黑龙江省无霜期的气候变化

对黑龙江省的初，终霜日和无霜期按地区，年代进行较详细的统计，分析。结果表明：６０，７０年代终霜较晚，初霜较早，无霜期较短，８０年代以来，多数地区终霜日有所提前，初霜日推后，无霜期明显延长，９０年代前期（１９９１－１９９５年）有的地区终霜又有所提前，各区及全省初霜日明显推后，无霜期延长，反映了６０，７０的代较冷，８０年代变暖，９０年代前期持续变暖的气候特征。

A Climatic Analysis of the Frostless Season in the Heilongjiang Province

he spatial and temporal variations of the frost seasons in the Heilongjiang province were investigated. the main resules are as follows: During 1960's and 1970's,the onsets of the frost seasons are earlier than normals,the ends of the frost seasons are later,and the frostless seasons are shorter; Since 1980's,the ends of the frost seasons have been gotten earlier and its onsets is later in the most parts of Heilongjiang province,thus the frostless season is longer. These show that the climate is colder than normals before 1970's,after that it is changed into warmer.