What are the prospects for seasonal prediction of the marine environment of the Northwest European shelf?

Abstract

Abstract.Sustainable management and utilisation of the Northwest European Shelf Seas (NWS) could benefit from reliable forecasts 10 of the marine environment on monthly-to-seasonal timescales. Recent advances in global seasonal forecast systems, and regional marine reanalyses for the NWS, allow us to investigate the potential for seasonal forecasts of the state of the NWS.We identify three possible approaches to address this issue: A) basing NWS seasonal forecasts directly on output from the Met Office's GloSea5 global seasonal forecast system; B) developing empirical downscaling relationships between largescale climate drivers predicted by GloSea5, and the state of the NWS; and C) dynamically downscaling GloSea5 using a 15 regional model. We reject A) after showing that the GloSea5 system is inadequate for simulating the NWS directly. Turning to B), we explore empirical relationships between the winter North Atlantic Oscillation (NAO), and NWS variables estimated using a regional reanalysis. We find some statistically significant relationships, and present a skilful prototype seasonal forecast for English Channel sea surface temperature.We then consider the potential of C). We find large scale relationships between inter-annual variability in the boundary 20 conditions and inter-annual variability modelled on the shelf, suggesting that dynamic downscaling may be possible. We also show that for some variables there are opposing mechanisms correlated to the NAO, for which dynamic downscaling may improve on the skill possible with empirical forecasts. We conclude that there is potential for the development of reliable seasonal forecasts for the NWS, and consider the research priorities for their development. Copyright Statement 25The works published in this journal are distributed under the Creative Commons Attribution 4.0 License. This licence does not affect the Crown copyright work, which is re-usable under the Open Government Licence (OGL). The Creative Commons Attribution 4.0 License and the OGL are interoperable and do not conflict with, reduce or limit each other.

Copernicus Marine Service Ocean State Report, Issue 3

“…Instead, the regional mean time series are considered descriptors of the behaviour of the NWS reanalysis, rather than describing reality. The NWS reanalysis has been extensively evaluated in the Quality Information Documents (QUID), and given the data assimilation of observations, provides the statistical 'best guess' of the state estimate for the Northwest European Shelf Seas (Tinker et al 2018). Here we use the relevant parts of the QUID to inform the user of the scale of the model errors and biases that will be propagate into the regional mean time series product.…”

“…However, similar Northwest European Shelf Seas regional mean time series and summary statistics have been used in a number of recent studies. Tinker et al (2018) used regional mean time series of the previous NWS reanalysis, calculated on the Wakelin et al (2012) regions (Figure 3.5.1(B)) to investigate seasonal predictability on the Northwest European Shelf. Tinker et al (2015Tinker et al ( , 2016 used regional mean time series calculated from their Northwest European Shelf Seas climate projection to aid model evaluation, and to summarise their findings.…”