Workshop on Predictability, dynamics and applications research using the TIGGE and S2S ensembles
Session
This study assesses the medium-range flow-dependent forecast skill of Euro-Atlantic weather regimes: the positive and negative phases of the North Atlantic Oscillation (NAO+ and NAO−), Atlantic ridge (ATLR), and Euro-Atlantic blocking (EABL), for extended winters (November–March) in the periods 2006/2007–2013/2014 and 1985/1986–2013/2014 using The Interactive Grand Global Ensemble (TIGGE) and...
A major source of sub-seasonal predictability for the mid-latitudes during boreal winter and spring and austral spring is variability of the stratospheric polar vortex. While a number of studies have now demonstrated that surface predictability is enhanced during both sudden stratospheric warming (SSW) and strong vortex events, there has been little comparison of model performance beyond a...
Surface weather variability on subseasonal timescales influences energy production, demand, and prices. Improving the skill of subseasonal predictions of surface weather is thus of high interest for the energy industry. This is particularly the case for near-surface wind due to the ongoing shift toward more wind power generation. Anomalous states of the stratospheric polar vortex during winter...
Predictability of the MJO, especially the initiation and eastward propagation of the large-scale convection and precipitation over the Indian Ocean and West Pacific warm pool across the Maritime Continue, is extensively investigated using the S2S ensemble. The model forecasts are compared with the Large-scale Precipitation Tracking (LPT) of the MJP using the 20-years TRMM-GPM precipitation...
As a potential source of multiweek predictability, we investigate the MJO’s impact on temperature extremes during Austral spring. We find a significant MJO influence on weekly mean temperature extremes (defined here as exceeding the upper and lower quintiles) over southeastern Australia when the MJO is in phases 2, 3, and 6 and 7. During these phases, the occurrence of maximum and minimum...
The effect of the Madden-Julian Oscillation (MJO) on the Northern Hemisphere wintertime stratospheric polar vortex is evaluated in operational subseasonal forecasting models. Reforecasts which simulate stronger MJO-related convection in the Tropical West Pacific also simulate enhanced heat flux in the lowermost
stratosphere and a more realistic vortex evolution. The time scale on which vortex...
The natural variability of the extra-tropics is studied at seasonal and intra-seasonal time scales. Nonlinear oscillations in the extra-tropics are extracted from daily anomalies of 500-hPa geopotential height for the period 1979-2012 using a data-adaptive method. Three propagating oscillations with broad-band spectra centered at 120, 45, and 28 days are found. When combined, the oscillations...
Pentad forecast skill over the Northern polar region in boreal winter is evaluated for the subseasonal to seasonal prediction (S2S) systems from three operational centers: the European Centre for Medium-Range Weather Forecasts (ECMWF), the U.S. National Centers for Environmental Prediction (NCEP) and Environment and Climate Change Canada (ECCC). The former two systems are running with air-sea...