张伟^1,2,,
石汉青¹,
姜祝辉^3,,,
杨平吕¹,
常舒捷¹,
项杰¹,
买彦博¹
1. 国防科技大学气象海洋学院, 长沙 410073
2. 中国卫星海上测控部, 江苏 江阴 214431
3. 地理信息工程国家重点实验室, 西安 710054

基金项目: 国家自然科学基金(41275113)和地理信息工程国家重点实验室自主研究课题(SKLGIE2018-ZZ-8)资助


详细信息

作者简介: 张伟, 男, 1986年生, 博士研究生, 主要从事卫星资料反演研究.E-mail: zhangwei19@nudt.edu.cn

通讯作者: 姜祝辉, 男, 1982年生, 高级工程师, 主要从事卫星资料反演研究.E-mail: jiangzhuhui@mail.iap.ac.cn

中图分类号: P407

收稿日期:2020-08-17
修回日期:2021-05-10
上线日期:2021-07-10

Assessment of variational method schemes for synthetic aperture radar wind retrieval

ZHANG Wei^1,2,,
SHI HanQing¹,
JIANG ZhuHui^3,,,
YANG PingLü¹,
CHANG ShuJie¹,
XIANG Jie¹,
MAI YanBo¹
1. College of Meteorology and Oceanography, National University of Defense Technology, Changsha 410073, China
2. China Satellite Maritime Tracking and Controlling Department, Jiangyin Jiangsu 214431, China
3. State Key Laboratory of Geo-information Engineering, Xi'an 710054, China


More Information

Corresponding author: JIANG ZhuHui,E-mail:jiangzhuhui@mail.iap.ac.cn

MSC: P407

--> Received Date: 17 August 2020
Revised Date: 10 May 2021
Available Online: 10 July 2021


摘要
摘要:利用合成孔径雷达获取高空间分辨率的海面风场，对于研究沿岸海域大气海洋过程具有重要意义.应用CMOD地球物理模型直接反演风速受先验风向误差影响较大，30°的风向误差可导致高达40%的风速误差.变分方法考虑了雷达观测值及背景风场的不确定性，能够较好地降低先验风向对反演风速的影响.但不同的观测误差或地球物理模型选择会形成不同的变分方案，使得反演风场存在差异.本文基于Sentinel-1合成孔径雷达数据及NDBC浮标数据，对不同变分方案进行了系统评估.试验结果表明，当观测误差选取常值0.1 dB、地球物理模型选取CMOD7时，反演风速均方根误差为1.11 m·s^-1，总体最小；但在特定风速区间内，其他变分方案能获得相对更好的反演精度；各变分方案反演风速精度均显著高于背景风速及CMOD直接反演风速精度，但反演风向相对背景风向没有明显改善.试验结果可为变分方法在不同应用需求下的选择提供参考依据.
关键词: 合成孔径雷达/
海面风场/
变分方法/
Sentinel-1/
CMOD7

Abstract:Synthetic aperture radar (SAR) high spatial resolution sea surface wind retrieval is of great significance for studying atmospheric and ocean processes in the marine coastal area. The wind speed retrieved directly by CMOD geophysical model function is greatly affected by the prior wind direction error. A wind direction error of 30° introduces SAR wind speed uncertainty up to 40%. The variational method (VAR) considers the uncertainty of radar observation and background wind, which can reduce the influence of prior wind direction on the retrieved wind speed. However, different observation errors or geophysical model function choices will form different VAR schemes, which lead to different wind results. Based on Sentinel-1 SAR data and NDBC buoy data, different variational schemes are systematically assessed in this paper. The tests show that when the observation error is 0.1 dB and the geophysical model function is CMOD7, the RMSE of retrieved wind speed is 1.11 m·s^-1, which is the smallest overall. However, other VAR schemes can obtain relatively better retrieval accuracy in a specific wind speed range. The accuracy of retrieved wind speed by each VAR scheme is significantly higher than that of background wind speed and CMOD direct retrieved wind speed, but the retrieved wind direction is not significantly improved compared with the background wind direction. The results can provide a reference for the selection of VAR methods under different application requirements.
Key words:Synthetic aperture radar/
Sea surface wind/
Variational method/
Sentinel-1/
CMOD7



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