Ocean surface wind vectors (OVW) from scatterometers have been proved to be of great benefit to marine weather
analysis and numerical model prediction. Conventional single-frequency scatterometers are capable to measure
substantially accurate wind fields in clear atmospheric conditions, whereas winds obtained in marine extreme weather
conditions are not so satisfying due to the high wind speed saturation effect and the rain perturbation. Therefore, a dualfrequency
wind field measuring radar (WIFIR) to be onboard FengYun-3E is being predesigned to obtain relatively
accurate wind fields in all weather conditions, which will compensate for the single-frequency shortcomings.
The purpose of this study was to investigate the potential ability of WIFIR to measure OVW in tropical cyclones. A
high-fidelity forward model was developed to simulate the sea surface normalize radar cross sections (NRCS) measured
by WIFIR. The wind and rain rate fields used to drive the model are generated by UWNMS cloud model for Hurricane
Ivan in 2004. High-wind GMFs and a theoretical rain model, which includes attenuation and volume scattering effect,
have been utilized to describe the forward model. Based on the simulation results, the impact of rain on radar
measurements and a dual-frequency retrieval algorithm were studied. The dual-frequency method was shown to have the
ability to obtain information of rain rates up to 30mm/hr, and acquire more accurate wind vectors than single-frequency
measurements. This method will be more effective to improve wind retrieval accuracy in tropical cyclones with the
synchronous observation of microwave humidity sounder (MWHS) aboard FY-3 satellite.
When observing unchanging targets or slow-changing targets, a rotating array can be used instead of a stationary array in
an interferometric radiometer to reduce the complexity and the cost. The configuration of a stationary array determines
its coverage in spatial frequency domain. But for a rotating array, the baselines were distributing on a series of concentric
circles with radiuses of the baseline lengths, no matter what its configuration was. According to the characteristics of the
distribution of the baselines, the expressions of system sensitivity and spatial resolution of a rotating interferometric
radiometer were deduced in thwas paper. For a rotating interferometric radiometer with big synthetic aperture, like the
Geostationary Interferometric Microwave Sounding (GIMS) prototype, it was very difficult to find a suitable calibration
source to measure the system sensitivity. Therefore, the system sensitivity of the GIMS prototype was estimated based
on the sensitivity of all channels by the sensitivity formula. Since the array factor of an interferometric radiometer was
the pulse response of a point target, the spatial resolution of the GIMS prototype obtained by imaging an artificial quasi
point target was used to demonstrate the formula in this paper, and the results were nearly identical. In addition, some
different window functions were used to weight visibility samples of the prototype, and their effects on the sensitivity
and the spatial resolution were analyzed. The principle of selecting the weighted window was described at the end.
Spaceborne microwave scatterometers have successfully provided global ocean surface wind field for two decades. However current scatterometers still cannot satisfy the requirement of achieve ocean wind vectors in nearly all weather and all wind conditions. A new microwave scatterometer - the WindRadar with dual frequency onboard Chinese FengYun-3E meteorological satellite is being developed to attempt to overcome their shortcomings. This paper introduces the objectives of the WindRadar, then describes the design of its some key system characteristics, and the performance of the WindRadar is also analyzed at the end.
Active and passive microwave sensor are very important for atmospheric and surface parameters monitoring. In
past decades, microwave sensors like SSM/I, AMSR-E and PR have got great achievements in measuring global
temperature profile and Precipitation, as well as surface parameters like soil moisture and snow water
equivalent. FY3 series satellite is the new generation meteorological satellites of China. Its main objective is to
provide data needed for meteorological application. There are 2 microwave sounders and 1 microwave imager
onboard the FY3 satellite, provide the air temperature, humidity and surface parameters information under all
weather conditions. we plan to develop our own active microwave sensor In FY3-02 series satellites, which is
planed to be launched in 2012. In FY3-02 series, the active microwave sensor, together with other two sensors,
are to be setting in a low altitude orbit satellite, together with other two mid-altitude satellites, consists the
whole FY3-02 series meteorological satellite constellation. The main target of the active microwave sensor is to
monitor the precipitation and disaster weather in global scale.
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