1961—2010年山西终霜冻的周期分析及其突变特征

Analysis of the Last Frost Periodicity and Its Mutation Characteristics of Shanxi Province in 1961 to 2010

为了深入研究山西霜冻的发生演变规律,提高防霜减灾能力和农作物产量,利用山西62个测站1961—2010年的逐日最低地温资料,采用Morlet小波以及M-K突变检验等方法分析了山西终霜冻日1961—2010年的变化特征。结果表明:山西平均终霜冻日呈现提早结束的趋势并有显著波动变化,除1980—1989年及2005—2010年外,均表现为显著提早的趋势;2001—2010年是山西平均终霜冻日波动最为剧烈的时期。小波分析结果表明,1961—2010年山西轻微、中度、重度终霜冻的主要周期分别为14-17年、12-14年和7年;次周期分别为1年、1年和5年;目前,山西正处在轻微终霜冻的提前期以及中度和重度终霜冻的推后期。M-K突变检验表明,1961—2010年山西平均终霜冻日在1990年发生了一次显著的气候突变,且大部分站点的终霜冻日在1975—1996年之间都发生了突变,突变的空间分布总体表现为南部偏早北部偏晚,中部偏早、东部和西部偏晚的分布特征;突变在1980—1989年的分布区域最为广泛,中西部、西北部、东北部和中东部地区是突变最晚的地区。

Based on each year’s last frost date data and each day’s minimum ground temperature data of 62 meteorological stations in Shanxi Province from 1961 to 2010,the last frost date change characteristics and its periodicity of Shanxi Province were analyzed with Morlet analysis and Mutation test method.The results showed that： the average last frost date of Shanxi Province had an advancing trend with obvious fluctuations.Except during 1980 to 1989 and the time from 2005 to 2010,the average last frost dates all had advancing trend.The first decade of this century was the period that the average last frost date of Shanxi fluctuated smartly.The Morlet analysis results showed that,the main periodicity of the mild last frost,the moderate last frost and the severe last frost were 14 to 17 years,12 to 14 years,7 years,the secondary periodicity of the mild last frost,the moderate last frost and the severe last frost were 1 year,1 year,5 years.Now,Shanxi was at the stage when the mild last frost occurs in advance but the moderate and severe last frosts shift to later dates.It was found with M-K mutation test that the average last frost date of Shanxi Province had an obvious mutation in 1990,and the last frost dates of most stations in Shanxi Province had mutations,the mutation time were concentrated from 1975 to 1996,and the spatial distribution of the mutations over Shanxi Province showed as follows： the South was earlier than the North, the Central was earlier than the East and the West. Most mutations occurred in 1980s, the Midwest, Northwest, Northeast and Mideast regions were the latest areas.