Interannual Variability of Late-spring Circulation and Diabatic Heating over the Tibetan Plateau Associated with Indian Ocean Forcing
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The thermal forcing of the Tibetan Plateau (TP) during boreal spring, which involves surface sensible heating, latent heating released by convection and radiation flux heat, is critical for the seasonal and subseasonal variation of the East Asian summer monsoon. Distinct from the situation in March and April when the TP thermal forcing is modulated by the sea surface temperature anomaly (SSTA) in the North Atlantic, the present study shows that it is altered mainly by the SSTA in the Indian Ocean Basin Mode (IOBM) in May, according to in-situ observations over the TP and MERRA reanalysis data. In the positive phase of the IOBM, a local Hadley circulation is enhanced, with its ascending branch over the southwestern Indian Ocean and a descending one over the southeastern TP, leading to suppressed precipitation and weaker latent heat over the eastern TP. Meanwhile, stronger westerly flow and surface sensible heating emerges over much of the TP, along with slight variations in local net radiation flux due to cancellation between its components. The opposite trends occur in the negative phase of the IOBM. Moreover, the main associated physical processes can be validated by a series of sensitivity experiments based on an atmospheric general circulation model, FAMIL. Therefore, rather than influenced by the remote SSTAs of the northern Atlantic in the early spring, the thermal forcing of the TP is altered by the Indian Ocean SSTA in the late spring on an interannual timescale.
Key wordsIndian Ocean Tibetan Plateau circulation diabatic heating
青藏高原(以下简称高原)热力强迫作用, 包括地表感热, 大气凝结潜热以及气柱净辐射通量, 对东亚夏季风的季节以及次季节变率有着重要影响.本文基于台站观测资料以及MERRA再分析数据集, 发现北大西洋海温异常是3-4月高原非绝热加热年际变率的主控因子, 而晚春(5月)高原大气热源则主要受印度洋海盆一致模(IOBM)的影响.在IOBM正位相年, 伴随着西南印度洋的异常上升以及高原东南部的异常下沉运动, 印度洋上空的局地Hadley环流将会加强, 对应于高原近地层西风与地表感热的显著正异常, 而高原降水和凝结潜热总体受到抑制.与此同时, 高原上的辐射通量由于各分量之间的相互抵消适应仅有微弱变化;IOBM负位相年则相反.此外, 基于大气环流模式的一系列敏感性实验还进一步揭示了主要物理过程.
关键词印度洋 青藏高原 大气环流 非绝热加热
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This work was supported by the National Natural Science Foundation of China (Grant Nos. 91637312, 41725018 and 91437219), the UK China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership (CSSP) China as part of the Newton Fund, the Key Research Program of Frontier Sciences, and the Special Program for Applied Research on Super Computation of the National Natural Science Foundation of China (NSFC)–Guangdong Joint Fund (second phase) under Grant No. U1501501.
- Hu, J., and A. M. Duan, 2015: Relative contributions of the Tibetan Plateau thermal forcing and the Indian Ocean sea surface temperature basin mode to the interannual variability of the East Asian summer monsoon. Climate Dyn., 45, 2697–2711, https://doi.org/10.1007/s00382-015-2503-7. CrossRefGoogle Scholar
- Jin, R., L. Qi, and J. H. He, 2016: Effect of oceans to spring surface sensible heat flux over Tibetan Plateau and its influence to East China precipitation. Acta Oceanologica Sinica, 38, 83–95, https://doi.org/10.3969/j.issn.0253-4193.2016.05.008. (in Chinese)Google Scholar
- Joseph, P. V., J. K. Eischeid, and R. J. Pyle, 1994: Interannual variability of the onset of the Indian summer monsoon and its association with atmospheric features, El Niño, and sea surface temperature anomalies. J. Climate, 7, 81–105, https://doi.org/10.1175/1520-0442(1994)007<0081:IVOTOO>2.0.CO;2.CrossRefGoogle Scholar
- Li, W., G. X. Wu, W. P. Li, and Y. M. Liu, 2001: Thermal adaptation of the large-scale circulation to the summer heating over the Tibetan Plateau. Progress in Natural Science, 11(3), 207–214.Google Scholar
- Liu, S. F., and A. M. Duan, 2017: Impacts of the leading modes of tropical Indian Ocean sea surface temperature anomaly on sub-seasonal evolution of the circulation and rainfall over East Asia during boreal spring and summer. J. Meteorol. Res., 31, 171–186, https://doi.org/10.1007/s13351-016-6093-z. CrossRefGoogle Scholar
- Luo, H. B., and M. Yanai, 1983: The large-scale circulation and heat sources over the Tibetan Plateau and surrounding areas during the early summer of 1979. Part I: Precipitation and kinematic analyses. Mon. Wea. Rev., 111, 922–944, https://doi.org/10.1175/1520-0493(1983)111<0922:TLSCAH>2.0.CO;2.Google Scholar
- Luo, H. B., and M. Yanai, 1984: The large-scale circulation and heat sources over the Tibetan Plateau and surrounding areas during the early summer of 1979. Part II: Heat and moisture budgets. Mon. Wea. Rev., 112, 966–989, https://doi.org/10.1175/1520-0493(1984)112<0966:TLSCAH>2.0.CO;2.Google Scholar
- Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res., 108, 4407, https://doi.org/10.1029/2002JD002670. CrossRefGoogle Scholar
- Torres, M. E., M. A. Colominas, G. Schlotthauer, and P. Flandrin, 2011: A complete ensemble empirical mode decomposition with adaptive noise. Proceedings of 2011 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Prague, Czech Republic, IEEE, 4144–4147, https://doi.org/10.1109/ICASSP.2011.5947265. CrossRefGoogle Scholar
- Wang, M. R., S. W. Zhou, and A. M. Duan, 2012: Trend in the atmospheric heat source over the central and eastern Tibetan Plateau during recent decades: Comparison of observations and reanalysis data. Chinese Science Bulletin, 57, 548–557, https://doi.org/10.1007/s11434-011-4838-8. CrossRefGoogle Scholar
- Wu, G. X., and H. Z. Liu, 1995: Neighbourhood response of rainfall to tropical sea surface temperature anomalies. Part I: Numerical experiment. Scientia Atmospherica Sinica, 19, 422–434, https://doi.org/10.3878/j.issn.1006-9895.1995.04.05. (in Chinese)Google Scholar
- Wu, R. G., and S. W. Yeh, 2010: A further study of the tropical Indian Ocean asymmetric mode in boreal spring. J. Geophys. Res., 115, https://doi.org/10.1029/2009JD012999.
- Wu, Y., Y. Q. Li, X. W. Jiang, and Y. C. Dong, 2017: Parameters sensitivity analysis on simulation of rainfall in drought-flood year on Qinghai-Tibetan Plateau by WRF model. Plateau Meteorology, 36(3), 619–631, https://doi.org/10.7522/j.issn.1000-0534.2016.00057. (in Chinese)Google Scholar
- Wu, Z. W., W. Bin, J. P. Li, and F. F. Jin, 2009: An empirical seasonal prediction model of the East Asian summer monsoon using ENSO and NAO. J. Geophys. Res., 114, https://doi.org/10.1029/2009JD011733.
- Yang, J. L., Q. Y. Liu, S. P. Xie, Z. Y. Liu, and L. X. Wu, 2007: Impact of the Indian Ocean SST basin mode on the Asian summer monsoon. Geophys. Res. Lett., 34, https://doi.org/10.1029/2006GL028571.
- Ye, D. Z., and Y.-X. Gao, 1979: The Meteorology of the Qinghai-Xizang (Tibet) Plateau. Science Press, Beijing, 278 pp. (in Chinese)Google Scholar
- Yeh, T. C., 1950: The circulation of the high troposphere over China in the winter of 1945–46. Tellus, 2, 173–183, https://doi.org/10.1111/j.2153-3490.1950.tb00329.x. CrossRefGoogle Scholar
- Zhao, Y. F., and J. Zhu, 2015: Assessing quality of grid daily precipitation datasets in China in recent 50 years. Plateau Meteorology, 34, 50–58, https://doi.org/10.7522/j.issn.1000-0534.2013.00141. (in Chinese)Google Scholar