利用2009年12月27日～2010年4月2日天山积雪站站区内开阔地和雪岭云杉(Picea schrenkiana)林下6次降雪过程后雪层内时间间隔10 min的温度数据,探讨雪层温度变化特征。结果表明,越接近地表雪层温度越高,且在雪层表面形成冷中心和(局部)暖中心;在积雪稳定期林下雪层温度高于开阔地,融雪期林下低于开阔地;林下雪层冷、暖中心出现时间晚于开阔地,其强度也小于开阔地。林下雪层温度振幅小于开阔地,林下温度振幅拐点以上雪层温度振幅随深度和时间的递减率小于开阔地,拐点以下无明显差异。初冬,林下和开阔地雪层均为较小的正温度梯度,随着气温急剧下降,温度梯度逐渐增大,且从雪表向雪底递减,林下雪层负温度梯度出现时间晚于开阔地。开阔地和林下积雪表层正温度梯度最大值分别达到0.95℃/cm和0.82℃/cm,负温度梯度大值分别达到-0.84℃/cm和-0.35℃/cm;但开阔地全雪层日平均温度梯度小于林下雪层。
The snow temperature under Picea schrenkiana forest crown and on the open ground was observed at Tianshan Research Station for Snow-cover and Avalanche of the Chinese Academy of Sciences from Dec 27,2009 to Apr 2,2010.The spatial and temporal distributions as well as variations of snow temperature were analyzed in details.The results indicated that there is a higher snow temperature near the ground surface,and local cold and warm centre happen at the snow surface layer.The snow temperature under crown is higher than that on the open ground in stable period,which present a contrary trend in snowmelt period;the low and high temperature centre of forest snow appears later and weaker than that on the open ground.Besides,the decreasing rate of snow temperature amplitude with depth and time under crown is lower than that on the open ground above break point,but there is no statistical difference below break point at early stable period.The snow temperature gradient is small and positive,and it increases with air temperature decreasing but decreases with depth from surface down.The negative temperature gradient of forest snow appeases later than that on the open ground.Under crown and on the open ground,the maximum positive temperature gradient of snow reaches 0.95℃/cm and 0.82℃/cm,and the negative temperature gradient reaches-0.84℃/cm and-0.35℃/cm,respectively.Whereas the whole layer snow temperature gradient under forest crown is larger than that on the open ground.
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