基于WOD数据集的西北太平洋混合层内营养盐浓度初步研究

A Preliminary Study on Nutrients Concentration Within the Mixed Layer in the Northwest Pacific Based on WOD Data

本文将WOD13(World Ocean Database 2013)中营养盐(硝酸盐和磷酸盐)浓度的观测资料重新构成1°×1°的气候态平均场,结合Argo气候态月平均混合层深度数据,对西北太平洋混合层内营养盐浓度的季节变化进行了初步研究。结果表明,混合层内的营养盐平均浓度在30°N以北海域均沿纬向分布,且浓度随纬度的增加而增大。与夏季相比,在日本海和日本以东寒暖流交汇处的混合层内,冬季营养盐平均浓度明显增加;在黑潮主流及其附近海域,冬季营养盐平均浓度略有增加。根据混合层内营养盐总量的冬夏变化特点,可以总结为以下四种类型:冬季增加型、冬季减少型、冬夏不变型Ⅰ(垂向分布不变)和冬夏不变型Ⅱ(垂向对流补偿)。仅靠生物生化作用和垂向混合是无法完全解释这些变化的,海流的水平输运也会对混合层内的营养盐供给产生一定影响。

The WOD13（World Ocean Database 2013）data（nitrate and phosphate）is processed into 1°×1°gridded climatological mean fields.Combined with the Argo climatological mixed layer depth,the seasonal variation of nutrients concentration within the winter mixed layer is preliminarily examined in the northwest Pacific.Results show that in the region to the north of 30°N,the vertically mean nutrient concentration in the winter mixed layer shows zonal distribution and it increases as the latitude goes up.As for the seasonal variation,it is found that,the nutrients concentration increases significantly in the winter compared to the summer in the Japan Sea and to the east of Japan,and increases slightly in the mainstream and adjacent area of Kuroshio.The seasonal change of the total nutrient concentration can be divided into four types：increasing in winter,decreasing in winter,non-changeⅠ（unchanged in vertical distribution）,and non-changeⅡ（vertical convective compensation）.Obviously,these changes cannot be explained only by biochemical processes and vertical mixing,which implies the horizontal transport has remarkable influence on the nutrient supplying into the mixed layer.