Tropical precipitation anomalies and d -excess evolution during El Niño 2014-16

2016 ◽  
Vol 31 (4) ◽  
pp. 956-967 ◽  
Author(s):  
Ricardo Sánchez-Murillo ◽  
Ana M. Durán-Quesada ◽  
Christian Birkel ◽  
Germain Esquivel-Hernández ◽  
Jan Boll
Keyword(s):  
El Niño ◽  
El Nino ◽  
Tropical Precipitation ◽  
Precipitation Anomalies

scholarly journals Asymmetric Responses of Tropical Precipitation during ENSO

2007 ◽  
Vol 20 (14) ◽  
pp. 3411-3433 ◽  
Author(s):  
Chia Chou ◽  
Min-Hui Lo
Keyword(s):  
El Niño ◽  
El Nino ◽  
Hadley Circulation ◽  
Eastern Pacific ◽  
Tropospheric Temperature ◽  
Tropical Eastern Pacific ◽  
Low Level ◽  
Tropical Precipitation ◽  
Precipitation Anomalies ◽  
Gross Moist Stability

Abstract In response to the zonally symmetric El Niño–Southern Oscillation forcing, hemispherically asymmetric tropical precipitation anomalies associated with the Hadley circulation are found. In boreal spring after an El Niño peak phase, positive tropical precipitation anomalies occur in the Southern Hemisphere, while negative precipitation anomalies are found in the Northern Hemisphere. This zonal asymmetry is more apparent in the El Niño decaying phase than in the El Niño growing phase. The maximum amplitude of this zonal asymmetry lags one season behind the maximum SST anomalies over the tropical eastern Pacific. This lagged response of the asymmetry is mainly because of the tropical precipitation outside the tropical eastern Pacific, which is associated with the SST and tropospheric temperature anomalies outside the tropical eastern Pacific. A combination of the effect associated with the anomalous gross moist stability and the effect of the horizontal moist static energy (MSE) transport is responsible for the asymmetry. The above effects are associated with the seasonal migration of the Hadley circulation. Warm SST and tropospheric temperature anomalies increase the low-level moisture in the Tropics. In the effect associated with anomalous gross moist stability, the tropical precipitation over the ascending branch of the Hadley circulation is enhanced because of the decrease of effective moist stability, which is induced by the increase of low-level moisture. This enhancement associated with the Hadley circulation reduces the low-level moisture over the descending branch and creates a meridional moisture gradient. In the effect of the horizontal MSE transport, the tropical precipitation anomalies over margins of the ascending branch is reduced by dry advection from the descending branch, which is associated with mean Hadley circulation.

Hemispherical Asymmetry of Tropical Precipitation in ECHAM5/MPI-OM during El Niño and under Global Warming

2008 ◽  
Vol 21 (6) ◽  
pp. 1309-1332 ◽  
Author(s):  
Chia Chou ◽  
Jien-Yi Tu
Keyword(s):  
Global Warming ◽  
El Niño ◽  
El Nino ◽  
Hadley Circulation ◽  
Seasonal Migration ◽  
Boreal Summer ◽  
Max Planck ◽  
Tropical Precipitation ◽  
Precipitation Anomalies ◽  
Precipitation Changes

Abstract Similarities and differences between El Niño and global warming are examined in hemispherical and zonal tropical precipitation changes of the ECHAM5/Max Planck Institute Ocean Model (MPI-OM) simulations. Similarities include hemispherical asymmetry of tropical precipitation changes. This precipitation asymmetry varies with season. In the boreal summer and autumn (winter and spring), positive precipitation anomalies are found over the Northern (Southern) Hemisphere and negative precipitation anomalies are found over the Southern (Northern) Hemisphere. This precipitation asymmetry in both the El Niño and global warming cases is associated with the seasonal migration of the Hadley circulation; however, their causes are different. In El Niño, a meridional moisture gradient between convective and subsidence regions is the fundamental basis for inducing the asymmetry. Over the ascending branch of the Hadley circulation, convection is enhanced by less effective static stability. Over the margins of the ascending branch, convection is suppressed by the import of dry air from the descending branch. In global warming, low-level moisture is enhanced significantly due to warmer tropospheric temperatures. This enhances vertical moisture transport over the ascending branch of the Hadley circulation, so convection is strengthened. Over the descending branch, the mean Hadley circulation tends to transport relatively drier air downward, so convection is reduced.

scholarly journals Eastward shift and extension of ENSO-induced tropical precipitation anomalies under global warming

2020 ◽  
Vol 6 (2) ◽  
pp. eaax4177 ◽  
Author(s):  
Zixiang Yan ◽  
Bo Wu ◽  
Tim Li ◽  
Mat Collins ◽  
Robin Clark ◽  
...  
Keyword(s):  
Global Warming ◽  
El Niño ◽  
El Nino ◽  
Eastern Pacific ◽  
Tropical Precipitation ◽  
Enthalpy Changes ◽  
El Niño Events ◽  
Precipitation Anomalies ◽  
Sst Anomalies ◽  
El Nino Events

During El Niño events, increased precipitation occurs over the equatorial central eastern Pacific, corresponding to enhanced convective heating that modulates global climate by exciting atmospheric teleconnections. These precipitation anomalies are projected to shift and extend eastward in response to global warming. We show that this predicted change is caused by narrowing of the meridional span of the underlying El Niño–related sea surface temperature (SST) anomalies that leads to intensification of the meridional gradient of the SST anomalies, strengthening boundary-layer moisture convergence over the equatorial eastern Pacific, and enhancing local positive precipitation anomalies. The eastward shift and extension of these anomalies also intensify and extend eastward negative precipitation anomalies over the tropical western North Pacific, by strengthening equatorward advection of low mean moist enthalpy. Changes in El Niño–induced tropical precipitation anomalies suggest that, under global warming, El Niño events decay faster after their peak phase, thus shortening their duration.

Future Changes to El Niño Teleconnections over the North Pacific and North America

2021 ◽  
pp. 1-43
Author(s):  
Jonathan D. Beverley ◽  
Matthew Collins ◽  
F. Hugo Lambert ◽  
Robin Chadwick
Keyword(s):  
North America ◽  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Positive Temperature ◽  
Central Pacific ◽  
Wave Source ◽  
The North ◽  
Precipitation Anomalies ◽  
The North Pacific

AbstractThe El Niño-Southern Oscillation (ENSO) is the leading mode of interannual climate variability and it exerts a strong influence on many remote regions of the world, for example in northern North America. Here, we examine future changes to the positive-phase ENSO teleconnection to the North Pacific/North America sector and investigate the mechanisms involved. We find that the positive temperature anomalies over Alaska and northern North America that are associated with an El Niño event in the present day are much weaker, or of the opposite sign, in the CMIP6 abrupt 4×CO2 experiments for almost all models (22 out of 26, of which 15 are statistically significant differences). This is largely related to changes to the anomalous circulation over the North Pacific, rather than differences in the equator-to-pole temperature gradient. Using a barotropic model, run with different background circulation basic states and Rossby wave source forcing patterns from the individual CMIP6 models, we find that changes to the forcing from the equatorial central Pacific precipitation anomalies are more important than changes in the global basic state background circulation. By further decomposing this forcing change into changes associated with the longitude and magnitude of ENSO precipitation anomalies, we demonstrate that the projected overall eastward shift of ENSO precipitation is the main driver of the temperature teleconnection change, rather than the increase in magnitude of El Niño precipitation anomalies which are, nevertheless, seen in the majority of models.

scholarly journals El Niño-Southern Oscillation and Indian Ocean Dipole Modes: Their Effects on South American Rainfall during Austral Spring

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1437
Author(s):  
Mary T. Kayano ◽  
Wilmar L. Cerón ◽  
Rita V. Andreoli ◽  
Rodrigo A. F. Souza ◽  
Itamara P. Souza ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Indian Ocean ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Austral Spring ◽  
Precipitation Anomalies

This paper examines the effects of the tropical Pacific Ocean (TPO) and Indian Ocean Dipole (IOD) modes in the interannual variations of austral spring rainfall over South America (SA). The TPO mode refers to the El Niño-Southern Oscillation (ENSO). The isolated effects between IOD and TPO were estimated, events were chosen from the residual TPO (R-TPO) or residual IOD (R-IOD), and the IOD (TPO) effects for the R-TPO (R-IOD) composites were removed from the variables. One relevant result was the nonlinear precipitation response to R-TPO and R-IOD. This feature was accentuated for the R-IOD composites. The positive R-IOD composite showed significant negative precipitation anomalies along equatorial SA east of 55° W and in subtropical western SA, and showed positive anomalies in northwestern SA and central Brazil. The negative R-IOD composite indicated significant positive precipitation anomalies in northwestern Amazon, central–eastern Brazil north of 20° S, and western subtropical SA, and negative anomalies were found in western SA south of 30° S. This nonlinearity was likely due to the distinct atmospheric circulation responses to the anomalous heating sources located in longitudinally distinct regions: the western tropical Indian Ocean and areas neighboring Indonesia. The results obtained in this study might be relevant for climate monitoring and modeling studies.

scholarly journals CP El Niño and PDO Variability Affect Summer Precipitation over East China

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Wan-Jiao Song ◽  
Qi-Guang Wang
Keyword(s):  
El Niño ◽  
El Nino ◽  
Summer Precipitation ◽  
Western Pacific Subtropical High ◽  
Western Pacific ◽  
Subtropical High ◽  
East China ◽  
Central Pacific ◽  
Cp El Niño ◽  
Precipitation Anomalies

The summer precipitation produced by the East Asian summer monsoon (EASM) is significantly affecting agriculture and socioeconomics. Based on the Precipitation Reconstruction dataset in East China from 1950 to 2017, we investigate the spatiotemporal variations of summer precipitation, influencing environmental factors and their relation with the EASM and the Pacific Decadal Oscillation (PDO) in both central Pacific (CP) El Niño developing and decaying years. Results indicate the following: (1) The evolutions of CP El Niño events modulate the summer precipitation anomalies in East China. In the cool PDO phase, CP El Niño causes enhanced precipitation anomalies in the decaying years but less precipitation anomalies in the developing years, and vice versa for the warm PDO phase. (2) Atmospheric circulation anomalies drive the moisture transportation and combine the motion of western Pacific subtropical high resulting in the variation of precipitation patterns. Anomalous cyclone over the western North Pacific and the sustained Western Pacific Subtropical High (WPSH) are favorable for the increment of summer precipitation. (3) The different CP El Niño-EASM relationship is caused by the influences of PDO on the evolution of CP El Niño. CP El Niño develops slowly (decays rapidly) and is associated with rapidly developing (slowly decaying) anomalous warming in the north Indian Ocean during the developing (decaying) years.

scholarly journals Business experience of floods and drought-related water and electricity supply disruption in three cities in sub-Saharan Africa during the 2015/2016 El Niño

2018 ◽  
Vol 1 ◽  
Author(s):  
Kate Elizabeth Gannon ◽  
Declan Conway ◽  
Joanna Pardoe ◽  
Mukelabai Ndiyoi ◽  
Nnyaladzi Batisani ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Load Shedding ◽  
Sub Saharan Africa ◽  
Supply Disruption ◽  
Capital Cities ◽  
El Niño Event ◽  
Major Disruption ◽  
Precipitation Anomalies ◽  
Sub Saharan

Non-technical summaryThe El Niño event in 2015/2016 was one of the strongest since at least 1950. Through surveys and interviews with key informants, we found businesses in the capital cities of Zambia, Botswana and Kenya experienced major disruption to their activities from El Niño related hydroelectric load shedding, water supply disruption and flooding, respectively. Yet, during the 2015/2016 El Niño, fluctuations in precipitation were not extreme considering the strength of the El Niño event. Results therefore highlight that even fairly moderate precipitation anomalies can contribute to major disruption to economic activity. Addressing the risk of disruption – and supporting the private sector to adapt – is a development priority.

scholarly journals Possible Impact of the Indian Ocean SST on the Northern Hemisphere Circulation during El Niño*

2007 ◽  
Vol 20 (13) ◽  
pp. 3164-3189 ◽  
Author(s):  
H. Annamalai ◽  
H. Okajima ◽  
M. Watanabe
Keyword(s):  
Indian Ocean ◽  
Northern Hemisphere ◽  
El Niño ◽  
El Nino ◽  
Tropical Indian Ocean ◽  
Tropical Pacific ◽  
The Indian Ocean ◽  
Precipitation Anomalies ◽  
Sst Anomalies ◽  
The Tropical Pacific

Abstract Two atmospheric general circulation models (AGCMs), differing in numerics and physical parameterizations, are employed to test the hypothesis that El Niño–induced sea surface temperature (SST) anomalies in the tropical Indian Ocean impact considerably the Northern Hemisphere extratropical circulation anomalies during boreal winter [January–March +1 (JFM +1)] of El Niño years. The hypothesis grew out of recent findings that ocean dynamics influence SST variations over the southwest Indian Ocean (SWIO), and these in turn impact local precipitation. A set of ensemble simulations with the AGCMs was carried out to assess the combined and individual effects of tropical Pacific and Indian Ocean SST anomalies on the extratropical circulation. To elucidate the dynamics responsible for the teleconnection, solutions were sought from a linear version of one of the AGCMs. Both AGCMs demonstrate that the observed precipitation anomalies over the SWIO are determined by local SST anomalies. Analysis of the circulation response shows that over the Pacific–North American (PNA) region, the 500-hPa height anomalies, forced by Indian Ocean SST anomalies, oppose and destructively interfere with those forced by tropical Pacific SST anomalies. The model results validated with reanalysis data show that compared to the runs where only the tropical Pacific SST anomalies are specified, the root-mean-square error of the height anomalies over the PNA region is significantly reduced in runs in which the SST anomalies in the Indian Ocean are prescribed in addition to those in the tropical Pacific. Among the ensemble members, both precipitation anomalies over the SWIO and the 500-hPa height over the PNA region show high potential predictability. The solutions from the linear model indicate that the Rossby wave packets involved in setting up the teleconnection between the SWIO and the PNA region have a propagation path that is quite different from the classical El Niño–PNA linkage. The results of idealized experiments indicate that the Northern Hemisphere extratropical response to Indian Ocean SST anomalies is significant and the effect of this response needs to be considered in understanding the PNA pattern during El Niño years. The results presented herein suggest that the tropical Indian Ocean plays an active role in climate variability and that accurate observation of SST there is of urgent need.

scholarly journals Diversity of East China Summer Rainfall Change in Post-El Niño Summers

2020 ◽  
Vol 8 ◽  
Author(s):  
Wen Zhang ◽  
Xiaoye Zhou ◽  
Pang-Chi Hsu ◽  
Fei Liu
Keyword(s):  
El Niño ◽  
North China ◽  
El Nino ◽  
Summer Rainfall ◽  
La Niña ◽  
East China ◽  
La Nina ◽  
Huaihe River Valley ◽  
Precipitation Anomalies ◽  
Cluster 2

East China has experienced positive precipitation anomalies in post-El Niño summers, mainly in the Yangtze-Huaihe River Valley. This kind of monsoonal rainfall change induced by El Niño, however, is not always the same due to El Niño diversity and mean state change. Here, we use cluster analysis on the post-El Niño (PE) East China summer precipitation anomalies to identify the diversity of this El Niño-induced monsoon change. The result shows that PE East China summer rainfall anomalies mainly display three different modes for all selected 20 El Niño events from 1957 to 2016. Cluster 1 shows the middle and lower reaches of the Yangtze River demonstrate strong wet anomalies, while South and North China are dominated by dry anomalies, similar to a sandwich mode. Cluster 2 is distinguished by dry anomalies over South China and wet anomalies over North China, exhibiting a dipole mode. Compared with Cluster 1, the change caused by Cluster 3 is different, showing negative anomalies over the Yangtze-Huaihe River Valley. The three clusters are correlated with successive events of El Niño, a quick transfer to a strong La Niña and a quick transfer to a weak La Niña respectively. The associated anomalous anticyclone (AAC) focuses on (120°E, 20°N) in Cluster 1, which expands southward for Cluster 2 and moves eastward for Cluster 3. The feedback of AAC-sea surface temperature (SST) mainly works for supporting the AAC in Cluster 1, but it is weak for Cluster 2; the strong easterly anomalies related to La Niña contribute to the AAC location change for Cluster 2. Both AAC-SST feedback and easterly anomalies support the AAC of Cluster 3. The CMIP5 output can capture these diverse responses in circulation except that their simulated AAC for Cluster 1 is significant to the east of the observed.

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