Energy Budget over Seasonal Snow Surface at an Open Site and Beneath Forest Canopy Openness during the Snowmelt Period in Western Tianshan Mountains,China

In this study, meteorological factors and snowmelt rate at an open site on sunny slope(OPS) and beneath forest canopy openness on shady slope(BFC) were measured using an automatic weather station and snow lysimeter during the snowmelt period in 2009, 2010 and 2013. The energy budget over snow surface was calculated according to these meteorological datasets. The analysis results indicated that the net shortwave radiation(K) and sensible heat flux(H) were energy sources, and the latent heat flux(LVE) was energy sinks of snow surfaces at all sites. The net longwave radiation(L) was energy sink at OPS and 80% BFC, but energy source at 20% BFC. The gain of K, H, and the loss of LVE at BFC were obviously lower than those at OPS. The L was the maximum difference of energy budget between snow surface at BFC and OPS. In warm and wet years, the most important factor of the energy budget variation at OPS was air humidity and the second mostimportant factor was air temperature. However, the ground surface temperature on the sunny slope was the most important factor for L and energy budget at BFC. With the increases in forest canopy openness and the slope of adjacent terrains, the influences of ground surface temperature on the sunny slope on L and the energy budget over snow surface at BFC increased, especially when the snow cover on the sunny slope melts completely.

天山季节性积雪的能量平衡研究和融雪速率模拟

本文采用能量平衡法模拟计算中国西部天山山地季节性积雪的融雪速率。结果表明:在融雪期,净辐射和感热通量分别占融雪能量输入的75.3％和22.6％;用于融雪和雪面蒸发所消耗的能量分别占吸收能量的95.1％和4.9％。用能量平衡法所计算的融雪速率和实测的雪面数据吻合的较好,表明用能量平衡法估算天山山地季节性积雪的融雪速率是可行的。

冰雪反照率研究进展

冰雪反照率在地气能量平衡中起重要作用,其大小取决于两个方面,即冰雪面的反射属性以及大气或天空的状况.因此,影响冰雪反照率的因素除其自身的物理属性如积雪粒径、密度、含水量、杂质和污化程度等外,云对冰雪反照率也产生影响,从而使冰雪的反照率呈现出日变化、季节变化和空间变化规律.最后,评述了利用数值模式及卫星遥感反演方法对冰雪反照率的相关研究进展.

基于过程的融雪模型研发Ⅰ——原理

研究建立了基于物理过程的能量平衡融雪模型Snow Column。模型包含能量平衡、相变、水量传递、压实和粒径变化等过程,能详细刻画雪柱在消融过程中密度剖面、温度剖面和剖面液态水含量变化。选取美国洛基山脉科罗拉多Niwot实验场006号雪坑1996年4月~6月融雪观测资料验证模型,模拟结果在合理范围内。该模型可以为进一步认识雪盖对气候变化的响应提供基础。

建筑屋面滑移雪荷载的模拟方法研究

滑移雪荷载是屋面雪荷载的重要组成部分,该文发展了计算屋面滑移雪荷载的模拟方法。首先,基于前人提出的能量及质量平衡模型,并针对建筑屋面积雪的特点,构造了建筑屋面融雪模型。在此基础上,提出将屋面积雪中液态水超过积雪最大持水量时作为屋面雪层开始滑移的判定条件。利用该文方法对我国几个代表性地区的屋面滑移雪荷载进行了模拟,分析了不同地区的气象特征、邻近建筑对屋面积雪的遮挡等因素对滑移雪荷载的影响;同时定量分析了各个能量对滑移雪的贡献大小。