There must be something such as you suggest that keeps the Mars polar regions replenished.
Isn't Mars entering its "winter" period?
Very possibly. But it'd be one pole at a time, as on Earth. I believe Mars' North Pole was experiencing winter last summer when Mars made it's close approach to Earth . . . The North polar ice cap showed up nicely in my little 8" telescope. So, that was around August (is that right?) and a Martian year is approximately two Earth years . . . Hmmm . . . lol . . . I'm spinning my wheels here . . . I'll try to look it up, lol!