Diurnal Variations of Air Temperature and Relative Humidity in the Surface Layer on Clear Day in Summer in Marsh

Based on the micrometeorological observation data of Honghe National Nature Reserve in summer,2008(from June to August),the diurnal variations of air temperature and relative humidity in the surface layer on clear day in summer in marsh had been analyzed.The observation height was 15 m,including 6 different heights.The results indicated that,the diurnal variation curve of temperature was single peak type.Temperatures at different heights showed similar variation regularity,and the maximum and minimum temperature respectively appeared at 14∶00 and 03∶00 on clear day.Both the mean daily temperature and diurnal range decreased with height.Temperature profile varied obviously,and there were 4 types profile: night radiation pattern,morning transition pattern,daytime insolation pattern and evening transition pattern.on clear day in summer in marsh,average temperature lapse rate was 0.10 ℃/m at height of 0.5 to 1.5 m.The temperature lapse rate decreased with increasing height obviously,and the values respectively were 1.03 ℃/m(0.5 to1.5 m),0.41 ℃/m(1.5 to 3 m),0.03 ℃/m(3 to 5 m),-0.01 ℃/m(5 to 8 m) and-0.03 ℃/m(8 to 15 m).The diurnal variation of relative humidity in the surface layer showed a U-shape curve.The maximum and minimum relative humidity respectively appeared at 03∶00 and 14∶00 on clear day.The diurnal range of relative humidity decreased with height distinctly,while this discipline couldn't be applied to the mean relatively humidity.Relative humidity profiles could be divided into 2 categories: night pattern and daytime pattern.Relative humidity decreased with height in the evening,but performed humidity inversion below 8 m in the daytime,and the strongest humidity inversion occurred at 11∶00 to 13∶00.The humidity inversion was a result of the plants' transpiration in the daytime.Average relative humidity lapse rate was 0.16%/m at height of 0.5 to 1.5 m on clear day in summer in marsh.The average relative humidity lapse rates were-2.73%/m(0.5 to 1.5 m),1.43%/m(1.5 to 3 m),-0.02%/m(3 to 5 m),0.06%/m(5 to 8 m) and 0.39%/m(8 to 15 m).