南极夏季普里兹湾叶绿素a的时空变化研究

SPATIAL AND TEMPORAL VARIABILITY OF CHLOROPHYLL A DURING THE AUSTRAL SUMMER IN PRYDZ BAY,ANTARCTICA

利用SeaWiFs、MODIS卫星数据所获取的南极普里兹湾表层海水叶绿素a(Chl a)与海表温度(SST)的遥感数据,并结合中国2001—2011年南极科学考察所获得的现场数据,对该区域的海表温度、叶绿素a与营养盐的分布规律进行分析。结果表明:研究海区的叶绿素a的分布具有明显的区域特征,以陆架坡为界,湾内向湾外表现出明显的递减趋势;在湾内陆架区,浮游植物的旺发主要受海冰消融以及营养盐供给的影响,2001—2011年南极夏季叶绿素a浓度的遥感区域平均值为1.40 mg.m-3;在陆坡区,浮游植物的繁殖主要受到水文条件的影响,2001—2011年的夏季遥感平均值为0.44 mg.m-3;在湾外深海区,浮游植物的繁殖主要受到水文条件与铁元素的影响,浓度较低,2001—2011年的夏季遥感平均值为0.25 mg.m-3。在整个南极夏季,研究海域每月的叶绿素a浓度与海表温度呈现出一定的正相关性(R2=0.505),而在年际变化上,叶绿素a与海表温度的变化趋势也有着明显的相似性,表明温度是叶绿素a浓度的主要影响因素。通过研究多变量厄尔尼诺指数与湾内表层叶绿素a浓度的关系,可知在相对敏感的湾内陆架区,厄尔尼诺/拉尼娜可能会对叶绿素a的浓度产生影响,在厄尔尼诺年,叶绿素a的浓度较高;而在拉尼娜年,叶绿素a的浓度较低,表明高纬度海区浮游植物的生长与繁殖对中低纬度的ENSO事件存在一定的响应联系。

In this paper, the distributions of sea surface temperature （SST）, chlorophyll a （Chl a）, and ocean nutrients during the austral summer in Prydz Bay, Antarctica, are presented, and the influencing factors analyzed, chloro- phyll a and SST distributions were derived from SeaWiFs and MODIS satellite ocean color data, and combined with data collected in situ by the Chinese Antarctic Research Expedition （CHINARE） from 2001 to 2011. The distribu- tion of surface Chl a in Prydz Bay showed distinctive characteristics, and the surface Chl a concentrations decreased offshore. In the shelf area, the phytoplankton bloom was affected by the ablation of sea ice and the supply of nutri- ents. In the slope area, phytoplankton growth was mainly affected by hydrological conditions. Outside Prydz Bay, the Chl a concentration was much lower, and probably influenced by the lack of iron. Over the last decade, the av- erage Chl a concentrations derived from remote sensing were 1.40, 0.44, and 0.25 mg · m-3 over the shelf, slope, and outside the bay, respectively. In the austral summer, a high positive correlation exists between Chl a and SST in Prydz Bay （R2 = 0. 505 ）. The annual concentration variation showed that Chl a was strongly related to SST, indicating that temperature was the main determining factor. The relationship between the Multivariate ENSO Index （MEI） and the Chl a concentration over the inner shelf area demonstrated that Chl a concentration was much higher during E1 Nino events than during La Nina events. This finding suggests that the growth and reproduction of phytoplankton at high latitudes is strongly impacted by the ENSO occurring at middle and low latitudes.