过去1500年东亚季风气候年代—百年尺度变化特征及成因机制

发布时间：2019-06-05 05:09

【摘要】：利用通用地球系统模式(Community Earth System Model,简称CESM)开展的过去1500年气候模拟试验结果,在验证模式模拟性能的基础上,分析了过去1500年东亚夏季降水、冬季温度的年代-百年尺度时空变化特征以及典型暖期东亚夏季风年代际变化特征,揭示了影响东亚季风气候年代-百年尺度变化的成因机制,对提高未来十年至百年东亚季风气候变化的预测精度,更好地认识现代暖期的历史地位具有重要的科学意义。本文首先利用CESM模拟的地表温度、降水、850 hPa风场、气压场以及海表温度场与观测/再分析资料和重建资料进行对比分析,结果表明CESM模式能够较好地再现气候平均态的特征,模式模拟的东亚地区温度和降水的季节变化特征与观测/再分析资料较为一致;模式模拟与重建的中国区域温度在年代-百年尺度上的变率具有较好的对应。因此,CESM模式的模拟结果较为合理,可以用于本文研究。第二,对全强迫试验模拟的过去1500年东亚夏季降水、冬季温度年代-百年尺度变化分析发现,在1250年、1450年、1600年、1750年以及1815年左右均有年代尺度的干旱;在对应的空间分布上,长江以南和华北地区夏季降水偏多,黄河流域至日本南部一带夏季降水偏少,与中世纪暖期东亚夏季风降水年代际变化的空间特征一致。现代暖期东亚夏季风降水的主模态表现为南北反相的分布特征。两个典型暖期东亚夏季风变化的主周期均为准10年和准20年。百年尺度上,模拟的东亚夏季降水在530-710年、850-950年、1250-1350年、1440-1530年、1630-1860 为负距平,在 730-840 年、1060-1240 年、1330-1420 年、1520-1620年为正距平。空间分布上,整个中国东部地区夏季降水增加。东亚冬季温度在13世纪中期、15世纪中期以及1815年左右均有年代尺度的降温。空间分布上表现为全区一致增温的特征,陆地增温幅度大于海洋,东亚冬季风减弱。百年尺度上,冬季温度变化在800-1250年为正距平、1400-1900年为负距平以及1900-2000年为正距平,分别对应中世纪暖期、小冰期和现代暖期。空间分布上,整个东亚地区温度一致增加,中国东部110°E以西地区增温幅度高于110°E以东地区。第三,通过将各单因子强迫序列与其驱动下的敏感性试验与全强迫试验的东亚夏季降水、冬季温度年代-百年尺度变化进行对比发现,年代尺度上,太阳辐射、火山活动以及气候系统内部变率是影响过去1500年东亚夏季降水变化的主要影响因子,而土地利用/覆盖以及温室气体外强迫因子对东亚夏季降水的影响不大。空间分布上,东亚地区旱涝格局的主控因子是气候系统内部变率,太阳辐射和火山活动起到了较强的调制作用。在气候系统内部变率影响下,赤道中东太平洋的冷异常是东亚夏季降水呈“正-负-正”分布的主要原因。赤道中东太平洋的冷异常使得赤道东风增强,沃克环流加强,导致热带西北太平洋南部增暖,故对流加热增强,进而通过Gill型响应导致菲律宾海产生气旋距平环流,华南降水增多;大气扰动通过罗斯贝波形式向北极方向传播,导致西北太平洋产生反气旋性环流距平,进而使得黄河至日本一带对流减弱,夏季降水减少。在太阳辐射和火山活动外强迫因子调制作用下,西北太平洋西部海温冷异常与控制试验结果相比不明显,进而使得黄河流域至日本一带夏季降水幅度高于控制试验结果。进一步研究发现,北太平洋年代际振荡(Pacific Decadal Oscillation,简称PDO)与典型暖期东亚夏季风变化呈显著反相关。百年尺度上,过去1500年东亚夏季降水的波动变化主要受到太阳辐射、火山活动以及温室气体的共同影响,土地利用/覆盖外强迫因子对东亚夏季降水变化没有显著的影响。空间分布上,太阳辐射和火山活动外强迫因子是主控因子。在自然因子作用下,印度洋以及热带海洋潜热通量增加,说明印度洋以及热带海洋地区蒸发增加,使得向北的水汽输送增加,导致东亚地区夏季降水增加。东亚冬季温度在年代尺度上的时间变化主要是受火山活动以及内部变率共同影响,而太阳辐射和人为因子对冬季温度变化的影响较小。空间分布上,气候系统内部变率是过去1500年东亚冬季温度变化的主控因子,火山活动具有一定的调制作用。在火山活动调制作用下有效太阳辐射减弱,使得全强迫试验模拟的东亚大陆地区冬季温度相比控制试验偏低。百年尺度上,过去1500年东亚冬季温度波动变化主要受到太阳辐射和温室气体的影响,温室气体的影响主要体现在工业革命之后,C02浓度的增加使得冬季温度增加,而火山活动以及土地利用/覆盖对东亚冬季温度变化没有产生显著性影响。空间分布上,太阳辐射的分布决定了东亚大陆地区西部温度高于东部地区的特征,东亚大陆西部太阳辐射值高于东部地区,使得西部地区下垫面吸收更多的短波辐射,地表净辐射通量高于东部,导致东亚大陆西部温度高于东部。
[Abstract]:The past 1500 years of climate simulation test results of the Universal Earth System Model (CESM), on the basis of the simulation performance of the verification mode, analyzed the summer precipitation in East Asia in the past 1500 years, The characteristics of the time-space change in the age-100 scale of the winter temperature and the characteristics of the intertemporal change of the East Asian summer monsoon in the typical warm period have revealed the mechanism of the cause of the change of the East Asian monsoon climate-100-year scale, and the prediction accuracy of the change of the monsoon climate in East Asia for the next 10 to 100 years, It is of great scientific significance to better understand the historical position of the modern warm period. The paper makes a comparison and analysis of the surface temperature, precipitation,850 hPa wind field, air pressure field and sea surface temperature field and observation/ re-analysis data and reconstruction data simulated by the CESM, and the results show that the CESM mode can better reproduce the characteristics of the climate average state. The seasonal variation of temperature and precipitation in East Asia is consistent with the data of observation/ re-analysis. Therefore, the simulation results of the CESM model are more reasonable and can be used in this paper. Secondly, in the last 1500 years of the simulation of the full-force test, the summer precipitation in East Asia and the winter temperature's-100-year scale change analysis have found that in 1250,1450,1600,1750, and 1815, there was an age-scale drought; on the corresponding spatial distribution, The summer precipitation in the south of the Yangtze and North China is more and more, the summer precipitation in the Yellow River basin to the south of Japan is less, and the spatial characteristics of the intertemporal variation of the East Asian summer monsoon during the Middle Ages are the same. The main mode of the summer monsoon precipitation in East Asia in the modern warm period is characterized by the distribution of the north and the south. The main cycle of the two typical warm-time East Asian summer monsoon changes will be subject to 10-and 20-year periods. In the 100-year scale, the simulated East Asian summer precipitation is in the range of 530-710,850-950,1250-1350,1440-1530,1630-1860 as negative, in the range of 730-840,1060-1240,1330-1420,1520-1620. In the space distribution, the summer precipitation in the eastern part of China is increased. The winter temperature in East Asia was in the middle of the 13th century, the middle of the 15th century and the left and right in 1815. The spatial distribution shows the characteristics of uniform warming in the whole region, and the temperature of the land is greater than that of the sea, and the winter monsoon in East Asia is weakened. In the 100-year scale, the change of temperature in winter is from 800 to 1250 years, from 1400 to 1900, and from 1900 to 2000, respectively, corresponding to the warm periods of the Middle Ages, the small and the modern warm periods. In the space distribution, the temperature of the whole East Asia is increased, and the temperature of the region west of 110 掳 E in the east of China is higher than that of the east of 110 掳 E. Third, by comparing each single-factor forcing sequence with the sensitivity test under its driving and the East Asian summer precipitation of the full-force test, the change of the temperature of the winter-hundred years has been compared and found, in the age scale, the solar radiation, Volcanic activity and the internal variability of the climate system are the main factors that affect the change of summer precipitation in East Asia in the past 1500 years, and the effect of land use/ cover and the external force factors of greenhouse gases on the summer precipitation in East Asia is not great. The main control factors of the drought and flood pattern in East Asia are the internal variability of the climate system, the solar radiation and the volcanic activity. Under the influence of the internal variability of the climate system, the cold anomaly of the Pacific in the middle east of the equator is the main cause of the "positive-negative-positive" distribution of the summer precipitation in East Asia. The cold anomaly in the equatorial Middle East Pacific has led to the enhancement of the equatorial easterly wind and the enhancement of the Walker circulation, resulting in a warm-up in the southern part of the tropical northwest Pacific. The atmospheric disturbance is spread in the direction of the north pole through the form of roberwave, resulting in the anticyclone circulation in the northwest Pacific, so that the convection in the Yellow River to Japan is weakened, and the precipitation in the summer is reduced. Under the effect of the external force of the solar radiation and the volcanic activity, the cold anomaly of the SST in the western Pacific is not obvious compared with the control test results, so that the summer precipitation in the Yellow River basin to Japan is higher than the control test result. The further study found that the Pacific Decadal Oscillation (PDO) in the North Pacific was significantly anti-related to the changes in the summer monsoon in the typical warm-up period. In the past 1500 years, the change of precipitation in East Asia is mainly influenced by solar radiation, volcanic activity and greenhouse gas, and the external force of land use/ cover has no significant effect on the change of summer precipitation in East Asia. In the spatial distribution, the external force factors of solar radiation and volcanic activity are the main control factors. Under the effect of natural factors, the Indian Ocean and the tropical marine latent heat flux increase, indicating the increase in the evaporation of the Indian Ocean and the tropical marine area, resulting in an increase in the transport of water vapor to the north, resulting in an increase in summer precipitation in East Asia. The temporal changes of the East Asian winter temperature in the age scale are mainly influenced by the volcanic activity and the internal variability, while the effect of solar radiation and man-made factors on the winter temperature change is small. In the space distribution, the internal variability of the climate system is the main control factor of the temperature change of East Asian winter in the last 1500 years, and the volcanic activity has a certain modulation effect. The effective solar radiation is weakened under the action of the volcanic activity, so that the control test is low compared with the winter temperature in the East Asian continental region simulated by the full-force test. in that past 1500 year, the change of the temperature fluctuation of the east Asia is mainly influenced by the solar radiation and the greenhouse gas, and the influence of the greenhouse gas is mainly reflected in the increase of the concentration of the C02 after the industrial revolution, so that the temperature in the winter is increased, The volcanic activity and the land use/ coverage did not have a significant effect on the winter temperature change in East Asia. The distribution of the solar radiation on the distribution of the solar radiation determines that the temperature of the western region of the East Asian region is higher than that of the eastern region, and the solar radiation value in the western region of East Asia is higher than that of the eastern region, so that the lower surface of the western region can absorb more short-wave radiation, the net radiation flux of the surface is higher than that of the east, In that eastern part of east Asia, the temperature is higher than that of the east.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P532

【参考文献】