Peng Shuaixing, Yu Xiaolong, Lee Zhongping, Lin Hongyang, Liu Xin, Dai Minhan, Shang Shaoling
State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China.
Nat Commun. 2025 Jan 2;16(1):103. doi: 10.1038/s41467-024-55650-8.
Upwelling in the Equatorial Pacific nurtures an expansive, westward-stretching chlorophyll-rich tongue (CRT), supporting 18% of the annual global new production. Surrounding the CRT are the oligotrophic subtropical gyres to the north and south, which are suggested to be expanding under global warming. Yet, how this productive CRT has changed, expanding or contracting, remains unknown. By applying the empirical mode decomposition (EMD) method to 20-year monthly measurements of chlorophyll-a concentration from MODIS-Aqua satellite (2002-2022), we demonstrate that the CRT exhibited a significant westward extension, at an average expanding rate of 1.87 ( ± 0.82) × 10 km/yr. The westward extension of the CRT is attributed to strengthened equatorial upwelling and a strengthened South Equatorial Current from 2002 to 2022, driven by intensified easterly trade winds as the Pacific Decadal Oscillation predominantly remains in its negative phase during this period. Interestingly, EMD analysis on central locations of the Pacific gyres suggested simultaneous extension of the gyres and the CRT during 2002-2022, with the gyres extending poleward. Our findings imply a broader cover of productive water along the equator, while its impact on tropical climate, ecosystems, and carbon cycle deserves further investigation.
赤道太平洋的上升流孕育了一片广阔的、向西延伸的富含叶绿素的舌状区域（CRT），支撑着全球每年18%的新生产力。CRT的周围是南北两侧的贫营养亚热带环流，有人认为它们在全球变暖的情况下正在扩张。然而，这片多产的CRT是如何变化的，是扩张还是收缩，仍然未知。通过将经验模态分解（EMD）方法应用于MODIS-Aqua卫星20年（2002 - 2022年）每月的叶绿素a浓度测量数据，我们证明CRT呈现出显著的向西延伸，平均扩张速度为1.87（±0.82）×10 千米/年。CRT的向西延伸归因于2002年至2022年期间赤道上升流的增强以及南赤道流的增强，这是由东风信风增强驱动的，因为在此期间太平洋年代际振荡主要处于负相位。有趣的是，对太平洋环流中心位置的EMD分析表明，在2002 - 2022年期间，环流和CRT同时延伸，环流向两极延伸。我们的研究结果意味着赤道沿线多产水域的覆盖范围更广，而其对热带气候、生态系统和碳循环的影响值得进一步研究。
