近年來因全球暖化造成生態環境影響日漸加劇,而工業發展導致空氣品質日漸下降,其中空氣污染所衍生之氣溶膠(Aerosol),對於生態環境的影響非常嚴重。本研究以2005年至2009年的MODIS氣溶膠光學厚度(Aerosol Optical Depth, AOD)資料,進行台灣地區氣溶膠之時空變異分析,並探討其對森林之影響。由多期之MOD04之氣溶膠光學厚度資料分析顯示,台灣地區大氣中之懸浮微粒以中、南部地區較為嚴重,其中以彰化、雲林、高雄及屏東等地之氣溶膠光學厚度值最高,顯示空氣品質最差。氣溶膠分布受季風影響會有季節性變化,冬季及春季較為嚴重,其次為夏秋兩季。年降雨量的高低會影響氣溶膠光學厚度,以2005年至2009年的趨勢而言,當年降雨量高時,當年的氣溶膠光學厚度會降低。由歷年來之氣溶膠光學厚度變化與台灣酸雨pH值之變化趨勢分析得知,氣溶膠光學厚度會因懸浮微粒中之鹼性離子,如鉀離子(K+)、鎂離子(Mg2+)、鈣離子(Ca2+),對於雨水中的酸性離子具有中和作用,顯示台灣地區之懸浮微粒主要以大陸沙塵暴侵襲為主。本研究利用台灣地區2005年至2009年,MOD04之平均氣溶膠光學厚度與MODIS所推估之淨初級生產力(Net Primary Productivity, NPP)分布,由5年間之變化趨勢可知氣溶膠光學厚度與NPP呈現反向關係,當氣溶膠光學厚度高時,其NPP有下降之趨勢,但因森林生長衰退之影響因素複雜,NPP下降之原因是否受到空氣中之懸浮微粒所影響,值得進一步的研究。
In recent years, the impact of global warming on ecosystem has become more seriously day by day. Air quality becomes more and more deteriorated due to industrial development. Aerosol, which is generated from air pollution, severely affects ecosystem. In this study, we used the MODIS Aerosol Optical Depth (AOD) data from 2005 to 2009 to analyze and discuss the spatial and temporal variation of AOD in Taiwan. The MOD04 AOD multi-year data showed that the central and southern area in Taiwan have more suspended particulates, especially in Zhanghua, Yunlin, Kaohsiung, and Pingtung where have higher AOD. Aerosol distribution has seasonal variety because of monsoon. The value of aerosol in winter and spring are more seriously than those in summer and autumn. AOD would influenced by annual rainfall. The data from 2005 to 2009 showed that higher precipitation has lower AOD in a certain year, and vice versa. We analyzed the correlation between AOD and pH value of acid rain. The results showed that suspended particulates, which have alkaline ions, such as K+, Mg+, Ca+, could neutralize the acidic ions of rain. This result explains that the suspended particulates in Taiwan are from the sand storms mainly. This study evaluated the distribution of Net Primary Productivity (NPP) via MOD04 AOD and MODIS from 2005 to 2009 in Taiwan. We explored that the negative correlation between AOD and NPP, which means that higher AOD would make NPP lower. However, further research will be needed to see if suspended particulates are the only reasons of NPP decreasing due to the complicated factors of deforestation.