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71.
Fei ZHENG Yuan YUAN Yihui DING Kexin LI Xianghui FANG Yuheng ZHAO Yue SUN Jiang ZHU Zongjian KE Ji WANG Xiaolong JIA 《大气科学进展》2022,39(4):546-552
In the first half of winter 2020/21,China has experienced an extremely cold period across both northern and southern regions,with record-breaking low temperatures set in many stations of China.Meanwhile,a moderate La Ni?a event which exceeded both oceanic and atmospheric thresholds began in August 2020 and in a few months developed into its mature phase,just prior to the 2020/21 winter.In this report,the mid?high-latitude large-scale atmospheric circulation anomalies in the Northern Hemisphere,which were forced by the negative phase of Arctic Oscillation,a strengthened Siberian High,an intensified Ural High and a deepened East Asian Trough,are considered to be the direct reason for the frequent cold surges in winter 2020/21.At the same time,the synergistic effect of the warm Arctic and the cold tropical Pacific(La Ni?a)provided an indispensable background,at a hemispheric scale,to intensify the atmospheric circulation anomalies in middle-to-high latitudes.In the end,a most recent La Ni?a prediction is provided and the on-coming evolution of climate is discussed for the remaining part of the 2020/21 winter for the purpose of future decision-making and early warning. 相似文献
72.
2009/2010年冬季云南严重干旱的原因分析 总被引:11,自引:3,他引:11
2009/2010年冬季我国云南省出现严重干旱,这次大范围严重干旱是较长时期降水稀少所造成的。首先讨论云南省冬季降水偏多和偏少时大气环流和海温的统计特征,基于它们的统计关系,再对2009/2010年冬季我国云南省的严重干旱进行个例对比分析。研究表明西风带环流系统异常是造成这次干旱灾害的主要成因。贝加尔湖为高度负距平,东亚沿海为高度正距平,从贝加尔湖以西到东亚中高纬度西风带较平直,冬季冷空气偏弱,很难影响西南地区。尤其是副热带中东急流减弱,从欧洲东部到里海为高压脊控制,西风带的扰动系统不易东移到东亚上空;青藏高原上空为稳定的高压脊,孟加拉湾南支槽减弱,云南省受异常西北气流控制。对太平洋和印度洋海温的分析表明,虽然海温异常可以影响冬季的云南降水,但海温异常并不是2009/2010年冬季云南省降水偏少的最重要原因。 相似文献
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Prediction of the Asian-Australian Monsoon Interannual Variations with the Grid-Point Atmospheric Model of IAP LASG (GAMIL) 总被引:6,自引:2,他引:6
Seasonal prediction of Asian-Australian monsoon (A-AM) precipitation is one of the most important and challenging tasks in climate prediction. In this paper, we evaluate the performance of Grid Atmospheric Model of IAP LASG (GAMIL) on retrospective prediction of the A-AM interannual variation (IAV), and determine to what extent GAMIL can capture the two major observed modes of A-AM rainfall IAV for the period 1979-2003. The first mode is associated with the turnabout of warming (cooling) in the Nifio 3.4 region, whereas the second mode leads the warming/cooling by about one year, signaling precursory conditions for ENSO.
We show that the GAMIL one-month lead prediction of the seasonal precipitation anomalies is primarily able to capture major features of the two observed leading modes of the IAV, with the first mode better predicted than the second. It also depicts the relationship between the first mode and ENSO rather well. On the other hand, the GAMIL has deficiencies in capturing the relationship between the second mode and ENSO. We conclude: (1) successful reproduction of the E1 Nifio-excited monsoon-ocean interaction and E1 Nifio forcing may be critical for the seasonal prediction of the A-AM rainfall IAV with the GAMIL; (2) more efforts are needed to improve the simulation not only in the Nifio 3.4 region but also in the joining area of Asia and the Indian-Pacific Ocean; (3) the selection of a one-tier system may improve the ultimate prediction of the A-AM rainfall IAV. These results offer some references for improvement of the GAMIL and associated seasonal prediction skill. 相似文献
We show that the GAMIL one-month lead prediction of the seasonal precipitation anomalies is primarily able to capture major features of the two observed leading modes of the IAV, with the first mode better predicted than the second. It also depicts the relationship between the first mode and ENSO rather well. On the other hand, the GAMIL has deficiencies in capturing the relationship between the second mode and ENSO. We conclude: (1) successful reproduction of the E1 Nifio-excited monsoon-ocean interaction and E1 Nifio forcing may be critical for the seasonal prediction of the A-AM rainfall IAV with the GAMIL; (2) more efforts are needed to improve the simulation not only in the Nifio 3.4 region but also in the joining area of Asia and the Indian-Pacific Ocean; (3) the selection of a one-tier system may improve the ultimate prediction of the A-AM rainfall IAV. These results offer some references for improvement of the GAMIL and associated seasonal prediction skill. 相似文献
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根据1958-2008年华南48站降水资料、NOAA全球逐月海温格点资料、NCEP/NCAR再分析资料,采用EOF分解、相关、合成等统计方法,分析了华南夏季降水的变化特征及其与冬季热带太平洋海温的关系。结果表明,华南夏季降水变化特征主要表现为,空间分布以全区一致型为主,其次是南北反相对称型和东西反相对称型,且这3种分布模态都表现出显著的年际和年代际特征。全区一致型降水异常与热带太平洋海温显著相关,二者的相关性也具有年代际变化特征,其对应的热带太平洋海温具有沿赤道太平洋呈“负-正-负”的纬向分布型,类似于中部型El Nino。全区降水偏多时期,西南季风偏强,西太平洋副热带高压偏强、脊点位置偏西,南亚高压偏强、脊点位置偏东,总体的环流形势有利于华南地区的水汽输送和上升运动;降水偏少时期,情况相反。 相似文献
79.
Covariations in oceanic dimethyl sulfide,its oxidation products and rain acidity at Amsterdam Island in the Southern Indian Ocean 总被引:5,自引:0,他引:5
B. C. Nguyen N. Mihalopoulos J. P. Putaud A. Gaudry L. Gallet W. C. Keene J. N. Galloway 《Journal of Atmospheric Chemistry》1992,15(1):39-53
Simultaneous measurements of rain acidity and dimethyl sulfide (DMS) at the ocean surface and in the atmosphere were performed at Amsterdam Island over a 4 year period. During the last 2 years, measurements of sulfur dioxide (SO2) in the atmosphere and of methane sulfonic acid (MSA) and non-sea-salt-sulfate (nss-SO4
2-) in rainwater were also performed. Covariations are observed between the oceanic and atmospheric DMS concentrations, atmospheric SO2 concentrations, wet deposition of MSA, nss-SO4
2-, and rain acidity. A comparable summer to winter ratio of DMS and SO2 in the atmosphere and MSA in precipitation were also observed. From the chemical composition of precipitation we estimate that DMS oxidation products contribute approximately 40% of the rain acidity. If we consider the acidity in excess, then DMS oxidation products contribute about 55%. 相似文献
80.