Ryan A Hardy, NRC Research Associateship Program, NOAA National Geodetic Survey, Silver Spring, MD, United States, Kevin Ahlgren, NOAA's National Geodetic Survey, Silver Spring, MD, United States, Bryant D Loomis, NASA Goddard Space Flight Center, Greenbelt, MD, United States and Xiaopeng Li, DST at NGS, Geosciences Research Division, Silver Spring, MD, United States