Nice image, but I am totally mystified about the atmospheric qualities you want to enhance.
My first guess does not seem to fit. With images, atmospheric is often also called aerial perspective. That refers to changes due to the atmosphere which cause the appearance of objects to change as they recede into the background such as softening, decreased contrast and changes in color, typically a shift to more blue colors. These techniques create a feeling of depth which does not seem to apply to this image.
My next guess is that you are looking to achieve a more moody, muted, and hazy appearance. That is also going to be difficult with this image. There is a high, sharp contrast between the bright water and the dark background. That sharpness and contrast is part of what makes this image work. You are going to need to do some serious post processing to overcome those characteristic.
Can you be more specific about the direction you want to take this?