| Summary: | A performance evaluation of ocean color chlorophyll-a algorithms was conducted based on the in situ fluorescence
chlorophyll concentration (Fchl) measured by a sensor on the buoy SiMCosta-SC01 in coastal waters of South Brazil.
The operational algorithms are used in MODIS and VIIRS sensors to derive satellite chlorophyll concentration (Csat). Fchl
values were successfully corrected for nonphotochemical quenching (NPQ) by an interpolation of sunrise and sunset
daily measurements. A laboratory-derived calibration coefficient was applied to convert the unquenching Fchl values into
chlorophyll concentration (Cflu). Overall, linear regression analysis between Cflu and Csat for both sensors showed good
results, with the coefficient of determination (R²) varying between 0.88 and 0.96, slopes between 0.92 and 1.02 and
intercepts between -0.17 and 0.13. The MODIS algorithm (R² = 0.96, slope = 1.02, RMSE = 0.16 mg m-3, BIAS = 0.16 mg m-3,
for N = 222 and time interval ±1 h) presented slightly better performance than VIIRS (R² = 0.92, slope = 0.96, RMSE = 0.25
mg m-3, BIAS = -0.25 mg m-3, for N = 284 and time interval ±1 h). These results represent the most comprehensive satellite
data analysis for this region, suggesting that the approach may be applicable to other SiMCosta buoys
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