Acta Optica Sinica, Volume. 45, Issue 12, 1230001(2025)
Data Processing Methods for China’s Shipborne Apparent Optical Properties Observation System
Figures & Tables(16)
Fig. 1. Distribution of sampling stations and navigation route in the Yangzi River estuary (study area is 30.8°N‒33.0°N, 122.0°E‒124.5°E)
Fig. 2. Photographs of the AOP-Cruise system. (a) Sensor module; (b) research vessel; (c) installation at the forward section of the vessel; (d) software interface
Fig. 3. Rrs spectra based on different methods under varying water conditions. (a) Clear water; (b) turbid water
Fig. 4. Comparison of Rrs calculated by different methods with RSOA. (a) G01 method; (b) M99 method; (c) J20 method
Fig. 5. CVs of Rrs(551) under different wind speeds calculated by various methods. (a) Wind speed is less than 5 m·s⁻¹; (b) 5‒8 m·s⁻¹; (c) wind speed exceeds 8 m·s⁻¹
Fig. 6. Relationships between retrieved and measured values of SPM and Chl-a mass concentrations from different methods. (a)(e) G01 method; (b)(f) RSOA method; (c)(g) M99 method; (d)(h) J20 method
Fig. 7. Rrs distributions from four methods at representative stations. (a) A45; (b) A47; (c) A17; (d) A28
Fig. 8. Effect of viewing azimuth angles on Rrs, SPM, and Chl-a at Station A45 (clear water). (a)‒(c) Standard viewing azimuth angles (130°‒140°); (d)‒(f) non-standard viewing azimuth angles (<130° or >140°)
Fig. 9. Effects of viewing azimuth angles on Rrs, SPM, and Chl-a at Station A17 (turbid water). (a)‒(c) Standard viewing azimuth angles (130°‒140°); (d)‒(f) non-standard viewing azimuth angles (<130° or >140°)
Fig. 10. Effects of wind speed on Rrs, SPM, and Chl-a retrievals from four methods at Station A47 (clear water). (a)‒(c) Low wind speed (<5 m·s⁻¹); (d)‒(f) moderate to high wind speed (≥5 m·s⁻¹)
Fig. 11. Effects of wind speed on Rrs, SPM, and Chl-a retrievals from four methods at Station A28 (turbid water). (a)‒(c) Low wind speed (<5 m·s⁻¹); (d)‒(f) moderate to high wind speed (≥5 m·s⁻¹)
Fig. 12. Consistency and differences between RSOA and other methods for SPM and Chl-a retrievals along the cruise line. (a) SPM; (b) Chl-a
Fig. 13. Spatial distribution of SPM and Chl-a along the cruise line in the Yangtze River estuary and adjacent waters. (a) SPM (linear scale); (b) Chl-a (log-transformed visualization)
Table 1. Probability distribution of QA for the Rrs spectra derived from each method
View tableTable 1. Probability distribution of QA for the Rrs spectra derived from each method
Method QA 2/9 3/9 4/9 5/9 6/9 7/9 8/9 1 G01 0.05 0.78 1.08 3.57 2.84 9.1 14.59 67.99 RSOA — 0.05 0.88 1.96 3.92 7.34 14.88 70.97 M99 1.03 1.42 1.37 2.15 3.18 6.31 15.42 69.02 J20 0.59 0.24 0.98 3.57 3.62 10.77 10.82 69.41
Table 2. Water type, wind speed range, and observation azimuth range at the four representative stations
View tableTable 2. Water type, wind speed range, and observation azimuth range at the four representative stations
Site Water type Wind speed /（m·s⁻¹） Observation azimuth angle range /（°） A45 Clear （blue water） 1.4‒4.6 103.2‒143.3 A47 Clear （blue water） 2.5‒8.6 104.3‒146.8 A17 Turbid （green and yellow water） 1.4‒3.9 124.9‒177.8 A28 Turbid （green and yellow water） 1.8‒5.6 104.3‒142.4
Table 3. Rrs and water color retrievals from four above-water correction methods under different wind speed and wiewing azimuth combinations at each station
View tableTable 3. Rrs and water color retrievals from four above-water correction methods under different wind speed and wiewing azimuth combinations at each station
Site Method Wind speed /（m·s⁻¹） Observation azimuth angle range /（°） STD ofRrs（555） /sr⁻¹ STD of SPM /（mg·L⁻¹） STD of Chl‑a /（mg·m⁻³） A45 G01 <5 130.0‒140.0 2.09×10⁻⁴ 0.11 0.39 M99 <5 130.0‒140.0 2.74×10⁻⁴ 0.14 0.39 RSOA <5 130.0‒140.0 2.16×10⁻⁴ 0.11 0.39 J20 <5 130.0‒140.0 5.36×10⁻⁴ 0.27 0.39 G01 <5 <130.0 or >140.0 2.91×10⁻⁴ 0.15 0.53 M99 <5 <130.0 or >140.0 2.39×10⁻⁴ 0.12 0.54 RSOA <5 <130.0 or >140.0 2.41×10⁻⁴ 0.12 0.53 J20 <5 <130.0 or >140.0 3.47×10⁻⁴ 0.17 0.52 A47 G01 <5 104.3‒146.8 2.73×10⁻⁴ 0.13 0.24 M99 <5 104.3‒146.8 2.60×10⁻⁴ 0.13 0.24 RSOA <5 104.3‒146.8 2.22×10⁻⁴ 0.11 0.24 J20 <5 104.3‒146.8 2.60×10⁻⁴ 0.13 0.24 G01 ≥5 104.3‒146.8 5.58×10⁻⁴ 0.27 0.30 M99 ≥5 104.3‒146.8 5.37×10⁻⁴ 0.25 0.31 RSOA ≥5 104.3‒146.8 5.33×10⁻⁴ 0.25 0.30 J20 ≥5 104.3‒146.8 5.22×10⁻⁴ 0.25 0.31 A17 G01 <5 130.0‒140.0 3.64×10⁻⁴ 0.18 0.64 M99 <5 130.0‒140.0 2.57×10⁻⁴ 0.13 0.65 RSOA <5 130.0‒140.0 3.02×10⁻⁴ 0.15 0.64 J20 <5 130.0‒140.0 3.95×10⁻⁴ 0.20 0.63 G01 <5 <130.0 or >140.0 3.35×10⁻⁴ 0.17 0.64 M99 <5 <130.0 or >140.0 2.65×10⁻⁴ 0.13 0.65 RSOA <5 <130.0 or >140.0 3.15×10⁻⁴ 0.15 0.65 J20 <5 <130.0 or >140.0 4.37×10⁻⁴ 0.22 0.65 A28 G01 <5 104.3‒142.4 1.85×10⁻⁵ 0.10 0.40 M99 <5 104.3‒142.4 2.13×10⁻⁵ 0.11 0.39 RSOA <5 104.3‒142.4 3.18×10⁻⁵ 0.17 0.40 J20 <5 104.3‒142.4 2.60×10⁻⁴ 0.14 0.39 G01 ≥5 104.3‒142.4 1.87×10⁻⁴ 0.10 0.60 M99 ≥5 104.3‒142.4 1.77×10⁻⁴ 0.09 0.59 RSOA ≥5 104.3‒142.4 2.98×10⁻⁴ 0.16 0.58 J20 ≥5 104.3‒142.4 2.51×10⁻⁴ 0.13 0.59
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Yongming Ren, Guifen Wang, Wenlong Xu, Long Jiang, Zhaohua Sun. Data Processing Methods for China’s Shipborne Apparent Optical Properties Observation System[J]. Acta Optica Sinica, 2025, 45(12): 1230001
Paper Information
Category: Spectroscopy
Received: Jan. 16, 2025
Accepted: Mar. 10, 2025
Published Online: Jun. 18, 2025
The Author Email: Guifen Wang (guifenwang@hhu.edu.cn), Zhaohua Sun (Sunzh@sustech.edu.cn)
CSTR:32393.14.AOS250508
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