Assessment of GNSS-IR-Based Snow-Depth Retrievals Using Observations from Different Receivers with the Same Antenna

  Objectives  The emerging global navigation satellite system (GNSS) interferometric reflectometry (GNSS-IR) technique can obtain the information of reflector using geodetic GNSS receiver, and has been extensively applied to the research on snow depth, tide level, soil moisture, sea surface wind and so on. However, multipath suppression technique is often adopted in geodetic GNSS receiver and the reflected signal will be weakened or even eliminated, which will undoubtedly reduce the performance of GNSS-IR. Therefore, the influence of multi-receiver and multi-frequency on GNSS-IR should be carefully investigated.

  Methods  By learning from the method of zero baseline, we design an experiment of snow depth retrievals using GNSS-IR at Chinese Arctiv Yellow River Station in Svalbard, and quantitatively illustrate the influence of receiver performance on the accuracy of snow depth retrievals. In the experiment, two different GNSS receivers are connected to the same antenna with a power divider. It brings a special benefit that the observations of two receivers at three frequencies are derived from absolutely the same reflector. After collecting enough data, the daily average retrievals of the two receivers in the three frequencies are compared in order to verify the effectiveness of the retrieval strategy. Then the differences in the retrieval of different receivers are compared and analyzed to check the influence of receivers.

  Results  The results show that the observations of each receiver and each frequency can be used to retrieve snow depth and the bias is in 3 cm. However, in spite of the same reflector, the differences between the snow depth retrievals from two receivers and three frequencies remain, especially when the snow depth changes rapidly.

  Conclusions  Different receivers have different methods to suppress multipath effect, which will affect the retrieval effect of GNSS-IR. Therefore, when using geodetic GNSS receivers for GNSS-IR retrievals, the difference brought by receivers cannot be ignored. If the method of multipath suppression can be properly considered in GNSS data processing, it should be helpful to improve the accuracy of GNSS-IR retrievals.