IOCAS-IR  > 海洋地质与环境重点实验室
南极冬季云量异常对海冰变化调控研究
王云鹤
Subtype博士
Thesis Advisor黄海军
2020-05-15
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Name理学博士
Keyword 海冰 南极 辐射强迫 大气环流
Abstract

与以往不同,南极海冰自2014年以来波动增大,多次降至历史低点。海冰的快速变化,可引起气-海间的热量和水汽交换异常,进而造成云、大气及海洋环境的异常。而云辐射对地表的能量收支起重要作用,将加深或减弱大气与海洋环境异常。在极地环境剧烈变化的背景下,极地海冰和气候预报成为了当今环境保护、社会安全和经济发展的需要。然而,因人们对云在极地大气系统中的角色及过程认识不清,导致模型的模拟结果与观测值间存在明显误差。


针对该问题,本文探究了南极冬季云对海冰的短期和长期调控机制。冬季云对海冰的短期强迫研究,主要以探究2011年冬季南极云对海冰的强迫,及对2012年夏季海冰范围的贡献量为例。结果表明,冬季云量异常与大尺度大气环流相关的垂向运动及径向平流吻合较好,说明2011年冬季云负异常可能是由气压系统异常造成的。南极上空少云,地表长波辐射则会大量穿过云层释放到太空,使地表因热量流失而降温、结冰,使得海冰厚度增加、面积增大。这些面积大且厚的海冰抵抗融化的能力增强,尽管后面经历一系列的海冰漂流,但到次年夏季仍有大量海冰存留下来,使夏季海冰呈现正异常。


在云对海冰季节尺度上的调控机理研究基础上,本文进一步探究了南极冬季云对海冰长期耦合机制。结果证明了大气强迫海冰有两个途径:一是在对流层低层,大气可以通过大尺度大气环流,对海冰直接进行动力和热力强迫。大尺度大气环流以风的形式对海冰进行动力驱动,也可以通过携带冷暖空气,使海冰生消。二是通过云辐射对海冰强迫。南极冬季,影响海冰的大尺度大气环流主要受Wave-3和SAM控制。随着高度的增加,大气环流受Wave-3控制越强。在对流层低层,受Wave-3和SAM共同控制的大尺度大气环流,决定着风向和携带气体的暖湿属性,与南极和安第斯山地形的共同影响下,形成了与海冰变化相位相同的低层云异常场。此低层云异常场对地表的辐射影响,会在一定程度上减弱大尺度大气环流对海冰的直接影响。对流层中高层,云的形成主要受Wave-3控制的大气环流调控,径向输送和垂向运动的共同作用,产生中云异常。而云模态对地表的辐射影响,促进了低层大尺度大气环流对海冰的直接强迫。这项研究首次揭示了对流层不同高度层的云量,在影响海冰分布中所起的不同作用。


基于云对海冰的调控机理探究,发现云对海冰有着显著的辐射影响,且海冰对这种辐射影响具有较好的记录,在南极多个海域都有体现。另外,强的云异常对海冰的强迫痕迹可保留季节尺度的时间。说明,云具有较好的预报海冰潜能。因此,本文最后尝试设计了线性马尔科夫海冰预报模型。以不同高度的云量和气候因子(包括位势高度、径向风、纬向风和气温)及海冰自身,定义南极气候的状态,并以这些变量的多元经验正交函数,作为模型的组成部分。以交叉验证的方式评价模型的预测能力,并进行一系列敏感性实验,最终确定最佳模型。虽然这种统计模型不能像热动力耦合模型那样对自然进行仿真,这种线性统计模型具有较好的实用价值和应用空间。


在极地气候剧变的背景下。我们理解和定量模拟云-气-海冰耦合过程及反馈的能力,对于极地地区海冰、天气及气候模拟及预报具有极高的参考价值。

Other Abstract

The fluctuation of Antarctic sea ice has strengthened since 2014 and hit the historical low several times, which is different from the past. The rapid change of sea ice can touch off the abnormal variations of heat-moisture exchange between atmosphere and ocean, break the balance between the atmospheric and the marine system. Cloud anomalies occur in this process, which is capable of controlling the sea-ice growth and melting processes, through its influences on the surface energy budget, via reducing shortwave radiation and transmitting longwave radiation. Sea ice prediction in the polar region becomes very valuable for environmental protection, social security, and economic development, in the context of dramatic changes in the polar climate. However, the sea ice prediction model behaves not well due to a lack of knowledge of cloud processes in the polar climate system.


Aim to solve this problem, the short-term and long-term influence mechanism of Antarctic winter clouds on sea ice is investigated. The study on the short-term forcing of winter clouds on sea ice is mainly to investigate the forcing of winter Antarctic clouds on sea ice in 2011, and their contribution to the area and thickness of summer sea ice in 2012. The results show that the cloud anomaly in winter is in agreement with the convection and the advection related to the large-scale atmospheric circulation. The negative cloud anomaly in winter 2011 may be caused by the atmospheric pressure anomalies. The longwave radiation from the surface is released into space in the less-cloud region, which cools and freezes the surface due to heat loss and increase the sea-ice area and thickness. Although this extra sea ice has experienced drifting, there is still much sea ice that survived in the following summer, which makes the summer sea ice show a positive anomaly.


Based on the study of the influence mechanism of cloud to sea ice seasonally, this paper further investigates the long-term coupling mechanism of the Antarctic winter cloud to sea ice. The results show that atmosphere forces sea ice in two ways: in the low-troposphere, the atmosphere can directly force sea ice dynamics and thermodynamics through large-scale atmospheric circulation. The wind related to the large-scale atmospheric circulation can drive sea ice dynamically, and also generate or melt sea ice by carrying warm or cold air. On the other hand, clouds related to the large-scale atmospheric circulation can force sea ice by the radiative effect. In the Antarctic winter, the large-scale atmospheric circulation is mainly controlled by wave-3 and SAM. In the low-troposphere, the large-scale atmospheric circulation controlled by wave-3 and SAM determines the wind direction, air temperature, and moisture. Under the influence of the Antarctic and Andes topography, a negative cloud anomaly with the same phase of sea ice anomaly is formed. The radiation effect of the negative cloud anomaly on the surface weakens the direct impact of large-scale atmospheric circulation on sea ice. In the mid-troposphere, the formation of clouds is mainly related to the atmospheric circulation anomaly controlled by wave-3, and the combined action of advection and convection results in the anomalies of middle clouds. However, in the mid- and upper troposphere, the radiative effects of cloud mode on the surface promote the direct forcing of low-tropospheric large-scale atmospheric circulation on sea ice. This result reveals, for the first time, the different effects of cloud cover in the different level troposphere on the sea ice distribution.


Based on the study of the short-term and long-term influence mechanism of clouds on sea ice, it is found that clouds have a significant radiation impact on sea ice, and sea ice has a good record of this impact, which is reflected in many Antarctic regions. Besides, the trace of robust cloud forcing to sea ice can retain for seasonal time scales. It shows that clouds have great potential to predict sea ice. Based on these understandings, a linear Markov sea-ice prediction model is designed. We chose to define the coupled Antarctic climate system with many variables: cloud cover, sea ice concentration, and other climate factors (including geopotential height, wind vector, and air temperature in different levels of the troposphere). The multivariate empirical orthogonal function of these variables is taken as the component of the model. The prediction ability of the model is evaluated by cross-validation. A series of sensitivity experiments are carried out to determine the best model. Although this kind of statistical model can't simulate nature, it has better practical value and application space before the birth of an ideal climate dynamic prediction model.


With the increasing demand for sea ice and climate prediction in polar. Our ability to understand and quantitatively simulate the cloud-air-sea ice coupling process is valuable to the sea ice, synoptic, and climate simulation and prediction.

MOST Discipline Catalogue理学::海洋科学
Language中文
Table of Contents

第一章 绪论    1
1.1 背景、目的和意义    1
1.2 国内外研究现状    6
1.2.1 南极云观测现状    6
1.2.2 南大洋云量数据的研究现状    8
1.2.3 极地云与海冰相互作用的研究现状    8
1.3 本文的主要内容及章节安排    11
第二章 云、海冰数据及处理方法    13
2.1 云量数据    13
2.1.1 云量再分析数据    13
2.1.2 云量卫星数据    15
2.2 海冰数据    17
2.3 云模态的提取方法    18
2.4 极地矢量的可视化方法    21
2.5 研究区介绍及分区方法    23
第三章 南极冬季海冰与云的时空分布    27
3.1 南极海冰变化的空间特征    27
3.2 南极海冰变化的时间特征    29
3.3 南极云空间特征    32
3.4 南极云变化趋势    34
3.5小结    35
第四章 南极冬季云对海冰的短期强迫    37
4.1 2011-2012年冬季海冰反弹量    37
4.2 2011年冬季云异常量统计    39
4.3 云异常对地表辐射的影响量    43
4.4 冬季云强迫对海冰影响    45
4.5 冬季云对次年夏季海冰的强迫    47
4.6小结    49
第五章 南极冬季云对海冰的长期耦合    51
5.1 南极云-大气-海冰的耦合模态探究的必要性    51
5.2 低层云对海冰的强迫    52
5.3 中层云-海冰的耦合模态    55
5.4 高层云-海冰的耦合模态    60
5.5 对流层各层云模态的代表性    63
5.6小结    64
第六章 基于云-海冰耦合的海冰预报设想    67
6.1 海冰预报背景    67
6.2 预测模型的建立    69
6.3 确定最优预报模型    71
6.4 小结    72
第七章 结论与展望    73
7.1 结论    73
7.2 创新点    75
7.3 不足    75
7.4 展望    75
参考文献    77
致 谢    89
简历及研究成果    91
 

Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/164755
Collection海洋地质与环境重点实验室
Recommended Citation
GB/T 7714
王云鹤. 南极冬季云量异常对海冰变化调控研究[D]. 中国科学院海洋研究所. 中国科学院大学,2020.
Files in This Item:
File Name/Size DocType Version Access License
王云鹤-博士毕业论文-扫描版.pdf(7895KB)学位论文 暂不开放CC BY-NC-SAApplication Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[王云鹤]'s Articles
Baidu academic
Similar articles in Baidu academic
[王云鹤]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[王云鹤]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.