Study on Probability Model of Freezing Damage of Walnut’s florescence in Central and Southern Hebei Province

Abstract

Based on the surface meteorological data of 11 national meteorological stations in the main walnut producing areas of central and southern Hebei province from 1960 to 2017, three distribution functions, including normal distribution, Gumbel distribution and Weibull distribution functions are used to fit the minimum temperature of walnut flowering period, and a probability model of low temperature freezing damage is proposed. The results show that the commonly used probability model is not generally applicable to the freezing damage of walnut’s florescence; different sites of freezing damage of walnut blossom obeyed different probabilistic distribution, Weibull distribution model is more fitting to Gaocheng and Shexian than that of normal distribution fitting model, and the normal distribution model is much suitable for 9 sites such as Lianyuan than Weibull distribution model; comparing the stations in mountainous and plain areas, the mean value varies with the latitudes. The mean value of stations in the eastern foot of Taihang Mountains decreases with the increase of latitude. However, the mean value of stations in the Inner Hill is lower than that of other stations at the same altitude and latitude due to the influence of geographical topography and microclimate. Therefore, the probability of freezing damage is affected by both mean and standard deviation. The extreme weather is more likely to occur in Laiyuan, Inner Hill, Shexian and Gaocheng. The probability of low temperature occurrence is generally consistent with the altitude and latitude and it is also greatly affected by the geographical topography and microclimate.