Evaluation of the hourly rainfall in the ECMWF forecasting over southwestern China

Abstract

AbstractThe performance of the forecasts of the European Centre for Medium‐Range Weather Forecasts' (ECMWF) Integrated Forecasting System (IFS) with a horizontal resolution of 0.125° is assessed through comparison with station rain‐gauge data in the warm season (May–October) in the period 2017–2018 over southwestern China. The mean state of rainfall amount, frequency and intensity, as well as the diurnal cycle of precipitation, are involved in the evaluation. The IFS can capture well the spatial distributions of rainfall amount, frequency and intensity in the gauge data, but the rainfall frequency is generally larger and the intensity is weaker in the IFS. The rainfall events of the IFS usually start and peak much earlier, and the afternoon rainfall peaks are overestimated. The discrepancy between the gauge data and the IFS is larger over the western part of southwestern China. The results indicate that the IFS forecasts show considerable uncertainty when moving to the sub‐daily scale, especially over areas with complex topography. When the IFS forecasts are applied operationally, the deviations (as revealed in this study) should be paid more attention.