Precision of Ku-Band Reflected Signals of Opportunity Altimetry

Abstract

This letter provides a proof-of-concept experiment and validation of an error model for bistatic altimetry using signals of opportunity (SoOps). Coastal sea surface height plays a prominent role in measuring the total water-level envelope directly and is one of the key quantities required by storm surge applications and services. Nadir satellite altimeters have a long history of mapping the variability of the earth’s open ocean. However, they exhibit problems operating in coastal areas due to the effects, such as land contamination, rapid variations due to tides, and atmospheric effects. One technique for filling this gap is bistatic altimetry using SoOp (e.g., digital communication signal reflections). In this letter, we investigate capabilities of this technique. Twenty three days of data were collected at platform harvest from a single channel of the Ku-Band direct broadcast satellite. The wind speed observed during the experiment was between 4 and 14 m/s and significant wave height was between 0.7 and 4 m as measured by buoy 46 218 located 8 km away. The standard deviation in the estimation of height was found to be 7.2 cm (the same as predicted from theory). Using a least-squares approach improved the precision reducing the standard deviation to 6.8 cm. It is shown that the error in the estimation of height can be reduced to 3.5 cm by utilizing the full bandwidth (all the channels) of the SoOp. Extrapolating these results, we predict a precision of 5.3 cm from a typical (e.g., Jason) orbit of 1380 km.