| Abstract: |
Jason-3, launched on 17 January 2016, is the latest in a series of international satellite mission that extends the ocean surface topography measurements started by the Topex/Poseidon mission launched in 1992, followed by Jason-1 in 2001 and Jason-2 in 2008. The Advanced Microwave Radiometer (AMR) is one of the primary instruments on-board the Jason-3 satellite that determines radar travel time delay, also known as path delay (PD), caused by atmospheric water vapor and liquid water content in the atmosphere using three frequency channels (23.8, 18.7 and 34.0 GHz). Once the PD measurements are known, corrections can be applied to altimeter’s radar signals in removing the effects of water in the atmosphere.
The heritage wet path delay algorithm was developed prior to the launch of TOPEX/Poseidon in 1992, and uses only radiometer measurements at the three frequencies to derive the wet path delay correction. Although, there is a dual-frequency radar onboard the Jason altimetry missions, their information content is not utilized in the PD algorithm. Therefore, in this work, we propose a novel PD algorithm that uses all information available in both active/passive radar and radiometer measurement systems. The proposed active/passive path delay algorithm is based on an integrated optimal estimation system, where, path delay and other atmospheric parameters, including wind speed and cloud liquid water are derived simultaneously using both the information available from the radiometer brightness temperature and radar backscatter measurements. The new active/passive algorithm will be applied to the Jason-3 and Jason-2 data, and derived path delay corrections will be compared against heritage path delay product, to understand the impact of radar/radiometer measurements in the determination of PD correction. |
