The winter north Atlantic oscillation downstream teleconnection: insights from large-ensemble climate model simulations

Environmental Research Letters IOP Publishing (2025)

Authors:

Sing Lau, Kunhui Ye, Tim Woollings

Abstract:

<jats:title>Abstract</jats:title> <jats:p>The winter North Atlantic Oscillation (NAO) is the dominant pattern of atmospheric circulation variability over the North Atlantic region. It influences climate and weather such as surface air temperatures (SAT) downstream over Eurasia through establishing a large-scale teleconnection, but past studies on the NAO’s downstream teleconnection have been largely limited to observational data, and further evidence of downstream impacts and associated mechanisms from comprehensive climate modelling is desirable. This study quantifies and analyzes this teleconnection on an interannual timescale by using both ERA5 reanalysis, and five large ensembles from four climate simulation models. A particular focus is placed on dynamical pathways, as well as variability among ensemble members that modulates the teleconnection strength. Results suggest that NAO signals are propagated downstream by Rossby waves, efficiently transmitted through waveguides along both the polar and subtropical jet streams to Eastern Eurasia; while heat can be advected weakly from upstream, advection plays a rather local effect inducing temperature anomalies from the Pacific Ocean onshore. Multiple linear regression shows that internal climate variability significantly modulates the teleconnection: a more locally dominant NAO pattern, and narrower waveguides could strengthen the teleconnection. These two factors combine to explain up to 70% of variance in the teleconnection strength, with each contributing almost equally. Reanalysis data marginally agree with the regression model (1.9 standardized residuals higher in strength), suggesting potential model biases in jets and the NAO variability. Monitoring these modulating factors would be crucial to understanding downstream climate predictability and improving climate prediction models linked to the NAO.</jats:p>

AGNI: A radiative-convective model for lava planet atmospheres

Journal of Open Source Software The Open Journal 10:109 (2025) 7726-7726

Authors:

Harrison Nicholls, Raymond Pierrehumbert, Tim Lichtenberg

Escaping Helium and a Highly Muted Spectrum Suggest a Metal-enriched Atmosphere on Sub-Neptune GJ 3090 b from JWST Transit Spectroscopy

The Astrophysical Journal Letters American Astronomical Society 985:1 (2025) l10

Authors:

Eva-Maria Ahrer, Michael Radica, Caroline Piaulet-Ghorayeb, Eshan Raul, Lindsey Wiser, Luis Welbanks, Lorena Acuña, Romain Allart, Louis-Philippe Coulombe, Amy Louca, Ryan MacDonald, Morgan Saidel, Thomas M Evans-Soma, Björn Benneke, Duncan Christie, Thomas G Beatty, Charles Cadieux, Ryan Cloutier, René Doyon, Jonathan J Fortney, Anna Gagnebin, Cyril Gapp, Hamish Innes, Heather A Knutson, Thaddeus Komacek, Joshua Krissansen-Totton, Yamila Miguel, Raymond Pierrehumbert, Pierre-Alexis Roy, Hilke E Schlichting

Attributing climate and weather extremes to Northern Hemisphere sea ice and terrestrial snow: progress, challenges and ways forward

npj Climate and Atmospheric Science Nature Research 8:1 (2025) 166

Authors:

Kunhui Ye, Judah Cohen, Hans W Chen, Shiyue Zhang, Dehai Luo, Mostafa Essam Hamouda

Abstract:

Sea ice and snow are crucial components of the cryosphere and the climate system. Both sea ice and spring snow in the Northern Hemisphere (NH) have been decreasing at an alarming rate in a changing climate. Changes in NH sea ice and snow have been linked with a variety of climate and weather extremes including cold spells, heatwaves, droughts and wildfires. Understanding of these linkages will benefit the predictions of climate and weather extremes. However, existing work on this has been largely fragmented and is subject to large uncertainties in physical pathways and methodologies. This has prevented further substantial progress in attributing climate and weather extremes to sea ice and snow change, and will potentially risk the loss of a critical window for effective climate change mitigation. In this review, we synthesize the current progress in attributing climate and weather extremes to sea ice and snow change by evaluating the observed linkages, their physical pathways and uncertainties in these pathways, and suggesting ways forward for future research efforts. By adopting the same framework for both sea ice and snow, we highlight their combined influence and the cryospheric feedback to the climate system. We suggest that future research will benefit from improving observational networks, addressing the causality and complexity of the linkages using multiple lines of evidence, adopting large-ensemble approaches and artificial intelligence, achieving synergy between different methodologies/disciplines, widening the context, and coordinated international collaboration.

The latent heating feedback on the mid-latitude circulation

(2025)

Authors:

Henrik Auestad, Abel Shibu, Paulo Ceppi, Tim Woollings