Research on Revision of 2m Temperature Forecasted by WRF-RUC Model in Shandong Based on Vertical Temperature Gradient
Based on vertical temperature gradient,two schemes were designed to reduce the forecast error originated from the difference between observed terrain height and model terrain height.The first scheme was on basis of a hypothesis that the vertical temperature gradient of the whole atmospheric layer is-0.006 5 ℃ · m-1,while the vertical temperature gradient was calculated between the two model layers which were closer to the observed terrain height,and it was utilized by the second method.These two schemes were used to make revision on day-to-day 2 m forecast temperature of WRF (weather research and forecast)-RUC (rapid update cycle) model during the period from October to December in 2016 in Shandong.The revised and unrevised 2 m forecast temperature of WRF-RUC model were compared and some research work was focused on 2 m forecast temperature at Mount Tai station.The results were as follows:(1)The difference between observed terrain height and model terrain height in most of observing stations in Shandong was so small that revision effect of two schemes was unnoticeable.For stations with observed terrain height being lower than or equal to model terrain height,the RMSE calculated by the second scheme was significantly greater than that calculated by the unrevised and the first scheme,so the revision effect of the second method was negative.(2) The revision effect on Mount Tai 2 m forecast temperature of the first schemes was positive in former forecast period,while it was negative in later forecast period,and that of the second method was positive in the whole forecast period.The relative error of 2 m forecast temperature at Mount Tai station revised by the second method maintained between-2 and 2 ℃.(3) The negative systematic deviation of WRF-RUC on 2 m temperature caused negative revision effect in later forecast period by using the first scheme,the second scheme was more skillful on Mount Tai 2 m forecast temperature revision because it diminished the influence of temperature inversion.
WRF-RUC2m temperatureterrain heightvertical temperature gradientMount Tai
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