利用1961—2020年黑龙江省冬季逐日气温资料,以连续5 d日平均气温低于一个标准差来判定极端冷事件,进而利用冷事件的持续天数和气温累计距平构建冬季极端寒冷指数(Extreme Cold Index of Winter,ECIW)。在此基础上深入研究了ECIW的年代...利用1961—2020年黑龙江省冬季逐日气温资料,以连续5 d日平均气温低于一个标准差来判定极端冷事件,进而利用冷事件的持续天数和气温累计距平构建冬季极端寒冷指数(Extreme Cold Index of Winter,ECIW)。在此基础上深入研究了ECIW的年代际变化特征及其环流差异。结果表明:近60 a来黑龙江省ECIW呈显著上升趋势,且在1987年前后发生了年代际突变,突变后冬季冷事件强度显著减小。回归分析表明,突变前的1961—1985年,当ECIW强度偏强时,环流呈现北极涛动负位相和弱的欧亚遥相关型正位相分布特征,西北高东南低的环流配置下东亚中高纬环流经向度加大,影响黑龙江省的冷空气较强。而突变后的1991—2020年,环流呈现典型的欧亚遥相关型正位相分布,东亚温带急流显著偏弱,北高南低的配置下黑龙江上空低值系统活跃。对北极涛动、欧亚遥相关型、西伯利亚高压、东亚冬季风等指数与ECIW的相关和偏相关分析表明,北极涛动和欧亚遥相关型是影响ECIW的重要环流因子,1961—1985年北极涛动是主导因子,1991—2020年欧亚遥相关型是主导因子。展开更多
Fire numbers, burned areas and return intervals in each large scale forest type with average patch area of 500?km 2 in Heilongjiang Province during the period of 1980 to 1999 were obtained by overlapping the ignition ...Fire numbers, burned areas and return intervals in each large scale forest type with average patch area of 500?km 2 in Heilongjiang Province during the period of 1980 to 1999 were obtained by overlapping the ignition points and areas of 1482 forest fires with the Province’s forest type maps in the same period by means of GIS software ARC/INFO. Analysis on the data indicated that the effects of the forest types on fire occurrence and burned areas in the Province were not significant, thus it was not necessary to take forest types into consideration when forest fire hazard was rated on a large scale. Years long human fire suppression activities increased fire return intervals in the region. Comparison was also made on the effects of forest types on fires at various scales.展开更多
文摘利用1961—2020年黑龙江省冬季逐日气温资料,以连续5 d日平均气温低于一个标准差来判定极端冷事件,进而利用冷事件的持续天数和气温累计距平构建冬季极端寒冷指数(Extreme Cold Index of Winter,ECIW)。在此基础上深入研究了ECIW的年代际变化特征及其环流差异。结果表明:近60 a来黑龙江省ECIW呈显著上升趋势,且在1987年前后发生了年代际突变,突变后冬季冷事件强度显著减小。回归分析表明,突变前的1961—1985年,当ECIW强度偏强时,环流呈现北极涛动负位相和弱的欧亚遥相关型正位相分布特征,西北高东南低的环流配置下东亚中高纬环流经向度加大,影响黑龙江省的冷空气较强。而突变后的1991—2020年,环流呈现典型的欧亚遥相关型正位相分布,东亚温带急流显著偏弱,北高南低的配置下黑龙江上空低值系统活跃。对北极涛动、欧亚遥相关型、西伯利亚高压、东亚冬季风等指数与ECIW的相关和偏相关分析表明,北极涛动和欧亚遥相关型是影响ECIW的重要环流因子,1961—1985年北极涛动是主导因子,1991—2020年欧亚遥相关型是主导因子。
文摘Fire numbers, burned areas and return intervals in each large scale forest type with average patch area of 500?km 2 in Heilongjiang Province during the period of 1980 to 1999 were obtained by overlapping the ignition points and areas of 1482 forest fires with the Province’s forest type maps in the same period by means of GIS software ARC/INFO. Analysis on the data indicated that the effects of the forest types on fire occurrence and burned areas in the Province were not significant, thus it was not necessary to take forest types into consideration when forest fire hazard was rated on a large scale. Years long human fire suppression activities increased fire return intervals in the region. Comparison was also made on the effects of forest types on fires at various scales.
