Emblem of the Naval Air Station Alameda, California, USA, about 1946.
USN
Coloured version <a rel="nofollow" class="external autonumber" href="http://www.militaryuniformsupply.com/files/products/n/nas-alameda-california-usmc-patch.jpg">[1]</a> of emblem found in U.S. Naval Aviation News April 1947 <a rel="nofollow" class="external autonumber" href="http://www.history.navy.mil/nan/backissues/1940s/1947/apr47.pdf">[2]</a>