Improved Backscattering Measurements with the CFOSAT Rotating Fan-beam
Scatterometer
Risheng Yun

CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences
Corresponding Author:yunrisheng@mirslab.cn
Author ProfileRisheng Yun
CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences
Author ProfileXiaolong Dong

CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences., CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences., CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences.
Author ProfileDi Zhu
CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences
Author ProfileJianying Ma
CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences
Author ProfileZhisen Wang
CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences, CAS Key Laboratory of Microwave Remote Sensing, National Space Science Center, Chinese Academy of Sciences
Author ProfileAbstract
The China-France Oceanography Satellite (CFOSAT) was successfully
launched on October 29, 2018, which carried two innovative payloads,
i.e., the surface waves investigation and monitoring (SWIM) instrument
and the rotating fan beam scatterometer (RFSCAT). CFOSAT scatterometer
(CSCAT) is dedicated to the monitoring of sea surface wind vectors and
variety of climate studies, but also provides useful data for the
applications over land and polar regions. CSCAT employs a “rotationg
fan-beam” design rather than “pen-beam” approach previously used with
SeaWinds on NASA QuikSCAT and “fixed fan-beam” approach with ASCAT on
METOP-A. The CSCAT produces large overlaps on the observation regions
within the total swath by successive sweeps and provides a large number
of backscatter acquisitions with diverse azimuth and elevation
combinations for a single surface resolution cell. In order to obation
higher resolution and precise backscatter of rotating fan-beam
scatterometer, however, some special considerations have been made in
the design of CSCAT signal and data processing. In this paper, the data
processing approach of CSCAT are proposed completely for the first time.
The geolocation reference mapping model is employed in CSCAT slice
geolocation. In noise processing, CSCAT adopts the method of weighted
least square polynomial surface fitting to conduct the adaptive noise
correction factor estimation. The attitude cubic algorithm used for X
integral factor computation is developed to obtain the precise
backscatter coefficients based on the radar equation. Because of the
high relevance between the CSCAT data processing and the hardware
configuration and onboard signal processing of the instrument, the
instrument module configuration and signal processing design are also
analyzed and presented comprehensively. Especially, the influence and
compensation of Doppler frequency on signal processing and range
filtering processing are introduced. The instrument performance and data
processing algorithm are verified by the accuracy analysis on the CSCAT
backscattering coefficient data. The backscatter coefficient accuracy is
estimation on the Amazon forest, and the results shows that the
backscattering coefficient accuracy of CSCAT on 25km × 25km grid is less
than 0.5dB except that the near end and far end of the beam are slightly
higher. The statistical results of wind field obtained from the
backscattering coefficient inversion of CSCAT are also provided, and the
better wind field inversion results are obtained based on the CSCAT
backscattering coefficient measurement.