A Study On The Characteristics Of Turbulence In The Tropical Seasonal Rainforest Of Xishuangbanna, SW China

Using the flux data between 2003 and 2005 years measured by eddy covariance system as well as wind speed, wind direction and temperature data, we discussed the characteristic of the wind speed and the temperature of the tropical seasonal rainforest. Then we discussed the frequency distribution of atmospheric stability above the tropical seasonal rainforest canopy by z/L and Ri methods. And then the characteristic of the turbulence and turbulent parameter were analyzed above the tropical seasonal rainforest in Xishuangbanna, Southwest China. The results showed that:1. The yearly average wend speed and lowest average temperature in night of the foggy-cool season were the important limit factors for the existed of the tropical seasonal rainforest. The atmosphere layer was usually stable during night in foggy-cool and dry-hot season. Together with the daily range of temperature was large during a day. Both of them were helpful for accumulating the C in the tropical seasonal rain forest in Xishuangbanna;2. The result of the turbulence intensity showed that it was not always content for measurement of turbulence in tropical seasonal rainforest. Along with increasing of the average wind speed, the turbulence intensity changed. It was valued to consider to use average wind speed >0.5m/s as a data judging standard. There were obviously diurnal variation and seasonal change with the turbulence coefficient. Under some conditions, the characteristics of the turbulence in the tropical seasonal rainforest were similar to uniform flatness terrain;3. The results showed that the frequency of atmospheric stability had significant diurnal variation. Stable atmospheric condition was dominant in the daytime, and unstable atmospheric condition mainly occurred at night. There were differences among different seasons and years. The results also showed that atmospheric stability was control by thermal factor in this area;4. The diurnal variation of the Richardson number presented turbulence developed well during daytime, but in night the stable layer of the atmosphere restrained the developing of the turbulence. The relationship between the Monin-Obukhov length z/L and Richardson number showed more complex pattern with experiential expression.