scholarly journals Validation and Calibration of Significant Wave Height and Wind Speed Retrievals from HY2B Altimeter Based on Deep Learning

2020 ◽  
Vol 12 (17) ◽  
pp. 2858
Author(s):  
Jiuke Wang ◽  
Lotfi Aouf ◽  
Yongjun Jia ◽  
Youguang Zhang
Keyword(s):  
Deep Learning ◽  
Wind Speed ◽  
Wave Height ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Significant Wave ◽  
Sea Surface Wind Speed ◽  
Sea Surface Wind ◽  
Key Parameter

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.

scholarly journals Improved CYGNSS Wind Speed Retrieval Using Significant Wave Height Correction

2021 ◽  
Vol 13 (21) ◽  
pp. 4313
Author(s):  
Daniel Pascual ◽  
Maria Paola Clarizia ◽  
Christopher S. Ruf
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Satellite System ◽  
Significant Wave ◽  
Sea Surface Wind Speed ◽  
Sea Surface Wind ◽  
The Difference

This article presents the methodology for an improved estimation of the sea surface wind speed measured by the cyclone global navigation satellite system (CYGNSS) constellation of satellites using significant wave height (SWH) information as external reference data. The methodology consists of a correcting 2D look-up table (LUT) with inputs: (1) the CYGNSS wind speed given by the geophysical model function (GMF); and (2) the collocated reference SWH given by the WW3 model, which is forced by winds from the European Centre for Medium-Range Weather Forecasts (ECMWF) organization. In particular, the analyzed CYGNSS wind speeds are the fully developed seas (FDS) obtained with the GMF 3.0, and the forcing winds are the ECMWF forecast winds. Results show an increase in sensitivity to large winds speeds and an overall reduction in the root mean square difference (RMSD) with respect to the ECMWF winds from 2.05 m/s to 1.74 m/s. The possible influence of the ECWMF winds on the corrected winds (due to their use in the WW3 model) is analyzed by considering the correlation between: (1) the difference between the ECMWF winds and those from another reference; and (2) the difference between the corrected CYGNSS winds and those from the same reference. Results using ASCAT, WindSat, Jason, and AltiKa as references show no significant influence.

The seasonal variations in the significant wave height and sea surface wind speed of the China’s seas

2015 ◽  
Vol 34 (9) ◽  
pp. 58-64 ◽  
Author(s):  
Chongwei Zheng ◽  
Jing Pan ◽  
Yanke Tan ◽  
Zhansheng Gao ◽  
Zhenfeng Rui ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
Seasonal Variations ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Sea Surface ◽  
Significant Wave ◽  
Sea Surface Wind Speed ◽  
Sea Surface Wind

scholarly journals HF SKYWAVE RADAR MEASUREMENT OF HURRICANE WINDS AND WAVES

1978 ◽  
Vol 1 (16) ◽  
pp. 9
Author(s):  
Joseph W. Maresca ◽  
Christopher T. Carlson
Keyword(s):  
Wind Speed ◽  
Gulf Of Mexico ◽  
Wave Height ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Radial Distance ◽  
Surface Wind Speed ◽  
Open Ocean ◽  
Significant Wave ◽  
Wave Measurements

We measured significant wave height, and surface wind speed and direction for the first two Gulf of Mexico hurricanes of the 1977 season using a high frequency (HF) skywave radar. The radar measurements were made from California by using the SRI-operated Wide Aperture Research Facility (WARF). We recorded sea backscatter for hurricanes Anita and Babe, at distances more than 3000 km from the WARF, by means of single F-layer ionospheric reflection. We compiled real-time maps of the surface wind direction field within a radial distance of 200 km of the storm center, then estimated the hurricane position from these radar wind maps, and developed a track for Anita over a 4 day period between 30 August and 2 September 1977 as the storm moved westward across the Gulf of Mexico. The radar track was computed from 17 independent position estimates made before Anita crossed the Mexican coast, and was subsequently compared to the official track produced by National Hurricane Center (NHC). Agreement between the WARF position estimates and coincident temporal positions on the NHC smooth track was ±19 km. At approximately 0000Z on 1 September 1977, Anita passed within 50 km of the National Data Buoy Office (NDBO) open ocean moored buoy EB-71, and provided us with the opportunity to compare WARF estimates of the significant wave height, and surface wind speed and direction in all four quadrants of the storm with those made at the buoy. Agreement between the WARF and EB-71 measurements was within 10%. Two days after Anita crossed land, tropical storm Babe—a weaker, short-lived storm—developed. WARF estimates of the significant wave height, and surface wind speed and direction were made for selected regions of the storm.* No in situ wave measurements were available for comparison to the WARF measurements. WARF estimates of the wind speed were compared to wind speed measurements made at nearby oil platforms, and surface wind speeds computed from flight level winds (305 m) measured by a NOAA reconnaissance aircraft. Agreement was again within 10%. The purpose of this paper is to describe the capability of remotely monitoring hurricanes and other open ocean storms by using an HF skywave radar. We will describe the important aspects of the WARF skywave radar, the sea echo Doppler spectra, the method of analysis used to estimate the wave and wind parameters, and the accuracy of these radar-derived quantities.

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