Shortwave radiation budget of Sahelian vegetation .1. Techniques of measurement and results during HAPEX-Sahel

被引:29
作者
Begue, A
Roujean, JL
Hanan, NP
Prince, SD
Thawley, M
Huete, A
Tanre, D
机构
[1] UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD 20742
[2] METEO FRANCE,CNRM,F-31057 TOULOUSE,FRANCE
[3] UNIV ARIZONA,DEPT SOIL & WATER SCI,TUCSON,AZ 85721
[4] UNIV SCI & TECH LILLE FLANDRES ARTOIS,OPT ATMOSPHER LAB,F-59655 VILLENEUVE DASCQ,FRANCE
基金
美国国家航空航天局;
关键词
D O I
10.1016/0168-1923(95)02270-8
中图分类号
S3 [农学(农艺学)];
学科分类号
0901 ;
摘要
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 NTR 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.
引用
收藏
页码:79 / 96
页数:18
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