热带东太平洋淡水池的季节变化 *
池建伟(1990—), 男, 福建省三明市人, 博士研究生, 主要从事海洋盐度研究。E-mail: chijianwei@scsio.ac.cn |
Copy editor: 殷波
收稿日期: 2018-12-27
要求修回日期: 2019-02-16
网络出版日期: 2019-10-09
基金资助
中国科学院战略性先导科技专项(XDA19060501)
中国科学院战略性先导科技专项(XDA13010404)
国家海洋局“全球变化与海气相互作用”专项(GASI-IPOVAI-02)
国家自然科学基金(41525019)
国家自然科学基金(41506019)
国家自然科学基金(41805057)
国家自然科学基金(41830538)
版权
Seasonal variability of the Eastern Tropical Pacific Fresh Pool *
Copy editor: YIN Bo
Received date: 2018-12-27
Request revised date: 2019-02-16
Online published: 2019-10-09
Supported by
Strategic Priority Research Program of Chinese Academy of Sciences(XDA19060501)
Strategic Priority Research Program of Chinese Academy of Sciences(XDA13010404)
State Oceanic Administration of China(GASI-IPOVAI-02)
Natural Science Foundation of China(41525019)
Natural Science Foundation of China(41506019)
Natural Science Foundation of China(41805057)
Natural Science Foundation of China(41830538)
Copyright
文章利用观测和模式数据, 并基于混合层盐度收支方法, 研究了热带东太平洋淡水池的季节变化。研究发现: 热带东太平洋淡水池具有显著的季节变化, 由海表强迫(蒸发与降水)、水平平流和次表层过程共同控制。淡水池的季节变化主要分为扩张与收缩两个阶段。4月至11月为扩张阶段, 淡水池向西扩张, 最大体积和面积比最小时扩大将近一倍, 分别达到2.83×10 5km 3和8.94×10 6km 2。热带辐合带向北移动带来的强降水是淡水池扩张的主要原因, 海表强迫决定了混合层盐度降低。12月至3月为淡水池收缩阶段, 海表淡水通量的减弱、水平平流和次表层过程的增强导致混合层盐度升高, 淡水池向东收缩。
池建伟 , 曲堂栋 , 张莹 , 施平 , 杜岩 . 热带东太平洋淡水池的季节变化 *[J]. 热带海洋学报, 2019 , 38(5) : 1 -9 . DOI: 10.11978/2018142
Using the observations and a mixed layer salinity budget from an ocean general circulation model, we investigate the seasonal variability of the eastern tropical Pacific freshwater pool (EPFP). The EPFP has significant seasonal variation, which is controlled by the surface forcing (evaporation and precipitation), horizontal advection and subsurface processes. The seasonal changes in EPFP are mainly divided into two phases: expansion and contraction phases. From April to November, the freshwater pool expands to the west and the freshwater volume and area doubles to 2.83×10 5 km 3 and 8.94×10 6 km 2, respectively. The strong precipitation brought by the northward movement of the intertropical convergence zone is the main reason for the expansion of the EPFP: the surface forcing determines the reduction of the mixed layer salinity. From December to March, when the EPFP shrinks, the increasing of the mixed layer salinity is attributed to the weakening of surface freshwater flux and the enhancement of horizontal advection and subsurface processes.
图1 多年年平均热带太平洋海表盐度(a)、海表盐度季节变化标准差(b)、温度(c)和流场(d)图中红色实线代表多年年平均34‰等盐度线。图d中矢量箭头代表流速, 填色为纬向流速, 正值代表东向流, 负值为西向流 Fig. 1 Long-term mean sea surface salinity (a), standard deviation of the seasonal variability of sea surface salinity (b), surface temperature (c) and surface currents (d). The red contour denotes the annual mean 34‰ isohaline. The vector and shading represent sea surface current and its zonal component, respectively. The positive value of shading represents eastward current |
图2 北半球春季(a, 3—5月)、夏(b, 6—8月)、秋(c, 9—11月)和冬(d, 12—2月)热带东太平洋海表盐度分布黑色实线为各季节34‰等盐度线, 红色实线为多年年平均34‰等盐度线 Fig. 2 Seasonal variability of sea surface salinity. Mar-May (a); June-August (b); September-November (c); December-February (d). The black contour denotes seasonal 34‰ isohalines, and the red denotes the annual mean 34‰ isohaline |
图3 热带东太平洋淡水池季节变化a. 淡水池体积、海表面积; b. 经度位置、淡水池深度; c. 海表平均盐度、淡水池平均盐度; d. 淡水池内降水、海表高度异常 Fig. 3 Seasonal variability of the eastern tropical Pacific freshwater pool. (a) The EPFP volume (dashed line) and area (solid line); (b) the deepest depth (dashed line) and westernmost longitude (solid line) of the EPFP; (c) the mean of the sea surface salinity and the salinity in the whole EPFP; (d) the mean precipitation and sea level anomaly in the EPFP |
图4 北半球春季(a, 3—5月)、夏(b, 6—8月)、秋(c, 9—11月)和冬(d, 12—2月)热带东太平洋降水(填色)及海表风速(箭头)黑色实线为各季节34‰等盐度线, 红色实线为多年年平均34‰等盐度线, 蓝色实线为热带辐合带各季节位置 Fig. 4 Seasonal variability of the precipitation (shading) and surface wind (arrows) in the eastern tropical Pacific. Mar-May (a); June-August (b); September-November (c); December-February (d). The black contour denotes seasonal 34‰ isohalines, the red denotes the annual mean 34‰ isohaline, and the blue denotes the seasonal position of the intertropical convergence zone |
图6 2005—2016年多年年平均混合层盐度收支a、b为观测数据结果; c、d、e为模式结果。a、c: 海表强迫; b、d: 水平平流项; e: 次表层过程。图a中黑色矩形范围为研究区域(5°S—15°N, 150°W—110°W)。图a中蒸发数据来自全球海洋客观分析海气通量项目(Objectively Analyzed Air-Sea Fluxes, OAFlux) 降水来自全球降水气候计划(Global Precipitation Climatology Project, GPCP); 图b中海表流场来自海表流场实时分析数据(Ocean Surface Current Analyses - Real Time, OSCAR)。红色实线为多年年平均淡水池西边界(34‰等盐度线) Fig. 6 Comparison of long-term mean mixed layer salinity budget in the eastern tropical Pacific. Shown are surface forcing (a, c), horizontal advection (b, d) and subsurface processes (e). (a) and (b) are estimated using observations; (c), (d) and (e) are estimated using ECCO-JPL. The red contour is the annual mean 34‰ isohaline |
图7 海表盐度(a)、海表淡水通量(b)和混合层盐度收支的季节变化(c、d、e、f)研究区域为 Fig. 7 Seasonal variabilities of the sea surface salinity (a), surface freshwater flux (b) and mixed layer salinity budget terms (c, d, e, f). All values are averaged in the black box of |
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