對數常態分布在氣膠消光係數廓線擬合之應用;Application of lognormal distribution to aerosol extinction profile mapping

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Title:	對數常態分布在氣膠消光係數廓線擬合之應用;Application of lognormal distribution to aerosol extinction profile mapping
Authors:	李宗庭;Lee,Tsung-Ting
Contributors:	遙測科技碩士學位學程
Keywords:	單峰氣膠垂直廓線;對數常態分布;行星邊界層高度;氣膠光學厚度;消光廓線極值高度;Aerosol extinction profile;Lognormal distribution;Planetary boundary layer height;Aerosol optical depth;Mode
Date:	2016-08-22
Issue Date:	2016-10-13 14:45:48 (UTC+8)
Publisher:	國立中央大學
Abstract:	大氣中的懸浮微粒(氣膠)除在地球輻射收支及氣候變遷之影響外，對於人體健康亦有著相當的衝擊，尤其是近地表的細懸浮微粒(PM2.5)。對於PM2.5的監測，通常以地面測站為主要觀測方式，雖能提供高品質之觀測資料，但常受限於測站的點位，無法滿足空間上的需求。衛星遙測雖能進行大範圍的觀測，對於近地表資訊之提供仍有其限制性，主要關鍵在於氣膠垂直分布訊息之不足。因此本研究旨在結合地面及衛星觀測資料，建立獲取氣膠垂直廓線之方法。由於對數常態分布曲線與單峰氣膠垂直廓線之分布型態頗為相似，本文嘗試利用氣膠光學厚度(AOD)及行星邊界層高度(PBLH)，配合消光廓線極值高度(Mode)之定義，建立對數平均(μ)和對數標準差(σ)之轉換關係，以對數常態分布進行氣膠垂直廓線之擬合。藉由10年地面觀測資料之測試結果顯示，Mode和σ參數反演之平均誤差分別為16.1%和25.3%，其中在PBLH與Mode差距較大的情況下，則可獲得較佳之結果，σ平均誤差為16.5%。最後將所建立的方法應用於MODIS AOD的產品進行測試，結果指出在525公尺高度以下為均勻混合層的假設下，近地面PM2.5濃度的計算結果與地面觀測資料頗為吻合，顯示對數常態分布在單峰氣膠垂直廓線擬合之可行性，對於後續衛星觀測資料在近地面PM2.5監測之應用幫助很大。 ;The effect of atmospheric aerosols is an important component on environmental issues such as earth radiation budget and climate change. Heavy loading of particulate matter (PM2.5) also has significant impact on human health, especially in the level near surface. The ground-based measurement is usually employed for the PM2.5 monitor, but the stationed location cannot meet the request in spatial distribution. On the other hand, satellite remote sensing could be a better way to provide the spatial distribution in both regional and global aerosols, but the information near surface is still restrictive by the vertical distribution of aerosols. Therefore, this study aims at aerosol extinction profile mapping by means of the mathematical function. Because of the similarity in distribution pattern, the lognormal distribution is examined for mapping the aerosol extinction profile with single peak. The variables of lognormal distribution are log mean (μ) and log standard deviation (σ), which will be correlated with the parameters of aerosol optical depht (AOD) and planetary boundary layer height (PBLH) associated with the altitude of extinction peak (Mode) defined in this study. With 10 years ground-based measurements, the results showed that the mean error of Mode and σ retrieval are 16.1% and 25.3%, respectively. The mean error of σ retrieval can be reduced to 16.5% under the cases of larger distance between PBLH and Mode. The proposed method is further applied to MODIS AOD product in mapping extinction profile for the retrieval of PM2.5 in terms of satellite observations. The results indicated well agreement between retrievals and ground measurements when aerosols under 525 meters are well-mixed. The feasibility of proposed method to satellite remote sensing is also suggested by the case study.
Appears in Collections:	[Master of Science Program in Remote Sensing Science and Technology ] Electronic Thesis & Dissertation

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