What's the exact meaning of “down below” here?

Question

Through the tinted glass you can see Upper Manhattan; down below, the traffic on Riverside Drive crawls through this desolate area of dark high-rises, housing projects, and barbed wire.

I didn't find any meaning for "down below" in trusted online dictionaries, although I find the link below:

Does 'Down below' mean the same thing as 'Bottom'?

but I still don't understand the exact meaning of the phrase "down below".

So could you please explain it to me?

The fuller text is here:

His twelfth-floor office is simply furnished but inviting [...] On the windowsill are photos of his family and colleagues. Through the tinted glass you can see Upper Manhattan; down below, the traffic on Riverside Drive crawls through this desolate area of dark high-rises, housing projects, and barbed wire.

Answer 1

This is a description of someone looking at, then out a window on the 12th floor. At eye level, he can see the other buildings of Upper Manhattan. If he looks down below, towards the street, he can see the traffic.

Down below is a general description that means something is some unspecified distance lower. You could achieve the same meaning with "below" by itself but "down below" emphasizes distance, in my opinion.

It would be very natural for looking out an airplane window:

The airplane took off. Down below, the cars looked like ants.

Answer 2

No special meaning: In a low place, relative to the speaker.

"twelfth-floor office" means the speaker is up high. So the traffic (cars etc) on the road is below him. The phrase is adverbal, indicating the place where the traffic is crawling, and contrasting with the first part of the sentence (where you can see Upper Manhattan)