The relationship between ENSO events and California streamflows

1992 ◽  
Author(s):  
Ercan Kahya ◽  
John A. Dracup
Keyword(s):  
Enso Events ◽  
The Relationship

The Importance of Central Pacific Meridional Heat Advection to the Development of ENSO

2021 ◽  
pp. 1-59
Author(s):  
Caihong Wen ◽  
Arun Kumar ◽  
Michelle L’ Heureux ◽  
Yan Xue ◽  
Emily Becker
Keyword(s):  
Water Volume ◽  
Primary Role ◽  
Equatorial Pacific Ocean ◽  
Central Pacific ◽  
Enso Prediction ◽  
Enso Events ◽  
Ocean Reanalyses ◽  
Equatorial Thermocline ◽  
Warm Water Volume ◽  
The Relationship

AbstractThe relationship between the Warm Water Volume (WWV) ENSO precursor and ENSO SST weakened substantially after ~2000, coinciding with a degradation in dynamical model ENSO prediction skill. It is important to understand the drivers of the equatorial thermocline temperature variations and their linkage to ENSO onsets. In this study, a set of ocean reanalyses is employed to assess factors responsible for the variation of the equatorial Pacific Ocean thermocline during 1982-2019. Off-equatorial thermocline temperature anomalies carried equatorward by the mean meridional currents associated with Pacific Tropical Cells are shown to play an important role in modulating the central equatorial thermocline variations, which is rarely discussed in the literature. Further, ENSO events are delineated into two groups based on precursor mechanisms: the western equatorial type (WEP) ENSO, when the central equatorial thermocline is mainly influenced by the zonal propagation of anomalies from the western Pacific, and the off-equatorial central Pacific (OCP) ENSO, when off-equatorial central thermocline anomalies play the primary role. WWV is found to precede all WEP ENSO by 6-9 months, while the correlation is substantially lower for OCP ENSO events. In contrast, the central tropical Pacific (CTP) precursor, which includes off-equatorial thermocline signals, has a very robust lead correlation with the OCP ENSO. Most OCP ENSO events are found to follow the same ENSO conditions, and the number of OCP ENSO increases substantially since the 21st century. These results highlight the importance of monitoring off-equatorial subsurface preconditions for ENSO prediction and to understand multi-year ENSO.

Composite Analysis of the Effects of ENSO Events on Antarctica

2016 ◽  
Vol 29 (5) ◽  
pp. 1797-1808 ◽  
Author(s):  
Lee J. Welhouse ◽  
Matthew A. Lazzara ◽  
Linda M. Keller ◽  
Gregory J. Tripoli ◽  
Matthew H. Hitchman
Keyword(s):  
El Niño ◽  
Geopotential Height ◽  
El Nino ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
La Niña ◽  
Austral Spring ◽  
Enso Events ◽  
La Nina ◽  
The Relationship

Abstract Previous investigations of the relationship between El Niño–Southern Oscillation (ENSO) and the Antarctic climate have focused on regions that are impacted by both El Niño and La Niña, which favors analysis over the Amundsen and Bellingshausen Seas (ABS). Here, 35 yr (1979–2013) of European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim) data are analyzed to investigate the relationship between ENSO and Antarctica for each season using a compositing method that includes nine El Niño and nine La Niña periods. Composites of 2-m temperature (T2m), sea level pressure (SLP), 500-hPa geopotential height, sea surface temperatures (SST), and 300-hPa geopotential height anomalies were calculated separately for El Niño minus neutral and La Niña minus neutral conditions, to provide an analysis of features associated with each phase of ENSO. These anomaly patterns can differ in important ways from El Niño minus La Niña composites, which may be expected from the geographical shift in tropical deep convection and associated pattern of planetary wave propagation into the Southern Hemisphere. The primary new result is the robust signal, during La Niña, of cooling over East Antarctica. This cooling is found from December to August. The link between the southern annular mode (SAM) and this cooling is explored. Both El Niño and La Niña experience the weakest signal during austral autumn. The peak signal for La Niña occurs during austral summer, while El Niño is found to peak during austral spring.

scholarly journals Modulation of the Relationship between ENSO and Its Combination Mode by the Atlantic Multidecadal Oscillation

2020 ◽  
Vol 33 (11) ◽  
pp. 4679-4695 ◽  
Author(s):  
Xin Geng ◽  
Wenjun Zhang ◽  
Fei-Fei Jin ◽  
Malte F. Stuecker ◽  
Aaron F. Z. Levine
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
Circulation Model ◽  
Atlantic Multidecadal Oscillation ◽  
Climate Impacts ◽  
Enso Events ◽  
Combination Mode ◽  
The Relationship

AbstractRecent studies demonstrated the existence of a conspicuous atmospheric combination mode (C-mode) originating from nonlinear interactions between El Niño–Southern Oscillation (ENSO) and the Pacific warm pool annual cycle (AC). Here we find that the C-mode exhibits prominent decadal amplitude variations during the ENSO decaying boreal spring season. It is revealed that the Atlantic multidecadal oscillation (AMO) can largely explain this waxing and waning in amplitude. A robust positive correlation between ENSO and the C-mode is detected during a negative AMO phase but not during a positive phase. Similar results can also be found in the relationship of ENSO with 1) the western North Pacific (WNP) anticyclone and 2) spring precipitation over southern China, both of which are closely associated with the C-mode. We suggest that ENSO property changes due to an AMO modulation play a crucial role in determining these decadal shifts. During a positive AMO phase, ENSO events are distinctly weaker than those in an AMO negative phase. In addition, El Niño events concurrent with a positive AMO phase tend to exhibit a westward-shifted sea surface temperature (SST) anomaly pattern. These SST characteristics during the positive AMO phase are both not conducive to the development of the meridionally asymmetric C-mode atmospheric circulation pattern and thus reduce the ENSO/C-mode correlation on decadal time scales. These observations can be realistically reproduced by a coupled general circulation model (CGCM) experiment in which North Atlantic SSTs are nudged to reproduce a 50-yr sinusoidally varying AMO evolution. Our conclusion carries important implications for understanding seasonally modulated ENSO dynamics and multiscale climate impacts over East Asia.

scholarly journals Interactions of ENSO, the IOD, and the SAM in CMIP3 Models

2011 ◽  
Vol 24 (6) ◽  
pp. 1688-1704 ◽  
Author(s):  
Wenju Cai ◽  
Arnold Sullivan ◽  
Tim Cowan
Keyword(s):  
Southern Oscillation ◽  
Global Climate ◽  
Coupled Model ◽  
Southern Annular Mode ◽  
Enso Events ◽  
Intercomparison Project ◽  
Wave Trains ◽  
Induced Signal ◽  
The Impact ◽  
The Relationship

Abstract Simulations of individual global climate drivers using models from the Coupled Model Intercomparison Project phase 3(CMIP3) have been examined; however, the relationship among them has not been assessed. This is carried out to address several important issues, including the likelihood of the southern annular mode (SAM) forcing Indian Ocean dipole (IOD) events and the possible impact of the IOD on El Niño–Southern Oscillation (ENSO) events. Several conclusions emerge from statistics based on multimodel outputs. First, ENSO signals project strongly onto the SAM, although ENSO-forced signals tend to peak before ENSO. This feature is similar to the situation associated with the IOD. The IOD-induced signal over southern Australia, through stationary equivalent Rossby barotropic wave trains, peak before the IOD itself. Second, there is no control by the SAM on the IOD, in contrast to what has been suggested previously. Indeed, no model produces a SAM–IOD relationship that supports a positive (negative) SAM driving a positive (negative) IOD event. This is the case even in models that do not simulate a statistically significant relationship between ENSO and the IOD. Third, the IOD does have an impact on ENSO. The relationship between ENSO and the IOD in the majority of models is far weaker than the observed. However, the ENSO’s influence on the IOD is boosted by a spurious oceanic teleconnection, whereby ENSO discharge–recharge signals transmit to the Sumatra–Java coast, generating thermocline anomalies and changing IOD properties. Without the spurious oceanic teleconnection, the influence of the IOD on ENSO is comparable to the impact of ENSO on the IOD. Other model deficiencies are discussed.

scholarly journals A re-examination of ENSO/ anti-ENSO events and simultaneous performance of the Indian summer monsoon

MAUSAM ◽  
2021 ◽  
Vol 47 (1) ◽  
pp. 59-66
Author(s):  
J. CHATTOPADHYAY ◽  
R. BHATLA
Keyword(s):  
Monsoon Rainfall ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Strong Association ◽  
Enso Events ◽  
The Pacific ◽  
Degree Of Confidence ◽  
High Degree ◽  
The Relationship ◽  
Very High

The relationship between ENSO/anti-ENSO events in the Pacific basin and simultaneous all India monsoon has been re-examined for the period 1901-1990 using Southern Oscillation Index (SOI). The result shows that there is fairly strong association between ENSO events and dry monsoon years. There exists a weak teleconnection between anti-ENSO events and wet monsoon indicating that anti-ENSO events have only a moderate impact on the Indian monsoon rainfall. Developing ENSO (anti-ENSO) episodes during the monsoon season indicates non-occurrence of simultaneous floods (droughts) with a very high degree of confidence 70 (50) percent of the droughts (floods) during the above period have occurred during ENSO (anti-ENSO) events indicating that extreme monsoon activities in the form of droughts (floods) might be important factors for the occurrence of simultaneous ENSO/anti-ENSO events.

scholarly journals North Atlantic Winter SLP Anomalies Based on the Autumn ENSO State

2005 ◽  
Vol 18 (1) ◽  
pp. 97-103 ◽  
Author(s):  
D. Pozo-Vázquez ◽  
S. R. Gámiz-Fortis ◽  
J. Tovar-Pescador ◽  
M. J. Esteban-Parra ◽  
Y. Castro-DÍez
Keyword(s):  
Northern Hemisphere ◽  
North Atlantic ◽  
Enso Event ◽  
Sea Level Pressure ◽  
Enso Events ◽  
The North ◽  
Nao Index ◽  
North Atlantic Climate ◽  
The North Atlantic ◽  
The Relationship

Abstract The winter sea level pressure (SLP) anomalies in the Northern Hemisphere have been analyzed over the period 1873–2000 based on the ENSO state during the previous autumn. First, a set of extreme cold and warm ENSO events and periods that may be regarded as normal is selected using the SST data of the Niño-3 region. This selection is carried out for autumn and with the constraint that the ENSO event is well developed. For the winters following these selected autumn events, composites of Northern Hemisphere SLP anomalies have been obtained and compared to each other. A study of the consistency among events of the relationship between ENSO and SLP anomalies was also carried out. Results show the preference for a positive NAO-like SLP anomaly pattern in the North Atlantic region during the winters following autumns of strong cold ENSO events and, thus, suggest the existence of a potential source of predictability for the North Atlantic climate. An additional analysis of the winter North Atlantic Oscillation (NAO) index confirms this finding. The possible physical basis of this source of predictability for the North Atlantic climate is discussed.

The Relationship between California Rainfall and ENSO Events

1989 ◽  
Vol 2 (11) ◽  
pp. 1258-1269 ◽  
Author(s):  
T. Schonher ◽  
S. E. Nicholson
Keyword(s):  
Enso Events ◽  
The Relationship
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