劉原華 魏偉 牛新亮
關(guān)鍵詞: 岸基; 理論模型; 相關(guān)時間; 冪函數(shù)模型; 海面風(fēng)速反演; 有理函數(shù)模型; 數(shù)據(jù)擬合
中圖分類號: TN911.1?34; TP7 ? ? ? ? ? ? ? ? ? ? 文獻標(biāo)識碼: A ? ? ? ? ? ? ? ? ? ? 文章編號: 1004?373X(2019)01?0065?03
Abstract: Under the shore?based condition, the waves can′t fully grow. The theoretical model of wave spectrum is not enough to fully describe the relationship between relevant time and wind speed. The empirical model with power function form is generally used to invert the wind speed of the sea surface. In this paper, a new empirical model with rational function form is proposed to replace the traditional empirical model with power function form for sea surface wind speed inversion. The experimental data shows that the correlation coefficient between wind speed inversed by the new empirical model with rational function form and actual wind is 0.986 2, and the root mean square error is 0.45 m/s. In comparison with the traditional exponential model with power function form, the correlation coefficient is increased by 0.80%, and the root mean square error is decreased by 20.19%.
Keywords: shore base; theory model; correlation time; power function model; sea surface wind speed inversion; rational function model; data fitting
全球?qū)Ш叫l(wèi)星定位系統(tǒng)反射信號(GNSS?R)是20世紀(jì)90年代逐漸發(fā)展起來的全球?qū)Ш蕉ㄎ幌到y(tǒng)衛(wèi)星系統(tǒng)(GNSS)的一個分支,利用GNSS?R技術(shù)反演海面風(fēng)速是一種新的海風(fēng)觀測方法[1?4]。
岸基條件下,由于海浪不能充分生長,海浪譜的理論模型將不能準(zhǔn)確地描述相關(guān)時間與海面風(fēng)速的關(guān)系[5],故需要針對海域特點建立相應(yīng)的經(jīng)驗?zāi)P?,目前一般使用的是冪函?shù)形式的經(jīng)驗?zāi)P头囱莺C骘L(fēng)速。
本文提出有理函數(shù)形式的經(jīng)驗?zāi)P头囱莺C骘L(fēng)速。首先介紹了傳統(tǒng)冪函數(shù)形式的經(jīng)驗?zāi)P头囱莺C骘L(fēng)速的方法,在此基礎(chǔ)上提出有理函數(shù)形式的經(jīng)驗?zāi)P头囱莺C骘L(fēng)速的方法,經(jīng)過試驗證明,有理函數(shù)形式的經(jīng)驗?zāi)P头囱萁Y(jié)果相比冪函數(shù)形式的經(jīng)驗?zāi)P头囱萁Y(jié)果其相關(guān)系數(shù)提高了0.80%,均方根誤差降低了20.19%。
岸基條件下,海面風(fēng)速一般可以通過干涉復(fù)數(shù)場(ICF)相關(guān)時間反演得到。
將[FRt]定義為GNSS反射信號最大相關(guān)值對應(yīng)的復(fù)數(shù)相關(guān)時間序列,[FDt]定義為GNSS直射信號最大相關(guān)值對應(yīng)的復(fù)數(shù)相關(guān)時間序列,干涉復(fù)數(shù)場函數(shù)為[6]:
通過有理函數(shù)形式的經(jīng)驗?zāi)P头囱蒿L(fēng)速值與實測風(fēng)速對比,得到有理函數(shù)形式的經(jīng)驗?zāi)P头囱莺C骘L(fēng)速的均方根誤差為0.450 6 m/s。
本文提出有理函數(shù)形式的經(jīng)驗?zāi)P腿〈鷥绾瘮?shù)形式的經(jīng)驗?zāi)P头囱莺C骘L(fēng)速,并用試驗數(shù)據(jù)對冪函數(shù)形式的經(jīng)驗?zāi)P秃陀欣砗瘮?shù)形式的經(jīng)驗?zāi)P瓦M行對比分析。有理函數(shù)形式的經(jīng)驗?zāi)P头囱萁Y(jié)果與冪函數(shù)形式的經(jīng)驗?zāi)P头囱萁Y(jié)果相比,其相關(guān)系數(shù)由0.978 4提升為0.986 2,提高了0.80%;均方根誤差由0.564 6 m/s降低為0.450 6 m/s,降低了20.19%,證明了本文模型的可行性,為岸基海面風(fēng)速反演提供了一種新的經(jīng)驗?zāi)P汀?/p>
參考文獻
[1] CARDELLACH E, RUFFINI G, PINO D, et al. Mediterranean balloon experiment: ocean wind speed sensing from the stratosphere, using GPS reflections [J]. Remote sensing of environment, 2003, 88(3): 351?362.
[2] THOMPSON D R, ELFOUHAILY T M, GARRISON J L. An improved geometrical optics model for bistatic GPS scattering from the ocean surface [J]. IEEE transactions on geosciences and remote sensing, 2005, 43(12): 2810?2821.
[3] PARK H, VALENCIA E, RODRIGUEZ?ALVAREZ N, et al. New approach to sea surface wind retrieval from GNSS?R measurements [C]// Proceedings of 2001 IEEE International Geo?sciences and Remote Sensing Symposium. Vancouver: IEEE, 2011: 1469?1472.
[4] 李穎,朱雪瑗,曹妍,等.GNSS?R海洋遙感監(jiān)測技術(shù)綜述[J].海洋通報,2015,34(2):121?129.
LI Ying, ZHU Xueyuan, CAO Yan, et al. Review on GNSS?R ocean remote sensing monitoring technique [J]. Marine science bulletin, 2015, 34(2): 121?129.
[5] FRASIER S J, CAMPS A J. Dual?beam interferometry for ocean surface current vector ?mapping [J]. IEEE transactions on geoscience and remote sensing, 2001, 39(2): 401?414.
[6] 楊東凱,張其善.GNSS反射信號處理基礎(chǔ)與實踐[M].北京:電子工業(yè)出版社,2012.
YANG Dongkai, ZHANG Qishan. GNSS reflected signal processing: fundamentals and applications [M]. Beijing: Publi?shing House of Electronics Industry, 2012.
[7] 李偉強.基于北斗GEO衛(wèi)星反射信號的臺風(fēng)風(fēng)速觀測[C]//第五屆中國衛(wèi)星導(dǎo)航學(xué)術(shù)年會.北京:中國衛(wèi)星導(dǎo)航學(xué)術(shù)中心,2014:1?3.
LI W Q. Typhoon wind speed observation utilizing reflected signals from BeiDou GEO satellites [C]// 5th Conference on China Satellite Navigation. Beijing: China Satellite Navigation Center, 2014: 1?3.
[8] 張陽,張鳳元,張波,等.北斗反射信號海風(fēng)海浪探測系統(tǒng)軟件設(shè)計[J].測控技術(shù),2015,34(11):103?106.
ZHANG Yang, ZHANG Fengyuan, ZHANG Bo, et al. Design on Beidou reflections ocean wind and waves exploration software system [J]. Measurement & control technology, 2015, 34(11): 103?106.
[9] 陳慶亮,郭業(yè)才,王強,等.北斗反射信號海風(fēng)探測數(shù)據(jù)分析與檢定[J].南京信息工程大學(xué)學(xué)報(自然科學(xué)版),2015,7(4):338?342.
CHEN Qingliang, GUO Yecai, WANG Qiang, et al. Analysis and verification of the ocean surface wind measurement detected with Beidou reflected signals [J]. Journal of Nanjing University of Information Science & Technology (natural science edition, 2015, 7(4): 338?342.
[10] 楊東凱,李偉強,楊威.北斗系統(tǒng)在海風(fēng)海浪探測中的應(yīng)用研究[J].導(dǎo)航定位學(xué)報,2014,2(2):97?101.
YANG Dongkai, LI Weiqiang, YANG Wei. Research on BSD applications in sea wind and wave detection [J]. Journal of navigation and positioning, 2014, 2(2): 97?101.
[11] VALENCIA E, CAMPS A, MARCHAN?HERNANDEZ J F, et al. Experimental determination of the sea correlation time using GNSS?R coherent data [J]. IEEE geoscience and remote sensing society, 2010, 7(4): 675?679.