摘要
利用内蒙古科尔沁沙地沙尘暴探测与监测试验站2008年和2009年春季沙尘和近地层观测资料,研究了不同沙尘天气条件下沙尘浓度随摩擦速度的变化规律,对比分析了不同天气(晴天、扬沙、沙尘暴和强沙尘暴)入射短波辐射和净辐射的演变,并利用两层高度沙尘浓度差,区分局地起沙和非局地起沙,有效地避免了沙尘水平输送引起的起沙阈值的低估。结果表明,起沙前,摩擦速度和沙尘浓度数值都较低;临近起沙阶段,摩擦速度迅速增大而沙尘浓度基本保持不变;起沙时,摩擦速度数值较高,沙尘浓度迅速增大;沙尘天气减弱阶段,沙尘浓度随摩擦速度近似呈线性减小。科尔沁沙地春季临界起沙摩擦速度u*t和临界起沙风速ut分别为0.62m.s-1和9.5m.s-1,扬沙、沙尘暴和强沙尘暴天气的起沙阈值依次略有增加。与晴天天气相比,沙尘天气到达地面的短波辐射和净辐射明显减少。
Based on the observations of dust concentration and micro-meteorological factors in the surface layer that were obtained from a duststorm station located in the Horqin sand land area in Inner Mongolia during the springs of 2008 and 2009,the variations in dust concentration and friction velocity during various dust events were investigated,and the evolution in downward short-wave radiation and net radiation for different dust weathers were analyzed.Distinguishing local and non-local dust emission by using the dust concentration observations at two levels avoided an underestimation on dust emission thresholds.The results showed that the values of friction velocity u＊ and dust concentration were both low before dust emission,and u＊ rapidly increased,while the values of dust concentration maintained small during the pre-emission stage.Then dust concentration quickly increased as u＊ was high during the dust emission stage,and dust concentration decreased nearly linearly with the decreasing u＊ at the decay stage.The threshold friction velocity u＊t and threshold velocity ut in the Horqin sand land area were estimated to be 0.62 and 9.5 m·s^-1,respectively.The thresholds slightly increased from blowing dust,dust storm to severe dust storm.In comparison with clear days,downward short-wave radiation and net radiation obviously decreased.
出处
《高原气象》
CSCD
北大核心
2012年第1期38-46,共9页
Plateau Meteorology
基金
国家自然科学基金项目(41075005)
国家重点基础研究发展规划项目(2010CB428501)
财政部/科技部公益性行业(气象)科研专项(GYHY201006014)
半干旱气候变化教育部重点实验室(兰州大学)开放基金项目共同资助
关键词
科尔沁沙地
沙尘天气
起沙
临界起沙摩擦速度
微气象学
Horqin sand land area Duststorm Dust emission Threshold friction velocity Micrometeorology
