[1] Understanding the energy balance on the Qinghai‐Tibetan Plateau is essential for
better prediction of global climate change. To characterize the energy balance on
the plateau, we examined the radiation partitioning over a Kobresia meadow, the most
widely distributed vegetation on the plateau, for the period from 2002 to 2005. The
incident solar radiation (Rs) and net radiation (Rn) averaged 6298 and 2779 MJ m−2 yr−1,
respectively. The albedo averaged 0.220 annually, with a slightly low value of 0.202
in the growing season from May to September. An increase in soil water or leaf area index
was correlated with a decrease of albedo over the meadow. The annual solar radiation
lost 34% as longwave radiation, which was higher than values reported for lowland
grasslands. The annual radiation efficiency (Rn/Rs) over the meadow, at an average of 0.44,
was, however, much lower than that for lowland grasslands. The net longwave radiation
(Ln) and the normalized effective radiation (Ln/Rs) over the meadow were much higher
than that for the global surface or for lowland grasslands, indicating that the longwave
exchange between alpine meadow and atmosphere is the most important component
of energy losses. A path analysis suggests that the water vapor pressure, air temperature,
and cloud cover are the major factors governing the variations of both the net radiation and
the net longwave radiation in the alpine meadow ecosystem.
Citation: Zhang, X., et al. (2010), Radiation partitioning and its relation to environmental factors
better prediction of global climate change. To characterize the energy balance on
the plateau, we examined the radiation partitioning over a Kobresia meadow, the most
widely distributed vegetation on the plateau, for the period from 2002 to 2005. The
incident solar radiation (Rs) and net radiation (Rn) averaged 6298 and 2779 MJ m−2 yr−1,
respectively. The albedo averaged 0.220 annually, with a slightly low value of 0.202
in the growing season from May to September. An increase in soil water or leaf area index
was correlated with a decrease of albedo over the meadow. The annual solar radiation
lost 34% as longwave radiation, which was higher than values reported for lowland
grasslands. The annual radiation efficiency (Rn/Rs) over the meadow, at an average of 0.44,
was, however, much lower than that for lowland grasslands. The net longwave radiation
(Ln) and the normalized effective radiation (Ln/Rs) over the meadow were much higher
than that for the global surface or for lowland grasslands, indicating that the longwave
exchange between alpine meadow and atmosphere is the most important component
of energy losses. A path analysis suggests that the water vapor pressure, air temperature,
and cloud cover are the major factors governing the variations of both the net radiation and
the net longwave radiation in the alpine meadow ecosystem.
Citation: Zhang, X., et al. (2010), Radiation partitioning and its relation to environmental factors
above a meadow ecosystem on the Qinghai‐Tibetan Plateau, J. Geophys. Res., 115, D10106,
doi:10.1029/2009JD012373
The research has been published on JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115,
D10106, doi:10.1029/2009JD012373, 2010.
Xiaochun Zhang,1 Song Gu,1,2 Xinquan Zhao,2 Xiaoyong Cui,3 Liang Zhao,2 Shixiao Xu,2
Mingyuan Du,4 Sha Jiang,1 Yubao Gao,1 Chun Ma,5 and Yanhong Tang6
Received 4 May 2009; revised 12 December 2009; accepted 22 December 2009; published 20 May 2010.
Mingyuan Du,4 Sha Jiang,1 Yubao Gao,1 Chun Ma,5 and Yanhong Tang6
Received 4 May 2009; revised 12 December 2009; accepted 22 December 2009; published 20 May 2010.