“…The main data product, i.e., Level 1b data, is the Delay-Doppler Map (DDM) of GPS scattered power, which has been analyzed by different groups for various remote sensing applications, such as ocean scatterometry [e.g., Foti et al, 2015], ocean altimetry [e.g., Clarizia et al, 2016], and soil moisture [e.g., Chew et al, 2016]. The DDMs collected over sea ice have been also analyzed for sea ice detection and sea ice concentration retrieval [e.g., Yan and Huang, 2016;Yan et al, 2017;Alonso-Arroyo et al, 2017]. With the DDM, only the coarse delay of the reflected signal can be extracted from the ranging code, resulting in a very low altimetry precision, e.g., 7.4-8.1 m precision over sea surface with 1 s observations [Clarizia et al, 2016].…”