Study on the characteristics of the Distribution of the first and late frost dates in Harbin region

Based on the study on the distribution of the first and late different degree frost dates in the past fifty years, the results on frost study are developed. The results indicate that: (1) the annual discrepancy of late frost is more notable than that of first frost ; (2) the tedency exists that the annual discrepancy of intense frost is distinct and that of weak frost is rela- tively unremarkable. Moreover, the curves of frost indexes of different degrees and the re- sponding days of the guarantee rates in all degrees are given.