白令海海冰变化及其影响研究综述

白令海是北冰洋的边缘海,其海冰变化与北极其他海域存在巨大差异。近10年来,白令海海冰面积发生显著减少,对区域水文、大气甚至生态系统造成巨大影响,甚至影响到中纬度乃至我国气候系统。基于卫星观测、模式模拟等多种手段,学术界对白令海海冰时空变化特征及其影响因子进行了大量的研究。本文阐述了白令海近期海冰变化,回顾了海冰变化的影响因子,总结了白令海海冰变化对水文、大气、生态系统以及中纬度气候系统的影响。通过对已有研究进行综合分析指出,受研究方法缺陷和观测数据缺失,以及探索因果关系机制的综合性研究较少的影响,对于驱动季节内白令海海冰变化机理认识仍然不足。进一步指出,需要加强对前期海冰对后期海冰影响、风场对海冰的拖拽作用、暖平流对海冰的影响尺度以及海冰面积变化尺度演变等方向的研究。     

印尼北苏拉威西海蓝碧海峡水团性质的南北差异

Two field observations were conducted around the Lembeh Strait in September 2015 and 2016, respectively.Evidences indicate that seawater around the Lembeh Strait is consisted of North Pacific Tropical Water(NPTW),North Pacific Intermediate Water(NPIW), North Pacific Tropical Intermediate Water(NPTIW) and Antarctic Intermediate Water(AAIW). Around the Lembeh Strait, there exist some north-south differences in terms of water mass properties. NPTIW is only found in the southern Lembeh Strait. Water mass with the salinity of 34.6 is only detected at 200–240 m between NPTW and NPTIW in the southern Lembeh Strait, and results from the process of mixing between the saltier water transported from the South Pacific Ocean and the lighter water from the North Pacific Ocean and Sulawesi Sea. According to the analysis on mixing layer depth, it is indicated that there exists an onshore surface current in the northern Lembeh Strait and the surface current in the Lembeh Strait is southward.These dramatic differences of water masses demonstrate that the less water exchange has been occurred between the north and south of Lembeh Strait. In 2015, the positive wind stress curl covering the northern Lembeh Strait induces the shoaling of thermocline and deepening of NPIW, which show that the north-south difference of airsea system is possible of inducing north-south differences of seawater properties.     

利用北冰洋多光谱数据计算光合有效辐射的研究

光合有效辐射（PAR）是重要的生物光学量,与海洋浮游植物的初级生产过程有密切联系。PAR通常由单波段的PAR传感器直接测量,也可以由多光谱数据计算。在极区用多光谱数据计算PAR不仅面对不同谱宽度的问题,而且还有海冰的影响。本文研究了4种可能导致PAR计算误差的主要因素。多光谱仪器避开了大气对太阳辐射的主要吸收带,用多光谱数据计算会对PAR高估。实测数据分析表明多光谱计算的PAR与高光谱数据的计算结果非常接近,误差在1%以内。用本文建立的拟合函数进行校正,校正后的结果与高光谱数据计算的结果达到同样的精度。计算PAR的衰减率要用到进入海水表面的PAR（PAR0）,本文提出先确定表层衰减系数,再通过最小二乘拟合确定PAR0值,与水下观测数据有很好的衔接。海上同一站位不同时间的观测数据计算的PAR衰减系数相差很小,表明PAR的衰减系数是海水的光学性质,与辐射强度无关。在海冰覆盖的条件下,PAR的观测结果与无冰海水的PAR有明显差别。由于海冰选择性的吸收,穿透海冰进入海洋的PAR组分已经不同,海水对PAR的衰减系数也会相应变化。由此可以推断,不同海冰中成分的差别将导致进入海水中PAR的差别,影响PAR的衰减特性。通过本文的研究,解决了在极区用多光谱计算PAR的各种问题,使多光谱数据成为PAR的重要数据源。