Meteorology and dust in the central Sahara: Observations from Fennec supersite-1 during the June 2011 Intensive Observation Period
Meteorology and dust in the central Sahara: Observations from Fennec supersite-1 during the June 2011 Intensive Observation Period
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撒哈拉中部的气象和沙尘：2011 年 6 月密集观测期间 Fennec supersite-1 的观测
DOI：
10.1002/jgrd.50211
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Marsham J
中科院分区：
文献类型：
--
作者：
Marsham J
我们描述了在2011年6月芬内克密集观测期间在Bordj Badji Mokhtar（BBM）的芬内克超地点进行的观测。这是第一次对撒哈拉中部的气象和尘埃进行详细的原位观测，靠近撒哈拉热量低和夏季尘埃最大的中心。从历史上看，缺乏这种撒哈拉观测造成了评估过程，模型和遥感的问题。在6月8日之前和6月12日之后，BBM受到季风影响，其间有干燥的Harmattan风。分裂的边界层，从大西洋的通风所产生的，坚持在干燥阶段。定期观察到广泛的冷池（haboobs）和微下击暴流类型事件。夜间，季风和嵌入式Haboobs的湿气到达BBM。除了定期出现的夜间低空急流（LLJ）外，还观测到撒哈拉上边界层（650 hPa）急流，下午风受到干对流的阻力。这种急流与水汽和云的日循环有关。大多数沙尘都是在受季风影响的多云时期观测到的，而协变的沙尘和云量解释了控制地表可感通量的短波辐射的大部分变化。多尘与使用10米风（“抬升潜力”）的抬升标准参数化有关，并用于估计抬升。大约50%的隆起是夜间的。大约30%来自LLJ，50%来自主要在夜间活动的哈布斯。这是第一次从观测中证明了哈布斯的关键作用，这对模型来说是有问题的。
We describe observations from the Fennec supersite at Bordj Badji Mokhtar (BBM) made during the June 2011 Fennec Intensive Observation Period. These are the first detailed in situ observations of meteorology and dust from the central Sahara, close to the center of the Saharan heat low and the summertime dust maximum. Historically, a shortage of such Saharan observations has created problems for evaluating processes, models, and remote sensing. There was a monsoon influence at BBM before 8 June and after 12 June, with dry Harmattan winds in between. A split boundary layer, generated by ventilation from the Atlantic, persisted during the drier phase. Extensive cold pools (haboobs) and microburst‐type events were regularly observed. Moisture reached BBM at night from the monsoon and the embedded haboobs. As well as the regularly occurring nocturnal low‐level jet (LLJ), a Saharan upper boundary layer (650 hPa) jet was observed, where winds feel drag from dry convection in the afternoon. This jet is linked to the diurnal cycles of moisture and cloud. Most dust was observed in the cloudier monsoon‐affected periods, and covarying dust and cloud amounts explain most of the variations in shortwave radiation that control the surface sensible flux. Dustiness is related to a standard parameterization of uplift using 10 m winds (“uplift potential”), and this is used to estimate uplift. Around 50% of uplift is nocturnal. Around 30% is from the LLJ, and 50% is from haboobs, which are mainly nocturnal. This demonstrates, for the first time from observations, the key role of haboobs, which are problematic for models.