Temperature and precipitation long range forecasts over Europe at a monthly and shorter temporal resolution

Long range forecasts provide information about expected future atmospheric and oceanic conditions averaged over periods of one to three months and are attractive for many sectors. They have made considerable progress in recent years, but seasonal predictability remains a problem in many regions (for example in Europe). Demand is also for long range forecasts, which would predict shorter periods than months (for example 3 decades in each month).

This study considers four seasonal forecasting systems available in the Copernicus Climate Change Service (C3S) archive which provide near-surface air temperature and precipitation data at 1°by 1°spatial resolution: European Centre for Medium-range Weather Forecast System SEAS5 (ECMWF), Météo – France System 8 (MF), Deutscher Wetterdienst GCFS 2.1 (DWD) and Centro Euro-Mediterraneo sui Cambiamenti Climatici SPSv3.5 (CMCC). It quantifies their value in predicting temperature and precipitation at monthly and shorter (3 decades in each month) temporal resolution over Europe. There are two starting dates, May 1st, and November 1st, and forecasts at lead times up to 3 months for each year in the period 1993–2016 (the longest period of hindcasts common to all systems).

We focus on 2 domains: larger (Europe, latitude 42-55°N, longitude 2-30°E) and smaller (the Czech Republic, latitude 47-52°N, longitude 11-20°E). E-OBS daily gridded observational datasets for precipitation and temperature at 0.25°spatial resolution are used as a reference.

Several statistical measures such as mean bias and root mean square error are presented for temperature and precipitation at a monthly and shorter (3 decades in each month) temporal resolution over Europe and for the Czech Republic.