Representing uncertainty in ocean observations and the ocean model, for coupled ensemble data assimilation and ensemble extended-range prediction

There is currently a large effort in the development of general circulation model (GCM)-based seasonal to decadal prediction systems to provide climate forecasts. Such techniques are rather complex, technically challenging and still in their infancy. Any weather or climate forecast will be subject to three sources of uncertainty, namely observation uncertainty, the model-component of initial uncertainty, and model uncertainty over the forecast period.

The aim of this proposal is to improve the reliability of extended range forecast of weather and climate, mainly focusing on the ocean component of the coupled system. We propose to develop and incorporate various tools based on stochastic physics to improve the reliability of forecasts focusing on a more accurate representation of ocean observations and model uncertainties. The individual impacts of the different developments on the reliability of the forecasts will be quantified to provide estimates of the different sources of uncertainties in the forecasts. The development of reliable extended range forecasts can be extremely beneficial with major economical and societal consequences.

A key goal for any weather and climate forecast centre is production of reliable predictions. Since the basis of this proposal is to improve the reliability of extended range forecasts of weather and climate, the proposed developments will be directly beneficial to an enormous number of scientists and users alike - the latter ultimately encompassing anyone that consults, makes economic decisions based on, or otherwise uses weather and climate forecasts on monthly, seasonal and decadal timescales.

This is because the proposal has the potential to improve significantly the reliability of forecasts that make use of coupled ocean atmosphere models. The developments proposed will have such wide benefits because so many international and national operational forecasting bodies (UK Met Office, MPI, Meteo France, IPSL, EC-Earth etc) use the NEMO coupled ocean atmosphere model as part of their forecasting methodology.

Naturally the results will be of particular interest to climate scientists at these research institutions and meteorological agencies, who are charged with developing projections of future climate, as well as producing the next generation of coupled ocean-atmosphere climate models.

The general public, particularly in the UK, has always shown a keen interest in weather forecasting. Climate change on all timescales, and the role of the ocean and atmosphere in it, has captured the attention of the public and media, and there is a clear need for the relevant complex science to be communicated in a form that can be understood by a non-specialist. While the technical aspects of the project are not suitable for wider dissemination, the project will produce some highly relevant information regarding forecast reliability on monthly, seasonal and decadal timescales.