Effect of smoke and clouds on the transmissivity of photosynthetically active radiation inside the canopy
Effect of smoke and clouds on the transmissivity of photosynthetically active radiation inside the canopy
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DOI：
10.5194/acp-6-1645-2006
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发表时间：
2006-05
影响因子：
6.3
通讯作者：
M. Yamasoe;C. Randow;A. Manzi;J. Schafer;T. Eck;T. Eck;B. Holben
中科院分区：
文献类型：
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作者：
M. Yamasoe;C. Randow;A. Manzi;J. Schafer;T. Eck;T. Eck;B. Holben
生物质燃烧活动向大气中排放高浓度的气溶胶颗粒。这些粒子可以与太阳辐射相互作用，减少到达表面的光量，并通过散射过程增加漫射辐射的比例，从而对植物冠层内的光合作用产生影响。这项工作报告了LBA/SMOCC（亚马逊流域大规模生物圈-大气实验/烟雾、气溶胶、云、降雨和气候）期间在Reserva Bioldo Jaru（巴西朗多尼亚州）同时进行的光合有效辐射（PAR）和气溶胶光学深度（AOD）测量结果和RaCCI（干湿雨期间亚马逊地区的辐射、云和气候相互作用） 2002 年 9 月 15 日至 11 月 15 日进行了过渡季节）现场实验。AOD 值通过 AERONET（气溶胶机器人网络）辐射计、MODIS（中分辨率光谱辐射计）和美国农业部 - 林务局的便携式太阳光度计检索。由于烟雾气溶胶颗粒层，观察到冠层顶部 PAR 辐照度显着降低。这种辐射减少影响了显热和潜热的湍流通量。 AOD 的增加也增强了冠层内 PAR 的传输。结果，由于气溶胶颗粒的光散射，漫辐射的可用性得到了增强。树冠内的光可用性与净生态系统交换（NEE）之间存在复杂的关系。结果表明，气溶胶光学深度的增加对应于植被吸收二氧化碳的增加。然而，对于更高的 AOD 值，
Biomass burning activities emit high concentra- tions of aerosol particles to the atmosphere. Such particles can interact with solar radiation, decreasing the amount of light reaching the surface and increasing the fraction of dif- fuse radiation through scattering processes, and thus has im- plications for photosynthesis within plant canopies. This work reports results from photosynthetically active radia- tion (PAR) and aerosol optical depth (AOD) measurements conducted simultaneously at Reserva Bioldo Jaru (Rondonia State, Brazil) during LBA/SMOCC (Large-Scale Biosphere-Atmosphere Experiment in Amazonia/ Smoke, Aerosols, Clouds, Rainfall, and Climate) and RaCCI (Radia- tion, Cloud, and Climate Interactions in the Amazon during the Dry-to-Wet Transition Season) field experiments from 15 September to 15 November 2002. AOD values were re- trieved from an AERONET (Aerosol Robotic Network) ra- diometer, MODIS (Moderate Resolution Spectroradiometer) and a portable sunphotometer from the United States Depart- ment of Agriculture - Forest Service. Significant reduction of PAR irradiance at the top of the canopy was observed due to the smoke aerosol particles layer. This radiation reduction affected turbulent fluxes of sensible and latent heats. The in- crease of AOD also enhanced the transmission of PAR inside the canopy. As a consequence, the availability of diffuse radi- ation was enhanced due to light scattering by the aerosol par- ticles. A complex relationship was identified between light availability inside the canopy and net ecosystem exchange (NEE). The results showed that the increase of aerosol op- tical depth corresponded to an increase of CO2 uptake by the vegetation. However, for even higher AOD values, the