Solar radiation (light) is the fundamental energy source for marine ecosystems. The amount of light that penetrates the ocean and the depth to which it can reach not only governs the dynamics of marine life processes but also represents a critical scientific question that requires precise quantification in oceanographic research. The ocean surface is sometimes calm as a mirror, sometimes surging with waves; meanwhile, the open ocean appears deep blue, while estuarine waters are turbid and chaotic. These variations determine the patterns of light propagation within the ocean.
Satellite ocean color remote sensing analyzes the transfer of solar radiation through the atmosphere and ocean. By retrieving bio-optical parameters, shallow-water bathymetry, and benthic features from water color, it enables long-term, large-scale monitoring of primary productivity, ecosystem states, and water quality in inland, coastal and oceanic waters. At the same time, it provides vital real-time monitoring tools for events such as red tides and oil spills, as well as for coral reef and seagrass ecosystems.
Dr. Xiaolong Yu has long been engaged in research on the mechanisms and applications of ocean color remote sensing, with his current work centered on improving and optimizing the parameterization of shortwave solar radiation transfer across the air–sea interface and in the upper ocean. His earlier research was built upon extensive field surveys across diverse aquatic environments worldwide, generating valuable in situ datasets. Based on these observations, he has:
1) Developed and optimized remote sensing algorithms targeting key bio-optical parameters, significantly enhancing the retrieval accuracy and global applicability of inherent optical properties, diffuse attenuation coefficients, chlorophyll-a and suspended particulate concentrations, remote-sensing reflectance, and shallow-water substrates. With the developed algorithm, he corrected the long-standing misconception that the contribution of water-leaving albedo to sea-surface albedo and its spatiotemporal variability can be neglected.
2) Addressed the gap in field measurement of water-leaving albedo by designing, assembling, and testing self-developed instruments, along with data correction algorithms, to ensure the acquisition of high-quality observations.
3) Advanced multi-satellite data processing by proposing a cross-satellite atmospheric-correction scheme, providing a technical foundation for the integration of Chinese satellites and the generation of autonomous, consistent long-term ocean color products.
4) Building on these efforts, Dr. Yu has also initiated studies on the climate response of marine ecosystems using time-series ocean color observations. Notably, he was the first to reveal a westward expansion of the equatorial high-chlorophyll tongue over the past two decades, offering new insights into marine ecosystem variability.
Dr. Xiaolong Yu’s current research focuses:
1. Long-term evolution of bio-optical properties and their responses and feedbacks to climate change;
2. Parameterization of shortwave radiation transfer in the upper ocean and its applications in air–sea coupled and climate models;
3. Remote sensing retrieval of bio-optical properties, optically inactive aquatic environmental parameters, and shallow-water substrates (coral reefs, seagrass) based on artificial intelligence;
4. High-consistency data fusion of multi-source ocean color satellite products in coastal and open-ocean.
For more information about Dr. Yu, please visit his homepage: https://mel2.xmu.edu.cn/faculty/XiaolongYu/ or contact him at xlyu@xmu.edu.cn.
Biography：Dr. Xiaolong Yu received his B.Sc., M.Sc., and Ph.D. degrees from Tongji University, East China Normal University, and the University of Twente, the Netherlands, respectively. Since 2017, he worked at the University of Massachusetts Boston as visiting scholar, and in July 2019 he joined MEL as a postdoctoral researcher. He became a faculty member at the College of Ocean and Earth Sciences, Xiamen University, in January 2024 and officially rejoined MEL in August 2025. Over the past five years, he has published 12 SCI/EI papers as first or corresponding author in leading geoscience journals, including Nature Communications and Remote Sensing of Environment, with his research recognized by the International Ocean Colour Coordination Group as highlight achievements. He has led projects funded by the National Natural Science Foundation of China (General Program and Youth C Program), key R&D subprojects, and provincial/municipal programs, and has served as a core contributor to nearly ten national-level projects. He is currently a Young Editorial Board member for Intelligent Marine Technology and Systems and a guest editor for special issues in Remote Sensing and Sensors.
