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Wind speed inversion for imaging microwave altimeter

  • role： First author第一作者
  • Affiliation：

    Key Laboratory of Space Ocean Remote Sensing and Application, National Satellite Ocean Application Service, Beijing 100081, China

    Center for Earth System Science, Tsinghua University, Beijing 100084, China

  • Email：baoqingliu2000@163.com
  • Introduction：鲍青柳(1986—　)，男，博士后，研究方向为海洋遥感、遥感数据处理等。E-mail：baoqingliu2000@163.com
Qingliu BAO12,  
  • Affiliation：

    Key Laboratory of Space Ocean Remote Sensing and Application, National Satellite Ocean Application Service, Beijing 100081, China

Mingsen LIN1,  
  • Affiliation：

    Key Laboratory of Space Ocean Remote Sensing and Application, National Satellite Ocean Application Service, Beijing 100081, China

Youguang ZHANG1,  
  • Affiliation：

    Key Laboratory of Space Ocean Remote Sensing and Application, National Satellite Ocean Application Service, Beijing 100081, China

Yongjun JIA1,  
  • Affiliation：

    Key Laboratory of Space Ocean Remote Sensing and Application, National Satellite Ocean Application Service, Beijing 100081, China

Shuyan LANG1

resumen

As the development of space technology and the launch of new type microwave payloads, such as imaging microwave altimeter, more and more radars that observe the ocean at low incident will be in orbit, such as the Precipitation Radar (PR) (incident angle: 0°—18°) on Tropical Rainfall Measuring Mission (TRMM) satellite, the Imaging ALTimeter (IALT) (incident angle: 1°—7°) on the TG-2 space station which is lunched on September 15, 2016, and the Surface Ware Investigation and Monitoring (SWIM) (incident angle: 0°—10°) on China France Oceanography Satellite which is scheduled to launch in 2018. How to make use of the Normalized Radar Cross Section (NRCS) at low incident angle effectively is a very hot topic. Can the NRCS at low incident angle be used for wind speed inversion? This is also the motivation of our research. This paper uses the PR data on TRMM to research the sea surface wind speed inversion method and analyze the inversion accuracy. In this paper, the empirical Geophysical Model Function (GMF) model is established by crossing the PRNRCS with the QuikScat wind speed, and the GMF Table is given out in section 2. The Maximum Likelihood Estimation (MLE) method is used for PR wind speed inversion, and the objective function of MLE is provided in section 3. At last, the retrieved wind speeds are compared with the buoy and advanced scatterometer (ASCAT) wind speed. The performance of MLE method and the wind speed inversion accuracy are analyzed. By the performance analysis, we find that the bias and standard deviation of retrieved wind speed is smaller than 0.28 m/s and 1.51 m/s respectively. Moreover, the wind speed retrieval performances versus wind speed and incident angle are analyzed. The wind speed retrieval performance at medium wind speed is better than that at low and high wind speed. The inversion accuracy with 0°—8° incident angles is better than that with 8°—12° incident angles. From the results of this paper we can concluded that the NRCS at low incident angle can be used for wind speed retrieval. And the wind speed retrieval accuracy is even higher than that of scatterometer (typically 2 m/s). Thus, for the radars that operate near nadir, such as the IALT and the SWIM on China France Oceanography Satellite, we can offer the product of wind speed.

palabra clave

TRMM PR;wind speed inversion;low incident angle;inversion accuracy

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