Detection of Bohai Bay Sea Ice Using GPS-Reflected Signals For preventing the effects of sea ice disaster, traditional methods for detecting sea ice have some disadvantages, such as inadequate robustness against weather and high cost of real-time detection. This paper evaluates the usage of Global Positioning System (GPS)-reflected signals for accurate real-time Earth observations to study the changes in the sea surface state through remote sensing (RS).GPS L1 signals received after reflection from Bohai Bay were analyzed for their sea-ice content. The results are in good agreement with a reflected power ratio model [the ratio of the direct right-hand circular polarization (RHCP) signals and the reflected left-handed circular polarization (LHCP) signals] and sea ice concentration. The average of the reflected power ratio on the sea ice surface (0.41) is much smaller than that on the sea water surface (2.61).