This study aims to explore the characteristics of ultraviolet (UV) radiation over Dong Lake (DL) and Tai Lake (TL) in the middle and lower reaches of the Yangtze River and to develop an innovative model for UV estimation under all weather conditions. The characteristic analysis of UV radiation shows distinctly hourly and monthly variations at two typical sites. The maximum values can represent the hourly UV feature, and the median and the arithmetic mean values are reasonably similar with little difference for both stations. The monthly means of hourly UV radiation range from 25.68 to 70.07 kJ m -2 for DL and between 36.00 and 92.62 kJ m -2 for TL. The monthly mean hourly UV fractions vary from 3.79% to 4.93% at DL and between 4.57% and 5.94% at TL. Comparisons on the monthly mean hourly values of UV radiation and UV fraction, the values at TL are always greater than those at DL. An innovative model is constructed based on two input parameters, namely the effect of the comprehensive attenuation factors for assumed cloud-free conditions (CAF UVclear ) and the effect of the clouds (K g ). CAF UVclear is derived from empirical models based on relative optical air mass and ozone. The effectiveness of the presented model is demonstrated by comparing with other two estimation models. This innovative model presents values of RMSE better than two reported models either at local place or a different locality. It indicates that this new model can provide satisfactory estimates of UV radiation at different localities other than the local place of origin where the relationships are developed.
Sand samplers were layed out in the grassland located in the northern foot of Yinshan Mountain for collecting soil flux samples from 0 to 1.5m height above the surface from Mar., 1, 2008 to Feb., 29, 2009.Exponential and Power functions were both used for describing vertical distribution of sand flux in the grassland, the results indicated that determination coefficient of Power function varied from 0.898 to 0.992 while 0.432 to 0.661 for exponential function. Power function is better than exponential function in describing the vertical distribution of both annual and seasonal soil flux, summer excluded. Annual cumulative percentage of each height was determined indirectly according to the power function mentioned above, the result indicated that up to 2m height,15-25% of soil flux concentrated with in 10cm above the surface,25-35% of soil flux concentrated within 20cm above the surface,30-40% of soil flux concentrated within 30 cm above the surface, 43-54% of soil flux concentrated within 50 cm above the surface,85-90% of soil flux concentrated within 150 cm above the surface, respectively. No significant differences of soil flux structures in spring, autumn, winter and in the whole year were found. The research on wind erosion of grassland in the vertical direction more dispersed, in the height range of sediment accumulated percentage was lower than that of the previous research.
Sand samplers were laid out in the grassland in the northern foot of Yinshan Mountain for collecting soil flux samples from 0 to 1.5m height above the surface from Mar, 1, 2008 to Feb,29,2009.Grain size parameters proposed by Folk and Ward, including average, SD, skewness and kurtosis of grain size were used. The vertical distribution of grain size characteristic of sediments trapped by sand samplers in different seasons was analyzed by using electrical mirror technology. The results indicated that size of aeolian sand in desert steppe is mainly sand and silt. The content of coarse silt, very fine sand and medium sand are 20~60%,10~30% and 10~20%,respectively,in the sediment–for all seasons. As height increased, the content of sand decreased while silt increased and the mean size of particle changed from fine sand to very fine sand. The mean diameter of particle ranged from 2.4~4.2and standard deviation ranged from 0.7~1.5Skewness is positive with the value ranges from 0 to 0.2,while Kurtosis mainly concentrated on 0.7 to 1.3.
According to different specifications of sand barrier and different parts of dunes, soil hardness of topsoil and different depths of soil were measured, then analyzed the influences of sandbag sand barrier on soil hardness, the results show: The soil hardness of dunes which lay 1m × 1m, 2m × 2m and diamond 3 kinds of specifications sand barrier are significantly higher than the soil hardness of bare dunes (P<0.05), and the soil hardness of 1m × 1m, 2m × 2m sand barrier does not differ obviously, but significantly higher than the soil hardness of diamond sand barrier. The soil hardness of different parts of dunes which lay 1m × 1m, 2m × 2m sand barrier have similar trend, both the lower of windward slope > middle > upper, and the soil hardness of the 3 parts have significantly different (p<0.01), while diamond sand barrier have no significant trend. The soil hardness of 3 specifications sand barrier within a single barrier grid is unevenly distributed. Sandbag sand barrier have impact on vegetation, the soil hardness at different depths is indirectly affected by the vegetation to be affected.
This study sampled and tested the soil samples in wind power station of Huitengxile. Analyze soil bulk density in the different space and time and study the effect of wind power station on soil bulk density in different space and time. Results show that the mean soil bulk density of each year has the tendency of increase with the increase of depth in the range of 0 to 50 centimeters, but the increase extent is not much. The increase of soil bulk density in deep soil layer is the biggest in 1996 and the smallest in 2009 comparing that in the surface soil. The soil bulk density in the range of 0 to 40 centimeters is without obvious change regularity contrasting the control samples. The soil bulk density of control sample is greater than other experiment samples in the range of 40 to 50 centimeters. The change of topsoil soil bulk density is not significant with the increase of wind power station production time in the 10 to 30 centimeters. The change of soil bulk density is significant with the increase of wind power station production time at the depth of 40 to 50 centimeters. The mean soil bulk density takes the trend of decrease with the distance increasing from the wind power station base in different production time. The trend of mean soil bulk density is decreasing more significant in range of 0-60 meters. The change of mean soil bulk density is not big in the range of 80 to 100 meters from the base, and the value of soil bulk density trend to stability. It has not significant change contrasting the mean soil bulk density of different direction. The electricity generated by wind power has not effect on the direction of soil bulk density.
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