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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48307
標題: | 臺灣土地型態對本土揚塵之影響 Influence of Land Cover on Local Mineral Dust Emission over Taiwan |
作者: | Ie-Feng Fu 傅譯鋒 |
指導教授: | 陳正平(Jen-Ping Chen) |
關鍵字: | 本土揚塵,土地利用型態,稻田,乾河床, local dust emission,land-use type,dry river beds,rice fields, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 礦物沙塵除了影響大氣輻射過程之外,對海洋生態以及人們的健康有相當程度的影響,也在降水過程中扮演冰核角色。沙塵揚起的主要條件為強風速以及植被稀疏的乾燥土壤,如沙漠地區。台灣大氣中的礦物沙塵不只來自於華北、蒙古一帶的長程傳輸,更多來自於本土貢獻。台灣容易發生揚塵的地方主要在沖積平原以及乾河床。此外,不同季節下的稻田因為土地利用型態的差異對於大氣揚塵也扮演重要角色。
本研究的目標為瞭解不同土地利用型態對於本土沙塵的貢獻,以及土地利用型態的轉變對於揚塵的影響。研究工具為MM5及TAQM/kosa模式,以MM5所提供的氣象場資料輸入TAQM/kosa以模擬沙塵揚起與傳輸。之外並利用1982年與1994年數位化的台灣土地調查資料來建立模式中的地表狀態,並且利用實際觀測的沙塵粒徑資料來調整揚沙參數。模擬結果顯示,台灣近地表本土沙塵對年平均PM10濃度的貢獻約6.69 μg m-3,其中稻田與河床分別貢獻了約0.24 μg m-3與1.16 μg m-3,而扣掉了稻田與河床後,剩下的其他土地型態則貢獻了5.29 μg m-3。在1982年至1994年的長期變化方面,由於稻田與旱作地成消長現象,使得旱田等其他土地利用型態的貢獻增加不少,提高了年平均濃度。最後針對兩個個案分析本土揚塵事件,以及不同氣象因子與沙塵粒徑分佈狀態對本土揚塵的影響。 Mineral dust particles play an important role in precipitation formation by acting as ice nuclei, affect atmospheric radiation, and make a great impact on the ecosystem and human health. The main conditions of dust emission are high wind speed, dry soil and sparse vegetation, such as over the deserts. In Taiwan, airborne mineral dust particles not only arrive by long-term transport from deserts over Northern China or Mongolia but can also be produced from local emissions over alluvial plains and dry river beds. Seasonal variation of irrigated cropland and pasture also influence the mineral dust production. The purpose of this study is to understand atmospheric dust production from different land-types and how it is affected by land-use change in Taiwan. The tools used for studying the land-use change effect on atmospheric dust are the MM5 and TAQM/kosa models. The former provides meteorological fields to drive the emission and transport of mineral dust in TAQM/kosa. Particular effort is placed on building up the land type classification according to the Taiwan Land Use Investigation Data for 1982 and 1994, as well as dust emission parameters derived from local measurements. Model simulations, show that the annual average concentration of near-surface PM10 from local dust emission is about 6.69 μg m-3 , with individual contribution of 0.24 μg m-3 and 1.16 μg m-3 from rice field and river beds, respectively, whereas other land-use types contribute to about 5.29 μg m-3 To further investigate the effect of long-term change, simulations with the 1982 and 1994 land-use types are compared. Due to an obvious shift of farming styles from rice fields to upland crops, dust emissions may have changed significantly over the years. A few episodes of local dust events are also analyzed to understand the meteorological conditions and land-type factors that contribute to strong production of airborne dust from Taiwan’s river beds. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48307 |
全文授權: | 有償授權 |
顯示於系所單位: | 大氣科學系 |
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