TOPEX ionospheric height correction precision estimated from prelaunch test results

Free electrons in the ionosphere will lengthen the electromagnetic path between the TOPEX/Poseidon altimeters and the ocean surface. The path delay is proportional to the total electron content of the ionosphere along the line of sight between the altimeter and the surface. Since these ionosphere delays are also inversely proportional to frequency squared, the nearly simultaneous use of both Ku-band (13.6-GHz) and C-band (5.3-GHz) TOPEX altimeters permits a first-order correction for ionospheric delays. Using results from prelaunch ground testing of the TOPEX satellite altimeters, the authors present the residual height tracking noise after application of the ionosphere correction algorithm. Results are presented as function of ocean significant wave height and for both the 320-MHz and 100-MHz bandwidth of the C-band altimeter.>