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| Mouche, Alexis; He, W.; Husson, R.; Guitton, Gilles; Chapron, Bertrand; Li, Huimin. |
| Sentinel-1 A now routinely acquires data over the ocean since 2014. Data are processed by ESA through the Payload Data Ground Segment up to Level-2 for Copernicus users. Level-2 products consist of geo-located geophysical parameters related to wind, waves and ocean current. In particular, Sentinel-1A wave measurements provide 2D ocean swell spectra (2D wave energy distribution as a function of wavelength and direction) as well as integrated parameters such as significant wave height, dominant wavelength and direction for each partition. In 2016, Sentinel-1 B will be launched by ESA and GF-3 by CNSA. Then in 2018, CFOSAT (China France Oceanography Satellite project), a joint mission from the Chinese and French Space Agencies, will be launched. They will... |
| Tipo: Text |
Palavras-chave: Ocean remote sensing; Synthetics aperture radar; Ocean wave-spectrometer; 2D ocean wave spectrum; Level-4. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00364/47469/47488.pdf |
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| Li, Huimin; Chapron, Bertrand; Mouche, Alexis; Stopa, Justin. |
| Space‐borne synthetic aperture radar (SAR) measurements have already been proven to be invaluable in detecting and quantifying properties of ocean swell systems. With the improved spatial resolution, Sentinel‐1 wave mode measurements can further be extended towards shorter scale waves, i.e. within the surface wave equilibrium range. In this study, a new parameter is derived from filtering SAR image cross‐spectra around range‐traveling intermediate wind waves (wavelengths 15‐20 m). This parameter captures both the radar cross section variability and its time evolution. Given the dependence of intermediate waves on local wind field, this parameter is statistically documented to confirm its sensitivity to both wind speed and wind direction. Comparable to... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00482/59394/62160.pdf |
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| Li, Huimin; Mouche, Alexis; Stopa, Justin E.; Chapron, Bertrand. |
| Sentinel-1 (S-1) is a two-satellite constellation for continuity of operational synthetic aperture radar (SAR) observations. Wave mode (WV) is the default mode over open ocean for S-1 to monitor global ocean waves and wind field. Therefore, proper radiometric calibration is essential to accurately infer these geophysical quantities. Based on the global data set acquired by S-1A WV, assessment of normalized radar cross section (NRCS) is carried out through comparison with CMOD5.N predictions over open ocean. The calibration accuracy quantified by NRCS residuals between SAR measurements and CMOD5.N demonstrates distinct features for two incidence angles (23.8° and 36.8°). Particularly, NRCS at 23.8° is overall consistent with CMOD5.N, while NRCS at 36.8°... |
| Tipo: Text |
Palavras-chave: CMOD5.N; Radiometric calibration; Sentinel-1A (S-1A); Wave mode (WV). |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00457/56882/59006.pdf |
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| Zhao, Yili; Li, Huimin; Chen, Chuntao; Zhu, Jianhua. |
| HY-2A is the first one of the Chinese HY-2 ocean satellite series carrying a microwave radiometer (RM) to measure sea surface temperature, sea surface wind speed, atmospheric water vapor, cloud liquid water content, and rain rate. We verified the RM level 1B brightness temperature (T-B) to retrieve environmental parameters. In the verification, T-B that simulated using the ocean-atmosphere radiative transfer model (RTM) was used as a reference. The total bias and total standard deviation (SD) of the RM level 1B T-B, with reference to the RTM simulation, ranged -20.6-4.38 K and 0.7-2.93 K, respectively. We found that both the total bias and the total SD depend on the frequency and polarization, although the values for ascending and descending passes arc... |
| Tipo: Text |
Palavras-chave: HY-2A; Microwave radiometer; Brightness temperature (T-B); Verification; Calibration. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00503/61427/65584.pdf |
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