Deep learning for inversion of significant wave height based on actual sea surface backscattering coefficient model

2019 ◽  
Vol 79 (45-46) ◽  
pp. 34173-34193 ◽  
Author(s):  
Tao Wu ◽  
Yun-Hua Cao ◽  
Zhen-Sen Wu ◽  
Jia-Ji Wu ◽  
Tan Qu ◽  
...  
2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
He Wang ◽  
Jingsong Yang ◽  
Jianhua Zhu ◽  
Lin Ren ◽  
Yahao Liu ◽  
...  

Sea state estimation from wide-swath and frequent-revisit scatterometers, which are providing ocean winds in the routine, is an attractive challenge. In this study, state-of-the-art deep learning technology is successfully adopted to develop an algorithm for deriving significant wave height from Advanced Scatterometer (ASCAT) aboard MetOp-A. By collocating three years (2016–2018) of ASCAT measurements and WaveWatch III sea state hindcasts at a global scale, huge amount data points (>8 million) were employed to train the multi-hidden-layer deep learning model, which has been established to map the inputs of thirteen sea state related ASCAT observables into the wave heights. The ASCAT significant wave height estimates were validated against hindcast dataset independent on training, showing good consistency in terms of root mean square error of 0.5 m under moderate sea condition (1.0–5.0 m). Additionally, reasonable agreement is also found between ASCAT derived wave heights and buoy observations from National Data Buoy Center for the proposed algorithm. Results are further discussed with respect to sea state maturity, radar incidence angle along with the limitations of the model. Our work demonstrates the capability of scatterometers for monitoring sea state, thus would advance the use of scatterometers, which were originally designed for winds, in studies of ocean waves.


2015 ◽  
Vol 101 ◽  
pp. 244-253 ◽  
Author(s):  
S. Salcedo-Sanz ◽  
J.C. Nieto Borge ◽  
L. Carro-Calvo ◽  
L. Cuadra ◽  
K. Hessner ◽  
...  

2021 ◽  
Author(s):  
Jichao Wang ◽  
Ting Yu ◽  
Fangyu Deng ◽  
Zongli Ruan ◽  
Yongjun Jia

2020 ◽  
Vol 12 (17) ◽  
pp. 2858
Author(s):  
Jiuke Wang ◽  
Lotfi Aouf ◽  
Yongjun Jia ◽  
Youguang Zhang

HY2B is now the latest altimetry mission that provides global nadir significant wave height (SWH) and sea surface wind speed. The validation and calibration of HY2B are carried out against National Data Buoy Center (NDBC) buoy observations from April 2019 to April 2020. In general, the HY2B altimeter measurements agree well with buoy observation, with scatter index of 9.4% for SWH, and 15.1% for wind speed. However, we observed a significant bias of 0.14 m for SWH and −0.42 m/s for wind speed. A deep learning technique is novelly applied for the calibration of HY2B SWH and wind speed. Deep neural network (DNN) is built and trained to correct SWH and wind speed by using input from parameters provided by the altimeter such as sigma0, sigma0 standard deviation (STD). The results based on DNN show a significant reduction of the bias, root mean square error (RMSE), and scatter index (SI) for both SWH and wind speed. Several DNN schemes based on different combination of input parameters have been examined in order to obtain the best model for the calibration. The analysis reveals that sigma0 STD is a key parameter for the calibration of HY2B SWH and wind speed.


2020 ◽  
Author(s):  
Ruizi Shi ◽  
Fanghua Xu ◽  
Li Liu ◽  
Zheng Fan ◽  
Hao Yu ◽  
...  

Abstract. It has been well known that ocean surface gravity waves have enormous effects on physical processes at the atmosphere–ocean interface. However, the effects of surface waves on global forecast in several days are less studied. To investigate this, we incorporated the WAVEWATCH III model into the Climate Forecast System Model version 2.0 (CFS2.0), with the Chinese Community Coupler version 2.0 (C-Coupler2). Two major wave-related processes, the Langmuir mixing and the sea surface momentum roughness, were considered. Extensive comparisons were performed against in-situ buoys, satellite measurements and reanalysis data, to evaluate the influence of the two processes on the forecast of sea surface temperature, mixed layer depth, significant wave height, and 10-m wind speed. A series of 7-day simulations demonstrate that the newly developed atmosphere-ocean-wave coupling system could improve the CFS global forecast. The Langmuir mixing parameterization could increase the vertical movement of water and effectively reduce the warm bias of sea surface temperature and shallow bias of mixed layer depth in the Antarctic circumpolar current in austral summer, whereas the significant wave height and 10-m wind speed are insensitive to it. On the other hand, the modified momentum roughness length could significantly reduce the overestimated 10-m wind speed and significant wave height in mid-high latitudes. This is because the enhanced frictional dissipation at high wind speed could reduce 10-m wind speed and consequently decrease the significant wave height. But its effect on the temperature structure in upper ocean is less obvious.


Author(s):  
Brandon Quach ◽  
Yannik Glaser ◽  
Justin Edward Stopa ◽  
Alexis Aurelien Mouche ◽  
Peter Sadowski

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