Exploring recent trends in Northern Hemisphere blocking by Barnes, E, Dunn-Sigouin, E, Masato, G, Woollings, T

“…Observed blocking trends are diagnosed to test the hypothesis that recent Arctic warming and sea ice loss has increased the likelihood of blocking over the Northern Hemisphere. To ensure robust results, we diagnose blocking using three unique blocking identification methods from the literature, each applied to four different reanalyses. …”

Dynamical differences between short and long blocks in the Northern Hemisphere by Drouard, M, Woollings, T, Sexton, DMH, McSweeney, CF

Winter and Summer Northern Hemisphere Blocking in CMIP5 Models by Masato, G, Hoskins, B, Woollings, T

Projections of northern hemisphere extratropical climate underestimate internal variability and associated uncertainty by O’Reilly, CH, Befort, DJ, Weisheimer, A, Woollings, T, Ballinger, A, Hegerl, G

Low frequency nonlinearity and regime behavior in the northern hemisphere extra-tropical atmosphere by Hannachi, A, Straus, D, Franzke, C, Corti, S, Woollings, T

Variability in seasonal forecast skill of Northern Hemisphere winters over the 20th century by O'Reilly, C, Heatley, J, MacLeod, D, Weisheimer, A, Palmer, T, Schaller, N, Woollings, T

“…Seasonal hindcast experiments, using prescribed SSTs, are analysed for Northern Hemisphere winters from 1900-2010. Ensemble mean Pacific/North American index (PNA) skill varies dramatically, dropping towards zero during the mid-twentieth century, with similar variability in North Atlantic Oscillation (NAO) hindcast skill. …”

Linking Northern Hemisphere blocking and storm track biases in the CMIP5 climate models by Zappa, G, Masato, G, Shaffrey, L, Woollings, T, Hodges, K

“…The relationship between biases in Northern Hemisphere (NH) atmospheric blocking frequency and extratropical cyclone track density is investigated in 12 CMIP5 climate models to identify mechanisms underlying climate model biases and inform future model development. …”

Multi-model analysis of Northern Hemisphere winter blocking: Model biases and the role of resolution by Anstey, J, Davini, P, Gray, L, Woollings, T, Butchart, N, Cagnazzo, C, Christiansen, B, Hardiman, S, Osprey, S, Yang, S

“…Blocking of the tropospheric jet stream during Northern Hemisphere winter (December-January-February) is examined in a multi-model ensemble of coupled atmosphere-ocean general circulation models (GCMs) obtained from the Coupled Model Intercomparison Project Phase 5 (CMIP5). …”

Linking Northern Hemisphere blocking and storm track biases in the CMIP5 climate models by Zappa, G, Masato, G, Shaffrey, L, Woollings, T, Hodges, K

“…The relationship between biases in Northern Hemisphere (NH) atmospheric blocking frequency and extratropical cyclone track density is investigated in 12 CMIP5 climate models to identify mechanisms underlying climate model biases and inform future model development. …”

Wave-Breaking Characteristics of Northern Hemisphere Winter Blocking: A Two-Dimensional Approach by Masato, G, Hoskins, B, Woollings, T

Multi-model analysis of Northern Hemisphere winter blocking: Model biases and the role of resolution by Anstey, J, Davini, P, Gray, L, Woollings, T, Butchart, N, Cagnazzo, C, Christiansen, B, Hardiman, S, Osprey, S, Yang, S

Forced summer stationary waves: the opposing effects of direct radiative forcing and sea surface warming by Baker, H, Woollings, T, Mbengue, C, Allen, M, O'Reilly, C, Shiogama, H, Sparrow, S

“…In large ensembles of three general circulation models, direct CO2 forcing produces a wavenumber 5 stationary wave over the Northern Hemisphere in summer. Sea surface warming produces a similar wave, but with the opposite sign. …”

How large are projected 21st century storm track changes? by Harvey, B, Shaffrey, L, Woollings, T, Zappa, G, Hodges, K

“…For the experiments considered, the 'middle-of-the-road' scenarios in each CMIP, there are regions of the Northern Hemisphere where the responses of up to 40% of the models exceed half of the inter-annual variability, and for the SouthernHemisphere there are regions where up to 60% of the model responses exceed half of the inter-annual variability. …”

Atmospheric blocking in a high resolution climate model: influences of mean state, orography and eddy forcing by Berckmans, J, Woollings, T, Demory, M, Vidale, P, Roberts, M

“…This article presents an analysis of Northern Hemisphere winter blocking in an atmospheric model with increased horizontal resolution. …”

Southern Hemisphere atmospheric blocking in CMIP5 and future changes in the Australia‐New Zealand sector by Patterson, M, Bracegirdle, T, Woollings, T

“…Many general circulation models (GCMs) fail to capture the observed frequency of atmospheric blocking events in the Northern Hemisphere, however few studies have examined models in the Southern Hemisphere (SH) and those studies that have, have often been based on only a few models. …”

Asymmetric hysteresis response of midlatitude storm tracks to CO2 removal by Hwang, J, Son, S-W, Garfinkel, CI, Woollings, T, Yoon, H, An, S-I, Yeh, S-W, Min, S-K, Kug, J-S, Shin, J

“…Compared to the present climate, the Northern Hemisphere storm track becomes stronger and the Southern Hemisphere storm track becomes weaker at the end of CO₂ removal. …”

A new Rossby wave-breaking interpretation of the North Atlantic Oscillation by Woollings, T, Hoskins, B, Blackburn, M, Berrisford, P

“…This is applied to Northern Hemisphere winter data from the 40-yr ECMWF Re-Analysis (ERA-40), and the events identified are then related to the NAO. …”

Higher CO2 concentrations increase extreme event risk in a 1.5C world by Baker, HS, Millar, RJ, Allen, MR, Karoly, DJ, Beyerle, U, Guillod, BP, Mitchell, D, Shiogama, H, Sparrow, SN, Woollings, T, Allen, MR

“…Here, using an ensemble of model simulations, we show that atmospheric CO2 increase - a more predictable consequence of emissions compared to global temperature increase - has a significant impact on Northern Hemisphere summer temperature, heat stress, and tropical precipitation extremes. …”

Wave-breaking characteristics of midlatitude blocking by Masato, G, Hoskins, B, Woollings, T

“…In this article, Northern Hemisphere winter midlatitude blocking is analysed through its wave-breaking characteristics. …”

Equator-to-pole temperature differences and the extra-tropical storm track responses of the CMIP5 climate models by Harvey, B, Shaffrey, L, Woollings, T

“…There are large regions in which the storm track responses are correlated with the temperature difference responses, and a simple linear regression model based on the temperature differences at either level captures the spatial pattern of the mean storm track response as well explaining between 30 and 60 % of the inter-model variance of the storm track responses. In the northern hemisphere the responses of the two temperature differences are not significantly correlated and their associations with the storm track responses are more complicated. …”