Publications


The Gulf Stream influence on wintertime North Atlantic jet variability

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 143 (2017) 173-183

CH O'Reilly, S Minobe, A Kuwano-Yoshida, T Woollings


Seasonal and decadal forecasts of Atlantic Sea surface temperatures using a linear inverse model

CLIMATE DYNAMICS 49 (2017) 1833-1845

B Huddart, A Subramanian, L Zanna, T Palmer


The impact of horizontal resolution on energy transfers in global ocean models

Fluids 2 (2017)

J Kjellsson, L Zanna

© 2016 by the authors; licensee MDPI, Basel, Switzerland. The ocean is a turbulent fluid with processes acting on a variety of spatio-temporal scales. The estimates of energy fluxes between length scales allows us to understand how the mean flow is maintained as well as how mesoscale eddies are formed and dissipated. Here, we quantify the kinetic energy budget in a suite of realistic global ocean models, with varying horizontal resolution and horizontal viscosity. We show that eddy-permitting ocean models have weaker kinetic energy cascades than eddy-resolving models due to discrepancies in the effect of wind forcing, horizontal viscosity, potential to kinetic energy conversion, and nonlinear interactions on the kinetic energy (KE) budget. However, the change in eddy kinetic energy between the eddy-permitting and the eddy-resolving model is not enough to noticeably change the scale where the inverse cascade arrests or the Rhines scale. In addition, we show that the mechanism by which baroclinic flows organise into barotropic flows is weaker at lower resolution, resulting in a more baroclinic flow. Hence, the horizontal resolution impacts the vertical structure of the simulated flow. Our results suggest that the effect of mesoscale eddies can be parameterised by enhancing the potential to kinetic energy conversion, i.e., the horizontal pressure gradients, or enhancing the inverse cascade of kinetic energy.


Ice-shelf damming in the glacial Arctic Ocean: dynamical regimes of a basin-covering kilometre-thick ice shelf

CRYOSPHERE 11 (2017) 1745-1765

J Nilsson, M Jakobsson, C Borstad, N Kirchner, G Bjork, RT Pierrehumbert, C Stranne


Variability in seasonal forecast skill of Northern Hemisphere winters over the twentieth century

GEOPHYSICAL RESEARCH LETTERS 44 (2017) 5729-5738

CH O'Reilly, J Heatley, D MacLeod, A Weisheimer, TN Palmer, N Schaller, T Woollings


Atmospheric seasonal forecasts of the twentieth century: multi-decadal variability in predictive skill of the winter North Atlantic Oscillation (NAO) and their potential value for extreme event attribution.

Quarterly journal of the Royal Meteorological Society. Royal Meteorological Society (Great Britain) 143 (2017) 917-926

A Weisheimer, N Schaller, C O'Reilly, DA MacLeod, T Palmer

Based on skill estimates from hindcasts made over the last couple of decades, recent studies have suggested that considerable success has been achieved in forecasting winter climate anomalies over the Euro-Atlantic area using current-generation dynamical forecast models. However, previous-generation models had shown that forecasts of winter climate anomalies in the 1960s and 1970s were less successful than forecasts of the 1980s and 1990s. Given that the more recent decades have been dominated by the North Atlantic Oscillation (NAO) in its positive phase, it is important to know whether the performance of current models would be similarly skilful when tested over periods of a predominantly negative NAO. To this end, a new ensemble of atmospheric seasonal hindcasts covering the period 1900-2009 has been created, providing a unique tool to explore many aspects of atmospheric seasonal climate prediction. In this study we focus on two of these: multi-decadal variability in predicting the winter NAO, and the potential value of the long seasonal hindcast datasets for the emerging science of probabilistic event attribution. The existence of relatively low skill levels during the period 1950s-1970s has been confirmed in the new dataset. The skill of the NAO forecasts is larger, however, in earlier and later periods. Whilst these inter-decadal differences in skill are, by themselves, only marginally statistically significant, the variations in skill strongly co-vary with statistics of the general circulation itself suggesting that such differences are indeed physically based. The mid-century period of low forecast skill coincides with a negative NAO phase but the relationship between the NAO phase/amplitude and forecast skill is more complex than linear. Finally, we show how seasonal forecast reliability can be of importance for increasing confidence in statements of causes of extreme weather and climate events, including effects of anthropogenic climate change.


A deformation-based parametrization of ocean mesoscale eddy reynolds stresses

OCEAN MODELLING 112 (2017) 99-111

JA Anstey, L Zanna


The statistical nature of turbulent barotropic ocean jets

OCEAN MODELLING 113 (2017) 34-49

TW David, DP Marshall, L Zanna


Scale-aware deterministic and stochastic parametrizations of eddy-mean flow interaction

OCEAN MODELLING 111 (2017) 66-80

L Zanna, PP Mana, J Anstey, T David, T Bolton


Drivers of uncertainty in simulated ocean circulation and heat uptake

GEOPHYSICAL RESEARCH LETTERS 44 (2017) 1402-1413

MB Huber, L Zanna


Linking the Climate and Thermal Phase Curve of 55 Cancri e

ASTROPHYSICAL JOURNAL 849 (2017) ARTN 152

M Hammond, RT Pierrehumbert


5 Things We Know to Be True.

Scientific American 315 (2016) 46-53

M Shermer, H Hall, R Pierrehumbert, P Offit, S Shostak


Oceanic Stochastic Parameterizations in a Seasonal Forecast System

MONTHLY WEATHER REVIEW 144 (2016)

M Andrejczuk, FC Cooper, S Juricke, TN Palmer, A Weisheimer, L Zanna


The influence of the Gulf Stream on wintertime European blocking

CLIMATE DYNAMICS 47 (2016) 1545-1567

CH O'Reilly, S Minobe, A Kuwano-Yoshida


The signature of low-frequency oceanic forcing in the Atlantic Multidecadal Oscillation

GEOPHYSICAL RESEARCH LETTERS 43 (2016) 2810-2818

CH O'Reilly, M Huber, T Woollings, L Zanna


Consequences of twenty-first-century policy for multi-millennial climate and sea-level change

NATURE CLIMATE CHANGE 6 (2016) 360-369

PU Clark, JD Shakun, SA Marcott, AC Mix, M Eby, S Kulp, A Levermann, GA Milne, PL Pfister, BD Santer, DP Schrag, S Solomon, TF Stocker, BH Strauss, AJ Weaver, R Winkelmann, D Archer, E Bard, A Goldner, K Lambeck, RT Pierrehumbert, G-K Plattner


How to decarbonize? Look to Sweden

BULLETIN OF THE ATOMIC SCIENTISTS 72 (2016) 105-111

R Pierrehumbert


CONVECTION IN CONDENSIBLE-RICH ATMOSPHERES

ASTROPHYSICAL JOURNAL 822 (2016) ARTN 24

F Ding, RT Pierrehumbert


The influence of Southern Ocean winds on the North Atlantic carbon sink

GLOBAL BIOGEOCHEMICAL CYCLES 30 (2016) 844-858

B Bronselaer, L Zanna, DR Munday, J Lowe


Suppression of Atlantic Meridional Overturning Circulation Variability at Increased CO2

JOURNAL OF CLIMATE 29 (2016) 4155-4164

DG MacMartin, L Zanna, E Tziperman

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