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A record‐breaking flooding event occurred in Zhengzhou, Henan Province of China during 17–23 July 2021, causing hundreds of deaths and vast economic losses. Here, we evaluated the predictability of this extreme rainfall event and the impacts of tropical cyclones (TCs) using subseasonal‐to‐seasonal (S2S) operational models. On the monthly timescale, most models initialized in late June reasonably predicted the wet‐in‐north and dry‐in‐south patterns of anomalous rainfall over China in July, accompanied by the well‐predicted westward extension of the western North Pacific subtropical high (WNPSH) and eastward stretching of the South Asian High. On the weekly timescale, only four models captured the location, probability, and sudden intensification of the rainfall extremes in advance of 1 week, largely due to their reasonable prediction of WNPSH variability in mid‐latitudes. However, the S2S models still underestimated the super extremeness of this event. The prediction discrepancies came from the poor predictability of Typhoon IN‐FA and its impact on the daily evolution of the extreme rainfall event, even within a few days forecast lead. Compared with the observation, the prediction bias of tropical disturbance changed the environmental monsoon airflow to induce the earlier warning of rainfall extremes prior to the formation of IN‐FA. After the formation of IN‐FA, the prediction bias of the typhoon's moving speed distorted the typhoon location, which incorrectly predicted the moisture convergence center and underestimated their remote impacts on this heavy rainfall event. Plain Language Summary: Unprecedented heavy rainfall reaches the warming Earth more frequently, creating the need for effective risk‐warning alerts that utilize subseasonal‐to‐seasonal (S2S) forecasting to integrate information from nowcasting, weather, and seasonal predictions. On 17–23 July 2021, persistent heavy rainfall affected Henan Province of China, triggering devastating flooding and traffic chaos in Zhengzhou city. Some skillful S2S models can reasonably predict the monthly rainfall pattern in July. Although the chance of exceeding the new record daily rainfall is only approx. 0.7% in mid‐late July, they provide a high probability of this heavy weekly rainfall 1 week in advance. Nevertheless, the S2S models underestimate this super extremeness, mainly due to the poor predictability of tropical cyclones, even within a few leading days. The deficits in the tropical disturbance and moving speed of Typhoon IN‐FA in the model forecast altered the moisture transmission, underestimating their remote impacts on this extreme event. Risk management on S2S timescales is essential for many public and private sectors, as it provides pivotal lead times that save lives and property. Each extreme event exposes challenges regarding the credibility and sensitivity of the outcomes for decision‐making. Future research should improve our awareness of the challenges that remain in the S2S forecasts. Key Points: Most subseasonal‐to‐seasonal models produce the wet‐in‐north and dry‐in‐south rainfall anomalies and general circulation configuration over China in JulySudden intensification of rainfall in Henan China was predicted 1 week ahead by four models with accurate mid‐latitude adjustmentsDeficits in tropical disturbance and moving speed of Typhoon IN‐FA underestimate their remote impacts in forecasting [ABSTRACT FROM AUTHOR]

The onset of the Asian summer monsoon (ASM) starts the rainy season in one of the most world populous regions. The present study found that the stepwise ASM onset process (ASMOP) in the Bay of Bengal, South China Sea (SCS), and India exhibits three distinct interannual modes induced by different sea surface temperature anomalies (SSTAs). The first mode features are in‐phase variation of ASMOP in southern Asia, which originates from the ENSO‐related SSTAs and anomalous circulations in the tropical Indo‐Pacific Ocean. The second mode indicates the anomalous ASMOP in India and depends on the southwestern Indian SSTAs that alter the low‐level cross‐equatorial flow over the Arabian Sea. In the third mode, the western North Pacific SSTAs and their resultant circulation anomalies regulate ASMOP in the northern SCS. These extra‐equatorial SSTAs and their associated air‐sea interaction serve as an additional source of seasonal predictability for ASMOP besides El Niño–Southern Oscillation events. Plain Language Summary: The onset of the Asian summer monsoon (ASM) begins the rainy season in South and East Asia, one of the world's most populous regions. In general, the ASM onset process (ASMOP) follows a stepwise progression over the Bay of Bengal (BOB), South China Sea (SCS), and India, in turn. The year‐by‐year relationship between the monsoon onset dates over these areas helps to predict the arrival of the monsoon in Asian countries. However, there is no consensus on the year‐by‐year relationship of ASMOP among these areas. The present study used a unified definition to revisit the distinct modes of interannual variation in ASMOP. The El Niño–Southern Oscillation (ENSO)–associated tropical sea surface temperature anomalies (SSTAs) in the Indian and Pacific oceans can modify ASMOP over BOB, the southern SCS, and India simultaneously. Besides the influence of ENSO, the SSTAs in the southwestern Indian Ocean can regulate ASMOP in India. At the same time, the SSTAs modulate ASMOP in the northern SCS in the western North Pacific. Results from numerical experiments verified that air–sea interaction is critical for the effect of extra‐equatorial SSTAs on ASMOP, which provides an additional source of seasonal predictability of ASMOP besides ENSO factors. Key Points: The Asian summer monsoon onset process (ASMOP) shows distinct interannual modes in the tropicsEl Niño–Southern Oscillation determines the interannual variability in ASMOP over India, the Bay of Bengal, and the southern South China Sea (SCS)The southwestern Indian and western Pacific sea surface temperature anomalies modulate ASMOP over India and the northern SCS via air–sea interaction, respectively [ABSTRACT FROM AUTHOR]

Accurate forecasting of the South China Sea summer monsoon (SCSSM) onset is critical for water resource management in the rainy season across East Asia. The present work evaluates the skill of the ECMWF subseasonal‐to‐seasonal (S2S) forecasting system in predicting SCSSM onset dates using a hindcast experiment. The model provides accurate predictions of the SCSSM onset date 10 days in advance. The predictability mainly arises from the sea surface temperature anomaly (SSTA) in the northern Indian Ocean and central‐eastern tropical Pacific, which usually coincides with moderate and extreme decaying El Niño, thus creating windows of opportunity for SCSSM onset forecasting. The model can reasonably reproduce the SCSSM‐related SSTA and its induced atmospheric teleconnections. However, when anomalous Ural blocking influences the mid‐high latitudes, the ECMWF model forecasts of the SCSSM onset are trapped in the synoptic timescale because of the limited ability of the model to consider blocking in forecasting. Plain Language Summary: Accurate predictions of when the monsoon arrives greatly influence agricultural planning. Agro‐based China relies on East Asian summer monsoon rainfall, which allows millions of farmers to feed the most populated country in the world. The summer monsoon over the South China Sea marks the start of the monsoonal rainy season in East Asia. Therefore, forecasting its arrival with a long lead time is essential. A subseasonal forecasting system is an effective tool for monsoon prediction, but little attention has been given to the South China Sea. We use the European Center for Medium‐Range Weather Forecasts system to evaluate subseasonal forecasts of the monsoon onset over the South China Sea. Skillful forecasts can be obtained 10 days in advance. The predictability originates from the accurate representation of the tropical sea surface temperature and its impact on the atmosphere, particularly concomitant with the moderate and extreme decaying El Niño. However, a synoptic system, called Ural blocking, constrains the forecast skill because it is difficult to model. Both the predictive sources and limitations are discussed in our results, which can be used to improve monsoon arrival forecasts. These improvements will benefit the proactive adaptation since policy changes may take several weeks to implement. Key Points: The European Center for Medium‐Range Weather Forecasts S2S model provides accurate 10‐day advance forecasts of the onset date of the South China Sea summer monsoon (SCSSM)The high S2S predictability of the SCSSM onset mainly arises from the forcing of slowly evolving tropical sea surface temperaturesUnpredictable Ural blocking at mid‐high latitudes may hinder forecasts of the SCSSM onset due to synoptic disturbance [ABSTRACT FROM AUTHOR]

Using daily atmospheric circulation data for 1981–2010, we identify the climatological intraseasonal oscillation (CISO) in the mid–upper troposphere and reveal its critical role in anchoring the Meiyu season to the period from mid‐June to mid‐July and the rainfall episode of northeastern China to begin in late July. Wavelet analysis shows a significant 20–90‐day period in the climatological 200‐ and 500‐hPa zonal winds during boreal summer, indicating the existence of the zonal wind CISO in the mid–upper troposphere. The leading mode of zonal wind CISO features a dipole pattern along the coast of East Asia controlled by convection over the southeastern China–western North Pacific (SC–WNP). In mid‐June, suppressed convection over the SC–WNP induces the negative phase of intraseasonal Pacific–Japan pattern, leading to the strong anticyclone with a poleward tilt with height to dominate over the WNP. Consequently, more moisture are transported to the middle and lower reaches of the Yangtze River Valley (YRV), and the mid‐tropospheric (upper‐tropospheric) East Asian westerly jet (EAWJ) is shifted north of 32°N (36°N), which further increases the YRV rainfall through enhancing warm advection and upper‐tropospheric divergence, thus facilitating the initiation of Meiyu season. In mid‐July, active convection occupies the SC–WNP instead, with the reversed circulation pattern terminating the Meiyu season. In late July, active convection shifts from the equator to the tropical western Pacific, leading to the second mode of zonal wind CISO, which is characterized by a quasi‐barotropic Mongolian anticyclone in the mid–upper troposphere. The upper‐tropospheric EAWJ is further shifted to 45°N, displacing the induced upper‐tropospheric divergence northward, thus initiating the rainfall episode of northeastern China. [ABSTRACT FROM AUTHOR]

Meiyu rainfall in June–July of 2020 hit the Yangtze‐Huaihe River basin, and the precipitation at lots of observational stations broke the records, inducing severe disasters there. Tibetan Plateau vortices (TPVs) generated over the Tibetan Plateau are local major rainfall triggers. In previous knowledge, TPVs can affect the rainfall in eastern China, only after emigrating from the Tibetan Plateau. In this work, roles of TPVs in the record Meiyu are revealed, implying that the effects of TPVs may be underestimated previously. Firstly, TPVs dying out over the Tibetan Plateau may be transformed into troughs and continue to move eastward, influencing the rainfall in Yangtze‐Huaihe River basin. Secondly, southwest vortices, the important rainfall producers in China, tend to be generated and maintained when TPVs are located over eastern plateau. The results give extended knowledge on the effects of TPVs, which are beneficial for the rainfall prediction in eastern China. [ABSTRACT FROM AUTHOR]

The Mid‐to‐Lower Reaches of the Yangtze River (MLRYR) suffered an extreme drought in the post‐monsoon season of 2019, contemporaneous with a strong Central Pacific (CP) El Niño and a super positive Indian Ocean Dipole (pIOD) event. The present work shows that CP El Niño‐related Pacific Sea Surface Temperature Anomalies (SSTAs) weakened the western North Pacific anticyclone to prevent moisture transport to the MLRYR and explained 60% of the drought intensity. The super pIOD with an extremely cold SSTA in the tropical Southeastern Indian Ocean contributed 40% of the drought amplitude via an atmospheric teleconnection. The Indian Ocean cold SSTAs first strengthened the post‐monsoon rainfall and enhanced diabatic heating over South Asia, leading to baroclinic circulation anomalies with induced descending motion over the MLRYR. The aggravated dry conditions there ultimately broke the historical drought record for the period since 1979. Plain Language Summary: In the post‐monsoon season of 2019, the Mid‐to‐Lower Reaches of the Yangtze River (MLRYR) experienced a record‐breaking drought, which severely disrupted water supplies and affected the planting of crops. At the same time, a super positive Indian Ocean Dipole (pIOD) event occurred, along with a central Pacific (CP) El Niño in the tropical Pacific. The present study indicates that in addition to the CP El Niño, the extremely cold SSTAs in the tropical Southeastern Indian Ocean associated with the super pIOD event was also an important factor in the record‐breaking drought event. This factor first shifted the intertropical convergence zone northward to intensify the post‐monsoon rainfall and its released condensation heating over South Asia. Then, a vertically baroclinic circulation was stimulated to strengthen a descending motion over the MLRYR via an atmospheric teleconnection. On the other hand, the tropical Pacific warm SSTAs related to the strong CP El Niño weakened the western North Pacific anticyclone, which reduced the moisture supply to the MLRYR. In this way, both the pIOD and CP El Niño events jointly resulted in the record‐breaking MLRYR drought in 2019 and explained approximately 40% and 60% of this extreme drought, respectively. Key Points: Drought over the mid‐to‐lower reaches of the Yangtze River (MLRYR) broke historical records in 2019 during the post‐monsoon seasonA strong central Pacific El Niño contributed ∼60% of the extreme MLRYR drought intensity due to the tropical Pacific air‐sea interactionAnother 40% of this MLRYR drought can be attributed to a super positive Indian Ocean Dipole via a teleconnection effect over South Asia [ABSTRACT FROM AUTHOR]

In 2020, the Yangtze River (YR) suffered a long‐persisting Meiyu season. The accumulated rainfall broke its record since 1961 and caused severe flooding and death in China. Our results show the sequential warm and cold Meiyu front regulated by the North Atlantic Oscillation (NAO) was responsible for this unexpected extreme Meiyu event. From 11 to 25 June with the positive NAO, the interaction between the South Asian High (SAH) and the western Pacific subtropical high maintained a warm front to strengthen the rainband north of the YR. Afterward, the coupling between SAH and midlatitude Mongolian Cyclone induced a cold front, which retreated the rainband to the south of YR from 30 June to 13 July with the negative NAO. Although the ECMWF S2S model successfully predicted the warm‐front‐related Meiyu rainband, it failed to forecast the Meiyu rainband in the cold‐front period, suggesting a great challenge of S2S forecasting on Meiyu rainfall. Key Points: Sequential warm Meiyu fronts in middle to late June and cold fronts in early to middle July directly cause record‐breaking Meiyu rainfall in 2020The NAO phase change leads to the alternation of the circulation regime of the East Asian summer monsoon from a warm‐ to cold‐front periodThe prediction skill of the ECMWF S2S model on the 2020 Meiyu rainband is higher in the warm front period but lower in the cold front period [ABSTRACT FROM AUTHOR]

The ascidian belongs to the sister group of vertebrates and shares many features with them. The gene regulatory network (GRN) controlling gene expression in ascidian embryonic development leading to the tadpole larva has revealed evolutionarily conserved gene circuits between ascidians and vertebrates. These conserved mechanisms are indeed useful to infer the original developmental programs of the ancestral chordates. Simultaneously, these studies have revealed which gene circuits are missing in the ascidian GRN; these gene circuits may have been acquired in the vertebrate lineage. In particular, the GRN responsible for gene expression in ectodermal cells of ascidian embryos has revealed the genetic programs that regulate the regionalization of the brain, formation of palps derived from placode‐like cells, and differentiation of sensory neurons derived from neural crest‐like cells. We here discuss how these studies have given insights into the evolution of these traits. [ABSTRACT FROM AUTHOR]

The late onset of the South China Sea (SCS) summer monsoon (SCSSM) has traditionally been attributed to El Niño events. However, the SCSSM built up around Pentad 26 in 2019, which was 10 days earlier than expected following the 2018/2019 El Niño event. The present study showed that the early onset of the SCSSM in 2019 could be ascribed to tropical cyclone (TC) Fani over the Bay of Bengal (BOB) from 27 April to 3 May 2019. Before the landfall in Pentad 24, the anomalous condensation heating released by the TC not only shifted the South Asian High (SAH) northward but also reinforced the upper‐level barotropic trough to the west of the Tibetan Plateau (TP) at midlatitudes. This phenomenon facilitated the early establishment of monsoon convection by intensifying the upper‐level pumping over the SCS. In addition, the TC carried abundant moisture to the eastern TP and the SCS when it landed in eastern India in Pentad 25 and strengthened the local rainfall in front of the deeper midlatitudinal trough in the upper troposphere over the TP, which in turn released more condensation heating to warm the tropospheric atmosphere. Afterwards, this warmer air advected downstream to the north of the SCS by the basic flow, resulting in the further northward shift of the SAH and the stronger monsoon onset convection over the SCS. Such an upscaling effect of the TC prevented the onset time of the 2019 SCSSM from being accurately forecasted by the ECMWF S2S model. Key Points: Tropical cyclone (TC) Fani boosted the onset of the South China Sea (SCS) summer monsoon (SCSSM) in 2019Northward shift of the South Asian High resulting from TC Fani provided upper‐tropospheric pumping to trigger early onset of the SCSSMDiabatic heating over the eastern Tibetan Plateau enhanced by atmospheric response to TC Fani to further advance the onset of the SCSSM [ABSTRACT FROM AUTHOR]

The robust negative correlation between the Siberian High (SH) intensity and winter surface air temperature (SAT) in Northeast China has been widely used for winter climate seasonal forecasting. However, this traditional viewpoint varies when considering the changes in SH spatial extension during boreal winter. Here, a newly defined SH index representing both SH intensity and spatial extension shows two distinct influences of a stronger SH on the SAT in Northeast China. The stronger SH with a decreasing eastern edge, which features a meridional see–saw dipole of abnormal circulations centred over the Arctic and Siberia, respectively, results in a warmer winter over Northeast China. In this situation, the decreasing SH is linked to the enhanced Arctic Polar vortex through a tropospheric–stratospheric interaction. However, a stronger SH with an expanding eastern edge is coupled with the East Asian trough (EAT) and results in a colder winter in Northeast China. The SH and EAT anomalies are embedded in a zonally oriented wave‐train originating from the North Atlantic in the troposphere. Because of the diversity of impacts, the SH intensity and zonal extension should be jointly considered for seasonal forecasting of winter SAT anomalies in Northeast China. [ABSTRACT FROM AUTHOR]

The amplitude of El Niño, measured by the Nino3.4 sea surface temperature anomaly (SSTA) index, has exhibited an interdecadal change with a weakening trend since the late 1990s, characterized by the distinct Bjerknes stability index between 1980–1998 and 1999–2014. Statistical results suggest that this was primarily induced by the attenuation of the zonal wind stress and low‐level wind anomalies in response to the zonal equatorial SSTA gradient. The weakened atmospheric responses to the zonal equatorial SSTA gradient were associated with the obvious westward extension of the negative sea level pressure anomalies (SLPA) over the tropics. This was mainly attributed to the transition of the dominant atmospheric circulation over the North Pacific, where the Aleutian Low (AL) mode was replaced by the North Pacific Oscillation (NPO) mode after the late 1990s. Numerical experiments from the long‐term historical simulations of the GFDL‐CM3 model indicate that both of the AL and NPO were dominant over the North Pacific and alternated on the interdecadal time‐scale. When the NPO mode was dominant, it became more effective at playing a role in triggering an El Niño in the central Pacific via the seasonal footprinting mechanism over the subtropical northeastern Pacific. Such a change might cause the westward shift of the tropical SLPA and the attenuated atmospheric responses to the zonal SSTA gradient, ultimately resulting in the weakening of the El Niño amplitude. [ABSTRACT FROM AUTHOR]

Sequential heavy rainfall clusters and resultant severe winter flooding was observed over South China during the 2015/2016 super El Niño event. In the present, the intra‐seasonal oscillations (ISOs) related with heavy rainfall over East Asia from late autumn to early winter in 2015/2016 were investigated using the daily in situ rainfall records and the NCEP‐DOE Reanalysis data set. Results suggested that the successive heavy winter rainfall events in 2015/2016 were contributed by the ISOs with significant periods of 10–25 and 30–45 days. The wet phase of 10–25‐day ISO was jointly induced by the anomalous convergence of the low‐level water vapour associated with the tropical–subtropical interaction and the upper‐level divergence attributed to the eastwards propagating wavetrain. However in the wet phase of the 30–45‐day ISO, the anomalous upper‐level divergence was possibly caused by the weaker East Asian trough and the stronger barotropic westerly in subtropics. The 30–45‐day ISO can facilitate the eastwards propagation of the 10–25‐day ISO by providing a benefit upper‐level waveguide. Afterwards, the low‐level southwesterly surrounding the Tibetan Plateau gets enhanced to bring more moisture into South China where the winter flooding was serious in 2015/2016. In contrast, the more‐than‐normal winter rainfall was weaker in the super El Niño of 1997/1998 due to the lack of the 30–45‐day ISO. Therefore, the strongest winter rainfall anomaly over SC was ascribed to the superposition between the wet phases of 10–25 and 30–45‐day ISOs in 2015/2016. [ABSTRACT FROM AUTHOR]

Observations have suggested that the 550‐nm aerosol optical depth (AOD) decreases over East Asia (EA) but increases over eastern United States (EUS) in boreal spring. Based on the NCEP CFSR reanalysis and TRMM 3A25 data set, the present work indicates that this asymmetry can be ascribed to the distinct feedback of general circulation and atmospheric heat source (AHS) between the two regions. In April and May, condensation heating becomes dominant in the AHS over EA and leads to low‐level southerly and upper‐tropospheric northerly flow in response. Subsequently, deep convection with strong ascending motion is generated, which reduces AOD over EA via the effect of vertical ventilation and rainfall‐related washout. Meanwhile, the AHS over EUS is induced by circulation originating from the Tropics and mid–high latitudes. Thus, AOD further increases over EUS due to the absence of vertical ventilation and the import of dust aerosols from EA in the upper troposphere during late spring. Also discussed is the role played by the Tibetan Plateau in this distinct AHS–circulation relationship between EA and EUS. (a) Time series of AOD estimated at 550 nm (red lines) and 950‐hPa meridional wind (blue lines, m/s) over EA (solid lines) and the EUS (dashed lines). (b, c) Pressure–latitude cross section of the AHS (shading, K/day) and meridional circulation (vectors, meridional wind and vertical pressure velocity, see scale at the bottom) averaged over (b) EA (110°–120°E) and (c) the EUS (90°–70°W) in May. [ABSTRACT FROM AUTHOR]

The onset of South China Sea (SCS) summer monsoon (SCSSM) in June 2018 was extremely late following a La Niña event, indicating a breakdown in the traditional positive relationship between ENSO and SCSSM onset. Although the weaker western Pacific subtropical high in early May facilitated the SCSSM establishment, the persistent weaker Mongolian cyclone featured by an anomalous barotropic anticyclone over Northeast Asia during mid–late May dramatically postponed the SCSSM onset in 2018. This not only reduced upper‐tropospheric divergence over the SCS, which suppressed monsoon convection by attenuating the South Asian High, but cooled the mid–upper troposphere to decrease the in‐situ vertical easterly shear. The convection over the Maritime Continent was therefore trapped in the tropics, which further delayed the SCSSM onset via an enhanced local Hadley cell. It suggests a potential effect of triple SSTA mode in North Atlantic on the SCSSM onset by changing the mid‐latitudinal circulation. Plain Language Summary: The onset of South China Sea (SCS) summer monsoon (SCSSM) with large interannual variation, as the indicator of the beginning of the East Asian summer rainy season, has been widely concerned in the seasonal forecast. The ENSO events have been treated as the most important precursor of the SCSSM onset. An El Nino (La Nina) event was usually followed by the late (early) onset of SCSSM. However, this relationship was failed in 2018, when the SCSSM built up extremely late in June after a previous La Nina in the winter of 2017/18. The present work shows an additional potential precursor, the strong positive triple SSTA mode in North Atlantic, is able to delay the onset of SCSSM in 2018 by weakening the Mongolian cyclone in the mid‐high latitude. On the one hand, the weaker Mongolian cyclone could decrease the upper‐level divergence to suppress the convection over the SCS by attenuating the South Asian High. On the other hand, the colder troposphere comes up over the northern SCS to inhibit the in‐situ vertical easterly shear. Thus, the convection over the Maritime Continent is trapped in the tropics to further postpone the SCSSM onset by enhancing a local Hadley cell. Key Points: The La Niña event in the previous winter cannot explain the extremely late onset of the South China Sea summer monsoon (SCSSM) in 2018A persistent weaker Mongolian cyclone and its resultant attenuated South Asian High postponed the SCSSM onset in 2018The triple mode of spring SST anomalies in the North Atlantic may modulate the onset time of the SCSSM [ABSTRACT FROM AUTHOR]

The western Pacific subtropical anticyclone ( WPSA), which bridges the El Niño events and the East Asian summer monsoon, is generally enhanced in boreal summer after El Niño events. However, it becomes weaker in boreal late summer (July-August) of 2016, following the 2015/2016 super El Niño event, indicating failure of the previous experience. Our results suggest that the weaker WPSA in late summer 2016 is associated with the extinction of the Indian Ocean capacitor effect, presenting the cold sea surface temperature anomalies ( SSTAs) in the western tropical Indian Ocean ( WTIO) after the fast decaying of the 2015/2016 super El Niño in spring. Compared with the case in 1982/1983 and 1997/1998, both data analysis and numerical experiments indicate that the cold WTIO SSTAs could induce an anomalous zonal circulation, with its descending branch over the WTIO and the ascending branch over the western North Pacific ( WNP). Afterwards, the thermal structure in the upper troposphere of the WNP is altered to enhance the local wave guide, which facilitate the equatorward propagation of the mid-latitudinal wave train into the WNP. Consequently, the abnormal ascending over the WNP weaken the WPSA in conjunction with the anomaly of the upper-tropospheric cyclone due to the southward intrusion of the wave train during late summer 2016. This implicates the possible influence of El Niño evolution in spring on the WPSA intensity in the subsequent summer. [ABSTRACT FROM AUTHOR]