Abstract 189

Abstract ID: 189

The Forecast Skill of the Northern Hemisphere Middle Latitudes Seasonal Oscillation and its impact on the surface air temperature

Lead Author: Cristiana Stan
George Mason University, United States of America

Keywords: Mid-latitude oscillations, S2S models

Abstract: This study examines the subseasonal forecast skill of the dominant mode of atmospheric circulation variability in the Northern Hemisphere (NH) mid-latitudes, the Middle Latitudes Seasonal Oscillation (MLSO), and the influence of MLSO on the forecast skill of surface weather in this area. The analysis is conducted using reforecasts produced by four forecast systems, which archive their output in the Subseasonal-to-Seasonal (S2S) Data Base. A reduced ensemble of reforecasts for each model is verified against the ERA- Interim reanalysis. The S2S models display significant ability to predict the MLSO on the S2S time scale. The MLSO prediction skill is higher in boreal winter than in summer. A relationship is found between the MLSO and the forecast skill of 2-meter temperature (T2m) in the NH mid-latitudes during the extended boreal winter. The prediction of T2m improves when MLSO events are in the initial conditions and the improvement depends on the phase of MLSO.