Impact of ENSO on stratospheric ozone

2021 ◽  
Author(s):  
Samuel Benito-Barca ◽  
Natalia Calvo ◽  
Marta Abalos
Keyword(s):  
Climate Model ◽  
Southern Oscillation ◽  
Global Climate ◽  
Stratospheric Ozone ◽  
Boreal Winter ◽  
Residual Circulation ◽  
Central Pacific ◽  
Large Variability ◽  
Enso Events ◽  
Middle Latitudes

<p>El Niño‐Southern Oscillation (ENSO) is the main source of interannual variability in the global climate. Previous studies have shown ENSO has impacts on stratospheric ozone concentrations through changes in stratospheric circulation. The aim of this study is to extend these analysis by examining the anomalies in residual circulation and mixing associated with different El Niño flavors (Eastern Pacific (EP) and Central Pacific (CP)) and La Niña in boreal winter. For this purpose, we use four 60-year ensemble members of the Whole Atmospheric Community Climate Model version 4, reanalysis and satellite data.</p><p>Significant ozone anomalies are identified in both tropics and extratropics. In the northern high-latitudes (70-90N), significant positive ozone anomalies appear in the middle stratosphere in early winter during both CP and EP El Niño, which propagates downward during winter to the lower stratosphere only during EP-El Niño events. Anomalies during La Niña events are opposite to EP-El Niño. The analysis of the different terms in the continuity equation for zonal-mean ozone concentration reveals that Arctic ozone changes during ENSO events  are mainly driven by advection due to residual circulation, although contributions of mixing and chemistry are not negligible, especially in upper stratosphere.</p><p>The ENSO impact on total ozone column (TOC) is also investigated. During EP-El Niño, a significant reduction of TOC appears in the tropics and an increase in the middle latitudes. During La Niña the response is the opposite. The TOC response to CP El Niño events is not as robust. In the Northern Hemisphere polar region the TOC anomalies are not significant, probably due to its large variability associated with sudden stratospheric warmings in this region.</p>

scholarly journals Black Carbon Increases Frequency of Extreme ENSO Events

2019 ◽  
Vol 32 (23) ◽  
pp. 8323-8333 ◽  
Author(s):  
Sijia Lou ◽  
Yang Yang ◽  
Hailong Wang ◽  
Jian Lu ◽  
Steven J. Smith ◽  
...  
Keyword(s):  
Black Carbon ◽  
Climate Models ◽  
Climate Model ◽  
Southern Oscillation ◽  
Global Climate ◽  
Global Climate Model ◽  
Co2 Concentration ◽  
Enso Events ◽  
Aerosol Forcing ◽  
Earth’S Climate

ABSTRACT El Niño–Southern Oscillation (ENSO) is the leading mode of Earth’s climate variability at interannual time scales with profound ecological and societal impacts, and it is projected to intensify in many climate models as the climate warms under the forcing of increasing CO2 concentration. Since the preindustrial era, black carbon (BC) emissions have substantially increased in the Northern Hemisphere. But how BC aerosol forcing may influence the occurrence of the extreme ENSO events has rarely been investigated. In this study, using simulations of a global climate model, we show that increases in BC emissions from both the midlatitudes and Arctic weaken latitudinal temperature gradients and northward heat transport, decrease tropical energy divergence, and increase sea surface temperature over the tropical oceans, with a surprising consequential increase in the frequency of extreme ENSO events. A corollary of this study is that reducing BC emissions might serve to mitigate the possible increasing frequency of extreme ENSO events under greenhouse warming, if the modeling result can be translated into the climate in reality.

scholarly journals Impact of geomagnetic excursions on atmospheric chemistry and dynamics

2014 ◽  
Vol 10 (3) ◽  
pp. 1183-1194 ◽  
Author(s):  
I. Suter ◽  
R. Zech ◽  
J. G. Anet ◽  
T. Peter
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Climate Model ◽  
Global Climate ◽  
Stratospheric Ozone ◽  
Surface Wind ◽  
Galactic Cosmic Rays ◽  
The Arctic ◽  
Boreal Winter ◽  
Austral Winter

Abstract. Geomagnetic excursions, i.e. short periods in time with much weaker geomagnetic fields and substantial changes in the position of the geomagnetic pole, occurred repeatedly in the Earth's history, e.g. the Laschamp event about 41 kyr ago. Although the next such excursion is certain to come, little is known about the timing and possible consequences for the state of the atmosphere and the ecosystems. Here we use the global chemistry climate model SOCOL-MPIOM to simulate the effects of geomagnetic excursions on atmospheric ionization, chemistry and dynamics. Our simulations show significantly increased concentrations of nitrogen oxides (NOx) in the entire stratosphere, especially over Antarctica (+15%), due to enhanced ionization by galactic cosmic rays. Hydrogen oxides (HOx) are also produced in greater amounts (up to +40%) in the tropical and subtropical lower stratosphere, while their destruction by reactions with enhanced NOx prevails over the poles and in high altitudes (by −5%). Stratospheric ozone concentrations decrease globally above 20 km by 1–2% and at the northern hemispheric tropopause by up to 5% owing to the accelerated NOx-induced destruction. A 5% increase is found in the southern lower stratosphere and troposphere. In response to these changes in ozone and the concomitant changes in atmospheric heating rates, the Arctic vortex intensifies in boreal winter, while the Antarctic vortex weakens in austral winter and spring. Surface wind anomalies show significant intensification of the southern westerlies at their poleward edge during austral winter and a pronounced northward shift in spring. Major impacts on the global climate seem unlikely.

scholarly journals Seasonal Gap Theory for ENSO Phase Locking

2021 ◽  
pp. 1-44
Author(s):  
Soong-Ki Kim ◽  
Soon-Il An
Keyword(s):  
Growth Rate ◽  
Large Scale ◽  
Climate Model ◽  
Southern Oscillation ◽  
Global Climate ◽  
Phase Locking ◽  
Global Climate Model ◽  
Coupled Processes ◽  
Single Peak ◽  
Boreal Winter

Abstract The life cycle of El Niño-Southern Oscillation (ENSO) typically follows a seasonal march, onset in spring, developing during summer, maturing in boreal winter, and decaying over the following spring. This feature is referred to as ENSO phase locking. Recent studies have noted that seasonal modulation of the ENSO growth rate is essential for this process. This study investigates the fundamental effect of a seasonally varying growth rate on ENSO phase locking using a modified seasonally-dependent recharge oscillator model. There are two phase locking regimes associated with the strength of the seasonal modulation of growth rate: (1) a weak regime in which only a single peak occurs; and (2) a strong regime in which two types of events occur either with a single peak or double peak. Notably, there is a seasonal gap in the strong regime, during which the ENSO peak cannot occur because of large-scale ocean-atmosphere coupled processes. We also retrieve a simple analytical solution of the seasonal variance of ENSO, revealing that the variance is governed by the time-integral of seasonally varying growth rate. Based on this formulation, we propose a seasonal energy index (SEI) that allows explaining the seasonal gap, and provides an intuitive explanation for ENSO phase locking, potentially applicable to global climate model ENSO diagnostics.

scholarly journals Impact of geomagnetic events on atmospheric chemistry and dynamics

2013 ◽  
Vol 9 (6) ◽  
pp. 6605-6633
Author(s):  
I. Suter ◽  
R. Zech ◽  
J. G. Anet ◽  
T. Peter
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Climate Model ◽  
Global Climate ◽  
Stratospheric Ozone ◽  
Surface Wind ◽  
The Arctic ◽  
Boreal Winter ◽  
Austral Winter ◽  
Heating Rates

Abstract. Geomagnetic events, i.e. short periods in time with much weaker geomagnetic fields and substantial changes in the position of the geomagnetic pole, occurred repeatedly in the Earth's history, e.g. the Laschamp Event about 41 kyr ago. Although the next such event is certain to come, little is known about the timing and possible consequences for the state of the atmosphere and the ecosystems. Here we use the global chemistry climate model SOCOL-MPIOM to simulate the effects of geomagnetic events on atmospheric ionization, chemistry and dynamics. Our simulations show significantly increased concentrations of nitrogen oxides (NOx) in the entire stratosphere, especially over Antarctica (+15%), due to enhanced ionization. Hydrogen oxides (HOx) are also produced in greater amounts (up to +40%) in the tropical and subtropical lower stratosphere, while their destruction by reactions with enhanced NOx prevails over the poles and in high altitudes (by −5%). Stratospheric ozone concentrations decrease globally above 20 km by 1–2% and at the northern hemispheric tropopause by up to 5% owing to the accelerated NOx-induced destruction. A 5% increase is found in the southern lower stratosphere and troposphere. In response to these changes in ozone and the concomitant changes in atmospheric heating rates, the Arctic vortex intensifies in boreal winter, while the Antarctic vortex weakens in austral winter and spring. Surface wind anomalies show significant intensification of the southern westerlies at their poleward edge during austral winter and a pronounced northward shift in spring. This is analogous to today's poleward shift of the westerlies due to the ozone hole. It is challenging to robustly infer precipitation changes from the wind anomalies, and it remains unclear, whether the Laschamp Event could have caused the observed glacial maxima in the southern Central Andes. Moreover, a large impact on the global climate seems unlikely.

Annual, Interannual, and Intraseasonal Variability of Tropical Tropopause Transition Layer Cirrus

2010 ◽  
Vol 67 (10) ◽  
pp. 3097-3112 ◽  
Author(s):  
Katrina S. Virts ◽  
John M. Wallace
Keyword(s):  
Annual Cycle ◽  
El Niño ◽  
Transition Layer ◽  
El Nino ◽  
Southern Oscillation ◽  
Cirrus Clouds ◽  
Boreal Winter ◽  
Central Pacific ◽  
Tropical Tropopause ◽  
The Pacific

Abstract Cloud fields based on the first three years of data from the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission are used to investigate the relationship between cirrus within the tropical tropopause transition layer (TTL) and the Madden–Julian oscillation (MJO), the annual cycle, and El Niño–Southern Oscillation (ENSO). The TTL cirrus signature observed in association with the MJO resembles convectively induced, mixed Kelvin–Rossby wave solutions above the Pacific warm pool region. This signature is centered to the east of the peak convection and propagates eastward more rapidly than the convection; it exhibits a pronounced eastward tilt with height, suggestive of downward phase propagation and upward energy dispersion. A cirrus maximum is observed over equatorial Africa and South America when the enhanced MJO-related convection enters the western Pacific. Tropical-mean TTL cirrus is modulated by the MJO, with more than twice as much TTL cirrus fractional coverage equatorward of 10° latitude when the enhanced convection enters the Pacific than a few weeks earlier, when the convection is over the Indian Ocean. The annual cycle in cirrus clouds around the base of the TTL is equatorially asymmetric, with more cirrus observed in the summer hemisphere. Higher in the TTL, the annual cycle in cirrus clouds is more equatorially symmetric, with a maximum in the boreal winter throughout most of the tropics. The ENSO signature in TTL cirrus is marked by a zonal shift of the peak cloudiness toward the central Pacific during El Niño and toward the Maritime Continent during La Niña.

Correction of monthly SST forecast in CFSv2 using the Local Dynamical Analog method

2021 ◽  
Author(s):  
Zhaolu Hou ◽  
Jianping Li ◽  
Bin Zuo
Keyword(s):  
Climate Model ◽  
Southern Oscillation ◽  
Correction Method ◽  
Forecast Skill ◽  
Forecast Errors ◽  
Model Forecast ◽  
Seasonal Forecasts ◽  
Probability Forecast ◽  
Central Pacific ◽  
Correction Scheme

AbstractNumerical seasonal forecasts in Earth science always contain forecast errors that cannot be eliminated by improving the ability of the numerical model. Therefore, correction of model forecast results is required. Analog-correction is an effective way to reduce model forecast errors, but the key question is how to locate analogs. In this paper, we updated the Local Dynamical Analog (LDA) algorithm to find analogs and depicted the process of model error correction as the LDA-correction scheme. The LDA-correction scheme was firstly applied to correct the operational seasonal forecasts of sea surface temperature (SST) over the period 1982–2018 from the state-of-the-art coupled climate model named NCEP Climate Forecast System version 2.The results demonstrated that the LDA-correction scheme improves forecast skill in many regions as measured by the correlation coefficient and Root Mean Square Error, especially over the extratropical eastern Pacific and tropical Pacific, where the model has high simulation ability. El Niño-Southern Oscillation (ENSO) as the focused physics process is also improved. The seasonal predictability barrier of ENSO is in remission and the forecast skill of Central Pacific ENSO also increases due to the LDA-correction method. The intensity of ENSO mature phases is improved. Meanwhile, the ensemble forecast results are corrected, which proves the positive influence from this LDA-correction scheme on the probability forecast of cold and warm events. Overall, the LDA-correction scheme, combining statistical and model dynamical information, is demonstrated to be readily integrable with other advanced operational models and has the capability to improve forecast results.

The MJO-QBO Relationship in a GCM with Stratospheric Nudging

2021 ◽  
pp. 1-69
Author(s):  
Zane Martin ◽  
Clara Orbe ◽  
Shuguang Wang ◽  
Adam Sobel
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Global Climate Models ◽  
Boreal Winter ◽  
Quasi Biennial Oscillation ◽  
Meridional Winds ◽  
Goddard Institute ◽  
Minimal Bias

AbstractObservational studies show a strong connection between the intraseasonal Madden-Julian oscillation (MJO) and the stratospheric quasi-biennial oscillation (QBO): the boreal winter MJO is stronger, more predictable, and has different teleconnections when the QBO in the lower stratosphere is easterly versus westerly. Despite the strength of the observed connection, global climate models do not produce an MJO-QBO link. Here the authors use a current-generation ocean-atmosphere coupled NASA Goddard Institute for Space Studies global climate model (Model E2.1) to examine the MJO-QBO link. To represent the QBO with minimal bias, the model zonal mean stratospheric zonal and meridional winds are relaxed to reanalysis fields from 1980-2017. The model troposphere, including the MJO, is allowed to freely evolve. The model with stratospheric nudging captures QBO signals well, including QBO temperature anomalies. However, an ensemble of nudged simulations still lacks an MJO-QBO connection.

The relationship between the El Niño Southern Oscillation and Australian monsoon rainfall on decadal time-scales

2021 ◽  
Author(s):  
Hanna Heidemann ◽  
Joachim Ribbe ◽  
Benjamin J. Henley ◽  
Tim Cowan ◽  
Christa Pudmenzky ◽  
...  
Keyword(s):  
Monsoon Rainfall ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Eastern Pacific ◽  
Central Pacific ◽  
Australian Monsoon ◽  
Enso Events ◽  
Pacific Decadal Variability ◽  
Prediction Systems ◽  
Different Response

<p>This research analyses the observed relationship between eastern and central Pacific El Niño Southern Oscillation (ENSO) events and Australian monsoon rainfall (AUMR) on a decadal timescale during the December to March monsoon months. To assess the decadal influence of the different flavours of ENSO on the AUMR, we focus on the phases of the Interdecadal Pacific Oscillation (IPO) over the period 1920 to 2020.  The AUMR is characterized by substantial decadal variability, which appears to be linked to the positive and negative phases of the IPO. During the past two historical negative IPO phases, significant correlations have been observed between central Pacific sea surface temperature (SST) anomalies and AUMR over both the northeast and northwest of Australia. This central Pacific SST-AUMR relationship has strengthened from the first negative IPO phase (mid-1940s to the mid-1970s) to the second (late 1990s to mid-2010s), while the eastern Pacific SST-AUMR influence has weakened. Composite rainfall anomalies over Australia reveal a different response of AUMR to central Pacific El Niño/La Niña and eastern Pacific La Niña events during positive IPO and negative IPO phases. This research clearly shows that ENSO's influence on AUMR is modulated by Pacific decadal variability, however this teleconnection, in itself, can change between similar decadal Pacific states.  Going forward, as decadal prediction systems improve and become more mainstream, the IPO phase could be used as a potential source for decadal predictability of the tendency of AUMR.  </p>

scholarly journals Influence of Arctic Stratospheric Ozone on Surface Climate in CCMI models

2018 ◽  
Author(s):  
Ohad Harari ◽  
Chaim I. Garfinkel ◽  
Olaf Morgenstern ◽  
Guang Zeng ◽  
Simone Tilmes ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Climate Model ◽  
Southern Oscillation ◽  
Stratospheric Ozone ◽  
Internal Variability ◽  
Tropical Circulation ◽  
Polar Cap ◽  
Sea Level Pressure ◽  
Surface Climate ◽  
Stratospheric Variability

Abstract. The Northern Hemisphere and tropical circulation response to interannual variability in Arctic stratospheric ozone is analyzed in a set of the latest model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project. All models simulate a connection between ozone variability and temperature/geopotential height in the lower stratosphere similar to that observed. A connection between Arctic ozone variability and polar cap sea-level pressure is also found, but additional analysis suggests that it is mediated by the dynamical variability that typically drives the anomalous ozone concentrations. The CCMI models also show a connection between Arctic stratospheric ozone and the El Nino Southern Oscillation (ENSO): the CCMI models show a tendency of Arctic stratospheric ozone variability to lead ENSO variability one to two years later. While this effect is much weaker than that observed, it is still statistically significant. Overall, Arctic stratospheric ozone is related to lower stratospheric variability and may also influence the surface in both polar and tropical latitudes, though these impacts can be masked by internal variability if data is only available for ~ 40 years.

scholarly journals Northern winter stratospheric temperature and ozone responses to ENSO inferred from an ensemble of Chemistry Climate Models

2009 ◽  
Vol 9 (22) ◽  
pp. 8935-8948 ◽  
Author(s):  
C. Cagnazzo ◽  
E. Manzini ◽  
N. Calvo ◽  
A. Douglass ◽  
H. Akiyoshi ◽  
...  
Keyword(s):  
Climate Models ◽  
Southern Oscillation ◽  
Polar Vortex ◽  
Atmospheric Modeling ◽  
Residual Circulation ◽  
Model Simulations ◽  
Enso Events ◽  
Stratospheric Temperature ◽  
The Mean ◽  
Column Ozone

Abstract. The connection between the El Niño Southern Oscillation (ENSO) and the Northern polar stratosphere has been established from observations and atmospheric modeling. Here a systematic inter-comparison of the sensitivity of the modeled stratosphere to ENSO in Chemistry Climate Models (CCMs) is reported. This work uses results from a number of the CCMs included in the 2006 ozone assessment. In the lower stratosphere, the mean of all model simulations reports a warming of the polar vortex during strong ENSO events in February–March, consistent with but smaller than the estimate from satellite observations and ERA40 reanalysis. The anomalous warming is associated with an anomalous dynamical increase of column ozone north of 70° N that is accompanied by coherent column ozone decrease in the Tropics, in agreement with that deduced from the NIWA column ozone database, implying an increased residual circulation in the mean of all model simulations during ENSO. The spread in the model responses is partly due to the large internal stratospheric variability and it is shown that it crucially depends on the representation of the tropospheric ENSO teleconnection in the models.

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