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Willis Eschenbach: Chinese Sunspots

Willis Eschenbach, Watts Up With That

I see that there is a new paper from China causing a great disturbance in the solar force … as discussed here on WUWT, the claim is that the El Nino Modoki Index, which is an index of sea surface temperatures, is significantly affected by some sunspot-related solar variable.

The first problem with their study is that the sea surface temperature (SST) “data” they have used to establish the relationship is not data as we understand it. It is not observations. It is not measurements of the actual sea surface temperature (SST). It is not stout-hearted men of oak going out and dipping up a bucket of water and inserting a thermometer.

Instead, their sea surface temperature “data” is the output of a climate model, a type called a reanalysis model. This reanalysis model is “tested” and adjusted by comparing it with the output of another climate model. That model is called the GFDL CM2.1.

So, we’re not looking at observed SST. Instead, we’re looking at the output of a couple of climate models.

This means the Chinese have found a correlation between sunspots and climate model output.

Now, having considered the OUTPUT of the climate models, would you care to guess what is used as the INPUT to the climate models?

According to one of the cited underlying documents, the inputs include variations in forcings by greenhouse gases, aerosols, and the “best available estimates of solar radiation changes”.

That means that the authors claim to have found statistically significant evidence of sunspot-related variations in the output of a climate model whose input includes sunspot-related variations … sorry, not impressed even if it were true.

However, there is a much deeper problem, which is that the claim of statistical significance is not true. Their results are not statistically significant, it’s just statistics gone bad. Let me see if I can explain the problems using mostly pictures. I’ll start by clarifying their underlying hypothesis.

Their basic claim is that the small ~11-year variations in the sun affect the sea surface temperature in some unspecified manner and by means of some unspecified solar phenomenon (TOA, solar wind, sunspots, heliomagnetism, etc.). And to their everlasting credit, and unlike far too many climate science authors, they have provided links in the paper to the datasets used in the study.

So, being a data guy, I went and got the ERSST sea surface temperature (SST) data they were using. At least when I got it I thought it was data, and I’m sure some of it is real data … but I digress. They used it, so we’ll use it.

Now, the obvious first step in this is to compare the global sea surface temperature to the sunspot record.  Being a graphics-oriented guy, I calculated the correlation between each and every 1°x1° gridcell on the surface of the ocean, and the sunspot record. However, as Figure 1 shows, there is basically no correlation between the sunspots and the global average ERSST sea surface temperature (0.008).

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