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Persistent extreme heat events (PEHEs) exert a more negative impact on society, including agriculture, plant phenology, power production and human health, compared to general EHEs. The temporal and spatial characteristics of summer PEHEs in eastern China were analysed based on a daily maximum temperature dataset from 759 stations over the period of 1961–2018. The results show the following: Persistent distributions of PEHEs show that they are characterized by an exponential decay with a drop in the decay rate. In terms of spatial distribution, there is an apparent regional difference in the duration of PEHEs. North China is dominated by multi-frequency and short-duration EHEs, while South China is the opposite. PEHEs in North China and the Huanghuai region mainly occur in June-July but mostly in July and August in South China. Strongly responding to global warming, the frequency and duration of PEHEs in North China have increased since the 1990s. However, the frequency of PEHEs in North China and the Huanghuai region has shown opposite trends in June-July since the beginning of the twenty-first century. Affected by the atmospheric circulations, the regional differences in PEHE frequency are also apparent. Since the beginning of the twenty-first century, the PEHEs in North China and the Huanghuai area have shown an increasing trend in August. The short-term PEHEs in the middle and lower reaches of the Yangtze River and South China increased rapidly in the 2000s, while long-term PEHEs increased in the 2010s. This study implies that attention should be paid to not only the frequency of EH days but also to the persistence of EHE which is a key characteristic of damaging EH. [ABSTRACT FROM AUTHOR]

With the influence of global warming, the global climate has undergone significant inter-decadal variation since the late 1970s. Although El Niño-Southern Oscillation (ENSO) has been the strongest signal for predicting global climate inter-annual variability, its relation with the summer rainfall in China has significantly changed, and its indicative function on the summer rainfall in China has weakened. This has led to a significant decrease in the accuracy rate of early conceptual prediction models for the Three Rainfall Patterns in the summer of eastern China. On the basis of the difference analysis of atmospheric circulation system configuration in summer, as well as the interaction of ocean and atmospheric in previous winter between two phases, i.e. before and after the significant global warming (1951 to 1978 and 1979 to 2012, respectively), we concluded that (1) Under different inter-decadal backgrounds, the atmospheric circulations that impacted the Three Rainfall Patterns in the summer of eastern China showed consistency, but in the latter phase of the global warming, the Western Pacific Subtropical High (WPSH) was on the strong side, the position of which was in the south, and the blocking high in the Eurasia mid-high latitudes was active, while the polar vortex extended to the south, and meridional circulation intensified. This circulation background may have been conducive to the increase of the circulation frequency of Patterns II and III, and the decrease of the circulation frequency of Pattern I, thus leading to more Patterns II and III and fewer Pattern I in the summer rainfall of eastern China. (2) In the former phase, the corresponding previous winter SST fields of different rainfall patterns showed visible differences. The impact of ENSO on North Pacific Oscillation (NPO) was great, and the identification ability of which on Patterns I and II of summer rainfall was effective. In the latter phase, this identification ability decreased, while the impact of ENSO on the Pacific/North American (PNA) teleconnection pattern increased, and the identification ability of the PNA on Patterns II and III also increased. Based on the new inter-decadal climate background, this study reconstructs the conceptual prediction model for the Three Rainfall Patterns in summer of eastern China by using the previous winter PNA and the Eurasian (EU) teleconnection indexes. The fitting effect was satisfying, though it is necessary to be further tested. [ABSTRACT FROM AUTHOR]

In this study, we investigate the interdecadal variation characteristics of the dominant mode of summer precipitation over East Asia‐Northwest Pacific (EA‐NWP) before and after late 1990s, reveal the physical mechanism, and address its possible connection with the regional ocean warming background. Study results show that the empirical orthogonal function mode 1 (EOF1) of summer precipitation anomalies over EA‐NWP during the global ocean warming acceleration period (1979–1998) present a more significant dipole pattern between Yangtze River Basin (YRB) and tropical NWP compared with that during the global ocean warming slowdown period (1999–2012). And then we find that the anomalous dipoles of low‐level winds, geopotential height, convection, and associated wave activity fluxes over NWP significantly shift westward (eastward) and enhance (weaken) in 1979–1998 (1999–2012), which are regarded as the direct cause of the adjustment of dipole pattern between YRB and tropical NWP. Further analysis reveals that the negative sea surface temperature (SST) anomalies in the tropical NWP are prominent (not prominent), resulting in the stronger (weaker) Pacific–Japan Teleconnection over Japan and Tropics in NWP during the period 1979–1998 (1999–2012), and ultimately lead to the change of summer precipitation EOF1 in EA‐NWP. By regressing vertical velocity, outgoing longwave radiation, relative vorticity, wave activity fluxes, and precipitation onto the NWP SST in the two periods, the impacts of the SST in the NWP on the interdecadal variation of summer precipitation EOF1 in EA‐NWP are verified. Finally, the mechanism diagram of interdecadal variation of summer precipitation is given, which can be useful for short‐term precipitation prediction of East Asia. [ABSTRACT FROM AUTHOR]