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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >A hemispheric dust storm affecting the Atlantic and Mediterranean in April 1994: Analyses, modeling, ground-based measurements and satellite observations
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A hemispheric dust storm affecting the Atlantic and Mediterranean in April 1994: Analyses, modeling, ground-based measurements and satellite observations

机译：1994年4月，一场影响大西洋和地中海的半球沙尘暴：分析，建模，地面测量和卫星观测

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One of the largest recorded dust tranpsort events originating from the great Sahara desert during April 1994 affected the entire region extending from the Caribbean to the Eurasian continent. This hemispherical transport of airborne dust took place during a series of storms that developed during the first three weeks of April in a background of low-index circulation. These repeated events are studied through the combined analyses and interpretation of atmospheric data, ground-based aerosol measurements, visibility observations, AVHRR and Meteosat visible band satellite data, and the results of Eta model simulations, including an aerosol transport component. The observations produce a consistent picture of the temporal and spatial development of the dust events, whose main features are used in parts to verify the model results. The rate of dust suspension from some areas of the western Sahara desert exceeded 1.5 mg m(-2) h(-1) and the maximum column integrated dust load reached 2 g m(-2) during April 3-5 1994, when the first major suspension event produced two simultaneous pulses of dust moving in opposite directions across the subtropical Atlantic Ocean and the eastern Mediterranean Sea. These dust suspensions were created by surface winds resulting from subsidence on the northeastern side of a blocking anticyclone in the Atlantic region and subsequent winds of an intense developing cyclone in the Mediterranean-African region. In the following period, maximum dust loads of 4.5 and 2.5 g m(-2) occurred on April 12 and 17, respectively, when new cyclones transported dust across the Mediterranean from Africa to Europe. The generation of the two dust pulses during the first even and the recurrent cyclone transport in the following period is shown to be the result of a large-scale, anomalous atmospheric circulation connected with blocking in the Atlantic Ocean and the interactions of tipper air jets downstream of the blocking. The particular state of the hemispheric circulation during the studied period corresponded to the positive phase of the North Atlantic Oscillation (NAO). While previous statistical evidence has consistently linked dust transport in the region with the NAO signatures, we show the same connection on the basis of this case study. [References: 65]
机译：1994年4月，最大的沙尘暴事件起源于撒哈拉大沙漠，影响了从加勒比海地区到欧亚大陆的整个地区。这种空气悬浮尘埃的半球形运输是在四月的前三周以低指数环流为背景的一系列风暴中发生的。通过对大气数据，地面气溶胶测量，能见度观测，AVHRR和Meteosat可见波段卫星数据以及Eta模型仿真结果（包括气溶胶传输成分）进行综合分析和解释，研究了这些重复事件。观测结果产生了尘埃事件的时间和空间发展的一致图景，其主要特征已在部分中用于验证模型结果。 1994年4月3-5日，撒哈拉沙漠西部某些地区的粉尘悬浮速率超过1.5 mg m（-2）h（-1），最大柱综合粉尘负荷达到2 gm（-2）。重大悬浮事件产生了两个同时发生的粉尘脉冲，它们沿相反的方向穿越亚热带大西洋和地中海东部。这些粉尘悬浮物是由大西洋上空的一个封闭反旋风器东北侧的沉降和随后在地中海-非洲地区形成的强烈旋风造成的地面风形成的。在接下来的时期中，当新的旋风将灰尘从非洲运往地中海到欧洲时，分别在4月12日和17日发生了最大尘埃负荷4.5和2.5 g m（-2）。在第一次偶数期间产生了两个尘埃脉冲，并在随后的周期中发生了周期性的旋风运输，这是由于大气异常大规模循环与大西洋的阻塞以及下游倾覆式喷气机的相互作用所致。的封锁。在研究期间，半球环流的特定状态对应于北大西洋涛动（NAO）的正相。尽管以前的统计证据始终将该区域的粉尘运输与NAO签名联系起来，但在此案例研究的基础上，我们也显示了相同的联系。 [参考：65]

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