An automated dust detection using SEVIRI: A multiyear climatology of summertime dustiness in the central and western Sahara
An automated dust detection using SEVIRI: A multiyear climatology of summertime dustiness in the central and western Sahara
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DOI：
10.1029/2011jd016845
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发表时间：
2012-04-25
影响因子：
4.4
通讯作者：
Washington, Richard
中科院分区：
文献类型：
--
作者：
Ashpole, Ian;Washington, Richard
在这里，我们提出了一种使用旋转增强型可见光和红外成像仪 (SEVIRI) 的红外 (IR) 通道的自动灰尘检测方案，该成像仪搭载在第二代气象卫星 (MSG) 卫星上，从中创建了目前广泛用于撒哈拉灰尘研究的灰尘方案图像。这提供了一种客观、易于重复且快速的方法来建立灰尘存在的气候学，该方法与白天主观识别的灰尘存在进行了很好的比较。在夜间，由于表面温度的强烈昼夜循环，自动检测方案不太可靠。我们的 SEVIRI 粉尘旗 (SDF) 与表面的气溶胶光学深度 (AOD) 进行比较，结果发现，尽管清晨和傍晚的成功率较低，但可以成功且一致地识别中重度粉尘爆发。 SDF 对应于臭氧监测仪器 (OMI) 的吸收气溶胶指数 (AAI)，也表明撒哈拉中部和西部的中度沙尘爆发，但多年来产生的气候空间模式存在差异，这可能是由于检测方案的灵敏度不同所致。尽管存在这些差异，SDF和AAI都将沙尘热点定位在阿尔及利亚南部以及与马里和尼日尔的南部边界，并且SDF 2004年6月至2010年8月的气候显示，北半球夏季撒哈拉中部和西部的沙尘存在存在很大程度的年际变化。
Here we present an automated dust detection scheme using the Infrared (IR) channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI), carried on board Meteosat Second Generation (MSG) satellites, from which dust scheme images that are now widely used in Saharan dust studies are created. This provides an objective, readily reproducible and quick way to build up climatologies of dust presence which compares well with subjectively identified dust presence in the daytime hours. At nighttime the automated detection scheme is less reliable due to the strong diurnal cycle of surface temperatures. Our SEVIRI Dust Flag (SDF) is compared to Aerosol Optical Depth (AOD) from the surface and found to successfully and consistently identify moderate-heavy dust outbreaks, although success rate is lower in the early morning and late evening. SDF corresponds to Absorbing Aerosol Index (AAI) from the Ozone Monitoring Instrument (OMI) that is also indicative of moderate-heavy dust outbreaks across the central and western Sahara, but there are differences in the spatial patterns of climatologies created over a number of years that are likely to be due to the different sensitivities of the detection schemes. Despite these discrepancies, SDF and AAI both place dust hot spots in southern Algeria and across its southern borders with Mali and Niger, and SDF climatologies for June-August 2004-2010 reveal that there is a substantial degree of interannual variability in dust presence in the central and western Sahara in the boreal summer.