composite based on all the stations, to the composite based on combining the five separate regions with equal weighting. And here they are:
The red curve is labeled “Area Weighted” but it really means based on the five regions rather than all the stations together, which is called “Not”.
We can also look at how each region deviates from the composite average, which underscores the rapid sea level rise in region 2, compared to the rest:
It’s interesting to compare the rates for the different regions:
All of them except region5 (which is really islands) show a pronounce episode of rapid rise around 1940. And of course we can compute the rate for the composite:
Based on recent requests for data, I suspect some of you want to play around with things yourself. I might have solved the problem of sharing text files without WordPress getting in the way. If I’ve got this right, you can get:
Reconstructions for the N.Amer regions here
Stations used in North America: here
Code for vw.align.r program (hopefully, with indentation intact): here
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