Two helicopters (Aerospatiale AS355F1 Twin Squirrels) were active during the morning: one in a high(~2000 ft?) hover over the CBD (like the British AAC Gazelles used to do over Belfast in the 80s) and the other seeming to have a low level roving brief.  Probably related to the visit that morning by German Chancellor Angela Merkel and the Canadian Prime Minister Stephen Harper
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/11905963@N06">XPinger (Chris Sutton)</a> from Rotorua, New Zealand
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/xpinger/15256624384/">NZ Police helicopter</a>