9:30 AM - 9:45 AM
[AOS13-03] Seasonal mixed-layer dissolved Iron variation in the Oyashio region
Keywords:Iron, seasonal variation, Oyashio region
The Oyashio area, which is located in the offshore region of Hokkaido, is characterized by a high level of primary production and is able to support considerable fishery production and a large amount of CO2 biological absorption. The primary production in the Oyashio region has a distinct feature with spring maximum. This phenomenon, which is called the spring bloom, has been studied for many years. Previous studies have found that dissolved Iron (dFe) is the key factor in limiting primary productivity and also has a similar seasonal variability with spring maximum. Therefore, understanding the dFe variability is curial to explain the primary production variability in the Oyashio region. Using an ocean-biogeochemical coupled model, this study aims to examine the seasonal mixed-layer dFe variation in the Oyashio region and clarify its driving mechanism.
The model well reproduced the seasonal feature of dFe with spring maximum and summer minimum, although the amplitude of the seasonal variation was half of that based on observation. The budget analysis for the mixed-layer dFe showed that the lateral advection by the large-scale ocean currents predominated the seasonal dFe variation in the Oyashio region. The upstream condition in the Sea of Okhotsk was found to be crucial in affecting the seasonal variation in the Oyashio region. During winter and early spring, more dFe was transported to the Oyashio region through the Kunashiri Strait. As a result, a low-salinity, cold water mass with high dFe concertation was formed in the Oyashio region. This result explains the charge of dFe during winter and spring in the Oyashio region. This paper investigated the seasonal dFe variation in the Oyashio region and highlighted the impact of the lateral advection by large-scale ocean currents on the seasonal dFe variation.
The model well reproduced the seasonal feature of dFe with spring maximum and summer minimum, although the amplitude of the seasonal variation was half of that based on observation. The budget analysis for the mixed-layer dFe showed that the lateral advection by the large-scale ocean currents predominated the seasonal dFe variation in the Oyashio region. The upstream condition in the Sea of Okhotsk was found to be crucial in affecting the seasonal variation in the Oyashio region. During winter and early spring, more dFe was transported to the Oyashio region through the Kunashiri Strait. As a result, a low-salinity, cold water mass with high dFe concertation was formed in the Oyashio region. This result explains the charge of dFe during winter and spring in the Oyashio region. This paper investigated the seasonal dFe variation in the Oyashio region and highlighted the impact of the lateral advection by large-scale ocean currents on the seasonal dFe variation.