| JI Yonggang,ZHANG Jie,ZHANG Youguang,MENG Junmin. 2006. Shenzhou-4 spaceborne altimeter waveform processing and significant wave height retrieval. Acta Oceanologica Sinica, (3):40－47 |
| Shenzhou-4 spaceborne altimeter waveform processing and significant wave height retrieval |
| Shenzhou-4 spaceborne altimeter waveform processing and significant wave height retrieval |
| Received:January 13, 2006 Revised:March 26, 2006 |
| DOI： |
| Key words:SZ-4 spaceborne altimeter significant wave height double peaks waveform retracking waveform fit |
| 中文关键词: SZ-4 spaceborne altimeter significant wave height double peaks waveform retracking waveform fit |
| 基金项目: |
| Author Name | Affiliation | E-mail | | JI Yonggang | Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
Graduate School of Chinese Academy of Sciences, Beijing 100039, China
First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | jiyongang@gmail.com | | ZHANG Jie | First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | | | ZHANG Youguang | National Satellite Ocean Application Service, Beijing 100081, China | | | MENG Junmin | First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | |
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| Abstract: |
| The Shenzhou-4 spaceborne (SZ-4) altimeter waveforms were processed, and then the significant wave heights (SWH) was retrieved on the basis of waveform fitting and waveform retracking. Waveforms processing includes the waveform 1 s averaging, the elimination of thermal noise and the waveforms normalization. Double peaks were found on each SZ-4 waveform, and it was pointed out that the region of waveforms with the second peak is abnormal and its effects on the whole waveform in the waveform fit should be taken into consideration. To obtain the width of the waveform leading-edge, a method was proposed to find the starting point of waveform, and the half-power point of waveform was found by retracking the waveform. The normalized waveforms were fitted with the Haynes model by using the weighting least square fit method. Then the selections of the weighting coefficients and their effects on significant wave hight retrieving were discussed, and the optimal five-region weighting method was proposed. At last, the SWH data of SZ-4 altimeter retrieved by using the proposed method were compared with those of ERS-2 and Jason-1 altimeter, and it was concluded that the SZ-4 altimeter can detect significant wave height. |
| 中文摘要: |
| The Shenzhou-4 spaceborne (SZ-4) altimeter waveforms were processed, and then the significant wave heights (SWH) was retrieved on the basis of waveform fitting and waveform retracking. Waveforms processing includes the waveform 1 s averaging, the elimination of thermal noise and the waveforms normalization. Double peaks were found on each SZ-4 waveform, and it was pointed out that the region of waveforms with the second peak is abnormal and its effects on the whole waveform in the waveform fit should be taken into consideration. To obtain the width of the waveform leading-edge, a method was proposed to find the starting point of waveform, and the half-power point of waveform was found by retracking the waveform. The normalized waveforms were fitted with the Haynes model by using the weighting least square fit method. Then the selections of the weighting coefficients and their effects on significant wave hight retrieving were discussed, and the optimal five-region weighting method was proposed. At last, the SWH data of SZ-4 altimeter retrieved by using the proposed method were compared with those of ERS-2 and Jason-1 altimeter, and it was concluded that the SZ-4 altimeter can detect significant wave height. |
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