南半球环状模年际与年代际变化的调控机理及其对Supergyre Circulation的影响

发布时间：2018-03-29 23:37

本文选题：SAM　切入点：ENSO　出处：《中国海洋大学》2014年博士论文

【摘要】：厄尔尼诺现象的发生带来全球平均温度的升高，同时导致南半球环状模变为负位相。厄尔尼诺的这种媒介作用，使得南半球环状模与全球平均温度在年际尺度上表现为负相关。然而，当温室效应主导的全球变暖发生时，全球平均温度呈现上升趋势，南半球环状模也趋向于向正位相发展，这使得两者呈正相关关系。这种变化趋势上的正相关性会削弱厄尔尼诺周期中两者的负相关性甚至使其彻底颠覆为正相关关系。由于ENSO强度的变化，在20世纪南半球夏季，全球平均温度和南半球环状模的关系呈现出非常明显的年代际振荡。在1925-1955年期间，ENSO强度的减弱使得全球平均温度和南半球环状模的负相关性变弱。在1970年之后，虽为ENSO强度的强烈期，但全球平均温度和南半球环状模的负相关性依然呈减弱趋势。深入分析表明，1970年之后两者相关性的下降是由全球气候变化导致的，这同时突出了一个非常罕见的现象，亦即，气候变化导致的两者变化趋势的相关性完全跟两者在年际尺度上具有的相关性相反，突出了温室气体排放导致的全球变暖对气候的影响。在近几十年内，除了温室气体的排放外，南极臭氧层臭氧消耗同样对南半球环状模产生了非常显著的正位相变化趋势，在海洋环流中表现为副热带地区的supergyre circulation向南移动并加强。其中，臭氧消耗的强迫作用对臭氧消耗时期（1961-2005年）南半球中高纬度环流场的变化趋势起到了主导作用，然而，南极臭氧层在蒙特利尔协约的签订后开始逐渐恢复并预计在21世纪中期完全恢复。臭氧层臭氧恢复同臭氧层臭氧消耗对南半球中高纬度的作用是相反的，因此，臭氧含量的恢复对南半球副热带环流的作用对温室气体所起到的作用提供了一种抵消机制。那么这种抵消机制中，臭氧层臭氧的恢复能够起到什么程度的作用？相对温室气体的排放，其作用占主导吗？本文利用CMIP5模型组中中等温室气体排放量（RCP4.5）以及高等温室气体排放量（RCP8.5）控制实验输出的模式结果对这些问题进行研究。两组控制实验都包含了臭氧恢复所起到的作用。本文显示出在臭氧恢复期间（2006-2045），臭氧恢复对南半球夏季副热带环流（Subtropical gyre,三个大洋各自的副热带环流是彼此相连的，又被称为Supergyre circulation）的影响基本可以抵消较温室气体排放对其的影响，以致该副热带环流在经向上并没有表现出向南极方向上的移动，而在臭氧层消耗时期以及高等温室气体排放量控制实验下的臭氧层恢复后时期（2046-2100年），该副热带环流的南向移动是非常显著的。同时，在2006-2045年南半球冬季，在高等温室气体排放量控制实验下，结果显示副热带环流呈现明显的南移趋势。在2006-2045年臭氧层恢复时期存在的这种季节变化同20世纪末几十年内所表现出来的季节变化趋势是完全相反的。此外，在臭氧层臭氧恢复后时期，，在没有臭氧层臭氧的作用下，副热带环流的经向移动没有表现出明显的季节变化，这是因为此时的主导作用是温室气体的排放，然而温室气体排放量的不同，对副热带环流的经向移动的影响是显著不同的。在中等排放量情景下，副热带环流表现出稳定的态势，而在高等排放量情景下，副热带环流表现出明显的南向移动，两种变化趋势的显著不同突出了温室气体的排放对南半球环流场的影响，在南半球环状模上亦有直接体现。
[Abstract]:El Nino has increased the average global temperature, which leads to the Southern Hemisphere annular mode becomes negative phase. This role of El Nino, the Southern Hemisphere annular mode and the average global temperature on the interannual scale are negatively related. However, when the greenhouse effect leading to global warming occurs, the average global temperature rising trend, the Southern Hemisphere annular mode also tend to develop to the positive phase, which makes both the positive correlation between the positive correlation. This trend will weaken the negative correlation between the cycle of El Nino and even to completely subvert the positive relationship. Because of the change of ENSO intensity in the southern hemisphere in summer twentieth Century, the relationship between the global average temperature and the Southern Hemisphere annular mode exhibits a decadal oscillation very obvious. During the 1925-1955 years, weakened the strength of ENSO makes the global average temperature and the southern hemisphere ring A negative correlation between the form becomes weak. After 1970, although the strong strength of ENSO, but a negative correlation between the average global temperature and the Southern Hemisphere annular mode still decreased. Further analysis shows that in 1970 after falling correlation is caused by the global climate change, it also highlights a very rare that is, the correlation between the phenomenon of climate change caused by the change of the two exactly on the interannual scale has the opposite, highlights the effects of global warming caused by greenhouse gas emissions on the climate.
In recent years, in addition to greenhouse gas emissions, the Antarctic ozone ozone depletion also had a positive phase change trend is very significant for the Southern Hemisphere annular mode, in the ocean circulation in the subtropical region of the supergyre circulation moved south and strengthened. The period of forcing ozone depletion of the ozone consumption (1961-2005 the change trend of years) in the southern hemisphere high latitude circulation plays a leading role, however, the Antarctic ozone layer in Montreal signed a treaty to gradually recovered and is expected to fully recover in mid twenty-first Century. Ozone ozone recovery with ozone ozone consumption is on the contrary, the effect of high latitude of the southern hemisphere in the ozone the content on the recovery of the Subtropical Gyre in the southern hemisphere on greenhouse gases which play an important role in providing an offsetting mechanism. Then this offset mechanism, the ozone layer of ozone Recovery can play to what extent? The relative emissions of greenhouse gases, the dominant? Using the medium of greenhouse gas emissions in the CMIP5 model group (RCP4.5) and higher emissions of greenhouse gases (RCP8.5) the mode control output of experiment on these problems were studied. Two control experiments are included the role played by ozone recovery. This paper shows the recovery period in the ozone, ozone (2006-2045) on the recovery of the Subtropical Gyre in the southern hemisphere summer (Subtropical gyre, the subtropical circulation of each of the three oceans are connected to each other, also known as Supergyre circulation) the effect can affect the offset a greenhouse gas discharge, so that the Subtropical Gyre in the meridional direction and showed no moves toward the direction of the Antarctic, and in the ozone layer depletion period and higher greenhouse gas emissions under the control of ozone experiment Layer recovery period after (2046-2100 years), the subtropical south movement is very significant. At the same time, in the 2006-2045 years of the southern hemisphere winter, higher in greenhouse gas emissions control experiment, results showed that the subtropical gyre showed obvious seasonal variation trend with the southward trend. At the end of twentieth Century decades has shown recovery the seasonal variation in the 2006-2045 year period of existence of the ozone layer is completely opposite. In addition, in the period of ozone ozone recovery, no effect in the ozone layer of ozone, the subtropical meridional movement showed no obvious seasonal changes, this is because the leading role of the greenhouse gas emissions however, greenhouse gas emissions, to move to the subtropical circulation is significantly different. In secondary emission scenarios, the subtropical circulation showed a stable trend, and in the higher Under the scenario of emission, the subtropical circulation shows obvious southward movement. The two trends are significantly different, highlighting the influence of greenhouse gas emissions on the southern hemisphere circumferential flow field, and also directly reflect the annular modes in the southern hemisphere.

【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】：P731.27

【参考文献】