臺灣國際科展

臭氧事件日-氣象與地形對臭氧於近地大氣層之生成與傳輸影響

科展類別
臺灣國際科展
屆次
2003年
科別
地球與太空科學
學校名稱
國立臺中第二高級中學
指導老師
劉宏文、黃啟仁
作者
梁辰睿
關鍵字
臭氧、氣象、地形、生成、傳輸、Ozone、Meteorology、 Topography、 Formation、Transformation
備註
美國第五十四屆國際科技展覽會

摘要或動機

2001、2002 年監測資料被用以探討風場、時間、地形對臭氧傳輸影響。完成沿海地區與盆地內各二次採樣分析,探討各污染物與風場之垂直變化,及地面臭氧分布與風場變化。結果顯示各月份與全年之日間,其相對濕度與O3
相關度最高,日照次之。提高濕度,最能抑制[O3]。夜間NO 與O3 的相關度最高,濕度次之。臭氧事件日時:(1).11:00 即可產生高臭氧,(2).沿海地區在臭氧事件日仍保持低[O3],
(3).盆地效應改變風場,使近山地區[O3]居高不下,(4).因處O3 不斷被吹入,沿海地區傍晚時之[O3]下降速度減緩。臭氧事件日之O3 生成速率R 與消失速率常數L
被求出,其中14:00 後之R 與L 值均由正值轉負值,顯示大氣反應型式明顯轉變。R 與L 值在14:00∼15:00 間最小,係因O3 反應生成光化學煙霧所致。16:00
後另一低R 與L 值,則可能導因O3 與微粒或水份反應。分析結果顯示:(1).污染物會隨高程而略增,最高濃度在300∼500 m 處,(2).各高程大氣均可分析出73
種主要HC,其隨高度之分布被繪出與探討,(3).低層大氣會有較多低分子量HC,而高層大氣則有較多高分子量HC。結果亦顯示: (1).盆地內[O3]、[NO]與[NO2]不僅較沿海地區高,且於各高程之變動亦較大,(2).沿海地區THC、烷、烯類均較高,且隨高程增加而增高,但在盆地內則相反,(3).二地區各高程之鹵化物、芳香族、氧化物與其他有機物之平均濃度相近,但沿海地區之濃度變動較大。探討O3

之二傳輸現象獲知:(1).風吹向盆地內時,[O3]隨風向遞增,R 與L 會由12:00 之正值,轉為14:00 之負值;(2).風由盆地內外吹時,[O3] 隨風向遞減,R
與L 值提前於12:00 即為–202.561 與–1.621,但14:00 時R 與L 值增大為–76.411 與0.244, (3).風向並非決定[O3]的主要因素,地形與環境因素才是。實驗結果證實:(1).不同HC
會影響O3 之生成與消失,(2).改變[NO]o 對[O3]影響不大,但高[NO]會使得[O3]下降略緩,(3).降低HC 與[NOx]雖可使 [O3]略降,但提高濕度最能抑制[O3],(4).在O3

的衰減量上,[O3]隨濕度增加而快速降低,但衰減率則隨[O3]o 的增加而降低。一個臭氧之統計模式被建立,臭氧與水反應速率常數與速率式也被求出。

The monitoring data were used to investigate the effect of surface wind, time, and
terrain on the transformation of ozone. The sampling and the analysis in the coastal
and in Taichung basin were completed. The vertical distribution of O3, NOX and HC
and the different altitude wind were investigated. The contour of O3 and surface
wind with 3D map were plotted. The results show that the correlation behaves relativity
of relative humidity with ozone is the best, and solar radiation is the next. Enhancing
environmental moisture can efficiently decrease ozone concentration. In each ozone
event day are: (1) the high [O3] always starts from 11:00, (2) the ozone concentration
on the coastal is always low due to the high humidity, (3) the high [O3] in the
east of the basin is due to the basin effect which causes changes the surface wind,
and (4) in the evening, the descend rate of [O3] in the coastal area is lower because
ozone blows into the coastal area. The formation rate (R) and disappear rate constant
(L) of the ozone event day were obtained. The values of R and L change from plus
to minus before 14:00. The values of R and L are lower at 14:00∼15:00 due to the
photochemical smog formation. And another lower R and L value before 16:00 may be
due to ozone react with particle or water. The results of analysis indicate that:
(1) the concentration increases with increasing altitude, and the maximum is at
300∼500 m height, (2) 73 kinds of hydrocarbons were identified, and the concentration
variation with altitude was also investigated, and (3) most of low molecular weight
HC are at lower altitude, otherwise high molecular weight HC are at higher altitude.
The results also show that: (1) [O3], [NO], and [NO2] on the basin are not only
lower than on the coastal, but also their variability of concentration are big,
(2) THC, paraffins, and olefins on the coastal are higher than on the basin, and
the concentrations increase with increasing altitude on the coastal, but on the
basin is decreasing, (3) the average concentrations of halides, aromatics, oxides,
and others are similar on both area, but concentration variability on the coastal
is obvious. Two types of O3 transformation was investigated, the phenomenon indicts
that: (1) when wind blew into the basin, [O3] increased with wind direction. The
value of R and L change from positive (12:00) to negative (14:00); (2) when wind
blew out of the basin, [O3] decreased with wind direction. The more small value
of R (−202.561) and L (−1.621) appeared at 12:00 earlier. But the value of R and
L will become bigger to –76.411 and 0.244; (3) ozone concentration does not just
dependent on wind direction., topography and surrounding conditionsa are more important
effect. The experimental results show that: (1) ozone formation or disappearance
depends on different HC, (2) the effect 2 of [NO]o is small for ozone photochemical
reaction, but [O3] decreases with increasing [NO], (3) the descend rate of O3 depends
on high humidity more than different kinds of HC or [NO], and (4) the descend amount
of ozone increases with increasing humidity strongly, and the descend rate of ozone
decreases with enhancing [O3]o. A statistical model was developed. The reaction
rate and rate constant of ozone reaction with water were also obtained.


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