Abstract:

The daily effective temperature was calculated using the observation data from Jinhua meteorological station from 1969 to 2018, and the annual and seasonal average effective temperatures were calculated.The linear trend was used to estimate the change trend and the characteristics of the cold/hot/comfort days were statistically analyzed on multiple time scales.The results show that the average effective temperature of Jinhua city shows significant fluctuation and rising trend throughout the year and seasons.It crosses the average value steadily around 2000 and shows the increasing trend with an annual climate tendency rate of 0.67℃/10 a, and the fluctuation amplitude and upward trend are different among seasons with the largest in winter and the smallest in summer.The probability of warm or cold winter increases first, then decreases, and then increases slightly as the N-type, while the probability of hot summer or cold summer increases weakly.The comfort period shows a bimodal distribution, mainly concentrates in April-June and September-October, with the most comfortable days in May.The 50-year average beginning and end dates of the comfort period are April 4 and November 8, respectively.Over time, the initial date shows a significant advance trend (about 5.7 d/10 a), while the end date shows a significant delay trend(about 4 d/10 a).The overall climate comfort rate shows a weak upward trend.The numbers of comfortable days and hot days increase significantly with the rates of 5.08 d/10 a and 2.31 d/10 a respectively, while the number of cold days decreases significantly, reaching 7.39 d/10 a.On the whole, the winter in Jinhua city is milder, while the summer is hotter relative to foretime.Meanwhile, the comfortable time in spring increases significantly, while the cold uncomfortable time in autumn reduces significantly.

Key words: Comfort degree, Cold days, Hot days