Shortwave radiation budget of Sahelian vegetation: 1. Techniques of measurement and results during HAPEX-Sahel
Shortwave radiation budget of Sahelian vegetation: 1. Techniques of measurement and results during HAPEX-Sahel
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DOI：
10.1016/0168-1923(95)02270-8
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发表时间：
1996-03
影响因子：
6.2
通讯作者：
A. Bégué;J. Roujean;N. Hanan;S. Prince;M. Thawley;A. Huete;D. Tanré
中科院分区：
文献类型：
--
作者：
A. Bégué;J. Roujean;N. Hanan;S. Prince;M. Thawley;A. Huete;D. Tanré
1992年在西非尼日尔进行的HAPEX-Sahel实地试验期间测量了萨赫勒热带稀树草原和一种小米作物的短波辐射收支。测量进行了四种土地覆盖类型：灌木休闲，草休闲，退化灌丛，和小米领域。每个土地单元都配备了传感器组，以测量冠层内的光合有效辐射（PAR）和近红外（NIR）辐射通量，并在整个生长季节进行操作。植被对PAR和NIR的日截获率较低（天然植被和作物分别低于60%和30%）。稀疏的植被和明亮的桑迪土壤意味着PAR的吸收和拦截是相似的（它们在大约20%的值相等）。样地的反射率日变化和季节变化不大，受土壤反射的影响很大。拦截和吸收，并在较小程度上，在太阳天顶角，表现出明显的方向性影响。
Shortwave radiative budgets of Sahelian savannas and a millet crop were measured during the 1992 HAPEX-Sahel field experiment, in Niger, West Africa. Measurements were conducted on four land cover types: shrub fallow, grass fallow, degraded shrubland, and a millet field. Each land unit was equipped with sets of sensors to measure the photosynthetically active radiation (PAR) and near-infrared (NIR) radiative fluxes within the canopies, and were operated throughout the entire growing season. Daily fractional PAR and NIR interception by vegetation was rather low (less than 60% and 30% for natural vegetation and crop, respectively). The sparse vegetation and bright sandy soils meant that the PAR absorption and interception were similar (they were equal at a value of approximately 20%). The albedo of the plots varied little diurnally and seasonally, and was strongly affected by the reflection from the soil. The interception and absorption and, to a lesser degree, the albedo exhibited distinct directional effects related to solar zenith angle.