Abstract
Having witnessed one of the most dramatic monsoons on record, the year 2020 established a record as the third highest, after 112% of the long period average (LPA) in 1994 and 110% of LPA in 2019. An analysis of upper tropospheric dynamic and thermodynamic variation was conducted to understand the abnormality in the 2020 monsoon. We found not only a dramatic variation in upper tropospheric temperature during 2020, with one centered over the Tibetan Plateau and another over the western Pacific, but also an interaction of these air temperatures. In tandem to this, induced thermal wind-driven circulation impacting the upper tropospheric relative humidity over the Indian subcontinent was observed. Interestingly, an east-to-west progression of relative humidity was found during 2020, while such emblematic progression was not seen in the LPA. The disparity in monsoon progression during 2020 from the LPA was found to be associated with the interaction of the as yet unexplored large-scale upper tropospheric dynamical features driven by the thermal wind relation. As implied by the thermal wind relation, distinctly different circulation patterns during 2020 over the two regions at 250 hPa, which were characterized by an anticyclonic and cyclonic circulation over the Tibetan Plateau and Western Pacific, provided the dynamical reason behind the moisture transport from the western Pacific towards the Indian subcontinent. A precise progression of east-to-west relative humidity further substantiated the findings: increased moisture flux from the western Pacific towards the Indian subcontinent during 2020.
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The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
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The code used in the current study is available from the corresponding author on reasonable request.
References
Alex, J. C., & Ian, G. M. (1999). Forecasting all-India summer monsoon rainfall using regional circulation principal components: A comparison between neural network and multiple regression models. International Journal of Climatology, 19, 1561–1578.
Deshpande, V. R., Kripalani, R. H., & Paul, D. K. (1986). Some facts about monsoon onset dates over Kerala and Bombay. Mausam, 37, 467–479.
Gadgil, S., Vinayachandran, P. N., & Francis, P. A. (2003). Droughts of Indian summer monsoon: Role of clouds over the Indian Ocean. Current Science, 85, 1713–1719.
Ghanekar, S. P., Bansod, S. D., Narkhedkar, S. G., & Kulkarni, A. (2019). Variability of the Indian summer monsoon rainfall over Kerala during 1971–2018. Theoretical and Applied Climatology, 138, 729–742.
He, J. J., Ju, J. H., Wen, Z. P., Lu, J. M., & Jin, Q. H. (2007). A review of recent advances in research on Asian monsoon in China. Advances in Atmospheric Sciences, 24, 972–992.
Holton, J. R. (2004). An introduction to dynamic meteorology (4th ed.). Elsevier Academic Press. Int. Geophys. Ser. 88.
Kanamitsu, M., Ebisuzaki, W., Woollen, J., Yang, S. K., Hnilo, J. J., Fiorino, M., & Potter, G. L. (2002). NCEP-DOE AMIP-II reanalysis (R-2). Bulletin of the American Meteorological Society, 83, 1631–1643.
Li, J., & Zhang, L. (2009). Wind onset and withdrawal of Asian summer monsoon and their simulated performance in AMIP models. Climate Dynamics, 32, 935–968.
Liu, X. D., & Yanai, M. (2001). Relationship between the Indian monsoon precipitation and the tropospheric temperature over the Eurasian continent. Quarterly Journal of the Royal Meteorological Society, 127, 909–937.
Pai, D. S., & Rajeevan, M. (2009). Summer monsoon onset over Kerala: New definition and prediction. Journal of Earth System Science, 118(2), 123–135.
Pant, G. B., & Parthasarathy, B. (1981). Some aspects of an association between the Southern Oscillation and Indian summer monsoon. Archives for Meteorology Geophysics and Bioclimatology, B29, 245–252.
Pant, G. B., Rupa, K. K., Parthasarathy, B., & Borgaonkar, H. P. (1988). Long term variability of the Indian summer monsoon and related parameters. Advances in Atmospheric Sciences, 5, 469–481.
Rasmussen, E. M., & Carpenter, T. H. (1983). The relationship between eastern equatorial Pacific SST and rainfall over India and Sri Lanka. Monthly Weather Review, 111, 517–528.
Rong, F., Dickinson, R. E., & Newkirk, B. (1997). Response of the upper tropospheric humidity and moisture transport to changes of tropical convection. A comparison between observations and a GCM over an ENSO cycle. Geophysical Research Letters, 24(19), 2371–2374.
Shukla, J. (1987). Interannual variability of monsoon. In J. S. Fein & P. L. Stephens (Eds.), Monsoons (pp. 399–464). New York: Wiley and Sons.
Sikka, D. R. (2011). Synoptic and mesoscale weather disturbances over South Asia during the southwest summer monsoon season. In C. P. Chang, Y. Ding, N. C. Lau, R. H. Johnson, B. Wang, & T. Yasunari (Eds.), The global monsoon system: Research and forecast (2nd ed., pp. 183–204). World Scientific.
Udelhofen, P. M., & Hartmann, D. L. (1995). Influence of tropical cloud systems on the relative humidity in the upper troposphere. Journal of Geophysical Research Atmosphere, 100, 7423–7440.
Vaid, B. H., & Kripalani, R. H. (2021). Strikingly contrasting Indian monsoon progressions during 2013 and 2014: Role of Western Tibetan Plateau and the South China Sea. Theoretical and Applied Climatology. https://doi.org/10.1007/s00704-021-03590-4
Vaid, B. H., & Liang, X. S. (2015). Tropospheric temperature gradient and its relation to the South and East Asian precipitation variability. Meteorological and Atmospheric Physics, 127(3), 579–585. https://doi.org/10.1007/s00703-015-0385-1
Vaid, B. H., & Liang, X. S. (2018a). The changing relationship between the convection over the western Tibetan Plateau and the sea surface temperature in the northern Bay of Bengal. Tellus a: Dynamic Meteorology and Oceanography, 70(1), 1–9.
Vaid, B. H., & Liang, X. S. (2018b). An abrupt change in tropospheric temperature gradient and moisture transport over east Asia in the late 1990s. Atmosphere-Ocean, 56, 268–276. https://doi.org/10.1080/07055900.2018.1429381
Vaid, B. H., & Liang, X. S. (2019a). Influence of tropospheric temperature gradient on the boreal wintertime precipitation over East Asia. Terrestrial, Atmospheric and Oceanic Sciences, 30(2), 1–10. https://doi.org/10.3319/TAO.2018.10.24.01
Vaid, B. H., & Liang, X. S. (2019b). The out-of-phase variation in vertical thermal contrast over the western and eastern sides of the northern Tibetan plateau. Pure and Applied Geophysics, 176(5337), 1–12.
Vaid, B. H., & Liang, X. S. (2020). Effect of upper tropospheric vertical thermal contrast over the mediterranean region on convection over the western Tibetan plateau during ENSO years. Atmosphere-Ocean, 58(2), 98–109.
Vaid, B. H., & Polito, P. S. (2016). Influence of the South China Sea biweekly SST on South China Sea Summer Monsoon especially during Indian Ocean Dipole. Atmosphere-Ocean, 54(1), 48–59. https://doi.org/10.1080/07055900.2015.1130682
Vaid, B. H., Preethi, B., & Kripalani, R. H. (2018). The Asymmetric Influence of the South China Sea Biweekly SST on the abnormal Indian monsoon rainfall of 2002. Pure and Applied Geophysics, 174(2017), 463–475.
Wang, B., & Lin, H. (2002). Rainy season of the Asian-Pacific summer monsoon. Journal of Climate, 15, 386–398.
Webster, P. J. (1987). The elementary monsoon. In J. S. Fein & P. L. Stephens (Eds.), Monsoons (pp. 3–32). John Wiley.
Wu, R., & Wang, B. (2000). Interannual variability of summer monsoon onset over the western North Pacific and the underlying processes. Journal of Climate, 13(14), 2483–2501.
Zhou, B. T., & Zhao, P. (2010). Influence of the Asian-Pacific oscillation on spring precipitation over central eastern China. Advances in Atmospheric Sciences, 27, 575–582.
Zuo, Z. Y., Yang, S., Kumar, A., Zhang, R. H., Xue, Y., & Jha, B. (2012). Role of thermal conditions over Asia in the weakening Asian summer monsoon under global warming background. Journal of Climate, 25, 3431–3436.
Acknowledgements
We are grateful to the editor and the anonymous reviewers for their valuable scientific feedback, which helped improve the manuscript in the present form. Thanks are due to the teams of NCEP-DOE AMIP 2 Reanalysis Version 2 for providing the respective datasets. The figures were prepared with GrADS.
Funding
This research was supported by the National Program on Global Change and Air–Sea Interaction (GASI-IPOVAI-06) and the “2015 Jiangsu Program for Innovation Research and Entrepreneurship Groups.”
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BHV planned, performed the analysis and wrote the paper. RHK added his expertise in the analyzed results and the text modification.
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Vaid, B.H., Kripalani, R.H. Monsoon 2020: An Interaction of Upper Tropospheric Thermodynamics and Dynamics Over the Tibetan Plateau and the Western Pacific. Pure Appl. Geophys. 178, 3645–3654 (2021). https://doi.org/10.1007/s00024-021-02844-6
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DOI: https://doi.org/10.1007/s00024-021-02844-6