Here are the RGB channels - the green in particular gives a pleasing rendition.

There is a lot of noise present in the blue channel and the image is heavily compressed.

We might gain a little by running Neatimage on the sky, then slightly curving to add more contrast, before de-saturating via Gray Gamma 2.2.
Hover to see the difference between the de-saturated image and the one with more contrast.


I am not happy with this rendition and although the contrast is better, I'm loosing detail in the bridge - so lets try it another way.