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排序方式: 共有1370条查询结果,搜索用时 31 毫秒
151.
Shaohua Zhao Yonghui Yang Guoyu Qiu Qiming Qin Yunjun Yao Yujiu Xiong Chunqiang Li 《International Journal of Applied Earth Observation and Geoinformation》2010
An approach for estimating soil moisture is presented and tested by using surface-temperature-based soil evaporation transfer coefficient (ha), a coefficient recently proposed through the equation ha = (Ts − Ta)/(Tsd − Ta), where Ts, Tsd, and Ta are land surface temperature (LST), reference soil (dry soil without evaporation) surface temperature, and air temperature respectively. Our analysis and controllable experiment indicated that ha closely related to soil moisture, and therefore, a relationship between field soil moisture and ha could be developed for soil moisture estimation. Field experiments were carried out to test the relationship between ha and soil moisture. Time series Aqua-MODIS images were acquired between 11 Sep. 2006 and 1 Nov. 2007. Then, MODIS derived ha and simultaneous measured soil moisture for different soil depths were used to establish the relations between the two variables. Results showed that there was a logarithmic relationship between soil moisture and ha (P < 0.01). These logarithmic models were further validated by introducing another ground-truth data gathered from 46 meteorological stations in Hebei Province. Good agreement was observed between the measured and estimated soil moisture with RMSE of 0.0374 cm3/cm3 and 0.0503 cm3/cm3 for surface energy balance method at two soil depths (10 cm and 20 cm), with RMSE of 0.0467 cm3/cm3 and 0.0581 cm3/cm3 for maximum temperature method at two soil depths. For vegetated surfaces, the ratio of ha and NDVI suggested to be considered. The proposed approach has a great potential for soil moisture and drought evaluation by remote sensing. 相似文献
152.
153.
This study assesses surface urban heat island (UHI) and its associated surface physical characteristics using remote sensing approaches. TERRA/MODIS images acquired in 2005 in three different seasons were selected to generate land surface tem-perature and surface characteristics for the Changsha-Zhuzhou-Xiangtan metropolitan area in China. The intensity of urban heat is-land effects and its seasonal variations were examined. The result showed that UHI effects were significant both in the summer and the spri... 相似文献
154.
《地学前缘(英文版)》2020,11(6):2169-2181
This study provides characteristics of aerosol columnar properties, measured over ten countries in Eastern Europe from 2002 to 2019. Aerosol optical depth (AOD) and Ångström exponent (AE) were obtained with the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6.1 merged Dark Target and Deep Blue aerosol product. The product is validated using ground-based Aerosol Robotic Network (AERONET) situated at Minsk, Belsk, Moldova and Kyiv. The results showed that 76.15% of retrieved AOD data are within the expected error. It was established that 64.2% of AOD points are between 0 and 0.2 and 79.3% of all AE points are over 1. Mean AOD values in the region vary from 0.130 ± 0.04 (Moldova) to 0.193 ± 0.03 (Czech Republic) with mean value in the region 0.162 ± 0.05. Seasonal mean AOD (AE) values were at the maximum during the summer from 0.231 ± 0.05 (1.482 ± 0.09 in winter) to minimum 0.087 ± 0.04 during the winter (1.363 ± 0.17 in summer). Gradual AOD reduction is observed in all countries with annual trend from −0.0050 (Belarus) to −0.0029 (Russia). Finally, the relationship between AOD and AE was studied to classify various aerosol types and showed seasonal non-uniformity of their contribution depending on variation in sources. The entire region is under significant impact of various aerosol types, including clean continental (СС), mixed (MX) and anthropogenic/burning (AB) aerosols types that are at 59.77%, 24.72%, and 12.97% respectively. These results form an important basis for further regional studies of air quality and distribution of sources of pollution. 相似文献
155.
The northern coast of Vietnam has accumulated a significant amount of sediment discharged from the multiple distributaries of rivers such as the Red River and Ma River.While recent decreases of the sediment supply appears to have a significant impact on coastal erosion,the complex network of these distributaries makes it difficult to determine the overall spatiotemporal characteristics of sediment discharges and related topographic changes.The goal of the current study is to develop a satellite-based monitoring system for observation of turbidity discharged from the multiple rivers and to investigate the applicability of the developed monitoring system through a case study on the northern coast of Vietnam.Based on the in-situ observed data,a formulawas determined for estimation of the surface water turbidity as a function of the red band reflectance of Moderate Resolution Imaging Spectro-radiometer(MODIS)images.The formula was then combined with a newly determined threshold for cloud-masking to obtain maps of the nearshore turbidity patterns.These maps capture the spatiotemporal water surface turbidity along the entire coast of the Red River Delta and the coast around theMa River mouth over the past sixteen years with frequency of twice a day.Finally,long-term trends of the turbidity patterns from multiple rivers were compared with the in-situ observation data and it was found that the Red River and the Ma River showed clearly contrasting characteristics,which reasonably explain the recent coastal shoreline changes and characteristics of sediment sampled along the coast. 相似文献
156.
2000年以来青藏高原湖泊面积变化与气候要素的响应关系 总被引:1,自引:0,他引:1
青藏高原星罗密布的湖泊对气候变化十分敏感,在自然界水循环和水平衡中发挥着重要作用.以MODIS MOD09A1和SRTM DEM为数据源,提取了2000-2016年青藏高原丰水期面积大于50 km2的湖泊边界,从内外流分区、湖泊主要补给来源和湖水矿化度三个方面对2000年以来湖泊面积变化进行分析,并结合青藏高原近36年气象数据,根据气象要素变化趋势分区,初步探讨青藏高原湖泊面积变化与气候要素的关系.结果表明:青藏高原面积大于50 km2的138个湖泊整体扩张趋势显著,总面积增加2340.67 km2,增长率为235.52 km2/a.其中,扩张型湖泊占67.39%,萎缩型湖泊占12.32%,稳定型湖泊占20.29%.内流湖扩张趋势显著,外流湖扩张趋势较明显;以冰雪融水为主要补给来源的湖泊整体扩张趋势明显,以地表径流和河流补给为主要补给源的湖泊也呈扩张趋势;盐湖和咸水湖以扩张为主,淡水湖的扩张、萎缩和稳定三种类型较均衡.在青藏高原气候暖湿化方向发展背景下,湖泊面积变化与气候要素具有显著的区域相关性.气温和降水变化趋势分区结果表明,气温增加、降水增加强趋势的高原Ⅰ区湖泊扩张程度(78.18%)依次大于气温降低、降水量呈增加趋势的Ⅴ区(66.67%),气温、降水量呈增加趋势的Ⅱ区(60.78%),气温呈降低、降水量呈增加强趋势的Ⅳ区(58.83%)和气温呈增加、降水量呈减少趋势的Ⅲ区(50.00%).湖泊面积变化对气候变化响应研究表明,升温引起的冰雪融水补给对Ⅰ区、Ⅱ区和Ⅲ区湖泊面积扩张的影响显著,加之降水量的增加,湖泊扩张速率明显;Ⅳ区和Ⅴ区湖泊面积扩张主要受降水量增加影响显著.整体而言,气温主要影响以冰雪融水为主要补给来源的湖泊,降水量主要影响以降水和地表径流为主要补给来源的湖泊. 相似文献
157.
应用MODIS遥感数据监测巢湖水质 总被引:18,自引:1,他引:17
以巢湖为研究对象,对MODIS的各个波段辐射率与水质参数叶绿素a浓度、悬浮物浓度和透明度进行拟合,分析了MODIS各个波段辐射率的拟合在监测大型内陆湖泊水质中的可行性.结果表明:MODIS波段辐射率的组合能与巢湖水质参数进行较好的匹配,MODIS波段1—4和10—11对于监测巢湖中叶绿素a浓度、悬浮物浓度和透明度有重要意义. 相似文献
158.
去除EOS/MODIS 1B数据中"弯弓"效应的方法 总被引:15,自引:7,他引:8
分析了中分辨率成像光谱仪EOS/MODIS的扫描方式,在此基础上研究了EOS/MODIS1B数据集“弯弓”效应的成因。对EOS/MODIS1B数据02级产品HDF文件的格式进行了探讨,并以250m分辨率资料为例,在2002年7月13日10时的MODIS资料中选取鄱阳湖以北部分地区,读取其数据进行插值、Lambert投影、重采样等处理,从而消除了影响资料使用的“弯弓”效应,同时也完成了对EOS/MODIS数据的几何校正,取得了一定的效果,为EOS/MODIS遥感资料在今后得以广泛应用作了有益的尝试。 相似文献
159.
160.
地物反射光谱对MODIS近红外波段水汽反演影响的模拟分析 总被引:14,自引:1,他引:14
在近红外辐射传输方程的基础上,利用近红外波段水汽的不同吸收属性,在MODTRAN的模拟下,深入分析了基于MODIS近红外数据的可降水汽反演算法,并着重讨论了地物反射光谱非线性在可降水汽反演中的影响。研究结果显示,当波段间反射率之比不等于1时,MODIS近红外波段反演水汽将存在较大偏差。同时,在地物光谱库基础上,计算了不同地物反射率比值,其分布表明,大部分地物波段反射率比值不等于1。研究表明,应用现有MODIS近红外波段水汽反演算法,如果不考虑地表反射率光谱变化的影响,由地表反射光谱造成的误差最大约为反射率比值与1偏差的15倍,同时,这一误差还与大气波段透过率之比有关。 相似文献