scholarly journals Cause of Extreme Heavy and Persistent Rainfall over Yangtze River in Summer 2020

2021 ◽  
Author(s):  
Xiao Pan ◽  
Tim Li ◽  
Ying Sun ◽  
Zhiwei Zhu
Keyword(s):  
High Pressure ◽  
El Niño ◽  
Yangtze River ◽  
El Nino ◽  
Northeast Asia ◽  
La Niña ◽  
Cp El Niño ◽  
La Nina ◽  
Pressure Anomaly ◽  
Heating Anomaly

AbstractRecord-breaking heavy and persistent precipitation occurred over the Yangtze River Valley (YRV) in June–July (JJ) 2020. An observational data analysis has indicated that the strong and persistent rainfall arose from the confluence of southerly wind anomalies to the south associated with an extremely strong anomalous anticyclone over the western North Pacific (WNPAC) and northeasterly anomalies to the north associated with a high-pressure anomaly over Northeast Asia. A further observational and modeling study has shown that the extremely strong WNPAC was caused by both La Niña-like SST anomaly (SSTA) forcing in the equatorial Pacific and warm SSTA forcing in the tropical Indian Ocean (IO). Different from conventional central Pacific (CP) El Niños that decay slowly, a CP El Niño in early 2020 decayed quickly and became a La Niña by early summer. This quick transition had a critical impact on the WNPAC. Meanwhile, an unusually large area of SST warming occurred in the tropical IO because a moderate interannual SSTA over the IO associated with the CP El Niño was superposed by an interdecadal/long-term trend component. Numerical sensitivity experiments have demonstrated that both the heating anomaly in the IO and the heating anomaly in the tropical Pacific contributed to the formation and maintenance of the WNPAC. The persistent high-pressure anomaly in Northeast Asia was part of a stationary Rossby wave train in the midlatitudes, driven by combined heating anomalies over India, the tropical eastern Pacific, and the tropical Atlantic.

scholarly journals The influence of interannual and decadal Indo-Pacific sea surface temperature variability on Australian monsoon rainfall

2021 ◽  
pp. 1-58
Author(s):  
Hanna Heidemann ◽  
Joachim Ribbe ◽  
Tim Cowan ◽  
Benjamin J. Henley ◽  
Christa Pudmenzky ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Sea Surface ◽  
Northern Australia ◽  
Central Pacific ◽  
Cp El Niño ◽  
La Nina

AbstractMonsoonal rainfall varies substantially in Northern Australia (AUMR) on interannual, decadal and longer time scales, profoundly impacting natural systems and agricultural communities. Some of this variability arises in response to sea surface temperature (SST) variability in the Indo-Pacific linked to both the El Niño-Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). Here we use observations to investigate unresolved issues regarding the influence of the IPO and ENSO on AUMR. Specifically, we show that during negative IPO phases, central Pacific (CP) El Niño events are associated with below average rainfall over northeast Australia, an anomalous anticyclonic pattern to the northwest of Australia, and eastward moisture advection towards the Dateline. In contrast, CP La Niña events (distinct from eastern Pacific La Niña events) during negative IPO phases drive significantly wet conditions over much of northern Australia, a strengthened Walker Circulation, and large-scale moisture flux convergence. During positive IPO phases, the impact of CP El Niño and CP La Niña events on AUMR is weaker. The influence of central Pacific SSTs on AUMR has been stronger during the recent (post-1999) negative IPO phase. The extent to which this strengthening is associated with climate change or merely natural, internal variability is not known.

scholarly journals Cold Season Southwest Asia Precipitation Sensitivity to El Niño–Southern Oscillation Events

2018 ◽  
Vol 31 (11) ◽  
pp. 4463-4482 ◽  
Author(s):  
Andrew Hoell ◽  
Mathew Barlow ◽  
Taiyi Xu ◽  
Tao Zhang
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Eastern Indian Ocean ◽  
El Nino Southern Oscillation ◽  
Southwest Asia ◽  
Cp El Niño ◽  
La Nina

Abstract The sensitivity of southwest Asia (25°–40°N, 40°–70°E) precipitation during the November–April rainy season to four types of El Niño–Southern Oscillation (ENSO) events, eastern Pacific (EP) and central Pacific (CP) El Niño and La Niña, is assessed using an ensemble of atmospheric model simulations forced by 1979–2015 boundary conditions. Sensitivity is assessed in terms of 1) the spread of precipitation across the ensemble members around the ensemble mean, 2) the probability of precipitation falling into the upper and lower terciles of the historical distribution, and 3) the relationship between the tropical atmosphere and southwest Asia precipitation during ENSO. During CP La Niña, the magnitude of the below-average mean precipitation exceeds the magnitude of the precipitation spread, thereby conditioning the probability of lower-tercile southwest Asia precipitation to greater than 70%. By contrast, EP La Niña does not alter the odds of southwest Asia precipitation terciles, as the magnitude of the near-zero mean precipitation is overwhelmed by the magnitude of the precipitation spread. EP and CP El Niño similarly result in above-average mean precipitation whose magnitude approaches the magnitude of the precipitation spread, thereby conditioning the probability of upper-tercile southwest Asia precipitation to around 50% region-wide. However, the notable effect of the precipitation spread during El Niño allows for a 20%–30% probability that the regional precipitation falls into the lower tercile. ENSO types simultaneously modify the probability of eastern Indian Ocean precipitation and southwest Asia precipitation, supporting the hypothesis that the tropical eastern Indian Ocean atmosphere serves as the medium by which ENSO forcing is communicated to southwest Asia.

scholarly journals Different El Niño Types and Tropical Cyclone Landfall in East Asia

2012 ◽  
Vol 25 (19) ◽  
pp. 6510-6523 ◽  
Author(s):  
Wei Zhang ◽  
H.-F. Graf ◽  
Yee Leung ◽  
Michael Herzog
Keyword(s):  
Tropical Cyclone ◽  
East Asia ◽  
El Niño ◽  
El Nino ◽  
The Philippines ◽  
La Niña ◽  
Malay Peninsula ◽  
Cp El Niño ◽  
La Nina ◽  
Ep El Niño

Abstract This study examines whether there exist significant differences in tropical cyclone (TC) landfall between central Pacific (CP) El Niño, eastern Pacific (EP) El Niño, and La Niña during the peak TC season (June–October) and how and to what extent CP El Niño influences TC landfall over East Asia for the period 1961–2009. The peak TC season is subdivided into summer [June–August (JJA)] and autumn [September–October (SO)]. The results are summarized as follows: (i) during the summer of CP El Niño years, TCs are more likely to make landfall over East Asia because of a strong easterly steering flow anomaly induced by the westward shift of the subtropical high and northward-shifted TC genesis. In particular, TCs have a greater probability of making landfall over Japan and Korea during the summer of CP El Niño years. (ii) In the autumn of CP El Niño years, TC landfall in most areas of East Asia, especially Indochina, the Malay Peninsula, and the Philippines, is likely to be suppressed because the large-scale circulation resembles that of EP El Niño years. (iii) During the whole peak TC season [June–October (JJASO)] of CP El Niño years, TCs are more likely to make landfall over Japan and Korea. TC landfall in East Asia as a whole has an insignificant association with CP El Niño during the peak TC season. In addition, more (less) TCs are likely to make landfall in China, Indochina, the Malay Peninsula, and the Philippines during the peak TC season of La Niña (EP El Niño) years.

scholarly journals The asymmetric response of Yangtze river basin summer rainfall to El Niño/La Niña

2018 ◽  
Vol 13 (2) ◽  
pp. 024015 ◽  
Author(s):  
Steven C Hardiman ◽  
Nick J Dunstone ◽  
Adam A Scaife ◽  
Philip E Bett ◽  
Chaofan Li ◽  
...  
Keyword(s):  
River Basin ◽  
El Niño ◽  
Yangtze River ◽  
El Nino ◽  
Yangtze River Basin ◽  
Summer Rainfall ◽  
La Niña ◽  
La Nina ◽  
Asymmetric Response

scholarly journals Different influencing mechanisms of two ENSO types on the interannual variation in diurnal SST over the Niño 3 and 4 regions

2021 ◽  
pp. 1-47
Author(s):  
XIAODAN YANG ◽  
YAJUAN SONG ◽  
MENG WEI ◽  
YUHUAN XUE ◽  
ZHENYA SONG
Keyword(s):  
El Niño ◽  
Interannual Variation ◽  
El Nino ◽  
Southern Oscillation ◽  
Equatorial Pacific ◽  
La Niña ◽  
Trade Wind ◽  
Enso Events ◽  
Cp El Niño ◽  
La Nina

AbstractIn this paper, the different effects of the eastern equatorial Pacific (EP) and central equatorial Pacific (CP) El Niño-Southern Oscillation (ENSO) events on interannual variation in the diurnal sea surface temperature (SST) are explored in both the Niño 3 and Niño 4 regions. In the Niño 3 region, the diurnal SST anomaly (DSSTA) is negative during both EP and CP El Niño events and becomes positive during both EP and CP La Niña events. However, the DSSTA in the Niño 4 region is positive in El Niño years and negative in La Niña years, which is opposite to that in the Niño 3 region. Further analysis indicates that the incident shortwave radiation (SWR), wind stress (WS), and upward latent heat flux (LHF) are the main factors causing the interannual variation in the DSST. In the Niño 3 region, the decreased/increased SWR and the increased (decreased) LHF lead to the negative (positive) DSSTA in EP El Niño (La Niña) years. In addition, the enhanced (reduced) WS and the increased (decreased) LHF cause the negative (positive) DSSTA in CP El Niño (La Niña) years. In the Niño 4 region, the reduced (enhanced) trade wind plays a key role in producing in the positive (negative) DSSTA, while the decreased (increased) SWR has an opposite effect that reduces/increases the range of the DSSTA during both EP and CP El Niño (La Niña) events.

scholarly journals Why Does the CP El Niño less Frequently Evolve Into La Niña than the EP El Niño?

2020 ◽  
Vol 47 (15) ◽  
Author(s):  
Shan He ◽  
Jin‐Yi Yu ◽  
Song Yang ◽  
Shih‐Wei Fang
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Cp El Niño ◽  
La Nina ◽  
Ep El Niño

scholarly journals The 10–20 d Low-Frequency Oscillation Characteristics of Summer Precipitation in Eastern China in the Decaying Year of CP ENSO

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 616
Author(s):  
Cong Cai ◽  
Lijuan Wang ◽  
Junyu Wang ◽  
Zhiqiang Wang
Keyword(s):  
El Niño ◽  
El Nino ◽  
Eastern China ◽  
Low Frequency ◽  
Summer Precipitation ◽  
La Niña ◽  
Low Frequency Oscillation ◽  
Cp El Niño ◽  
La Nina ◽  
Oscillation Characteristics

Using National Centers for Atmospheric Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data and observational data, the low-frequency oscillation characteristics of precipitation in eastern China during the decaying summer of central Pacific El Niño–Southern Oscillation (CP ENSO) and the corresponding low-frequency atmospheric oscillation characteristic were investigated. The results showed that summer precipitation in eastern China during the decaying year of CP El Niño (La Niña) was more (less) than the climatological mean and that 10–20 d was its dominant period. Low-frequency oscillations at different tropospheric levels had different effects on low-frequency precipitation. In the upper troposphere, Eastern China was dominated by low-frequency divergence and positive (negative) anomaly of low-frequency height during the decaying year of CP El Niño (La Niña), and there was strong (weak) northwest–southeast wave-active flux transport. In the middle troposphere, the range and intensity of the subtropical western Pacific High (SWPH) of CP El Niño was larger and stronger than that of CP La Niña, which may be related to the low-frequency height fields. Meanwhile, the correspnding low-frequency wind field, water vapor circulation systems and moisture transport channels in the lower troposphere, along with the low-frequency vertical movement were significantly different, causing the low-frequency precipitation of CP El Niño to be stronger than CP La Niña.

scholarly journals Mechanisms determining diversity of ENSO-driven equatorial precipitation anomalies

2021 ◽  
pp. 1-47
Keyword(s):  
El Niño ◽  
El Nino ◽  
Longwave Radiation ◽  
Walker Circulation ◽  
Precipitation Anomaly ◽  
La Niña ◽  
Central Pacific ◽  
Cp El Niño ◽  
La Nina ◽  
Precipitation Anomalies

Abstract The longitudinal location of precipitation anomalies over the equatorial Pacific shows a distinctive feature with the westernmost location for La Niña, the easternmost location for eastern-Pacific (EP) El Niño and somewhere between for central-Pacific (CP) El Niño, even though the center of the sea surface temperature anomaly (SSTA) for La Niña is located slightly east of that of CP El Niño. The mechanisms for such a precipitation diversity were investigated through idealized model simulations and moisture and moist static energy budget analyses. It is revealed that the boundary layer convergence anomalies associated with the precipitation diversity are mainly induced by underlying SSTA through the Lindzen-Nigam mechanism, that is, their longitudinal locations are mainly controlled by the meridional and zonal distributions of the ENSO SSTA. The westward shift of the precipitation anomaly center during La Niña relative to that during CP El Niño is primarily caused by the combined effects of nonlinear zonal moist enthalpy advection anomalies and the Lindzen-Nigam mechanism mentioned above. Such a zonal diversity is further enhanced by the “convection-cloud-longwave radiation” feedback, the SST-induced latent heat flux anomalies and the advection of mean moist enthalpy by anomalous winds. This diversity in the longitudinal location of precipitation anomalies has contributions to the diversities in the longitudinal locations of anomalous Walker Circulation and western North Pacific anomalous anticyclone/cyclone among the three types of ENSO.

ANALISIS DAERAH RAWAN KEKERINGAN LAHAN JAGUNG BERDASARKAN IKLIM OLDEMAN DAN KETERSEDIAN AIR TANAH DI NUSA TENGGARA TIMUR SAAT PERIODE EL NINO DAN LA NINA

2019 ◽  
Vol 3 ◽  
pp. 1219
Author(s):  
Oki Adrianto ◽  
Sudirman Sudirman ◽  
Suwandi Suwandi
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
La Nina

Perekonomian Provinsi Nusa Tenggara Timur secara sektoral masih didominasi sektor pertanian.Tanaman jagung menjadi salah satu produksi tanaman pangan terbesar berdasarkan data dari Dinas Pertanian dan Perkebunan Provinsi Nusa Tenggara Timur tahun 2015. Peningkatan produksi pertanian dapat dilakukan melalui berbagai strategi adaptasi dan upaya penanganan bencana, salah satu upaya tersebut adalah dengan penyediaan informasi iklim terkait penentuan daerah-daerah rawan kekeringan. Tujuan dari penelitian ini adalah untuk mengetahui sebaran wilayah rawan kekeringan lahan jagung bulanan di Provinsi Nusa Tenggara Timur saat kondisi El Nino dan La Nina dengan periodeisasi bulanan januari hingga desember. Data yang digunakan dalam penelitian ini adalah data curah hujan rata rata bulanan di 19 pos hujan di Provinsi Nusa Tenggara Timur dan suhu udara rata-rata bulanan dihitung menggunakan pendekatan teori Brack dengan titik referensi Stasiun Klimatologi Lasiana Kupang. Periode dari masing-masing data yang digunakan adalah dari tahun 1991 dan 1997 digunakan sebagai tahun El Nino dan tahun 1999 dan 2010 digunakan sebagai tahun La Nina. Metode yang digunakan untuk menentukan tingkat rawan kekeringan dengan menggunakan pembobotan berdasarkan penjumlahan bobot tipe iklim Oldeman dan bobot ketersediaan air tanah. Hasil penelitian menunjukkan sebaran daerah kekeringan di Provinsi Nusa Tenggara Timurpada tahun el nino lebih luas dibandingkan tahun la nina.

A Influência dos fenômenos El Niño e La Niña sobre a dinâmica climática da região Amazônica

2018 ◽  
Vol 1 ◽  
pp. e2018014
Author(s):  
Samya de Freitas MOREIRA ◽  
Cleiciane Silva da CONCEIÇÃO ◽  
Milla Cristina Santos da CRUZ ◽  
Antônio PEREIRA JÚNIOR
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
La Nina
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