change data

Hello, How to change data format from 10 january 2016 to 2016-01-10 ? I make a template which take DOM that Regex "(?<=<span\ class="articleDate">([\w_]+),).*(?=</span>)" It change 26 January 2013 (21:20) to 26 January 2013 and I would like to change that to 2013-01-26 and put to variable...