Impact of sea surface temperature on stratiform cloud formation over the North Sea

Fallmann, Joachim; Lewis, Huw; Castillo, J.; Ramsdale, Steven

doi:10.1002/2017gl073105

Cited by 26 publications

(25 citation statements)

References 46 publications

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“…More detailed evaluation of the case studies introduced here will be published as their analysis continues (e.g. Fallmann et al, 2017). Future work will also need to focus on performing longer simulations (months-years) in order to build more robust evaluation of system performance and to understand the impact of coupling on any long-term drifts in any component.…”

Section: Discussion and Ongoing Developmentmentioning

confidence: 99%

The UKC2 regional coupled environmental prediction system

et al. 2018

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Abstract. It is hypothesized that more accurate prediction and warning of natural hazards, such as of the impacts of severe weather mediated through various components of the environment, require a more integrated Earth System approach to forecasting. This hypothesis can be explored using regional coupled prediction systems, in which the known interactions and feedbacks between different physical and biogeochemical components of the environment across sky, sea and land can be simulated. Such systems are becoming increasingly common research tools. This paper describes the development of the UKC2 regional coupled research system, which has been delivered under the UK Environmental Prediction Prototype project. This provides the first implementation of an atmosphere-land-ocean-wave modelling system focussed on the United Kingdom and surrounding seas at km-scale resolution. The UKC2 coupled system incorporates models of the atmosphere (Met Office Unified Model), land surface with river routing (JULES), shelf-sea ocean (NEMO) and ocean waves (WAVEWATCH III). These components are coupled, via OASIS3-MCT libraries, at unprecedentedly high resolution across the UK within a north-western European regional domain. A research framework has been established to explore the representation of feedback processes in coupled and uncoupled modes, providing a new research tool for UK environmental science. This paper documents the technical design and implementation of UKC2, along with the associated evaluation framework. An analysis of new results comparing the output of the coupled UKC2 system with relevant forced control simulations for six contrasting case studies of 5-day duration is presented. Results demonstrate that performance can be achieved with the UKC2 system that is at least comparable to its component control simulations. For some cases, improvements in air temperature, sea surface temperature, wind speed, significant wave height and mean wave period highlight the potential benefits of coupling between environmental model components. Results also illustrate that the coupling itself is not sufficient to address all known model issues. Priorities for future development of the UK Environmental Prediction framework and component systems are discussed.

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Section: Discussion and Ongoing Developmentmentioning

confidence: 99%

The UKC2 regional coupled environmental prediction system

et al. 2018

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“…Results of the case studies described by Lewis et al (2018) demonstrated that 20 model performance could be achieved with the UKC2 system that was at least of comparable skill to its component control simulations, with examples where improvements in agreement against in situ observations could be achieved for atmosphere, ocean and wave variables assessed. Further research relevant to the UKC2 system is also described by Fallmann et al, (2017) and Martinez et al (2018).…”

Section: Recent Progress In Regional Coupled Model Research Developmmentioning

confidence: 99%

The UKC3 regional coupled environmental prediction system

Lewis¹,

Sanchez²,

Fallmann³

et al. 2018

Preprint

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Abstract. This paper describes an updated configuration of the regional coupled research system, termed UKC3, developed and evaluated under the UK Environmental Prediction collaboration. This represents a further step towards a vision of simulating the numerous interactions and feedbacks between different physical and biogeochemical components of the environment across sky, sea and land using more integrated regional coupled prediction systems at km-scale resolution. The UKC3 coupled system incorporates models of the atmosphere (Met Office Unified Model), land surface with river routing (JULES), shelf-sea ocean (NEMO) and ocean surface waves (WAVEWATCH III), coupled together using OASIS3-MCT libraries. The major update introduced since the UKC2 configuration is an explicit representation of wave processes in the ocean and their feedbacks through wave-to-ocean coupling. Ocean model results demonstrate that wave coupling, in particular representing the wave modified surface drag, has a small but positive improvement on the agreement between simulated sea surface temperatures and in situ observations, relative to simulations without wave feedbacks. Other incremental developments to the coupled modelling capability introduced since the UKC2 configuration are also detailed. Coupled regional prediction systems are of interest for applications across a range of timescales, from hours to decades ahead. The first results of simulations run over extended periods, covering four experiments each of order one month in duration are therefore analysed and discussed in the context of further characterising the potential benefits of coupled prediction on forecast skill, and on the stability of such systems over longer time periods. Results across atmosphere, ocean and wave components are shown to be of at least comparable skill to the equivalent uncoupled control simulations, with notable improvements demonstrated in surface temperature and wave state predictions in some near-coastal regions, and in wind speeds over the sea.

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“…The fully coupled system with interactive atmosphere, wave, and ocean components is termed CPL. For analysing the sensitivity of model results to lead time, a reduced‐complexity coupled system similar to Fallmann et al () is used, consisting of atmosphere and ocean coupling only with no wave interactions (CPL_ao). In this study, uncoupled atmosphere simulations are termed FIX, given the assumptions that the ocean boundary condition is at rest and SSTs are persisted SSTs.…”

Section: Model and Methodsmentioning

confidence: 99%

“…A diverse range of large-scale atmospheric processes can be impacted, including storm-track location (Brayshaw et al, 2011;Woollings et al, 2012), frontal propagation (Parfitt et al, 2016;Passalacqua et al, 2016) and precipitation (Minobe et al, 2008), the evolution of the Madden-Julian Oscillation (Seo et al, 2014;DeMott et al, 2015;Stan et al, 2018), the El Niño-Southern Oscillation (ENSO: for example, Ham et al, 2010;Masson et al, 2012), and Indian (for example, Terray et al, 2012) and Australian monsoon systems (Wang and Zang, 2017). The variation of SST has also been shown to impact more local-scale processes, including the development of boundary-layer cloud (for example, Fallmann et al, 2017), urban heat islands (Oda and Kanda, 2009), and sea-breeze circulations (for example, Sweeney et al, 2014;Lombardo et al, 2016). This article focuses on the impact of SST variability on the development of coastal and sea fog, using a high-resolution atmosphere-ocean-wave regional coupled prediction system.…”

Section: Introductionmentioning

confidence: 99%

Impact of high‐resolution ocean–atmosphere coupling on fog formation over the North Sea

Fallmann

Lewis

Sanchez

et al. 2019

Quart J Royal Meteoro Soc

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Sea‐surface temperature (SST) is a key driver for various interactions and feedbacks between components of the Earth System and can control local weather and climate. The formation of marine fog, for example, can be sensitive to small changes in SST at a scale of a few kilometres. As a contribution to understanding processes at the interface between air and sea, this article discusses results from a state‐of‐the‐art fully coupled regional atmosphere–land–ocean–wave prediction system for the UK at km scale. This study focuses on the impact of the changes in surface forcing resulting from coupling SST in the marine boundary layer and formation of summertime coastal fog over the North Sea. A study from July 2013 provided a good case to evaluate the role of SST in fog evolution. The benefit of an evolving SST in the coupled simulation is shown in capturing a warming trend in observed SST over the five‐day case study period, with a root‐mean‐square error (RMSE) against in situ observations of 1.1 K. In contrast, in uncoupled atmosphere‐only simulations, the initial‐condition SST is persisted for the duration of the case, as is more typical in current operational numerical weather prediction (NWP). In the uncoupled simulations, a cold bias develops over the modelling period and the RMSE against observed SST is 2.4 K. The impact of coupling is shown to propagate into the overlying marine boundary layer and therefore affect the formation of coastal fog. Increased heat flux from a relatively warmer sea surface in the coupled simulations led to near‐surface atmospheric instability, hampering stratus lowering and destroying the fog‐promoting inversion layer. This significantly reduced fog fractions in selected regions. The value of model coupling was assessed by comparing coupled and uncoupled simulations initialized at different times ahead of fog development.

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Impact of sea surface temperature on stratiform cloud formation over the North Sea

Cited by 26 publications

References 46 publications

The UKC2 regional coupled environmental prediction system

The UKC2 regional coupled environmental prediction system

The UKC3 regional coupled environmental prediction system

Impact of high‐resolution ocean–atmosphere coupling on fog formation over the North Sea

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