Energy Distribution And The Degree Of Energy Closure Of Songnen Meadow Steppes By Eddy Covariance Measurement

In the water and heat balance of grassland ecosystems there were two basic conversion process water circulation and heat exchange. Eddy-Covariance(EC)open path system, in this study to investigate energy balance and water budget at the different temporal scales,The study site was located in the northeast songnen meadow steppes. In this paper, net radiation flux, latent heat flux, sensible heat flux and soil heat flux for the four major energy factor of different time scales,we will get the allocation ratio of its energy and influence factors. The primary goal was to estimate energy closure level within the growing season. The application as measured by eddy covariance method to assess the reliability of data.The results showed: the variation of energy partitioning contribution was quite great in different soil water conditions. Net radiation flux as the sum of energy, had been in the highest position.A analyse of energy balance showed that the ratio of LE/Rn was higher during moist condition. And after the rainy season and the rainy season for some time has been maintained at the highest level. In the time period of water stress, the ratio of Hs/Rn was higher during dry period. And it has been maintain at a high level In non-growing season. there was a clear process of water-heat coupling between Energy distribution and water conditions in such ecosystem. Grassland ecosystems at different time scales had the different energy closure level. the closure slope of date scale was higher than the closure slope of hours scale . Closure level during the day was higher than the closure level of the night. Both the closure slope and Correlation coefficient were higher. However, in the northeast Songnen meadow steppes also existed the phenomenon of energy was not closed. but a relatively high degree of closure can be used to evaluate the reliability of data by the eddy covariance measurement.