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Gulf Stream Moisture Fluxes Impact Atmospheric Blocks Throughout the Northern Hemisphere
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  • Jamie Mathews,
  • Arnaud Czaja,
  • Frederic Vitart,
  • Christopher David Roberts
Jamie Mathews
Imperial College London

Corresponding Author:[email protected]

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Arnaud Czaja
Imperial College, Dept. Physics
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Frederic Vitart
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Christopher David Roberts
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In this study, we explore the impact of oceanic moisture fluxes on atmospheric blocks using the ECMWF Integrated Forecast System. Artificially suppressing surface latent heat flux over the Gulf Stream region leads to a significant reduction (up to 30%) in atmospheric blocking frequency across the northern hemisphere. Affected blocks show a shorter lifespan (-6%), smaller spatial extent (-12%), and reduced intensity (-0.4%), with an increased detection rate (+17%). These findings are robust across various blocking detection thresholds. Analysis indicates a resolution-dependent response, with resolutions lower than Tco639 (~18km) showing no significant change in some blocking characteristics, even with reduced blocking frequency. Exploring the broader Rossby wave pattern, we observe that diminished moisture flux favours eastward propagation and higher zonal wavenumbers, while air-sea interactions promotes stationary and westward-propagating waves with zonal wavenumber 3. This study underscores the critical role of western boundary current’s moisture fluxes in modulating atmospheric blocking.
21 Feb 2024Submitted to ESS Open Archive
26 Feb 2024Published in ESS Open Archive