Identification and physical retrieval of dust storm using three MODIS thermal IR channels
Identification and physical retrieval of dust storm using three MODIS thermal IR channels
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DOI：
10.1016/j.gloplacha.2006.02.014
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发表时间：
2006-07
期刊：
影响因子：
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通讯作者：
Peng Zhang;Naimeng Lu;Xiuqing Hu;C. Dong
中科院分区：
文献类型：
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作者：
Peng Zhang;Naimeng Lu;Xiuqing Hu;C. Dong
本文利用MODIS三个红外波段对2001年4月7日发生在北方的沙尘天气进行了研究。结果表明，对于沙尘云，观测到的11μm-12μm亮温差（BTD）总是负值，而8.5μm-11μm的BTD则随沙尘浓度的变化而由正变负。基于这些区别的属性，我们开发了一个灰尘掩模算法来识别沙尘暴的发生和空间范围。该算法可以成功地用于白天和夜间。利用Mie球面散射理论，采用DISTORT正演模型模拟了单尘埃层的热辐射传输。计算结果表明，虽然气溶胶的复折射率和粒径对BTD有显著影响，但类尘气溶胶可以很好地解释观测到的BTD。当复折射率固定时（本文中为类尘埃气溶胶），可以分别由11μm通道的亮温（BT）和11μm-12μm通道的亮温分布（BTD）反演尘埃光学厚度和尘埃粒子有效半径。积分尘柱密度也可以由反演的尘埃光学厚度和有效半径得到。
In this paper, the dust event on 7 April 2001 in northern China is investigated with three MODIS thermal infrared (IR) bands. It is found that for the dust cloud, the observed 11μm minus 12μm brightness temperature difference (BTD) is always negative, while the BTD of 8.5μm minus 11μm varies from positive to negative depending on the dust concentration. Based on these distinguishing properties, we develop a dust mask algorithm to identify the dust storm occurrence and spatial extent. The algorithm can be used successfully in both the daytime and nighttime. Using the Mie spherical scattering theory, the thermal radiation transfer through the single dust layer is performed with the widely used forward model DISTORT. Our calculations show that the dust-like aerosols can well explain the observed BTD although both of the complex refractive index and particle size of aerosols will significantly influence the BTD. When the complex refractive index is fixed (dust-like aerosols in this paper), then the dust optical thickness and effective radii of dust particles can be retrieved from the brightness temperature (BT) of the 11μm channel and the BTD of 11μm minus 12μm channels, respectively. The integral dust column density can also be derived from the retrieved dust optical thickness and effective radius.