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Variability of soil moisture and its relationship with surface albedo and soil thermal parameters over the Loess Plateau 总被引：9，自引：0，他引：9
Data from July 2006 to June 2008 observed at SACOL(Semi-Arid Climate and Environment Observatory of Lanzhou University,35.946°N,104.137°E,elev.1961 m),a semi-arid site in Northwest China,are used to study seasonal variability of soil moisture,along with surface albedo and other soil thermal parameters, such as heat capacity,thermal conductivity and thermal diffusivity,and their relationships to soil moisture content.The results indicate that surface albedo decreases with increases in soil moisture content,s... 相似文献
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利用2008年7月兰州大学半干旱气候与环境观测(SACOL)站的观测资料,对比分析了地表土壤热通量的三种计算方法,即谐波法、温度预报校正法(TDEC法)以及结合自校正热通量板(HFP01SC)测量的温度积分法(ITHP法);进而分析了三种不同方法的计算结果对地表能量平衡的影响。比较5cm深度处谐波法和TDEC法的计算结果与HFP01SC的实测结果,三者的相位基本一致,相互之间均具有很好的线性关系;谐波法与TDEC法的计算值较为接近,但分别比HFP01SC的实测值偏大了2%和6%(主要发生在夜间)。对于地表的土壤热通量(G0),谐波法与TDEC法两者的计算结果仅偏差约1%;TDEC法与ITHP法的计算结果之间也具有很好的线性关系(R2=0.99),但偏差达到9%左右。相对于HFP01SC的实测结果,由谐波法和TDEC法计算的G0可将SACOL站的地表能量闭合率分别提高6%和7%左右;利用温度积分法将HFP01SC的实测结果校正到地表后,地表能量闭合率也提高了约6%。因此,在对涡动相关通量做了常规订正的情况下,当充分考虑了土壤热存储后,SACOL站的地表能量闭合率可提高6%～7%,达到82%～83%左右。 相似文献
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半干旱区不同类型土地利用的蒸散量及水分收支差异分析——以通榆为例 总被引：1，自引：0，他引：1
利用吉林通榆半干旱区农田站和退化草地站2008年的外场试验观测资料,对比分析了不同土地利用方式对蒸散和地表水分收支的影响。结果表明：从全年来看,尽管两个站点相距仅5 km,但农田站的全年总蒸散量比代表自然土地覆盖状况的退化草地站高28.2 mm;且生长季两种下垫面的蒸散量较为接近,差异主要发生在非生长季。同时,农田站的年水分收支总量为51.1 mm,比退化草地站低35.6％。具体来说,生长季,两个站点的水分收支均有盈余;但在非生长季,退化草地站的水分收支仍有盈余,而农田站则处于水分亏损状态。这说明在半干旱区,代表人为土地利用状况的农田站面临着更大的水分供给压力,人类活动导致的土地利用会加剧该地区的干旱化趋势。
进一步的分析表明,水分盈余并不代表地表的水分状况良好。从 Priestley-Taylor 系数来看,两个站点的Priestley-Taylor系数均远小于1.0,说明在半干旱区,由于表层土壤水分条件的限制,实际蒸散量远未达到平衡蒸散量,土壤面临着水分供给的压力。其可能的原因是,对半干旱区而言,尽管水分收支有盈余,但是由于土壤沙化严重,土壤孔隙度大,大气降水很容易下渗,并以地下水的形式存储起来,使得表层土壤水分供应反而不足。 相似文献
进一步的分析表明,水分盈余并不代表地表的水分状况良好。从 Priestley-Taylor 系数来看,两个站点的Priestley-Taylor系数均远小于1.0,说明在半干旱区,由于表层土壤水分条件的限制,实际蒸散量远未达到平衡蒸散量,土壤面临着水分供给的压力。其可能的原因是,对半干旱区而言,尽管水分收支有盈余,但是由于土壤沙化严重,土壤孔隙度大,大气降水很容易下渗,并以地下水的形式存储起来,使得表层土壤水分供应反而不足。 相似文献
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Surface turbulent flux measurements over the Loess Plateau for a semi-arid climate change study 总被引：2，自引：0，他引：2
In order to provide high quality data for climate change studies, the data quality of turbulent flux measurements at the station
of SACOL (Semi-Arid Climate & Environment Observatory of Lanzhou University), which is located on a semi-arid grassland over
the Loess Plateau in China, has been analyzed in detail. The effects of different procedures of the flux corrections on CO2, momentum, and latent and sensible heat fluxes were assessed. The result showed that coordinate rotation has a great influence
on the momentum flux but little on scalar fluxes. For coordinate rotation using the planar fit method, different regression
planes should be determined for different wind direction sectors due to the heterogeneous nature of the ground surface. Sonic
temperature correction decreased the sensible heat flux by about 9%, while WPL correction (correction for density fluctuations)
increased the latent heat flux by about 10%. WPL correction is also particularly important for CO2 fluxes. Other procedures of flux corrections, such as the time delay correction and frequency response correction, do not
significantly influence the turbulent fluxes. Furthermore, quality tests on stationarity and turbulence development conditions
were discussed. Parameterizations of integral turbulent characteristics (ITC) were tested and a specific parameterization
scheme was provided for SACOL. The ITC test on turbulence development conditions was suggested to be applied only for the
vertical velocity. The combined results of the quality tests showed that about 62%–65% of the total data were of high quality
for the latent heat flux and CO2 flux, and as much as about 76% for the sensible heat flux. For the momentum flux, however, only about 35% of the data were
of high quality. 相似文献
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利用兰州大学半干旱气候与环境观测站(SACOL站)2009—2010年的地基微波辐射计亮温资料和榆中站探空资料,建立了应用于地基微波辐射计温度、相对湿度和水汽密度反演的径向基神经网络,并将反演结果与地基微波辐射计自带反演产品进行了对比,探究了径向基神经网络在地基微波辐射计气象要素反演算法本地化的应用效果。结果表明:径向基神经网络反演的温度、相对湿度和水汽密度的均方根误差最大值分别为2.72 K、22.32%和0.73 g·m^-3,在所有高度层上径向基神经网络的反演结果均优于微波辐射计,反演产品对2—10 km、1—7 km、0—3 km的大气温度、相对湿度和水汽密度廓线的反演均有明显改善,径向基神经网络能够应用于地基微波辐射计气象要素的反演算法的本地化。 相似文献
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