第九届青年地学论坛

Nutrient are the material basis for the growth of marine phytoplankton. In the oligotrophic subtropical gyre, the nutrient concentrations are usually low, which limit the new (export) production. Mesoscale eddies are ubiquitous in subtropical ocean. Among these mesoscale eddies, cyclonic eddies can bring nutrient-rich water from deep into the euphotic zone, thereby stimulating the growth of phytoplankton. However, field observations often focus on certain stages of eddies due to lack of comprehensive survey on the entire life cycle of eddies. Here, we tracked a mesoscale eddy (EYG-01) using a high-resolution three-dimensional physical-biogeochemical coupled model (ROMS-COSINE-Fe), covering its entire life from formation to disappear. This is crucial for studying the nutrient variations. The concentrations of phosphate, silicate, and nitrate during the stable period are 0.147±0.007, 2.497±0.059, and 1.034±0.072 millimole/m³, respectively, which are lower than those during the dissipation phase of 0.149±0.006, 2.628±0.085 and 1.182±0.099 millimole/m³, respectively. This seems to be attributed to overall evaluation of nutrients in the entire western North Pacific Subtropical Gyre. Our results show that both N/Si and N/P exhibit an increasing trend during the generation and mature phases. During the decay phase, the Redfield ratio approaches 16:1. The results are under analyzing, which are hopefully to be finished and presented during the meeting.

Nutrinets,mesoscale eddy,three-dimensional physical-biogeochemical coupled model