Heterogeneous surface displacement pattern at the Hatchobaru geothermal field inferred from SAR interferometry time-series     

《International Journal of Applied Earth Observation and Geoinformation》2016

We estimated surface displacements using persistent scatterer SAR interferometry (PS-InSAR) around the Hatchobaru geothermal field, Japan, from 18 ALOS/PALSAR images acquired from July 2007 to December 2010. Generally, geothermal fields, covered with natural targets such as rocky terrain and vegetation, have been one of the difficult targets for PS-InSAR analysis. However, we applied space adaptive filtering to increase the number of pixels for measuring surface displacement. The results of our analysis demonstrate ground subsidence with decaying velocity over the observation period around the geothermal field. The spatial pattern of ground subsidence includes sharp boundaries of subsidence that can be interpreted as fault traces. We demonstrated the usefulness of PS-InSAR analysis with the space adaptive filtering to estimate surface displacements with high spatial resolution and high spatial density around a geothermal field.  相似文献   

Classification of forest land attributes using multi-source remotely sensed data     

《International Journal of Applied Earth Observation and Geoinformation》2016

The aim of the study was to (1) examine the classification of forest land using airborne laser scanning (ALS) data, satellite images and sample plots of the Finnish National Forest Inventory (NFI) as training data and to (2) identify best performing metrics for classifying forest land attributes. Six different schemes of forest land classification were studied: land use/land cover (LU/LC) classification using both national classes and FAO (Food and Agricultural Organization of the United Nations) classes, main type, site type, peat land type and drainage status. Special interest was to test different ALS-based surface metrics in classification of forest land attributes. Field data consisted of 828 NFI plots collected in 2008–2012 in southern Finland and remotely sensed data was from summer 2010. Multinomial logistic regression was used as the classification method. Classification of LU/LC classes were highly accurate (kappa-values 0.90 and 0.91) but also the classification of site type, peat land type and drainage status succeeded moderately well (kappa-values 0.51, 0.69 and 0.52). ALS-based surface metrics were found to be the most important predictor variables in classification of LU/LC class, main type and drainage status. In best classification models of forest site types both spectral metrics from satellite data and point cloud metrics from ALS were used. In turn, in the classification of peat land types ALS point cloud metrics played the most important role. Results indicated that the prediction of site type and forest land category could be incorporated into stand level forest management inventory system in Finland.  相似文献   

Impact of sub-pixel heterogeneity on modelled brightness temperature for an agricultural region     

《International Journal of Applied Earth Observation and Geoinformation》2016

Knowledge of sub-pixel heterogeneity, particularly at the passive microwave scale, can improve the brightness temperature (and ultimately the soil moisture) estimation. However, the impact of surface heterogeneity (in terms of soil moisture, soil temperature and vegetation water content) on brightness temperature in an agricultural setting is relatively unknown. The Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12) provided an opportunity to evaluate sub-pixel heterogeneity at the scale of a Soil Moisture Ocean Salinity (SMOS) or the Soil Moisture Active Passive (SMAP) radiometer footprint using field measured data. The first objective of this study was to determine if accounting for surface heterogeneity reduced the error between estimated brightness temperature (T_b) and T_b measured by SMOS. It was found that when accounting for variation in surface soil moisture, temperature and vegetation water content within the pixel footprint, the error between the modelled T_b and the measured T_b was less than if a homogeneous pixel were modelled. The correlation between the surface parameters and the error associated with not accounting for surface heterogeneity were investigated. It was found that there was low to moderate correlation between the error and the coefficient of variance associated with the measured soil moisture, soil temperature and vegetation volumetric water content during the field campaign. However, it was found that the correlations changed depending on the stage of vegetation growth and the amount of time following a precipitation event. At the start of the field campaign (following a precipitation event), there was strong correlation between the error and all three surface parameters (r ≥ 0.75). Following a precipitation event close to the middle of the field campaign (during which there was rapid growth in vegetation), there was strong correlation between the error and the variability in vegetation water content (r = 0.89), moderate correlation with soil moisture (r = 0.61) and low correlation with soil temperature (r = 0.26).  相似文献   

非匀一冠层热辐射方向性3维模型构建——以玉米冠层为例     

马红章  刘素美  孙根云  杜永明  孙林  柳钦火 《遥感学报》2016,20(3):374-381

建立适用于多类型植被场景的热辐射方向性模型是进行地表热辐射方向性研究的一种手段。利用真实植株几何及生理参数的统计平均值来刻画理念植株,并给定其空间分布特征,进行不同生长期植被冠层的描述。基于冠层双向孔隙率思想构建了冠层热辐射方向性3维模型,模型继承了孔隙率模型在计算冠层热辐射方向性上的简洁优势同时以几何光学的思想考虑了冠层空间异质性对冠层热辐射方向性的影响。以玉米冠层为例,进行了不同生长期玉米冠层热辐射方向亮温的模拟,通过与实地测量数据的比对表明,本文发展的模型能够较准确地模拟不同生长期玉米植被场景的方向亮温变化规律,模拟误差主要来自理念株的刻画误差、玉米叶片形状的近似以及忽略了多次散射贡献等3个方面。模型的构建方法对稀疏植被场景、浓密植被场景、多类型植被的混合场景均可适用,不同观测几何下的植被场景4组份面积比计算结果有望应用于复杂地表条件下地表返照率的研究。  相似文献   

气溶胶大气辐射校正区域性分析     

刘小力  王琪洁  张勇  梁忠壮 《测绘科学》2016,41(4):55-60,82

针对使用6S模型中标准气溶胶模型进行大气辐射校正时结果较差的问题,该文提出使用实测气溶胶模型代替其进行计算。利用AERONET数据产品分析了香河、榆中等部分站点的气溶胶成分及其区域性分布特点,证明了中国气溶胶的成分具有明显的区域特性;并对6S模型中标准气溶胶模型与香河地基观测气溶胶光学参数进行比较,结果表明,两者具有较大的差异;最后使用不同的气溶胶模型校正Landsat5TM影像,结果表明,采用实测气溶胶数据进行大气辐射校正结果较优。  相似文献   

海洋卡盾藻对青岛大扁藻的化感作用及其对UV-B辐射的响应     

唐弘硕  袁梦琪  杨雷  王影 《海洋与湖沼》2016,47(4):730-738

本研究以海洋微藻——赤潮藻海洋卡盾藻(Chattonella marina)与饵料藻青岛大扁藻(Platymonas helgolandica var.tsingtaoensis)为研究对象,采用单培养和共培养的方法,研究二者间的竞争关系,并在此基础上研究海洋卡盾藻去藻过滤液和藻细胞裂解液对青岛大扁藻的化感作用,同时进一步探讨两种海洋微藻间的化感作用对UV-B辐射增强的响应。结果显示:共培养条件下,海洋卡盾藻在2个高浓度下对青岛大扁藻的生长产生显著抑制(P0.05);海洋卡盾藻去藻过滤液和藻细胞裂解液对青岛大扁藻的生长也具有显著抑制作用(P0.05),且藻细胞裂解液的抑制作用更强,说明海洋卡盾藻对青岛大扁藻产生化感作用,且通过细胞间直接接触传递的化感物质多于通过介质传递的。不同密度比例的2种藻共培养组用UV-B辐射(2.16J/m2)处理后,海洋卡盾藻对青岛大扁藻生长的化感作用有所减弱。  相似文献   

Development of a new method for efficiently calculating of evaporation from the phreatic aquifer in variably saturated flow modeling          下载免费PDF全文

HAO Qi-chen  SHAO Jing-li  CUI Ya-li  ZHANG Qiu-lan 《地下水科学与工程》2016,4(1):26-34

In this paper, we proposed a new method that has been developed based on the surface soil moisture content (SSMC) to more efficiently calculate the groundwater evaporation in variably saturated flow modeling. In this method, the empirical formula to calculate evaporation was modified and the value of the formula varies from zero to one as a closed interval. In addition, the simulation code for calculating the groundwater evaporation based on the SSMC method was incorporated into the EOS9 module of Tough2, a variably saturated flow modeling code. Finally, two numerical tests and a case simulation were conducted to verify the feasibility and accuracy of the SSMC method. Simulation results indicate that the SSMC method is capable of appropriately simulating the characteristics of water flow in vadose zone and the amount of evaporation with the variable water table. And such results are in coincidence with the value calculated by the logistic function method, and fit well with the measured data globally rather than locally.  相似文献   

Twenty-five years of spectral UV-B measurements over Canada,Europe and Japan: Trends and effects from changes in ozone,aerosols, clouds,and surface reflectivity     

《Comptes Rendus Geoscience》2018,350(7):393-402

Spectral UV records of solar irradiance at stations over Europe, Canada, and Japan were used to study long-term trends at 307.5 nm for a 25-year period, from 1992 to 2016. Ground-based measurements of total ozone, as well as satellite measurements of the Aerosol Index, the Total Cloud Cover and the surface reflectivity were also used in order to attribute the estimated changes of the UV to the corresponding changes of these factors. The present study shows that over the Northern Hemisphere, the long-term changes in UV-B radiation reaching the Earth's surface vary significantly over different locations, and that the main drivers of these variations are changes in aerosols and total ozone. At high latitudes, part of the observed changes may also be attributed to changes in the surface reflectivity. Over Japan, the UV-B irradiance at 307.5 nm has increased significantly by ∼3%/decade during the past 25 years, possibly due to the corresponding significant decrease of its absorption by aerosols. It was found that the greatest part of this increase took place before the mid-2000s. The only European station, over which UV radiation increases significantly, is that of Thessaloniki, Greece. Analysis of the clear-sky irradiance for the particular station shows increasing irradiance at 307.5 nm by ∼3.5%/decade during the entire period of study, with an increasing rate of change during the last decade, possibly again due to the decreasing absorption by aerosols.  相似文献   

内蒙古翁公敖包航磁异常的推断与解释          下载免费PDF全文

郭玉峰  张鹏  万佳宇  黄金辉  田华  田亮  李乐 《地质找矿论丛》2018,33(4):634-638

文章对内蒙古四子王旗—土默特右旗中北部近年发现的翁公敖包航磁异常进行推断与解释,在对找矿有望的航磁异常进行筛选后,对翁公敖包航磁异常进行了野外地质-地球物理查证,确定异常为铁矿所致;采用向上延拓、垂向导数、斜导数及小波变换等方法对航磁异常进行数据转换处理,以获取铁矿体的横向及纵向分布信息,取得了较好的效果。  相似文献   

IPCC AR6报告解读：未来的全球气候——基于情景的预估和近期信息     

周天军  陈梓明  陈晓龙  左萌  江洁  胡帅 《气候变化研究进展》2021,17(6):652-663

依据IPCC第六次评估报告（AR6）第一工作组报告第四章的内容,对未来全球气候的预估结果进行解读。报告对21世纪全球表面气温、降水、大尺度环流和变率模态、冰冻圈和海洋圈的可能变化进行了系统评估,并对2100年以后的气候变化做了合理估计。评估指出全球平均表面气温将在未来20年内达到或超过1.5℃,平均降水也将增加,但随季节和区域而异,同时变率将增大。大尺度环流和变率模态受内部变率影响较大。到21世纪末,北冰洋可能出现无冰期;全球海洋会继续酸化,平均海平面将持续上升,百年内上升幅度依赖不同排放情景,都在2100年后继续升高。在最新的评估中采用多种约束方法,减小了预估不确定性的范围。AR6对于低排放情景以及“小概率高增暖情节”的关注为应对气候变化提供了更多、更完整的信息。综合报告的评估结果指出,未来需要进一步减小区域,特别是季风区气候预估的不确定性,并从科学研究和模式发展两方面加强我国气候预估能力的建设。  相似文献