Lagrangian ocean analysis: Fundamentals and practices

OCEAN MODELLING 121 (2018) 49-75

E van Sebille, SM Griffies, R Abernathey, TP Adams, P Berloff, A Biastoch, B Blanke, EP Chassignet, Y Cheng, CJ Cotter, E Deleersnijder, K Doos, HF Drake, S Drijfhout, SF Gary, AW Heemink, J Kjellsson, IM Koszalka, M Lange, C Lique, GA MacGilchrist, R Marsh, CGM Adame, R McAdam, F Nencioli, CB Paris, MD Piggott, JA Polton, S Ruehs, SHAM Shah, MD Thomas, J Wang, PJ Wolfram, L Zanna, JD Zika

Seasonal Sensitivity of the Hadley Cell and Cross-Hemispheric Responses to Diabatic Heating in an Idealized GCM


HS Baker, C Mbengue, T Woollings

Daily to Decadal Modulation of Jet Variability

JOURNAL OF CLIMATE 31 (2018) 1297-1314

T Woollings, E Barnes, B Hoskins, Y-O Kwon, RW Lee, C Li, E Madonna, M McGraw, T Parker, T Parker, R Rodrigues, C Spensberger, K Williams

First Successful Hindcasts of the 2016 Disruption of the Stratospheric Quasi-biennial Oscillation


S Watanabe, K Hamilton, S Osprey, Y Kawatani, E Nishimoto

Linking Hadley Circulation and Storm Tracks in a Conceptual Model of the Atmospheric Energy Balance


C Mbengue, T Schneider

Report on the Joint SPARC Dynamics and Observations Work- shop: SATIO-TCS, FISAPS and QBOi, Kyoto, Japan

(2018) 50

J Anstey, S Yoden, M Geller, SM Osprey, K Hamilton, N Butchart

Changing response of the North Atlantic/European winter climate to the 11 year solar cycle


H Ma, H Chen, L Gray, L Zhou, X Li, R Wang, S Zhu

SALSA2.0: The sectional aerosol module of the aerosol-chemistry-climate model ECHAM6.3.0-HAM2.3-MOZ1.0

Geoscientific Model Development Discussions Copernicus Publications (2018)

H Kokkola, T Kuhn, A Laakso, T Bergman, KEJ Lehtinen, T Mielonen, A Arola, S Stadtler, H Korhonen, S Ferrachat, U Lohmann, D Neubauer, I Tegen, C Siegenthaler-Le Drian, MG Schultz, I Bey, P Stier, N Daskalaski, CL Heald, S Ramakkaniemi

Descent rate models of the synchronization of the Quasi-Biennial Oscillation by the annual cycle in tropical upwelling

Journal of the Atmospheric Sciences American Meteorological Society (2018)

K Rajendran, I Moroz, SM Osprey, P Read

The response of the Quasi-Biennial Oscillation (QBO) to an imposed mean upwelling with a periodic modulation is studied, by modelling the dynamics of the zero wind line at the equator using a class of equations known as ‘descent rate’ models. These are simple mathematical models that capture the essence of QBO synchronization by focusing on the dynamics of the height of the zero wind line. A heuristic descent rate model for the zero wind line is described, and is shown to capture many of the synchronization features seen in previous studies of the QBO. Using a simple transformation, it is then demonstrated that the standard Holton-Lindzen model of the QBO can itself be put into the form of a descent rate model if a quadratic velocity profile is assumed below the zero wind line. The resulting non-autonomous ordinary differential equation captures much of the synchronization behaviour observed in the full Holton-Lindzen partial differential equation. The new class of models provides a novel framework within which to understand synchronization of the QBO, and we demonstrate a close relationship between these models and the circle map well-known in the mathematics literature. Finally, we analyse reanalysis datasets to validate some of the predictions of our descent rate models, and find statistically significant evidence for synchronization of the QBO that is consistent with model behaviour.

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)


N Butchart, JA Anstey, K Hamilton, S Osprey, C McLandress, AC Bushell, Y Kawatani, Y-H Kim, F Lott, J Scinocca, TN Stockdale, M Andrews, O Bellprat, P Braesicke, C Cagnazzo, C-C Chen, H-Y Chun, M Dobrynin, RR Garcia, J Garcia-Serrano, LJ Gray, L Holt, T Kerzenmacher, H Naoe, H Pohlmann, JH Richter, AA Scaife, V Schenzinger, F Serva, S Versick, S Watanabe, K Yoshida, S Yukimoto

Can bias correction and statistical downscaling methods improve the skill of seasonal precipitation forecasts?

CLIMATE DYNAMICS 50 (2018) 1161-1176

R Manzanas, A Lucero, A Weisheimer, JM Gutierrez

Transforming climate model output to forecasts of wind power production: how much resolution is enough?


D MacLeod, V Torralba, M Davis, F Doblas-Reyes

Southern Ocean carbon-wind stress feedback

Climate Dynamics (2018) 1-15

B Bronselaer, L Zanna, DR Munday, J Lowe

© 2017 The Author(s) The Southern Ocean is the largest sink of anthropogenic carbon in the present-day climate. Here, Southern Ocean (Formula presented.) and its dependence on wind forcing are investigated using an equilibrium mixed layer carbon budget. This budget is used to derive an expression for Southern Ocean (Formula presented.) sensitivity to wind stress. Southern Ocean (Formula presented.) is found to vary as the square root of area-mean wind stress, arising from the dominance of vertical mixing over other processes such as lateral Ekman transport. The expression for p\hbox {CO}_{2} is validated using idealised coarse-resolution ocean numerical experiments. Additionally, we show that increased (decreased) stratification through surface warming reduces (increases) the sensitivity of the Southern Ocean (Formula presented.) to wind stress. The scaling is then used to estimate the wind-stress induced changes of atmospheric (Formula presented.) in CMIP5 models using only a handful of parameters. The scaling is further used to model the anthropogenic carbon sink, showing a long-term reversal of the Southern Ocean sink for large wind stress strength.

Optimal-transport-based mesh adaptivity on the plane and sphere using finite elements

SIAM Journal on Scientific Computing Society for Industrial and Applied Mathematics 40 (2018) A1121-A1148

ATT MCRAE, CJ Cotter, CJ Budd

The Met Office Global Coupled Model 3.0 and 3.1 (GC3.0 and GC3.1) Configurations


KD Williams, D Copsey, EW Blockley, A Bodas-Salcedo, D Calvert, R Comer, P Davis, T Graham, HT Hewitt, R Hill, P Hyder, S Ineson, TC Johns, AB Keen, RW Lee, A Megann, SF Milton, JGL Rae, MJ Roberts, AA Scaife, R Schiemann, D Storkey, L Thorpe, IG Watterson, DN Walters, A West, RA Wood, T Woollings, PK Xavier

The roles of static stability and tropical–extratropical interactions in the summer interannual variability of the North Atlantic sector

Climate Dynamics (2018) 1-17

CO Mbengue, T Woollings, HF Dacre, KI Hodges

© 2018 The Author(s) Summer seasonal forecast skill in the North Atlantic sector is lower than winter skill. To identify potential controls on predictability, the sensitivity of North Atlantic baroclinicity to atmospheric drivers is quantified. Using ERA-INTERIM reanalysis data, North Atlantic storm-track baroclinicity is shown to be less sensitive to meridional temperature-gradient variability in summer. Static stability shapes the sector’s interannual variability by modulating the sensitivity of baroclinicity to variations in meridional temperature gradients and tropopause height and by modifying the baroclinicity itself. High static stability anomalies at upper levels result in more zonal extratropical cyclone tracks and higher eddy kinetic energy over the British Isles in the summertime. These static stability anomalies are not strongly related to the summer NAO; but they are correlated with the suppression of convection over the tropical Atlantic and with a poleward-shifted subtropical jet. These results suggest a non-local driver of North Atlantic variability. Furthermore, they imply that improved representations of convection over the south-eastern part of North America and the tropical Atlantic might improve summer seasonal forecast skill.

Frazil-ice growth rate and dynamics in mixed layers and sub-ice-shelf plumes

CRYOSPHERE 12 (2018) 25-38

DWR Jones, AJ Wells

Impact of Gulf Stream SST biases on the global atmospheric circulation

Climate Dynamics (2018) 1-19

RW Lee, TJ Woollings, BJ Hoskins, KD Williams, CH O Reilly, G Masato

© 2018 The Author(s) The UK Met Office Unified Model in the Global Coupled 2 (GC2) configuration has a warm bias of up to almost (Formula presented.) in the Gulf Stream SSTs in the winter season, which is associated with surface heat flux biases and potentially related to biases in the atmospheric circulation. The role of this SST bias is examined with a focus on the tropospheric response by performing three sensitivity experiments. The SST biases are imposed on the atmosphere-only configuration of the model over a small and medium section of the Gulf Stream, and also the wider North Atlantic. Here we show that the dynamical response to this anomalous Gulf Stream heating (and associated shifting and changing SST gradients) is to enhance vertical motion in the transient eddies over the Gulf Stream, rather than balance the heating with a linear dynamical meridional wind or meridional eddy heat transport. Together with the imposed Gulf Stream heating bias, the response affects the troposphere not only locally but also in remote regions of the Northern Hemisphere via a planetary Rossby wave response. The sensitivity experiments partially reproduce some of the differences in the coupled configuration of the model relative to the atmosphere-only configuration and to the ERA-Interim reanalysis. These biases may have implications for the ability of the model to respond correctly to variability or changes in the Gulf Stream. Better global prediction therefore requires particular focus on reducing any large western boundary current SST biases in these regions of high ocean-atmosphere interaction.

Climate Impacts From a Removal of Anthropogenic Aerosol Emissions


BH Samset, M Sand, CJ Smith, SE Bauer, PM Forster, JS Fuglestvedt, S Osprey, C-F Schleussner

How Well Can We Represent the Spectrum of Convective Clouds in a Climate Model? Comparisons between Internal Parameterization Variables and Radar Observations

Journal of the Atmospheric Sciences American Meteorological Society (2018)

L Labbouz, Z Kipling, P Stier