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1.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(2-3):149-151
A simple deterministic simulation model for landscape-scale soil water deficits has been developed. Standard weather station data are used to estimate ‘daily’ precipitation and actual (regional) evapotranspiration (AET). The balance is added to soil moisture, which is accounted by a simple bucket model. AET is the daily integral of the lesser of supply and demand: supply is governed by current soil moisture, demand by estimated net radiation and temperature. The model estimates geographical patterns of soil water deficit at a scale suitable for comparison with the distributions of plant species and vegetation types. The model provides a way of quantifying soil moisture stress in biogeographical research. 相似文献
2.
Stephen J. Walsh 《自然地理学》2013,34(3):287-297
Soil moisture and soil temperature at 15, 61, and 91 cm depths were measured through use of a neutron probe and thermocouple/psychrometers, respectively, at 12 sample sites distributed along a 200 km east-west transect in west-central Oklahoma. The data were collected weekly from May 7 to August 13, 1985. Multiple regression analysis was used to explain soil moisture and soil temperature variability at the three sample depths through a combination of selected biophysical variables representing temporal and spatial site characteristics, meteorologic inputs, energy variables, and soil conditions. The multiple regression analysis showed that 83, 91, and 82% of the variation in soil moisture, and 79, 91, and 92% of the variation in soil temperature for the three depths sampled could be explained by a combination of the selected biophysical variables. 相似文献
3.
一种改进的土壤水分微波遥感反演模型 总被引：2，自引：0，他引：2
利用微波遥感数据反演地表土壤水分有着较好的物理基础,可实现大范围土壤水分状况的遥感监测。本文基于被动微波传感器AMSR-E的X波段数据,将土壤水分值分解成基准值和日变化量两个部分,并分别建立反演模型,同时引入降雨修正因子来进一步提高土壤水分的估算精度;利用IDL语言实现了我们所研发的模型,并集成为新疆土壤水分遥感反演系统模块之一;利用Watch Dog2400与传统铝盒采样获取的新疆地面土壤水分数据,提取适合的模型经验参数,并对模型结果进行精度评价。结果表明,经改进的模型反演得到的新疆土壤水分结果比美国冰雪数据中心的土壤水分产品在精度上有显著提高:均方根误差由8.4%降低为4.25%;所研发的软件模块可为相关应用部门提供快速的大范围土壤水分监测产品。 相似文献
4.
荒漠地区地表反照率与土壤湿度相关性研究 总被引：5，自引：0，他引：5
本试验分别对腾格里沙漠东南缘沙坡头地区流动沙丘和1964年建植的人工固沙植被区生物土壤结皮的地表反照率和土壤湿度进行了同步测定。分析了该区这两种地表类型的反照率与太阳高度角和土壤湿度的相关性,分别提出了地表反照率与太阳高度角和土壤表层(0～2 cm)湿度的经验拟合关系式。结果表明,地表反照率随太阳高度角增加呈指数递减;排除太阳高度角的影响后,地表反照率随土壤湿度的增加也呈指数递减关系;流沙地表反照率对土壤湿度变化的响应要比生物土壤结皮地表敏感。 相似文献
5.
From May 7 to August 13, 1985, soil moisture was measured at 12 study sites located along a 200-km east-west trending transect in west-central Oklahoma. Soil moisture was sampled at three depths at each site: 15 cm, 61 cm, and 91 cm. Study site location and the time (week) of data collection were analyzed through correlation and regression analysis in order to assess their impact on soil moisture variability measured at the three sampled depths. Along the transect for the study period, soil moisture increased with depth; soil moisture also increased with depth from west to east along the transect during the sample period. The correlation between the location of the sample site and soil moisture was weak at the 15 cm depth (0.48), but was stronger at greater depths (0.78 at 61 cm; 0.65 at 91 cm). The location of the study site along the transect explained 25% of the variation in soil moisture at a 15 cm depth; 62% at a 61 cm depth; and 51% at a 91 cm depth. The time (week variable) of data collection at each sample site was less useful in explaining the variability in soil moisture than site location. Time explains 15, 23, and 16% of the variability observed in soil moisture along the transect for the depths of 15, 61, and 91 cm, respectively. A combination of time and location variables, however, explained 46% of the variability in soil moisture for all three depths. The same time and location variables explained 55%, 76%, and 52% of the variability observed in soil moisture for the three individual depths: 15, 61, and 91 cm, respectively. Unusual precipitation events affected the transect throughout the study period and diminished the impact of location as a significant explanatory variable for describing variability in soil moisture. 相似文献
6.
《自然地理学》2013,34(1):54-78
The sensitivity of the near-surface weather variables and small-scale convection to soil moisture for Western Kentucky was investigated with the aide of the MM5 Penn State/NCAR mesoscale atmospheric model for three different synoptic conditions in June 2006. The model was initialized with FNL reanalysis from NCEP containing soil moisture data calculated with the Noah land surface model. Dry and wet experiments were performed in order to find the influence of soil moisture specification on boundary layer atmospheric variables. Dry experiments showed less available atmospheric moisture (between 2 and 6 g kg-1) at near-surface levels during all synoptic events consistent with slightly deeper boundary layers, higher lifting condensation levels and a larger Bowen ratio. As expected, precipitation rates were generally smaller than those of the control simulation. However, during a moderately strong synoptic event in early June, the dry experiments displayed larger precipitation rates compared to the control experiment (up to 5 mm in 3 hr) as the soil volumetric fraction was decreased from 0.05 to 0.15 (m3 m-3) with respect to the control simulation. Precipitation rates in wet experiments were also modulated by characteristics of synoptic conditions. In early June, precipitation rates slightly were larger than the control run (from 0.2 mm 3 h-1 to 1.4 mm 3 h-1) while in the other periods precipitation was reduced significantly. Both dry and wet anomaly experiments experienced reduced precipitation for different reasons. It was found, lifting condensation level, CAPE and low Bowen ratio were not sensitive markers of changes in soil moisture. Equivalent potential temperature was a better indicator of precipitation changes among all experiments. The controlling factor in these responses was the soil moisture content forcing vertical velocities. Thermodynamic conditions such as local stability played a less substantial role in controlling the precipitation processes. It was found that the response of planetary boundary layer variables under a variety of soil moisture conditions can be modified due to degree of synoptic forcing. Weak-to-moderate forcing favored convection while strong synoptic forcing tended to suppress it under dry soil moisture conditions. Wetter soils did not produce a response in horizontal wind fields as large as under the drier soils. 相似文献
7.
LIANGFuyuan SONGLinhua TANGTao 《地理学报(英文版)》2003,13(2):250-256
Lunan stone forest is a kind of typical karst in China,Which is mainly developed under red soil.In the winter of 1999,three study sites were chosen in stone forest national park according to vegetation cover,geomporphologic location and soil types,CO2 concentration was measured with Gastec punp at different dephts of soil (20,40,60cm) and at the same time soil samples were gatered and soil properties such as soil moisure,pH,soil organic content were analyzed and the total nmuber of viable microbes were counted in laboratory,In the study,dependent variable was chosen as the mean soil log(PCO2),and soil properties were chosen as the independent variables.Multiple stepwise regression analysis showed that the totla amount of microbes and soil moisture are the best indicators of the CO2 production,With the equation LOG(PCO2)=-0.039(TNM)-0.056 (Mo) 1.215 accounting for 86% of the variation of the soil CO2 concentration,where TNM is the total number of microbes in teh soil and Mo is the moisture of soil sample. 相似文献
8.
Lunan stone forest is a kind of typical karst in China, which is mainly developed underred soil. In the winter of 1999, three study sites were chosen in stone forest national park accordingto vegetation cover, geomorphologic location and soil types. CO2 concentration was measured withGastec pump at different depths of soil (20, 40, 60 cm) and at the same time soil samples weregathered and soil properties such as soil moisture, pH, soil organic content were analyzed and thetotal number of viable microbes were counted in laboratory. In the study, dependent variable waschosen as the mean soil log (PCO2), and soil properties were chosen as the independent variables.Multiple stepwise regression analysis showed that the total amount of microbes and soil moisture arethe best indicators of the CO2 production, with the equation LOG(PCO2) = - 0.039(TNM) - 0.056(Mo) + 1.215 accounting for 86% of the variation of the soil CO2 concentration, where TNM is thetotal number of microbes in the soil and Mo is the moisture of soil sample. 相似文献
9.
Lunan stone forest is a kind of typical karst in China, which is mainly developed under red soil. In the winter of 1999, three study sites were chosen in stone forest national park according to vegetation cover, geomorphologic location and soil types. CO2 concentration was measured with Gastec pump at different depths of soil (20, 40, 60 cm) and at the same time soil samples were gathered and soil properties such as soil moisture, pH, soil organic content were analyzed and the total number of viable microbes were counted in laboratory. In the study, dependent variable was chosen as the mean soil log (PCO2), and soil properties were chosen as the independent variables. Multiple stepwise regression analysis showed that the total amount of microbes and soil moisture are the best indicators of the CO2 production, with the equation LOG(PCO2) = - 0.039(TNM) - 0.056(Mo) + 1.215 accounting for 86% of the variation of the soil CO2 concentration, where TNM is the total number of microbes in the soil and Mo is the moisture of soil sample. 相似文献
10.
Estimation of Areal Soil Moisture by use of Terrain Data 总被引：2，自引：0，他引：2
J.R. Sulebak L.M. Tallaksen & B. Erichsen 《Geografiska Annaler: Series A, Physical Geography》2000,82(1):89-105
In this study measured soil moisture is related to primary and secondary topographical attributes within two small-scale drainage basins. The study sites are the Buddby and the Dansarhllarna drainage basins within the NOPEX area. The primary topographic attributes slope, aspect, plan and profile curvature, and the secondary topographic attribute, the wetness index, are derived from a 5 m resolution digital elevation model. The relationship with measured soil moisture in the Buddby basin is investigated by linear regression analysis. Based on mean plot measurements for the whole measurement period two different models were established, resulting in a high R 2 value. The best model was achieved with slope, profile curvature and aspect as regression variables. The models obtained were further used to regionalise the results into basin scale at both Buddby and Dansarhällarna. This demonstrated a soil moisture pattern different from the pattern resulting from the wetness index. Finally, models were established, based on two different dates of field campaigns. The results showed a good agreement with the observed soil moisture values, and a higher R 2 value was obtained when using the wetness index for the medium wet period compared to the wettest period. Further analysis is needed to verify the physical significance of the results and their suitability for hydrological modelling. 相似文献
11.
干旱半干旱区山地土壤水分动态变化 总被引：100，自引：1，他引：100
水分是干旱半干旱区山地植物生长的主要限制因子，在这些地区开展土壤水分动态变化研究对农业生产和生态恢复的重要性是不言而喻的。近年来土壤水分测定技术有了很大进步，中子水分仪和时城反射仪已成为常规测量仪器，新型仪器不断出现，总的趋势是仪器的精度和自动化水平不断提高。土壤水分有其时空变化规律，一方面土壤水分随季节变化而变化，另一方面土壤水分随土壤深度和水平位置的变化发生相应变化。降水是影响干旱半干旱区山地土壤水分的最重要因素，气温、太阳辐射等其它气象因子对土壤含水量也用一定影响。此外，坡向、坡度、坡位等地形因子以及土壤特性、地表植被、土地利用情况等对土壤含水量空间分布也有重要影响。总之土壤含水量的时空变化是各种环境因子综合作用的结果。目前土壤水分动态变化的研究重点是对其影响因子的研究。就我国而言，宜加强干旱河谷区土壤水分动态变化的研究，促进土壤水分动态变化研究工作全面深入地开展。 相似文献
12.
中国东北地区地表水资源与气候变化关系的研究 总被引：32，自引：15，他引：17
利用NCEP/NCAR 1948~2000年共53年的月平均再分析资料,统计分析了东北地区不同区域和季节气温和(或)降水变化对蒸发量、地表径流量以及浅层和深层土壤含水量的影响。结果表明,东北地区地表水资源各分量与气温和降水之间有着较好的相关关系。还建立了气温和(或)降水变化对水资源各分量影响的简单统计评估模型,利用这些模型研究了东北地区地表水资源各分量对气温和(或)降水变化的响应情况,得出东北地区较小的"气候扰动"可能会导致径流量等地表水资源较大的变化和其它一些有意义的结果。 相似文献
13.
陇东黄土高原土壤水分演变及其对气候变化的响应 总被引：12，自引：4，他引：8
以西峰为例,利用近45 a气象观测资料和近25 a的土壤水分观测资料,分析全球气候变暖背景下陇东主要气象要素及土壤水分的变化特征,探讨了气候变化对土壤水分的影响,以及影响土壤水分变化的主要气象因素。1993年以后,土壤水分以负距平为主,土壤干旱严重,0—50 cm和60—100 cm土层土壤水分含量在1997年和1995年降到最低值。春季是土壤水分减少最明显的季节,其中表层土壤水分对气候变化的响应更为明显,而夏秋季,较深层的水分变化更为明显。影响土壤水分的气象因子以降水、蒸发为主,气温通过影响蒸发间接产生影响。通过对土壤水分演变特征及其影响因子的分析,为进一步理解土壤水分条件的恶化原因,采取措施,合理利用气候资源,调整农业生态布局,恢复生态环境,积极应对气候变化提供决策方面的参考。 相似文献
14.
东北黑土区土壤剖面地温和水分变化规律 总被引：3，自引：1，他引：2
东北黑土区土壤侵蚀的结果使土壤在坡面上发生再分配,土壤腐殖质层厚度的空间变异增大。腐殖质层厚度的变化又引起地温和土壤水分等土壤物理性质的变化,地温和水分是影响和反映冻融侵蚀作用的重要因子,也是影响地表和土壤剖面物质运移的重要因素。本文通过实测不同厚度腐殖质层剖面的地温和土壤水分,分析了地温和水分随时间和土壤剖面深度的变化规律。结果显示腐殖质层厚度对土壤温度和含水量有显著影响,腐殖质层较厚的剖面解冻速度比薄层黑土区要慢,不同深度土层温度到达0℃的日期也不相同,腐殖质层较厚的剖面冻结时间要滞后1周左右。同时,腐殖质层较厚的黑土区土壤含水量明显大于薄层黑土区,土壤水分运移的深度范围也大。 相似文献
15.
基于卫星遥感和再分析数据的青藏高原土壤湿度数据评估 总被引：5，自引：1，他引：4
土壤水是地表与大气在水热交换方面的关键纽带,是关键水循环要素,更是地表产汇流过程的关键控制因子。青藏高原是地球第三极,也是亚洲水塔,探讨青藏高原土壤水变化对于探讨青藏高原热力学特征变化及其对东亚乃至全球气候变化的影响具有重要意义,而获取高精度长序列大尺度土壤水数据集则是其关键。本文利用青藏高原100个土壤水站点观测数据,从多空间尺度（0.25°×0.25°,0.5°×0.5°,1°×1°）、多时间段（冻结和融化期）等角度,采用多评价指标（R、RMSE、Bias）,对多套遥感反演和同化数据（ECV、ERA-Interim、MERRA、Noah）进行全面评估。结果表明：① 除ERA外,其他数据均能反映青藏高原土壤水变化,且与降水量变化一致。而在那曲地区,遥感反演和同化数据均明显低估实测土壤水含量。从空间分布来看,MERRA和Noah与植被指数最为一致,可很好地反映土壤水空间变化特征;② 青藏高原大部分地区土壤水变化主要受降水影响,其中青藏高原西部边缘与喜马拉雅地区土壤水变化则受冰雪融水和降水的共同影响;③ 除阿里地区外,大部分遥感反演和同化数据在融化期与实测土壤水相关性高于冻结期,其中在那曲地区,遥感反演和同化数据均高估冻结期土壤含水量,却低估融化期土壤含水量。另外,遥感反演和同化数据对中大空间尺度土壤水的估计要好于对小空间尺度土壤水的估计。本研究为青藏高原土壤水研究的数据集选择提供重要理论依据。 相似文献
16.
《地理学报(英文版)》2019,(3)
Based on the data of relative soil moisture in 653 agricultural meteorological stations during the period of 1993-2013 in China, the characteristics and regularity of spatial and temporal variation of relative soil moisture in China's farmland were analyzed and discussed using geostatistical methods. The results showed that the relative soil moisture of China's farmland has shown a fluctuant increasing trend since 1993. The relative soil moisture of China's farmland is more than 60% in general, its distribution area has been expanded northward and westward with the summer monsoon since mid-April and began to shrink eastward and southward in late October. The value of relative soil moisture increases with the increase of soil depth. On an interannual scale, the relative soil moisture of farmland increased fastest in summer and autumn, and its variation range decreased with the increase of soil depth. The relative soil moisture was positively correlated with precipitation, and negatively correlated with potential evaporation and temperature. The correlation between relative soil moisture and various meteorological factors weakened as soil depth increased. The meteorological factors have a great influence on relative soil moisture of dry land in spring, summer and autumn and they also have a greater impact on relative soil moisture of paddy fields in winter. 相似文献
17.
18.
不同植被盖度沙质草地生长季土壤水分动态 总被引：1，自引：1，他引：1
水分是干旱半干旱沙地生态系统最大的限制因子，研究植被盖度和土壤水分之间的关系有助于沙地生态恢复和保护。基于生长季科尔沁沙质草地不同植被盖度下土壤水分动态和降水的观测试验，分析了沙质草地植被盖度和土壤水分的耦合关系。结果表明：在土壤剖面上土壤水分存在明显的分层结构，依次为水分剧变层（0~40 cm）、缓变层（40~100 cm）和稳定层（100~180 cm）；植被盖度对土壤水分有很大影响，不同植被盖度下土壤含水量存在显著差异，土壤水分与盖度之间呈倒“V”型关系，土壤水分状况在28%的盖度下最优；不同的植被盖度下土壤水分对降水的响应也存在差异，在13%盖度下响应最敏感，28%和46%的盖度下响应微弱，后二者的土壤水分也相对稳定。在沙地生态恢复建设过程中合理的植被盖度配置可提高降水利用效率，并能使土壤水分和植被达到一种良好的平衡状态，从而有利于生态系统的稳定。 相似文献
19.
以祁连山北麓中段青海云杉林为研究对象,利用5套土壤温湿度自动监测系统对海拔2 500~3 300 m的青海云杉连续监测3 a,旨在探讨青海云杉林土壤水热的变化特征及土壤水热间的互作效应。结果表明：（1）7：00~19：00,土壤温度整体上呈升高趋势,8：00土壤均温最低,为1.03 ℃,18：00土壤均温最高,为1.32 ℃;土壤湿度的变化幅度较小,且差异不显著（P>0.05）。（2）冷期（1~4月、11~12月）、暖期（5~10月）,各占全年的50%;8月前随月份增大土壤温湿度增大,月份增大1月,土壤均温增大2.21 ℃,湿度增大0.021 m3·m-3,8月后随月份增大逐渐减小,月份增大1月,土壤均温减小3.12 ℃,湿度减小0.017 m3·m-3。（3）土壤温度与海拔之间有负相关关系（R2=0.81,P<0.05）;土壤湿度与海拔之间存在二项式相关关系（R2=0.95,P <0.05）。（4）土壤温度与土层深度间呈负相关关系（P <0.05）,而土壤湿度与土层深度呈线性正相关关系（P <0.05）,土层每增加一层,土壤均温减小0.142 ℃,度约增加0.009 m3·m-3。（5）青海云杉林土壤温度和湿度间呈显著线性负相关关系（P <0.05）。 相似文献
20.
《自然地理学》2013,34(2):121-139
Using a hydrologic model to estimate daily soil moisture at 258 evaluation locations over a 30-year period, the spatial variability and persistence of soil moisture across Oklahoma is examined. The Soil and Water Assessment Tool (SWAT) uses readily available meteorological inputs with detailed land surface information. Spatial variability of soil moisture across Oklahoma is extremely dynamic and exhibits a remarkable range of individual characteristics due to the heterogeneous land surface. An autocorrelation analysis is used to evaluate the persistence of soil moisture at each evaluation location. In general, soil moisture across Oklahoma persists from 5 to 10 weeks in the eastern portion of Oklahoma to over 30 weeks in western Oklahoma as a result of the large-scale climatic variability of precipitation supply and evapotranspiration demand. However, the lags are not spatially coherent due to the heterogeneity of the land surface. Land surface characteristics potentially influencing the persistence of soil moisture across Oklahoma are examined, including vegetation type and soil texture and depth. Of the three parameters, soil depth plays a significant role in the memory of soil moisture conditions. As the soil profile depth increases, a corresponding increase in the persistence of soil moisture occurs. 相似文献