The new operatives introduced this event are:
Acacia - Chrono Echo <-- click to go to her article Click here for my opinions on Chrono Echo
Marian - Aquila <-- click to go to her article Click here for my opinions on Aquila
Aquila is freely claimable between the 12th of Feb and the 12th of March, although this period may be extended due to the downtime [below].

Snowbreak went into maintenance mode on the 2nd of March (or the 3rd, depending on your time zone.)
We don't know when it'll finish, but you'll get a free 6* operative and weapon selector in the mail afterwards, as well as some free pulls.
Apparently the selector will go up to v2.8 Fragments of Truth (that was the patch of Vidya - Celestial Swan).