Inverted color scale

[CommonClimate]

This is my first issue here and I first want to congratulate xeofs' contributors for a tremendously useful and usable package.

Describe the bug
The color scale in
this xeof tutorial is opposite the general expectation.

Expected behavior
It is well-known to physicists that blue stars burn hotter than red stars; more generally, red light has a lower energy than blue light. Nevertheless, most people on this Earth expect cold water to come out of the blue tap, and warm water to come out of the red tap. Accordingly, the color scale in the example cited above behaves contrary to expectations, with blue = warm, and red = cold. It is easy enough to invert the color scale by passing kwargs = {"cmap": "RdBu_r", "transform": PlateCarree()}, but that is not very intuitive.

Can anyone explain why the code behaves in this counter-intuitive way?

Desktop (please complete the following information):

• MacOS Sonoma 14.6.1 (23G93)
• xeofs version [e.g. 3.0.4]

[nicrie]

Thanks for the kind words @CommonClimate! Yeah, you're absolutely right--the colorbar does go against the usual expectation. I think the reason here was that the associated time series (PCs) are blue, so you can interpret it like this: blue regions $\implies$ follow the associated blue PC, and red regions $\implies$ follow the inverted PC.

That said, I don't have a strong opinion about it. That's just how I'd interpret it, but as you pointed out, it's clear that others might see it differently.

[nicrie]

for such changes it would be really helpful to have a "Suggest edit" button like the on in the xarray documentation: