| 千年时间尺度南亚高压和西太平洋副热带高压关系的时空变化特征 |
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| 引用本文： | 王宁, 张肖剑, 靳立亚. 千年时间尺度南亚高压和西太平洋副热带高压关系的时空变化特征[J]. 第四纪研究, 2015, 35(6): 1425-1436. doi: 10.11928/j.issn.1001-7410.2015.06.12 |
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| 作者姓名： | 王宁 张肖剑 靳立亚 |
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| 作者单位： | ① 兰州大学大气科学学院, 兰州 730000;; ② 兰州大学资源环境学院, 兰州 730000 |
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| 摘 要： | 利用全新世的气候模拟结果(KCM)以及1948~2013年NCEP/NCAR 逐月再分析资料, 分析了大型大气环流系统南亚高压和西太平洋副热带高压(以下简称"西太副高")在千年时间尺度上的特征和它们之间的空间位置变化关系以及与东亚夏季风的关系, 并比较了它们与现代气候背景年际时间尺度变化特征的异同。结果表明, 在千年尺度上, 南亚高压的东进(西移)对应西太副高的西伸(东撤)。这与年际尺度上南亚高压与西太副高存在的"相向而行"及"相背而去"的时空特征是一致的。耦合气候模式模拟的全新世9.5ka B.P. 以来东亚夏季风总体呈现振荡减弱趋势。早全新世(9.5~7.5ka B.P.)时期, 东亚夏季风强度较强, 此时南亚高压位置偏东而西太副高位置偏西; 在中全新世(7~4ka B.P.)期间, 东亚夏季风呈现百年尺度大幅振荡, 而此时南亚高压(西太副高)的位置大致位于112°~115°E(145°~155°E)之间; 晚全新世(4~0ka B.P.)期间, 东亚夏季风持续减弱, 对应南亚高压位置向东移动、西太副高位置向西移动。全新世时期(9.5~0ka B.P.), 北半球春季(4月、5月份)赤道地区接收的太阳辐射呈现先减弱,至5~4ka B.P. 期间达到最低值, 之后逐渐增强的变化趋势, 这与南亚高压的位置变化趋势一致, 而与西太副高位置变化趋势相反, 即赤道春季太阳辐射强(弱)时, 南亚高压位置偏东(偏西)、西太副高位置偏西(偏东)。同时, 模拟的全新世热带印度洋-西太平洋夏季温度变化也呈现出与春季赤道太阳辐射一致的变化趋势, 且与南亚高压有显著的正相关关系, 海温的加热作用可以通过激发Matsuno-Gill型大气响应使得南亚高压增强。西太副高主要由哈德莱环流在副热带地区的下沉作用造成, 而热带印度洋-西太平洋夏季的增温可引起哈德莱环流增强, 从而使西太副高的强度增强、面积扩大导致其西脊点位置偏西。因此, 赤道春季太阳辐射可以通过影响热带印度洋-西太平洋夏季温度对南亚高压东脊点和西太副高西脊点的位置产生影响。
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| 关 键 词： | 全新世 南亚高压 西太副高 太阳辐射 东亚夏季风 |
| 收稿时间： | 2014-12-20 |
| 修稿时间： | 2015-05-09 |
THE SPATIAL AND TEMPORAL VARIATION CHARACTERISTICS OF THE SOUTH ASIA HIGH AND WESTERN PACIFIC SUBTROPICAL HIGH ON MILLENNIAL TIME SCALE |
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| Wang Ning, Zhang Xiaojian, Jin Liya. The spatial and temporal variation characteristics of the South Asia high and Western Pacific Subtropical High on millennial time scale[J]. Quaternary Sciences, 2015, 35(6): 1425-1436. doi: 10.11928/j.issn.1001-7410.2015.06.12 |
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| Authors: | Wang Ning Zhang Xiaojian Jin Liya |
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| Affiliation: | ① College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000;; ② College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 |
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| Abstract: | The Western Pacific subtropical high(WPSH) and South Asian high(SAH) are closely related to the East Asian summer(June-July-August, JJA) monsoon(EASM). Previous researches found a close relationship between the WPSH and SAH on the inter-annual time scale in present-day climate. However, their behaviors and relationship are rarely discussed on millennial time scale during the Holocene. In this study, we explore the spatial and temporal variation characteristics of the WPSH and SAH on millennial time scale for the period of Holocene from 9.5ka B.P. to 0ka B.P. using the model results from a series of numerical experiments in an atmosphere-ocean-sea ice coupled climate model, the Kiel Climate Model(KCM). The simulations include two time-slice equilibrium experiments for Early Holocene(9.5ka B.P.) and present-day(0ka B.P.), respectively and one transient simulation(HT) using a scheme for model acceleration regarding to the Earth's orbitally driven insolation forcing for the whole period of Holocene(from 9.5ka B.P. to 0ka B.P.). In addition, the National Centers for Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR) Reanalysis dataset is used in this study to compare with the model results. The model results show an eastward extension of the WPSH before 5ka B.P. and a westward extension after then. The behavior of the SAH showed a complete opposite trend with the WPSH, displaying a westward shift before 5ka B.P. and an eastward shift after then. The contrast in the behavior between the WPSH and SAH on millennial time scale during the Holocene resembles to that on inter-annual time scale in present-day climate. The model results show that the stronger EASM during the Early Holocene(9.5~7.5ka B.P.) was accompanied by a gradual westward(eastward) shift of the SAH(WPSH). In the Mid-Holocene(7~4ka B.P.), the EASM shows a multi-centennial time scale oscillations with the SAH(WPSH) relatively located between 112°~115°E(145°~155°E). During the Late Holocene(4~0ka B.P.), the EASM intensity decreases continuously with the SAH(WPSH) shifting eastwards(westwards) gradually. By analyzing Holocene evolution of spring insolation at the equator and the tropical sea surface temperature(SST) during summer season(JJA), it is suggested that the spatial and temporal evolution of the SAH and WPSH is closely related to the orbitally induced changes in spring insolation at the equator. Model result shows that since the Early Holocene the spring insolation at the equator and the Western Pacific SST gradually decreased until Mid-Holocene, and then they gradually increased until present day. This trend is consistent with the zonal migration of SAH and the summer mean surface temperature of tropical Indian-Western Pacific Ocean(averaged over 5°~20°N and 70°~140°E). The SAH has a positive correlation with the summer mean surface temperature of tropical Indian-Western Pacific Ocean, which then forces a Matsuno-Gill-type response that strengthen the SAH. The result means that the increasement of the equatorial spring insolation may result in the summer mean surface temperature of tropical oceans leading to the eastward(westward) shift of SAH(WPSH). In summary, the evolutions of the WPSH and SAH on millennial time scale are probably controlled by spring insolation at the equator. The formation of the SAH is closely related to the land surface heating of the Tibetan Plateau that is affected by the tropical ocean, whereas the WPSH is associated with the Hadley Circulation that is influenced by the tropical ocean. The tropical oceans receive most of the solar insolation in spring that exerts a sustained impact on the tropical ocean in summer. The extension of the WPSH and SAH is closely related to their strength. Therefore, the tropical oceans can influence zonal migration of the WPSH and SAH via affecting their intensity. |
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| Keywords: | Holocene South Asia high Western Pacific subtropical high insolation East Asian summer monsoon |
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