Energy Distribution and the Degree of Energy Closure of Songnen Meadow Steppes by Eddy Covariance Measurement
|School||Northeast Normal University|
|Keywords||Latent heat flux Sensible heat flux Energy distribution Hydrothermal coupling Energy closure|
In grassland ecosystems water and heat balance , there are two basic conversion process, that water circulation and heat exchange . 2008-2009 years , the use of eddy covariance method open system at different time scales in the Northeast Songnen meadow ecosystem energy balance and water balance and its influencing factors were studied. In this paper, net radiation flux, latent heat flux , sensible heat flux and soil heat flux four main energy factors at different time scales , and find that the energy distribution ratio and the impact factor , and in the growing season on the energy balance closing level of research carried out in order on the application of the measured eddy covariance method to assess the reliability of data . The results showed that: the energy balance ratio of the components in different environmental conditions, changes in soil water is large, the net radiation flux as the sum of energy , has been in the highest position. Moisture conditions better time, latent heat flux accounted for a larger proportion of net radiation flux , and in the rainy season and the rainy season, after a period of time has been maintained at a high level ; while the period of time under water stress , sensible heat flux accounted for a larger proportion of net radiation flux , and in the non-growing season has maintained a high level. Energy distribution of ecosystems and water situation there is a clear water thermal coupling process . Grassland ecosystems at different time scales varying degrees of energy closure , day rate of closure scale than an hourly rate of closure scale , degree of closure during the day is better than the night closed degree slope and closed higher correlation coefficients . But in Songnen grassland in Northeast energy is not closed on the same phenomenon exists , but the relatively high degree of closure that can be used to evaluate the measured eddy covariance method data reliability.