藏北高原典型季节冻土区和多年冻土区小气候特征对比研究

利用藏北高原位于季节冻土区的那曲BJ站和多年冻土区的唐古拉站2008年气象要素观测资料,对两站点的小气候特征进行了分析和对比,得到以下结论:那曲BJ站最大冻结深度可达1.5 m左右;唐古拉站活动层最大融化深度超过了3.0 m.两站的气温、比湿、降雨和积雪均有明显的季节变化;降雨和比湿均是5-10月较大,其他时段较小;积雪均基本集中在1-3月和10-12月.各层土壤温度及日变幅、温度的月均值和月最高/低值及月较差、比湿的月均值和瞬时最大值、风速瞬时最大值均是那曲BJ站大于唐古拉站.那曲BJ站与唐古拉站的风速、气温、比湿的年平均值分别是4.73 m·s~(-1)、-1.34℃、3.96 g·kg~(-1)和4.02 m·s~(-1)、-5.80℃、3.25 g·kg~(-1),年降雨量和积雪日数分别为590.50 mm、114 d和405.27 mm、135 d,两站5-10月的降雨量分别占全年降雨量的96.20%和86.55%.两站在2月初和11月初由于较大降雪均出现了气温陡降的现象,最大积雪日均出现在11月,日最大积雪深度BJ站小于唐古拉站.典型晴天日,那曲BJ站在冬季而唐古拉站在冬春季节风速日变化明显;比湿日变化夏秋季节较冬春季节明显.

A comparison study of the microclimate characteristics between the typical seasonally frozen ground regions and permafrost regions in the northern Tibet Plateau

Based on the meteorological observation in Naqu BJ site located in a seasonal frozen ground region and Tanggula site in a permafrost region in 2008,the characteristics of microclimate at Naqu BJ site and Tanggula site are analyzed.The results show that the maximum frozen depth in Naqu BJ site is about 1.5 m and the maximum thawed depth of the active layer in Tanggula site is beyond 3.0 m.The seasonal variations of the air temperature,specific humidity,precipitation and snow cover are obvious.Specific humidity and precipitation are concentrated in the period from May through October.Most of the snow cover are appeared in the period from January to March and from October to December.The monthly average ground temperature,air temperature and specific humidity,instantaneous maximum values of specific humidity and wind velocity,monthly range of air temperature in the Naqu BJ site are all greater than those in the Tanggula site.The annual average values of wind velocity,air temperature and specific humidity in the two sites are 4.73 m · s-1,-1.34 ℃,3.96 g · kg-1 and 4.02 m · s-1,-5.80 ℃,3.25 g · kg-1,respectively.The annual precipitation and number of snow cover days of the two sites are 590.50 mm,114 days and 405.27 mm,135 days,respectively;the precipitation from May to October of the two sites are 96.20％ and 86.55％ of the annual precipitation,respectively.The air temperatures of the two sites sudden drop in early February and early November owing to heavy snowfall;the largest daily maximum snow depths of the two sites are in November;the daily maximum snow depth in the Tanggula site is greater than that in the Naqu BJ site.On a typical sunny day,in Naqu BJ site the diurnal variation of wind velocity is distinct in winter and in Tanggula site that is distinct in spring and winter;the daily variation of specific humidity is distinct in summer and autumn rather than in spring and winter in the two sites.