The Role of an Indian Ocean Heating Dipole in the ENSO Teleconnection to the North Atlantic European Region in Early Winter during the Twentieth Century in Reanalysis and CMIP5 Simulations

Joshi, Manish K.; Abid, Muhammad Adnan; Kucharski, Fred

doi:10.1175/jcli-d-20-0269.1

Cited by 24 publications

(24 citation statements)

References 67 publications

(62 reference statements)

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“…After many decades of research, interest in ENSO teleconnections in the North Atlantic remains high and new results continue to appear (e.g., recent review by Domeisen et al, 2019). A number of recent studies have contributed to the continuous improvement in understanding the mechanisms behind the ENSO teleconnection to the North Atlantic, including details about how the late-fall signal may arise from an atmospheric bridge via the tropical Atlantic (Ayarzagüena et al, 2018;King et al, 2018a) or diabatic heating over the Indian Ocean (Abid et al, 2021;Joshi et al, 2021). Such studies (and Molteni et al, 2020) have also found that "freerunning" coupled model or SST-forced atmospheric model experiments do not, or only weakly, reproduce the ENSO teleconnection to the North Atlantic through the cold season, while initialized hindcasts perform better.…”

Section: Discussionmentioning

confidence: 99%

“…Ayarzagüena et al (2018) suggest that Rossby wave propagation in the troposphere excited by atmospheric diabatic heating (a result of latent heating related to precipitation) in the western tropical Atlantic is responsible for the November-December teleconnection. The late-fall response may also be modulated by SST forcing from the tropical west Pacific (Bladé et al, 2008) or atmospheric diabatic heating over the Indian Ocean, which is itself amplified by ENSO (Abid et al, 2021;Joshi et al, 2021). A number of studies (Ayarzagüena et al, 2018;Joshi et al, 2021;King et al, 2018a;Molteni et al, 2020) report that models are generally able to simulate the varying teleconnection to the North Atlantic from November through February in initialized hindcasts, while "freerunning" coupled-model experiments have less success, producing an NAO-like pattern similar to the observed latewinter teleconnection through all these months with at best a weak signature of the transition.…”

Section: Introductionmentioning

confidence: 99%

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Resampling of ENSO teleconnections: accounting for cold-season evolution reduces uncertainty in the North Atlantic

King

Sobolowski

2021

Weather Clim. Dynam.

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Abstract. We re-examine the uncertainty of the El Niño–Southern Oscillation (ENSO) teleconnection to the North Atlantic following the investigation of Deser et al. (2017) (DES2017). Our analyses are performed on the November–December (ND) and January–February (JF) means separately and for a geographical area that covers a larger extent in the midlatitude North Atlantic than DES2017. The motivation for splitting the cold season in this way arises from the fact that the teleconnection patterns and underlying physical mechanisms are different in late fall compared to midwinter. As in DES2017, our main technique in quantifying the uncertainty is bootstrap resampling. Amplitudes and spatial correlations of the bootstrap samples are presented together effectively using Taylor diagrams. In addition to the confidence intervals calculated from Student's t tests and the percentiles of anomalous sea level pressure (SLP) values in the bootstrap samples, we also investigate additional confidence intervals using techniques that are not widely used in climate research but have different advantages. In contrast to the interpretation by DES2017, our results indicate that we can have confidence (at the 5 % significance level) in the patterns of the teleconnected SLP anomalies. The uncertainties in the amplitudes remain large, with the upper-percentile anomalies at up to 2 times those of the lower percentiles in the North Pacific and 2.8 times in the North Atlantic.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Resampling of ENSO teleconnections: accounting for cold-season evolution reduces uncertainty in the North Atlantic

King

Sobolowski

2021

Weather Clim. Dynam.

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show abstract

“…After many decades of research, interest in ENSO teleconnections in the North Atlantic remains high and new results continue to appear (e.g., recent review by Domeisen et al 2018). A number of recent studies have contributed to the continuous improvement in understanding the mechanisms behind the ENSO teleconnection to the North Atlantic, including details about how the late fall signal may arise from an atmospheric bridge via the tropical Atlantic (Ayarzagüena et al 2018;King et al 2018a) or diabatic heating over the Indian Ocean (Abid et al 2020;Joshi et al 2020). Such studies have also found that "free-running" coupled model or SST-forced atmospheric model experiments do not, or only weakly, reproduce the ENSO teleconnection to the North Atlantic through the cold season, while intialized hindcasts perform better.…”

Section: Confidence Intervals and T-testmentioning

confidence: 99%

Resampling of ENSO teleconnections: accounting for cold season evolution reduces uncertainty in the North Atlantic

King¹,

Li²,

Sobolowski³

2021

Preprint

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Abstract. We re-examine the uncertainty of the El Niño–Southern Oscillation teleconnection to the North Atlantic following the investigation of Deser et al. (2017) (DES2017). Our analyses are performed on the November–December (ND) and January–February (JF) means separately, and for a geographical area that covers a larger extent in the midlatitude North At- lantic than DES2017. The motivation for splitting the cold season in this way arises from the fact that the teleconnection patterns and underlying physical mechanisms are different in late fall compared to mid-winter. As in DES2017, our main technique in quantifying the uncertainty is bootstrap resampling. Amplitudes and spatial correlations of the bootstrap samples are presented together effectively using Taylor diagrams. In addition to the confidence intervals calculated from Student's t tests and the percentiles of anomalous sea-level pressure (SLP) values in the bootstrap samples, we also investigate additional confidence intervals using techniques that are not widely used in climate research, but have different advantages. In contrast to the interpretation by DES2017, our results indicate that we can have some confidence in the signs of the teleconnection SLP anomalies. The uncertainties in the amplitudes remain large, with the upper-percentile anomalies at up to 2 times those of the lower percentiles in the North Pacific, and 2.8 times in the North Atlantic.

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“…ENSO teleconnection to the North Atlantic European region (NAE) is currently an active topic of research (Lorenzo et al, 2010;Rodríguez-Fonseca et al, 2016;Joshi et al, 2021). El Niño usually impacts climate with a time lag (Hertig et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

ENSO Teleconnection to Interannual Variability in Carbon Monoxide Over the North Atlantic European Region in Spring

Liu

Xie

et al. 2022

Front. Environ. Sci.

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Carbon monoxide (CO) is an important trace gas in the troposphere, while the El Niño-Southern Oscillation (ENSO) phenomenon is the most important tropical climate variability. ENSO is known to influence interannual variation in meteorological variables on the global scale but its influence on atmospheric CO over large areas in a long term is uncertain. Here we report a strong positive teleconnection between the El Niño–Southern Oscillation (ENSO) in winter (November to February) to tropospheric CO over the North Atlantic European region (NAE) in the following spring (March to May). This ENSO teleconnection is evident in trajectory-mapped airborne CO data (In-service Aircraft for a Global Observing System, IAGOS) over 2002–2019. CO concentrations in El Niño years are 5–20 ppbv higher than those in La Niña years over the NAE troposphere. The regional mean difference from the surface to 300 hPa is 9.4 ppbv (7.6% of the mean). The correlation coefficient (r) between the ENSO index and detrended CO concentrations in the NAE is 0.67 at 400 hPa and 0.63 near the surface, both statistically significant at the 95% level. Such a teleconnection is also observed in independent surface observations, with r ranging from 0.57 to 0.74, all at 95% significance level. From analysis of fire emissions and atmospheric conditions, combined with tagged CO simulations using a chemical transport model, GEOS-Chem, we conclude that this teleconnection results from the combined effects of ENSO on both biomass burning and atmospheric transport. We find that in El Niño years, CO emissions from biomass burning are significantly enhanced in Northern Hemispheric South America, Southeast Asia, and North America due to warmer air temperatures and lowered precipitation. In addition, ENSO enhances CO transport from these regions to the NAE by enhancing upward and northeastward motions in the fire regions, accelerating westerlies over 20°N–40°N, and prompting ascents over the Atlantic and descents over Europe, while reducing CO outflow at the eastern boundary of Europe. The combined effect of ENSO on both CO emissions and CO transport leads to interannual variability in tropospheric CO over the NAE.

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The Role of an Indian Ocean Heating Dipole in the ENSO Teleconnection to the North Atlantic European Region in Early Winter during the Twentieth Century in Reanalysis and CMIP5 Simulations

Cited by 24 publications

References 67 publications

Resampling of ENSO teleconnections: accounting for cold-season evolution reduces uncertainty in the North Atlantic

Resampling of ENSO teleconnections: accounting for cold-season evolution reduces uncertainty in the North Atlantic

Resampling of ENSO teleconnections: accounting for cold season evolution reduces uncertainty in the North Atlantic

ENSO Teleconnection to Interannual Variability in Carbon Monoxide Over the North Atlantic European Region in Spring

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