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Evaluations of land characteristics and SO2 deposition velocity at North Tungyen mountain flux tower
|關鍵字:||Eddy Covariance System;渦流協變性系統;Bowen Ratio;Albedo;EBR;Gradient Method;Resistance model;包溫率;反照率;能量缺口;梯度法;阻抗法||出版社:||環境工程學系所||引用:||Kell B. Wilson et al., 2002,”Energy partitioning between latent and sensible heat flux during the warm season at FLUXNET sites”, WATER RESOURCES RESEARCH, VOL. 38, NO. 12, 1294 P. Jitto et al., 2007, “Dry deposition velocity of sulfur dioxide over rice paddy in the tropical region”, Atmospheric Research 85, 140–147 Ben-Jei Tsuang et al. ,2003 , “Determining aerodynamic roughness using tethersonde and heat flux measurements in an urban area over a complex terrain”, Atmospheric Environment 37,1993–2003 Kell B. Wilson et al. , 2002, ”Energy partitioning between latent and sensible heat flux during the warm season at FLUXNET sites”, WATER RESOURCES RESEARCH, VOL. 38, NO. 12, 1294 Yoshiko Kosugi et al., 2008, CO2 exchange of a tropical rainforest at Pasoh in Peninsular Malaysia, agricultural and forest meteorology 148 , 439 – 452 Huimin Wang et al., 2004, “Net ecosystem CO2 exchange over a larch forest in Hokkaido, Japan”, Atmospheric Environment 38 , 7021–7032 Eugster and Zeeman, 2006, , “Micrometeorological techniques to measure ecosystem-scale greenhouse gas fluxes for model validation and improvement”, International Congress Series 1293 , 66–75 PAOLO MARTANO, 2000, “Estimation of Surface Roughness Length and Displacement Height from Single-Level Sonic Anemometer Data”, JOURNAL OF APPLIED METEOROLOGY, VOLUME 39, 708-715 JOHN H. SEINFELD SPYROS N.PAMDIS, “ATMOSPHERIC CHEMISTRY AND PHYSICS”, second edition. 蔡徵霖, 2001, ”以垂直剖面氣象廠及輻射資料計算地表粗糙度之研究”，碩士論文，國立中興大學環境工程研究所。 余思穎，”利用渦流協變性系統量測都會區紊流熱通量之研究”，碩士論文，國立中興大學環境工程研究所。 吳兆偉，”水稻田生長季及休耕期通量資料分析與比較”，碩士論文，國立中興大學環境工程研究所||摘要:||
目前國際間以渦流協變性系統(EC 系統)相關方法進行通量觀測，已組成一個全球性的組織－通量觀測網 (Fluxnet)，長期和連續測量陸地生態系統與大氣之間二氧化碳、水蒸氣和能量的交換行為。本研究將利用渦流協變性系統直接量測大氣地表層內森林之通量變化，可以進一步了解台灣原生林之大氣樹冠層能量收支動態變化行為。為了解污染物在沉降在植物上的空氣污染物(SO2)沉降速度，並使用兩種沉降理論(Gradient Method法、Bowen Ratio Method法)以校正Resistance Model中的參數，使Resistance Model能正確推估出於台灣森林空氣污染物(SO2)的沉降速度。
本研究場址為惠蓀林場北東眼山森林通量塔，是位於本校高冷地園藝試驗所之原始林地內(Location : 121.126 °E, 24.074 °N），從2007年10月開始進行觀測。北東眼山森林地勢起伏較為平緩，海拔高度約為二千一百多公尺，為原生的闊葉樹林，樹高約二十～三十公尺高左右。在北東眼山森林通量塔架設渦流協變性系統(EC系統)、氣象因子觀測儀器、空品自動監測儀器進行觀測。
觀測結果顯示，在2007年10、11月與2008年2、3、4、5月的Bowen Ratio Method平均値為0.25、0.15、0.20、0.25、0.19、0.2，實驗期間中午時段 (11:30 am、12:00 am、12:30 am的太陽短波輻射為100~1000 W m-2，相對濕度為40~100 %，反照率(Albedo)為0.07~0.20之間，當太陽短波輻射愈高，反照率會降低。當相對濕度大於90%，估算出的反照率皆高於0.15的現象。推估地表放射率( Emissivity )為0.92。在能量項的部分，實驗期間各月份全日平均EBR均在65 ~ 80 %。白天能量項Rn-G平均為254.9 W m-2，LE+H為169.5 W m-2，EBR為66%，晚上Rn-G平均為169.5 W m-2，LE+H為70.6 W m-2，EBR為73%。實驗期間平均CO2通量為0.5 ~ -1 mg m-2 s-1之間，Gradient Method、Bowen Ratio Method、Resistance model 三種模式在實驗期間各月份不同的LAI情況下推估SO2的平均乾沉降速度分別為0.20 cm s-1、0.47 cm s-1、0.51 cm s-1。利用Gradient Method 推估SO2乾沉降速度每日變化趨勢與Resistance model所推估出的趨勢較為相似。
Land surface characterization, ecological and environmental monitoring system has been established by integrating the North Tungyen Mt., forest flux station facility and Line Detect network system. Measurements of CO2, water vapor, energy and momentum flux between the forest ecosystem and atmosphere. Incidental radiations, measurements over vegetation characters, soil characteristics, hydro-meteorological and air quality measurements are also under progress to set up local database to parameterize land surface characteristics. The entire real time database shall be made online in the near future. In addition, this site has been associated with the global network, FLUXNET, which is a network of regional micrometeorological network focused on interactions between land surface and the atmosphere, as a member of network which is more than 500 sites. In addition, flux measurement was carried on over South China Sea; the data are rare and valuable. The eddy-covariance system could measure the meteorological factors, heat and pollutant concentrations flux. Then, the aerodynamic roughness, land surface parameters and the vertical profile of SO2 was determined for the study area.
The forest flux measurement study site is located at North Tungyen Mt., forest station (Location: 121.126 E, 24.074 N) with an elevation of 2000 m above mean sea level. This forest is dominated by broad leaved evergreen trees with the height ranges from 20-0 meters. It is a tower based micrometeorological station which employs eddy covariance method to measure the fluxes of CO2, water vapor, energy and momentum flux between the forest ecosystem and atmosphere. Meteorological variables such as temperature, relative humidity, incidental radiations and major air pollutants monitoring system were also installed. Measurements were made during 2007-10-11 to 2008-02-05 through automated measurement and data logging system. The monthly mean Bowen Ratio during the respective months is found to be 0.25, 0.15, 0.20, 0.25, 0.19, and 0.2 respectively. The observed incoming solar radiations measure during noon time (11.30 am, 12.00 am and 12.30 am) were ranges from 100~1000 W m-2. The relative humidity ranges from 40~100% and albedo ranges from 0.07~0.20 during the period of observation. It is observed that when the incoming solar radiation is more, then the albedo during the corresponding period tends to decrease. Whenever the relative humidity exceeds 90%, the value of albedo increased beyond 0.15. The parameterized emissivity of the forest vegetation is 0.92. The calculated monthly energy balance ratio (EBR) for this forest ecosystem ranges from 65~80%. The daily average flux of CO2 at this study site ranges from 0.5 to -1 mg m-2 s-1. With respect to air pollutant SO2, three methods; Gradient method, Bowen Ratio method and Resistance model were employed to quantify the deposition velocity of SO2 at different LAI and the corresponding deposition velocity for the respective methods are 0.20 cm s-1, 0.47 cm s-1 and 0.51 cm s-1. It is observed that the pattern of daily deposition velocity predicted by Resistance models follows as that of one observed through gradient method.
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