An International Altimetry Service – focussing altimetry for global Earth observing systems
Wolfgang Bosch(1) and C.K. Shum(2)
(2) OSU, 1958 Neil Avenue, Columbus, Ohio 43210, United States
Satellite altimetry has evolved into an operational observational technique and has demonstrated interdisciplinary application across oceanography, geodesy, hydrology, and glaciology, and geophysics qualifies itself as an essential component of global Earth observing systems (GOOS, GCOS, GGOS), coordinated by the international program, the Global Earth Observing System of Systems, GEOSS.
There is a generally accepted need for long, accurate time series of multi-mission altimeter data, which requires standards on formats, geophysical corrections and reference frames, as well as the knowledge of the long-term stability of altimeter and its ancillary sensors. The latter implies cross-calibration between past, present, and future altimeter missions as well as between different altimeter technologies (pulse limited, laser, lidar, wide swath, Delay Doppler, etc). All these requirements are best fulfilled by an International Altimeter Service (IAS), acting in a mission and agency independent capacity, with the purpose to advocate scientific and world-community use of satellite altimetry, and to promote further innovative applications of the sensor. International Services have been established after a comprehensive study commissioned by scientific organisations, including IOC/GLOSS, ESA, IAG. At present, it is proposed to be operating under the umbrella of the Federation of Astronomical and Geophysical Services (still under ICSU). They are in most cases based on voluntary contribution of processing and data centres working anyway with data and products. The most prominent example is IGS, the International GNNS Service, today recognised as an inalienable frame for the precise geolocation of sensors and satellites.
This model can be adapted to the envisaged IAS which would be founded on
voluntary contribution of existing national and international organisations and legal entities. The present paper reviews the feasibility and scope of an independent International Altimeter Service and discusses details on the current organisation plan and the proposed terms of Calls for Participation.