Influence of mixed layer depth on chlorophyll-a concentration in the Southern Ocean  

作　　者：Yuxin Shi Hailong Liu Quanan Zheng 

机构地区：[1]School of Oceanography,Shanghai Jiao Tong University,Shanghai 200240,China [2]Yunnan Key Laboratory of Meteorological Disasters and Climate Resources in the Greater Mekong Subregion,Yunnan University,Kunming 600650,China [3]Department of Atmospheric and Oceanic Science,University of Maryland at College Park,College Park 20742,USA

出　　处：《Acta Oceanologica Sinica》2024年第10期16-32,共17页海洋学报（英文版）

基　　金：The fund from Ministry of Science and Technology of the People’s Republic of China under contract No.2023YFF0805204;the Natural Science Foundation of Yunnan Province under contract No.202302AN360006;the National Natural Science Foundation of China under contract No.41776019.

摘　　要：The element iron limitation is one of the crucial factors contributing to high nutrient low chlorophyll in the Southern Ocean(SO).Mixed layer dynamics regulate the availability of iron to phytoplankton.In this paper,we investigate the influence of surface iron supplementation triggered by the mixed layer depth(MLD)variation on chlorophyll-a(Chl-a)concentration in the SO on seasonal and interannual timescales.This analysis is based on the Biogeochemical Southern Ocean State Estimate for the period from 2013 to 2021.We provide a comprehensive and systematic mapping of the regions within the SO,where Chl-a is affected by iron input related to MLD deepening.The relationship between the MLD and the Chl-a varies with the latitude on the seasonal time scale.Both the MLD and sea ice melting affect the distribution of Chl-a.On the interannual scale,iron supply due to MLD deepening occurs primarily north of 60°S.Horizontal advection-induced entrainment enhances the surface iron input during the austral summer,which favors Chl-a increase.In addition to the MLD,the melting of sea ice and cooling of the sea surface can also alter iron input and subsequently affect Chl-a distribution in the austral summer.During the austral winter,entrainment can boost iron stocks,stimulating a subsequent spring increase of Chl-a in the SO.Furthermore,sea surface temperature declines during the austral winter,promoting an increased iron supply and creating favorable conditions for the subsequent spring Chl-a increase in the SO.

关 键 词：mixed layer depth ENTRAINMENT chlorophyll-a concentration Southern Ocean 

分 类 号：Q948.8[生物学—植物学] P73[天文地球—海洋科学]