Persistence of seasonal Climate Anomalies: Drivers, Mechanisms and Process-based Diagnostics

With the ultimate goal of improving seasonal forecasts, we aim to advance mechanistic understanding of three key boundary conditions that influence European seasonal weather: North Atlantic upper-ocean heat content, Arctic sea-ice and the stratosphere. Summer weather and climate will be principal focus. The project will use a mixture of state-of-the-art coupled climate model experiments, idealised dynamical frameworks and advanced statistical techniques.

The work will be achieved by five interacting WorkPackages (WP): Our overall goal is to improve the skill of the Met Office Global Seasonal forecast System (GloSea5). To do this, the system must be critiqued, and deficiencies must be identified. Each WP addresses these needs in various ways.
WP1. Oceanic drivers - Upper-ocean heat content which may affect the position of the storm track in summer (and related blocking and NAO);
WP2. Sea ice drivers - Arctic sea-ice extent and thickness in winter/spring which may cause variations is summer rainfall in Europe;
WP3. Stratospheric drivers - Influence on the troposphere from stratospheric variations (including the QBO);
WP4. Hierarchy of idealised dynamical models to gain deep mechanistic understanding of how drivers can lead to persistence and seasonal anomalies;
WP5. Statistical modelling of sub-seasonal space-time processes for better quantification and understanding of the role of drivers on modes of variability.

1. Beneficiaries

The general public through improved seasonal to interannual forecasts Improved forecasts benefit the general public mainly through industry using the forecasts to plan ahead and hedge less against the impacts of undesirable weather events. For example, in agriculture, the choice of crop may depend on precipitation during the growing season. The power industry may decide to do maintenance on a plant when demand is least. Better forecasts allow businesses to better plan ahead, and they reduce the need to hedge against unforeseen events. Ultimately, this reduces costs (and retail prices), and contributes to the financial health of companies in which the public invests.

The financial sector, through better informed trades on contracts for commodities affected by the weather The financial industry trades contracts on weather-dependent commodities. The contracts have fixed lengths of a week, a month, 3 months, and calendar years. Weather can account for up to half the volatility on some contracts. The organisations that make the trades (on behalf of their investors) benefit by having better forecast information than their competitors. Many of these companies purchase and use GloSea5 output, along with competing systems. Aside from this specific benefit, the entire industry benefits if price volatility is reduced by improved knowledge of future weather.
By being on the "ground floor" of this research, our Project Partner Citadel has an expectation of financial benefits that exceed their investment. These benefits will continue to accrue until the scientific results are published in the literature and other forecasting centres implement the changes.

The Met Office. This research will help the Met Office achieve its goal of becoming the world leader in seasonal to decadal forecasting. This, of course, benefits the UK public, but it also raises the profile of the Met Office in the international scientific
community.