Application and Verification of the ECMWF Precipitation Type Forecast Product (PTYPE)
The ECMWF (European Centre for Medium-Range Weather Forecasts) precipitation type forecast products （PTYPE） were verified using the weather observations of more than 2 〖KG-*5〗000 stations in China over the winter months (October to the next March) during 2016-2018. The products include the deterministic forecasts from high-resolution model （HRD） and the probability forecasts from ensemble prediction system （EPS） and the verified precipitation types include rain, sleet, snow and freezing rain. The results show that the accuracy of deterministic forecasts of ECMWF HRD is mostly higher than 90% and the TSs of rain and snow are the highest, followed by the TS of freezing rain, and the TS of sleet is lower, which indicates that the forecast skill of sleet is limited. The rain and snow dividing line of deterministic forecasts shows the errors of a little southward in short range forecast and more and more significant northward following elongating lead times in medium range forecast. The area of sleet forecast is smaller than observations and the area of freezing rain forecast is bigger for the HRD forecast. The EPS offsets these errors partly by probability forecast. The probability forecast of rain from the EPS is smaller than the observation frequency and the probability forecast of snow is larger in short range and smaller in medium range forecasts than the observation frequency. However, there are some forecast skills for all of these probability forecasts. There are advantages of EPS compared to the HRD. For rain and snow, for some special cost/loss ratio events the EPS is better than the HRD. For sleet and freezing rain, the EPS is better than the HRD significantly, especially for the freezing rain.