MEDEA and the Declassification of Navy GEOSAT Radar Altimetry Data

Tuesday, 8 December 2020: 10:50
John A Orcutt, Univ. of California, San Diego, La Jolla, CA, United States
The declassification of US Navy radar altimetry data had a major impact on oceanography in the 1980’s. VADM Paul Gaffney, who was the Oceanography of the Navy and a member of MEDEA, was instrumental in making this happen. Coincidentally, Paul Gaffney and I were Midshipmen at the Naval Academy in the 60’s. I spent my Navy time in submarines relying on a knowledge of the gravity field for missile launches; Paul elected to pursue a career in Naval oceanography and was also concerned with the same issue. Both of us became members of MEDEA during the Clinton Administration (1993-2001) when VP Al Gore sought to investigate how data from the Intelligence Community might be used to understand better the phenomenon of climate change. The Navy successfully launched a US Geodetic Satellite (GEOSAT) on 21 March 1985, 35 years ago. The initial Geodetic Mission (GM) was conducted over a period of 18 months and the data were classified. Prof. Dave Sandwell joined MEDEA for a series of meetings at NAVOCEANO in 1995 to consider the declassification of the GM as well as seafloor topography and magnetics. Based on these deliberations, the GM data were declassified in July, 1995. Sandwell subsequently published the initial paper on these data in 1997 with W. H. F. Smith. The sea surface morphology revealed by the radar altimetry was used to infer seafloor topography. This was the first, uniform map of the global seafloor and is well depicted when using Google Earth. The Navy seafloor topography, obtained by early, detailed acoustic array data (SeaBeam) remain classified although this is largely restricted to the northern hemisphere. Many other radar altimetric satellites have been launched through 2017 and have contributed to the inference of global seafloor topography. The newest LIDAR satellite, ICESat-2 (15 SEP 2018), while of little use for studying the deep ocean, is revolutionizing the mapping of the seafloor in atolls and shallow, coastal waters. Given the lack of a high-resolution seafloor map, the UN Decade of Ocean Sciences for Sustainable Development has committed to mapping the entire seafloor at high resolution (2021-2030)