An examination of U.S. plans for meeting operational ocean observation needs with radar altimetry

The proven performance of space-based radar altimeter observations for accurate, systematic, quantifiable, and ubiquitous measurements of sea surface height has led to broad adoption of this technique as a means for satisfying existing and future observation needs. Associated requirements to meet U.S. user needs - from basic research to current operations - have been articulated by a broad cross section of stakeholders. The NPOESS IPO IORD-II represents a coordinated Federal strategy for operational environmental remote sensing from low Earth orbit and is the single existing source of U.S. approved operational requirements for observations using radar altimetry. Due to the projected availability of resources and the difficulty in translating user needs to system specifications, the ability of the NPOESS Program to address beyond-baseline improvements to meet the complete spectrum of user needs of U.S. national interest - in particular precise, continuous, and unbiased measurements of low frequency, large scale climatic signals critical to the unambiguous determination of global climate change - will be challenged without reliance on data sources external to the program. Existing altimeter sensor technologies necessitate multiple platforms in dissimilar orbits to meet requirements across the scales of interest. Emerging technologies and exploitation techniques have the capacity to provide increased efficiencies in performance and cost