Relationship between the thermal condition of the Tibetan Plateau and precipitation over the region from eastern Ukraine
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ORIGINAL PAPER
Relationship between the thermal condition of the Tibetan Plateau and precipitation over the region from eastern Ukraine to North Caucasus during summer Junming Chen 1,2
&
Xiaoyuan Yue 1 & Ge Liu 1,2 & Sulan Nan 1,2
Received: 26 October 2018 / Accepted: 7 September 2020 / Published online: 21 September 2020 # The Author(s) 2020
Abstract Remarkable climate anomalies occurred in Europe in recent years, but the reasons are not entirely disclosed. This entails further exploring the physical mechanism of anomalous climate variability over Europe on the basis of previous studies. Using NCEPNCAR reanalysis and CMAP precipitation datasets, we investigated the relationship between the thermal condition of the Tibetan Plateau (TP) and precipitation over Europe during summer and related mechanisms behind through observational analyses and simulation experiments. The results show that the summer TP surface air temperature (SAT) is significantly correlated with the simultaneous precipitation over the region from eastern Ukraine to the North Caucasus (EUNC; 43°–51° N, 34°–46° E) during the period 1979–2017. The effect of anomalous TP heating plays, to some extent, an active role in linking the summer TP SAT with EUNC precipitation. The variability of the TP SAT is a result of the anomalous TP heating, but it can reflect the variability in temperature of a thick tropospheric air column over the TP well. Corresponding to higher (lower) TP SAT, the higher (lower) temperature anomaly appears over the TP and extends westwards through the transport of anomalous temperature fluxes from the TP to the EUNC regions in the upper troposphere, resulting in the expansion (withdrawal) of the South Asian high (SAH) and associated less (more) precipitation over the EUNC region. Numerical simulations basically reproduce the above-mentioned physical process, which confirms that, through stimulating the variability of uppertropospheric temperatures over the TP and a larger area to its west and associated upstream large-scale atmospheric circulation, the summer TP’s thermal condition can modulate and expand the impact of the SAH to the EUNC region and therefore affect the concurrent precipitation in situ. This study implies an importance of the thermal anomaly of the TP to the variability of EUNC precipitation during summer.
1 Introduction Europe has experienced remarkable climate anomalies in recent years. For example, severe wet anomalies appeared over Northern Europe (15° W–20° E, 45–60° N) during the summers of 2007, 2011, and 2012, which were the first, fifth, and sixth wettest years during the period 1979–2012, respectively * Ge Liu [email protected] 1
State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing, China
2
Collaborative Innovation Centre on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China
(Screen 2013). Meanwhile, in contrast to the positive precipitation anomalies over Northern Europe in recent summe
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