|Place of Conferral||中国科学院海洋研究所|
|Keyword||印尼海 POC 气候事件 上升流 海洋碳汇|
印尼海及周边海域的近岸POC浓度始终保持在较高水平，随着离岸距离增加POC浓度逐渐降低。在上升流作用强烈的区域，如南爪哇海域和巴布亚南部海域，POC浓度分布具有明显的季节变化。POC浓度在东南季风（7-9月）期间最高，分布范围最广；在西北季风（1-3月）期间其浓度最低，分布范围最小。哈马黑拉附近海域POC分布变化具有相似特征，但是东南季风时期的POC浓度高值较南爪哇附近海域较低。望加锡海峡附近上升流区域有限，POC浓度通常在西北季风期间最高，在东南季风时最低。在年际变化上，南爪哇附近海域和哈马黑拉海附近受气候事件的影响呈现出明显的年际变化特征：在发生厄尔尼诺（El niño）事件或正偶极子（正IOD）的年份POC浓度升高，在发生拉尼娜（La niña）事件或负偶极子（负IOD）事件的年份POC浓度降低。而望加锡海峡附近的POC浓度年际变化则没有呈现类似特征。
印尼海及周边海域的气候事件、上升流与POC分布变化之间存在紧密关系。在La niña/负IOD事件发生的年份，研究区的降雨和河流径流量增加，有大量的淡水注入，加强了研究区的层化现象；同时对上升流形成有重要作用的东南季风也由于气候事件的影响而减弱，二者共同造成了研究区上升流减弱。在La niña/负IOD时期，赤道纬向西风会激发出下沉的Kelvin波，使温跃层加深，进一步阻碍了富含营养盐深层冷水的上涌，造成表层海水中初级生产力的下降和POC浓度的降低。在El niño/正IOD事件发生时，赤道纬向风多盛行东风，降雨以及河流径流量降低，研究区海域的层化现象减弱，上升的Kelvin波使温跃层变浅，与强烈的东南季风共同导致上升流的增强。上升流供应的营养物质提高了表层水体的初级生产力，有利于该海域POC的产出。
This paper uses remote sensing data on sea surface particulate organic carbon (POC) concentrations, sea surface temperature (SST), chlorophyll a (Chl a) concentrations and rainfall from 2007-2021 to conduct a comprehensive analysis of the spatial and temporal distribution of POC in the Indonesian Sea and surrounding waters, to investigate the factors affecting the spatial and temporal distribution of POC in the sea and its mechanism of action, and to discuss its application in the evaluation of carbon sinks in the sea.
Coastal POC concentrations in the Indonesian Sea and surrounding waters are consistently high, with POC concentrations decreasing with increasing distance offshore. POC concentration distribution in areas with strong upwelling, such as the South Java Sea and the South Papua Sea, has significant seasonal variation, with the highest POC concentration and widest distribution during the southeast monsoon (July-September) and the lowest concentration and widest distribution during the northwest monsoon (January-March). The distribution of POC in the sea off Hamahela has similar characteristics, but the high values of POC during the southeast monsoon are lower than those in the sea off South Java. The area of upwelling is limited near the Strait of Makassar and POC concentration is usually highest during the northwest monsoon and lowest during the southeast monsoon. In terms of inter-annual variability, the sea off South Java and the Hamahela Sea show clear inter-annual variability due to climatic events: POC concentration increases in years of El niño or positive dipole (positive IOD) events and decreases in years of La niña or negative dipole (negative IOD) events. The interannual variability of POC concentrations around the Strait of Makassar does not show similar characteristics.
Variations in the distribution of POC in the Indonesian Sea and surrounding waters are mainly influenced by rainfall and runoff inputs, upwelling, the Indonesian Throughflow (ITF) and human activities. In areas of strong upwelling, upwelling is the main factor influencing the spatial and temporal variability of POC. 70.6% of the variation in POC concentration in the coastal waters of South Java is caused by the action of South Java upwelling. The POC variability in the sea off the Hamahela Sea is also mainly influenced by seasonal upwelling, but the upwelling effect is not as strong as in the sea area off South Java. The variation of POC distribution in the sea off the Strait of Makassar is mainly influenced by rainfall, and there is a good correspondence between interannual variation of POC and rainfall variation. However, the relationship between the two is not obvious in individual years, which may be influenced by anthropogenic activities of river mining that interfere with the variation of POC distribution.
A strong relationship exists between climatic events, upwelling and changes in POC distribution in the Indonesian Sea and surrounding waters. During the years of La niña/negative IOD events, the study area experiences increased rainfall and river runoff with large freshwater infusions, enhancing stratification in the study area; at the same time, the southeast monsoon, which is important for upwelling formation, also weakens due to climatic events, and the two together cause weakening of upwelling in the study area. During the La niña/negative IOD period, the equatorial latitudinal westerly winds excite downwelling Kelvin waves that deepen the thermocline, further impeding the upwelling of nutrient-rich deep cold water and causing a decrease in primary productivity and POC concentrations in surface seawater. During the El niño/positive IOD event, the equatorial latitudinal winds were more easterly, rainfall and river runoff decreased, stratification in the study area waters weakened, and the rising Kelvin waves made the thermocline shallower, which together with the strong southeast monsoon led to enhanced upwelling. The nutrients supplied by the upwelling increase the primary productivity of the surface waters and facilitate the production of POC in the area.
POC concentrations at the bottom of the euphotic layer in the Indonesian Sea and surrounding waters show significant seasonal variation due to upwelling. Although rivers in Indonesia can influence the POC concentration at the bottom of the euphotic layer by transporting large amounts of sediment, the seasonal variation of POC at the bottom of the euphotic layer is fully consistent with the seasonal variation of upwelling, indicating that upwelling is important in the spatial and temporal distribution of carbon sink areas. Therefore, the South Java nearshore area, where upwelling is widely distributed, is the largest carbon sink area in the Indonesian Sea and surrounding waters. This study can provide theoretical support for the subsequent ecological evaluation, productivity and carbon sink assessment in the Indonesian Sea and surrounding waters.
|Table of Contents|
|温春龙. 印尼海及周边海域POC分布的影响因素及其碳汇评价应用[D]. 中国科学院海洋研究所. 中国科学院大学,2022.|
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