Riverine Carbon Flux
Riverine carbon flux/Terrestrial carbon flux from rivers into oceans
River-dominated organic carbon flux is defined as the total amount of organic carbon passing through a vertical section of a river over a fixed period, that is, the integral of the product of organic carbon concentration function and flow function of a river section with respect to time, depth, and width. Although the principle of remote sensing inversion of organic carbon concentration is similar in rivers to that in oceans, several difficulties remain. On the one hand, the spatial resolution of traditional ocean-color remote sensing products (e.g., from SeaWiFS, MERIS, MODIS) is on the km-scale, which is difficult to use for rivers with a width of only a few hundred meters to several kilometers. On the other hand, sensors such as the TM/Landsat and ETM+/Landsat, which have a spatial resolution of 30 m, have difficulty in distinguishing water component concentrations from low water signals due to their wideband and low signal-to-noise ratio design. With the development of remote sensing technology, Korea launched the world’s first Geostationary Ocean-Color Imager (GOCI) satellite in 2012, which has a spatial resolution of 500 m and a temporal resolution of 1 h. It is a good source of data for organic carbon inversion in rivers and highly dynamic estuarine areas.
Based on simultaneous optical-chemical field investigations from the Datong Hydrological Station section (monthly) and Yangtze River estuary (seasonal), the Yangtze River organic carbon flux was estimated using multi-source remote sensing and measured data, with the main findings as follows:
(1) Based on key parameters (e.g., flow, remote sensing cultivated area ratio, total primary productivity) of the watershed ecological characteristics, a multi-layer feedback neural network estimation model of DOC concentration in the Yangtze River was constructed, and the monthly transport flux of DOC, combined with the flow rate, was estimated at the Datong Hydrological Station during 2000–2013.
(2) A POC concentration remote sensing algorithm for Landsat data was constructed. Combined with the flow rate at Datong Station, the monthly transport flux of POC was estimated for 2000–2016.
(3) A POC concentration remote sensing algorithm based on the GOCI data was constructed. The monthly transport flux of POC from 2015–2016 at Xuliujin Station was estimated using the flow rate at Datong Hydrological Station.
It is worth noting that the organic carbon flux of rivers into estuaries is not equivalent to the effective flux of organic carbon transported by rivers into oceans. Organic carbon transported by rivers will be transformed, decomposed, and settle in estuarine freshwater areas, thereby reducing the organic carbon that eventually enters the oceans, which involves complex estuarine processes and lateral transport of organic carbon over shelves.

Representative articles
Bai, Y., Huang, T. H., He, X., Wang, S. L., Hsin, Y. C., Wu, C. R., et al. (2015). Intrusion of the Pearl River plume into the main channel of the Taiwan Strait in summer. Journal Of Sea Research, 95, 1-15.
Chen, C. T. A., Kandasamy, S., Chang, Y. P., Bai, Y., He, X., Lu, J. T., & Gao, X. (2016). Geochemical evidence of the indirect pathway of terrestrial particulate material transport to the Okinawa Trough. Quaternary International, 441, 51-61.
Chen, C. T. A., Yeh, Y. T., Yanagi, T., Bai, Y., He, X., & Huang, T. H. (2016). The tug‐of‐war between the West Philippine Sea and South China Sea Tropical Waters and Intermediate Waters in the Okinawa Trough. Journal of Geophysical Research Oceans, 121(3), 1736-1754.
He, X., Bai, Y., Chen, C. T. A., Hsin, Y. C., Wu, C. R., Zhai, W., et al. (2015). Satellite views of the episodic terrestrial material transport to the southern Okinawa Trough driven by typhoon. Journal of Geophysical Research Oceans, 119(7), 4490-4504.
He, X., Xu, D., Bai, Y., Pan, D., Chen, C. T. A., Chen, X., & Gong, F. (2016). Eddy-entrained Pearl River plume into the oligotrophic basin of the South China Sea. Continental Shelf Research, 124, 117-124.
KANG, Yan., Pan, Delu., He, Xianqiang., Xiaoyan, CHEN., et al. (2013). Areas of the global major river plumes. Acta Oceanologica Sinica, 32(1), 79-88.
Liu, D., Pan, D., Bai, Y., He, X., Wang, D., Wei, J. A., & Zhang, L. (2015). Remote Sensing Observation of Particulate Organic Carbon in the Pearl River Estuary. Remote Sensing, 7(7), 8683-8704.
Liu, D., Pan, D., Bai, Y., He, X., Wang, D., & Zhang, L. (2015). Variation of dissolved organic carbon transported by two Chinese rivers: The Changjiang River and Yellow River. Marine Pollution Bulletin, 100(1), 60-69.
Tu, Q., Hao, Z., & Pan, D. (2015). Mass Deposition Fluxes of Asian Dust to the Bohai Sea and Yellow Sea from Geostationary Satellite MTSAT&58; A Case Study. Atmosphere, 6(11), 1771-1784.