Principal Investigator: Lee-Lueng Fu, NASA Jet Propulsion Laboratory
Proposal Title: Advanced Altimeter for Oceans Studies
The importance of the oceans to the global energy budget and climate change cannot be overemphasized. The TOPEX/Poseidon (T/P) mission has demonstrated the ability of radar altimeters to provide measurements of seasonal and interannual ocean variability, planetary scale ocean waves, and precision tidal measurements, among many applications. The continuation, and improvement, of the measurements made by T/P are imperative to the understanding of ocean circulation and its effect on climate. The purpose of this proposal is to design the next generation ocean height measuring system, which will be able to extend traditional altimeter measurements by improving instrument accuracy and using radar interferometry to obtain two-dimensional measurements of geostrophic velocities. The use of interferometry represents a quantum jump in the capability of ocean current measurements since it allows the instantaneous mapping of the two-dimensional geostrophic velocity field, rather than the one-dimensional cuts obtained by traditional altimeters. These capabilities will allow better estimates of oceanic heat and mass transport, as well as statistical properties of the flow field such as mean and eddy energy, eddy-eddy, and eddy mean flow interactions. As part of the IIP, we will design an integrated Altimeter/Interferometer/Radiometer/GPS instrument to meet the science goals using advanced technology and packaging to reduce mass, power, and cost over traditional altimeter designs. Furthermore, we will prototype and test the key technological drivers for the integrated instrument, enabling the eventual implementation of the instrument in the 18 months envisioned by the IIP. The key systems to be prototyped include an advanced three-frequency radiometer, a five-frequency antenna feed, a solid state high bandwidth Ku-Band transmitter, an ultra-wideband chirp generator, a low power and mass altimeter receiver, processing algorithms for real-time altimetric and interferometric data processing, and a design of the interferometer baseline/metrology system.