北太平洋副热带模态水和副热带逆流的年代际变化及其对全球变暖的响应

发布时间：2018-05-14 06:20

本文选题：副热带模态水 + 北太平洋副热带逆流　；参考：《中国海洋大学》2014年博士论文

【摘要】：副热带模态水在气候变化中扮演着重要角色。为了揭示在年代际时间尺度上北太平洋副热带逆流和副热带模态水之间的对应关系，并预估两者在温室气体增加背景下可能的变化，本文使用来自国际耦合模式第5次比较计划（CMIP5）的系列气候模拟结果和预估试验结果，分析了北太平洋副热带模态水和副热带逆流的年代际自然变化及其对全球变暖的响应，提出了副热带逆流对气候变化的可能影响。通过模式结果与观测资料的对比，指出了目前气候模式对北太平洋副热带逆流和副热带模态水模拟中存在的问题。主要取得以下创新性成果： 1.发现了代表北太平洋副热带逆流的多年代际自然变化的主要信号，该信号可以用北太平洋副热带中部海区(170°E-130°W,15-35°N)的海平面异常EOF第一模来表示，，其变化周期约为50年；揭示了控制副热带逆流年代际变化的主要机制是在黑潮延伸体海域形成的副热带模态水的年代际变化：副热带模态水形成多（少）则副热带逆流强（弱）；提出了副热带逆流变化导致的混合层热平流效应变化对北太平洋SST的空间分布有一定的影响。 2.揭示了全球变暖背景下由于海洋上层层结加强，黑潮延伸体海域冬季混合层变浅，潜沉率减少了100m yr-1,副热带模态水核心密度变小约0.3kg m-3，厚度减少了150m,导致副热带逆流减弱了4cm/s。副热带逆流及其热平流效应的减弱进一步使副热带逆流所在海域海表温度的升温比周围海域要少近0.5°C，有利于北太平洋副热带海域海表温度对全球变暖响应的空间分布的非均匀性。发现全球变暖后，副热带逆流的年代际自然变化周期变小，振幅减弱。 3.依据17个CMIP5模式的情景实验，证实了副热带模态水和副热带逆流在温室气体持续增长和达到稳定两个阶段中的变化趋势不同：在温室气体浓度持续增长阶段，副热带模态水和副热带逆流快速减弱；而当温室气体浓度稳定后，副热带模态水和副热带逆流则出现缓慢变强的现象，后者与次表层海洋（300-600米）在该阶段增暖有关。 4.将气候模式结果与观测资料相比发现，气候模式中由于海洋模式对海洋涡旋模拟水平较低，副热带模态水形成过多且耗散弱，导致气候模式中的副热带逆流强度也偏强。通过涡分辨率海洋模式结果与气候模式结果的比对，发现海洋涡旋对副热带模态水潜沉和耗散都会有重要影响。
[Abstract]:Subtropical modal water plays an important role in climate change. In order to reveal the relationship between Subtropical Countercurrent and Subtropical Mode Water in the North Pacific, and to predict possible changes in the greenhouse gas background, this paper uses the series of the international coupling model fifth comparison plan (CMIP5) series. On the basis of the results of climate simulation and prediction, the interdecadal natural changes of subtropical and Subtropical Countercurrent in the North Pacific and their response to global warming are analyzed. The possible effects of Subtropical Countercurrent on climate change are proposed. By comparing the model results with the observed data, the current climate model has been pointed out for the northern Pacific subheat. The main problems in water simulation with counterflow and subtropical modes are as follows:
1. the main signal of the intergenerational natural change representing the Subtropical Countercurrent in the North Pacific is found. The signal can be expressed as the first model of the sea level anomaly EOF of the subtropical central region of the North Pacific (170 E-130 degrees, 15-35 degrees N), and its variation period is about 50 years, and the main mechanism of Interdecadal Change of the controlled Subtropical Countercurrent is revealed. The interdecadal change of the subtropical mode water formed by the Kuroshio extension sea area: the subtropical mode water is more (less) and the Subtropical Countercurrent is strong (weak). It is suggested that the thermal advection effect of the mixed layer caused by the Subtropical Countercurrent change has a certain effect on the spatial distribution of the SST in the North Pacific.
2. revealed that under the background of global warming, due to the strengthening of the upper layer of ocean layer, the winter mixed layer of the Kuroshio extension area became shallow, the submersible rate reduced 100m yr-1, the subtropical modal water core density decreased about 0.3KG M-3, the thickness reduced 150m, and the Subtropical Countercurrent weakened the 4cm/s. vice heat zone countercurrent and the weakening of the thermal advection effect. The temperature of the sea surface temperature in the sea area is less than 0.5 C less than that of the surrounding sea area, which is beneficial to the heterogeneity of the spatial distribution of the response of the sea surface temperature to the global warming in the subtropical area of the North Pacific.
3. according to the scenario experiments of 17 CMIP5 models, it is proved that the variation trend of Subtropical Mode Water and Subtropical Countercurrent in the two stages of greenhouse gas growth and stability is: the Subtropical Mode Water and Subtropical Countercurrent decrease rapidly in the continuous growth stage of the greenhouse gas concentration, while the secondary heat is stable and the secondary heat decreases. With the modal water and the Subtropical Countercurrent, there is a phenomenon of slow becoming stronger, which is related to the subsurface ocean (300-600 m) in this stage of warming.
4. comparing the results of the climate model with the observed data, it is found that in the climate model, the simulation level of the ocean vortex is low, the subtropical mode water is too much and the dissipation is weak, and the Subtropical Countercurrent intensity in the climate model is also strong. Rotation has an important influence on subtropical water potential and dissipation.

【学位授予单位】：中国海洋大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P731.2;P467

【参考文献】