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i Detection of Smoke and Dust Aerosols Using Multi-sensor Satellite ...

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1.6 Principal Results<br />

The principle results <strong>of</strong> this dissertation include developing an algorithm based on<br />

multi-spectral technique for detecting smoke <strong>and</strong> dust aerosols combining MODIS RSBs<br />

<strong>and</strong> TEBs; discussing the feasibility <strong>of</strong> dust detection with multi-<strong>sensor</strong> measurements;<br />

<strong>and</strong> assessing the impact <strong>of</strong> <strong>sensor</strong> calibration <strong>and</strong> characterization on detection results.<br />

1) The multi-threshold algorithm for automatically detecting smoke <strong>and</strong> dust<br />

aerosols is developed by combining measurements <strong>of</strong> both MODIS RSBs <strong>and</strong> TEBs. The<br />

spectral curves <strong>of</strong> various scene types are derived statistically from large amount <strong>of</strong><br />

training dataset collected at the selected areas within last several years. With the spectral<br />

<strong>and</strong> statistical analyses, the appropriate b<strong>and</strong>s are selected <strong>and</strong> proper thresholds are<br />

decided for eliminating unwanted pixels step by step. The algorithm is applied mainly to<br />

detect smoke plumes in USA <strong>and</strong> dust storms in Asia. The results are validated not only<br />

with MODIS true color images but also with products <strong>of</strong> OMI <strong>and</strong> CALIPSO, showing<br />

that the algorithm works well in the given areas with small errors. Pairs <strong>of</strong> measurements<br />

from both Terra <strong>and</strong> Aqua MODIS in consecutive days give the basic dynamic<br />

information about smoke <strong>and</strong> dust, which are helpful for estimating the spread direction,<br />

<strong>and</strong> magnitude change <strong>of</strong> these two types <strong>of</strong> aerosols.<br />

2) The tentative experiment for detecting dust aerosol with multi-<strong>sensor</strong>, CALIPSO<br />

<strong>and</strong> MODIS, is performed. Since both <strong>sensor</strong>s are operated in the same orbit with similar<br />

local equatorial crossing time, the temporal mis-registration is ignored in this dissertation.<br />

With the spatial registration, the dust aerosol is accurately identified by jointing the<br />

vertical information <strong>of</strong> CALIPSO measurements with MODIS thermal emissive<br />

8

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