Seasonal prediction of Euro-Atlantic teleconnections from multiple systems

Abstract

Seasonal mean atmospheric circulation in Europe can vary substantially from year to year. This diversity of conditions impacts many socioeconomic sectors. Teleconnection indices can be used to characterize this seasonal variability, while seasonal forecasts of those indices offer the opportunity to take adaptation actions a few months in advance. For instance, the North Atlantic Oscillation has proven useful as a proxy for atmospheric effects in several sectors, and dynamical forecasts of its evolution in winter have been shown skillful. However the NAO only characterizes part of this seasonal circulation anomalies, and other teleconnections such as the East Atlantic, the East Atlantic Western Russia or the Scandinavian Pattern also play an important role in shaping atmospheric conditions in the continent throughout the year. This paper explores the quality of seasonal forecasts of these four teleconnection indices for the four seasons of the year, derived from five different seasonal prediction systems. We find that several teleconnection indices can be skillfully predicted in advance in winter, spring and summer. We also show that there is no single prediction system that performs better than the others for all seasons and teleconnections, and that a multi-system approach produces results that are as good as the best of the systems.

Challenges in the selection of atmospheric circulation patterns for the wind energy sector

“…This skill is directly associated with the skill found for the SLP, with the systems showing a higher SLP regional skill having higher skill for the cluster frequency. Nevertheless, there are additional factors that can also play a role on the low skill in that area, such as the short hindcast length (1993–2016) or the limited ensemble size (from 40 to 25 members depending on the system) of the C3S seasonal forecast systems available (Scaife et al ., 2014; Manzanas et al ., 2019; Lledó et al ., 2020). The sensitivity of the skill to simulate the frequency of occurrence of the clusters depending on the ensemble size and the hindcast period has been tested (Figure S15) for the ECMWF‐S5 seasonal forecast system.…”

Verification: Assessment of Calibration and Accuracy

“…These patterns, such as the North Atlantic Oscillation, can be directly linked to surface weather variables, but are often easier to predict (Lledó et al, 2020 ).…”

Pattern‐based conditioning enhances sub‐seasonal prediction skill of European national energy variables

“…Despite the popularity of pattern-based methods to understand and predict the large-scale atmospheric circulation, they are associated with the key caveat that skill in forecasting the large-scale meteorological pattern (typically observed in 500 hPa geopotential height or surface pressure) does not in itself guarantee skill in terms of predicting a desired surface impact response (e.g., nearsurface wind speeds or temperatures, wind power generation or electricity demand). Recent work using historic reanalyses has, however, convincingly demonstrated that many Euro-Atlantic weather patterns (with various methods of construction) relate to relevant surface weather conditions (Bloomfield, Brayshaw, & Charlton-Perez, 2020a;Cortesi et al, 2019;Drücke et al, 2020;Garrido-Perez et al, 2020;Grams et al, 2017;Thornton et al, 2017;van der Wiel et al, 2019) and to European electricity demand, wind and solar power generation (Bloomfield, Brayshaw, & Charlton-Perez, 2020a;Grams et al, 2017;Lled o et al, 2020;van der Wiel et al, 2019). This suggests that, given these patterns can be forecast at lead times out to 2 weeks and 3 months for WRs and teleconnections respectively, they could potentially offer benefits over grid-point forecasts.…”

“…Much of the science within the meteorological community has focused on the skill present in forecasts of Euro‐Atlantic teleconnections at seasonal timescales (Lledó et al, 2020) such as the North Atlantic Oscillation (NAO; Baker et al, 2018; Dunstone et al, 2016; Scaife et al, 2014) and Euro‐Atlantic WRs at sub‐seasonal timescales (Büeler et al, 2020; Charlton‐Perez et al, 2018; Ferranti et al, 2015; Matsueda & Palmer, 2018). Forecast skill for the daily occurrence of WRs has, for example, been shown to extend to approximately 2 weeks for sub‐seasonal forecasts (Ferranti et al, 2018; Matsueda & Palmer, 2018) with similar results found for WRs over North America (Robertson et al, 2020).…”

“…Forecast skill for the daily occurrence of WRs has, for example, been shown to extend to approximately 2 weeks for sub‐seasonal forecasts (Ferranti et al, 2018; Matsueda & Palmer, 2018) with similar results found for WRs over North America (Robertson et al, 2020). Skill extends to 3 months for forecasts of seasonal‐mean teleconnection patterns (Lledó et al, 2020), with models showing skill out to a year‐ahead for the NAO teleconnection pattern in particular (Dunstone et al, 2016). The level of skill has been shown to be conditional on particular atmospheric states (e.g., Sudden Stratopsheric Warmings; Beerli et al, 2017; Büeler et al, 2020; Charlton‐Perez et al, 2018) or global teleconnections such as the El Niño–Southern Oscillation and the Madden–Julian oscillation (Lee et al, 2019), supporting the concept that particular atmospheric states offer windows of opportunity for enhanced predictability (Mariotti et al, 2020; Robertson et al, 2020).…”