共查询到19条相似文献,搜索用时 156 毫秒
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陆地总初级生产力遥感估算精度分析 总被引:1,自引:0,他引:1
准确估算陆地总初级生产力GPP(Gross Primary Productivity)数值对碳循环过程模拟有重要影响。本文介绍了多种基于植被指数以及基于光能利用率的遥感GPP算法,综述了不同算法在其研究区域的估算精度;并分析了MODIS/GPP以及BESS/GPP两种遥感GPP产品在不同植被类型的估算精度。通过对比全球碳通量站网络GPP数据表明,MODIS/GPP产品在全球估算结果具显著相关性(R2=0.59)及中等标准误差(RMSE=2.86 g C/m2/day),估算精度较高的植被类型有落叶阔叶林,草地等;估算精度较低类型包括常绿阔叶林,稀树草原等。本文对GPP产品中存在的不确定性进行分析,通过综述前人研究中发现的遥感估算GPP方法中存在的问题,指出可能的提高卫星遥感GPP产品估算精度的方法及发展趋势。 相似文献
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植被指数是地球陆表植被覆盖度和植被活力的指示因子,对环境监测、植被理化参量估算等应用研究有重要的意义。基于植被的反射光谱特征,通过遥感数据波段的组合,可以计算得到遥感植被指数。传统的植被指数如NDVI、EVI等仅利用有限波段信息的线性或非线性组合构建而成,没有充分利用遥感传感器所提供的多波段遥感信息,通用归一化植被指数UNVI(Universal Normalized Vegetation Index)充分利用了遥感传感器提供的多波段植被光谱信息,因此在反演植被叶绿素、生物量等植被理化参量上较其他传统植被指数更具优势。为方便UNVI指数的计算,本文基于IDL语言开发了UNVI软件插件,可直接作为ENVI商业遥感软件进行调用,并可满足多个传感器的UNVI计算需求。为了验证UNVI的应用效果,以植被总初级生产力GPP(Gross Primary Productivity)估算为例,比较了不同植被指数估算GPP的效果,结果表明:基于UNVI估算的GPP与通量站点获得的GPP具有较高的相关性(相关系数R2为0.79),验证了UNVI在GPP估算方面的优势。本文提供的UNVI软件插件可为遥感研究和应用人员提供便捷的计算工具。 相似文献
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基于遥感和美国碳通量观测数据的GPP模型比较研究 总被引:1,自引:0,他引:1
基于遥感和碳通量观测数据,本文采用VPM、EC-LUE、TG、GR、VI和MOD17六个模型估算了五种主要植被类型站点尺度的总初级生产力(GPP)。利用线性相关和定量分析方法评价并比较了上述模型在不同时间尺度上(8天、生长季和年际)的GPP模拟精度。结果表明:1)EC-LUE和VPM模型总体估算精度最高(R20.78);2)森林生态系统中,GPP估算值和实测值在季节和年累积总量上相对误差较小,而在草地和农田系统中,相对误差较大;3)GR、VI和TG模型在森林生态系统GPP估算中模拟精度较高,因其在形式上相对简单,需要的参数和输入数据相对较少,因而适用于大尺度的森林生态系统GPP估算。 相似文献
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遥感GPP模型在高寒草甸的应用比较 总被引:1,自引:0,他引:1
随着遥感数据时空分辨率的提高,大范围实时监测总初级生产力GPP(Gross Primary Productivity)的变化成为可能。本研究收集了黑河流域阿柔冻融观测站的气象观测资料和MODIS数据,驱动VPM、TG、VI和EC-LUE4个模型估算了该站点的GPP,并应用涡动相关观测的GPP验证了模拟结果,并比较了这4个模型的模拟精度。结果表明:阿柔站2009年的涡动相关观测的GPP、NEE(Net Ecosystem Exchange)和ER(Ecosystem Respiration)分别为:804.2gC/m2/yr、129.6gC/m2/yr和673.6gC/m2/yr。该站点光合作用固定的碳有83.8%通过生态系统的呼吸作用释放到大气中。基于遥感的GPP模型能够很好地模拟高寒草甸的GPP,全年的判定系数在0.94以上,生长季的判定系数大于0.84。 相似文献
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叶绿素吸收的光合有效辐射比率的遥感估算模型研究 总被引:8,自引:1,他引:8
光合有效辐射比率(FPAR)是陆地生态系统碳循环研究的重要参数。根据FPAR的物理意义,本文提出了有效FPAR的概念:即叶绿素吸收的FPAR(FPARchl),利用模拟数据建立了有效FPAR信息模型。探讨了基于叶绿素含量估算有效FPAR的可行性,为进一步采用有效FPAR来估算NPP/GPP提供思路和途径。利用实测数据对有效FPAR模型进行验证表明:(1)叶片吸收的FPAR(FPARleaf)与有效FPAR(FPARchl)之间的差异较大。FPARchl通常不足FPARleaf的50%,两者之间虽存在一定的相关性,而这种相关性是非线性的;(2)叶绿素含量与FPARleaf的相关性较高,而与FPARchl的相关性更高,基于叶绿素含量可以以较高的精度估算FPARleaf和FPARchl经过验证,估算的平均相对误差分别为2.90%和6.6%;(3)应用模拟数据建立的FPARleaf及有效FPAR模型均在叶绿素含量大于20μg/cm。时估算的精度较高,而低于20μg/cm^2时估算的精度较低,本文中叶绿素含量大于20μg/cm^2的60个样本的FPARleaf及FPARchl的估算的平均相对误差,分别为1.79%和5.07%。 相似文献
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融合多源遥感数据的高分辨率城市植被覆盖度估算 总被引:2,自引:0,他引:2
准确获取城市植被覆盖定量信息对城市生态环境评价,城市规划及可持续城市发展具有重要意义。遥感技术的发展为获取区域及全球植被覆盖信息提供了有效手段,目前基于单传感器、单时相遥感数据的城市植被覆盖度估算方法得到较为广泛的应用。然而,由于城市地表覆盖的复杂性、植被类型的多样性,在一定程度上影响了城市植被覆盖信息提取的精度。为此,本文提出一种基于多源遥感数据与时间混合分析的城市植被覆盖度估算方法。首先,通过时空融合、植被物候特征分析获得最佳时序的GF-1 NDVI数据;其次,基于时间序列的GF-1 NDVI及Landsat 8 SWIR1、SWIR2数据,采用时间混合分析方法以长沙市为例估算城市植被覆盖度。实验研究表明,基于多源遥感数据与时间混合分析方法获得了较高精度的城市植被覆盖度估算(RMSE为0.2485,SE为0.1377,MAE为0.1889),相对于单时相光谱混合分析、传统的像元二分法,本文提出的方法更为稳定,在低、中、高不同植被覆盖区均能获得较高的估算精度,为城市植被覆盖度定量估算提供了有效方法。 相似文献
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城市植被是低碳治理的重要因素之一,其固碳能力直接影响着城市碳排放。针对现有技术耗时费力、对环境造成一定的影响,本文提出了基于高光谱数据的城市植被碳储量估算研究,以绍兴市上虞区百官街道、曹娥街道、崧厦街道的中心城区为研究区域,将城市植被分为乔木、灌木、竹林和草地4种类型。利用提出的固碳指数对植被固碳能力进行定性分析,再通过生物量经验公式对碳储量进行定量计算,将两者结合得到高光谱植被碳储量估算模型,为大尺度碳储量快速估算提供一种新思路。结果表明:4种城市植被分类精度达88.10%,固碳能力排序为竹林>乔木>灌木>草地。 相似文献
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Chaoyang Wu Xiuzhen Han Jinsheng Ni Zheng Niu Wenjiang Huang 《International Journal of Applied Earth Observation and Geoinformation》2010
Gross primary production (GPP) is a parameter of significant importance for carbon cycle and climate change research. Remote sensing combined with other climate and meteorological data offers a convenient tool for large scale GPP estimation. This paper presents a study of GPP estimation using three methods with in situ measurements of canopy reflectance, LAI, and the photosynthetically active radiation (PAR). First, because LAI is considered as an indicator of the factor of absorbed PAR (fAPAR), it provides reasonable estimates of GPP for all types of wheat with coefficient of determination R2 of 0.7353. The second method uses four kinds of vegetation indices (VIs) to estimate GPP because these indices are suggested to be reliable candidates in the estimation of light use efficiency (LUE). Good determination coefficients were acquired in estimating GPP with R2 ranging from the lowest of 0.7604 for NDVI to the highest of 0.8505 for EVI. A new method was proposed for the estimation of GPP following the Monteith logic, which considering GPP as a product of VI × VI × PAR. Results indicated that this method can provide the best estimates of GPP as determination coefficient R2 increased largely compared to the other two methods. EVI × EVI × PAR was demonstrated to be the most suitable for the estimation of GPP with the highest R2 of 0.9207, which was about 10% larger as compared to GPP estimated from the single EVI. These results will be helpful for the development of new models of GPP estimation with all remote sensing inputs. 相似文献
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冠层光能利用率的叶绿素荧光光谱探测 总被引:4,自引:0,他引:4
设计了玉米生长期日变化试验,同步获取玉米冠层光谱和通量观测数据,探究从植被发射荧光光谱角度实现植被光能利用率可靠反演的可能性。运用涡度相关法获取群体生态系统净生产力(NEP),通过呼吸作用拟合得到冠层总初级生产力(GPP);在此基础上结合吸收光合有效辐射(APAR)获取冠层光能利用率(LUE);同时,利用叶绿素荧光光谱分离算法,提取了光合作用叶绿素荧光绝对强度和相对强度。结论表明,植被发射荧光光谱与光合有效辐射(PAR)显著正相关,760nm波段荧光与PAR的复相关系数R2在0.99以上;叶绿素荧光绝对强度与NEP和GPP显著正相关,荧光和NEP对环境日变化具有类似的响应特征;688nm和760nm植被发射的叶绿素荧光相对强度与LUEGPP存在可靠负相关关系,即叶绿素荧光强度越大,光能利用率越低。同时,通过比较几种植被指数与各种光合参量的相关性表明,叶绿素荧光能够更好的跟踪植被光合状态的变化,更适宜于植被光能利用率的探测。 相似文献
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日光诱导叶绿素荧光遥感反演及碳循环应用进展 总被引:4,自引:1,他引:4
在植被遥感领域,遥感植被指数在过去30年极大地促进了从宏观尺度上来理解和认识地球生物圈,但是以"绿度"观测为主的植被指数仅表征植被"潜在光合作用",而不能直接量化"实际光合作用"。植被叶绿素荧光在光合作用探测上具有优势,是"实际光合作用"的直接探测方法。日光诱导叶绿素荧光(SIF)遥感是近年快速发展起来的新型遥感技术,尤其是2011年实现全球尺度卫星反演以来,在反演算法、植被监测和碳循环应用等方面发展迅速,是近10年来植被遥感领域最具突破性的研究前沿。本文阐述了现阶段(2011年以来)SIF遥感反演及其在碳循环应用方面的进展。本文首先介绍了卫星SIF遥感的发展及其反演算法现状;然后重点剖析了其在陆地生态系统总初级生产力(GPP)估算、全球碳循环监测、物候和植被胁迫监测等方面的应用现状和特点;最后从卫星SIF反演算法优化、SIF-GPP关系机理、SIF多尺度综合观测和全球碳循环监测等方面对今后植被SIF遥感的发展前景进行了展望。 相似文献
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Global warming associated with climate change is one of the greatest challenges of today’s world. Increasing emissions of the greenhouse gas CO2 are considered as a major contributing factor to global warming. One regulating factor of CO2 exchange between atmosphere and land surface is vegetation. Measurements of land cover changes in combination with modelling the Gross Primary Productivity (GPP) can contribute to determine important sources and sinks of CO2.The aim of this study is to accurately model the GPP for a region in West Africa with a spatial resolution of 250 m, and the differentiation of GPP based on woody and herbaceous vegetation. For this purpose, the Regional Biomass Model (RBM) was applied, which is based on a Light Use Efficiency (LUE) approach. The focus was on the spatial enhancement of the RBM from the original 1000–250 m spatial resolution (RBM+). The adaptation to the 250 m scale included the modification of two main input parameters: (1) the fraction of absorbed Photosynthetically Active Radiation (FPAR) based on the 1000 m MODIS MOD15A2 FPAR product which was downscaled to 250 m using MODIS NDVI time series; (2) the fractional cover of woody and herbaceous vegetation, which was improved by using a multi-scale approach. For validation and regional adjustments of GPP and the input parameters, in situ data from a climate station and eddy covariance measurements were integrated.The results of this approach show that the input parameters could be improved significantly: downscaling considerably reduces data gaps of the original FPAR product and the improved dataset differed less than 5.0% from the original data for cloud free regions. The RMSE of the fractional vegetation cover varied between 5.1 and 12.7%. Modelled GPP showed a slight overestimation in comparison to eddy covariance measurements. The in situ data was exceeded by 8.8% for 2005 and by 2.0% for 2006. The model results were converted to NPP and also agreed well with previous NPP measurements reported from different studies. Altogether a high accuracy and suitability of the regionally adjusted and downscaled model RBM+ can be concluded. The differentiation between vegetation growth forms allows a separation of long-term and short-term carbon storage based on woody and herbaceous vegetation, respectively. 相似文献
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ABSTRACTAtmospheric aerosols can alter the direct and diffuse components of global solar radiation, which further influences terrestrial gross primary productivity (GPP) via photosynthesis. To investigate the impact of aerosols on GPP, GPP is modeled using the Boreal Ecosystem Productivity Simulator (BEPS) under two aerosol scenarios (S1& S2) over cropland and grassland ecosystems in the highly polluted North China. In S1, the aerosol-effect is not considered and an original empirical method is used when estimating direct and diffuse solar radiation in BEPS. In S2, BEPS is improved by a new empirical method which incorporates the impact of aerosols using the remote sensing-based aerosol optical depth (AOD). Results suggest that aerosols can reduce GPP of the sunlit leaves by decreasing direct solar radiation, but increase GPP of the shaded leaves by increasing diffuse solar radiation. The impact of aerosols on GPP is more significant over the cropland ecosystem (p < 0.05) with a more complex canopy structure during the peak period of the growing season. Furthermore, an AOD value of 0.3–0.6 with a diffuse fraction (the fraction of diffuse solar radiation in global solar radiation) around 30-40% can largely increase total GPP over the cropland ecosystem. The study improves the accuracy of GPP modeling using BEPS by highlighting the aerosol-effect on GPP via solar radiation over highly polluted regions.Abbreviations: gross primary productivity (GPP); aerosol optical depth (AOD); boreal ecosystem productivity simulator (BEPS) 相似文献
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Minna Ma Jie Dong Fawei Zhang Wenwen Cai Hongqin Li 《International Journal of Digital Earth》2018,11(11):1166-1183
Vegetation gross primary production (GPP) is an important variable for the carbon cycle on the Qinghai-Tibetan Plateau (QTP). Based on the measurements from 12 eddy covariance flux sites, we validated a light use efficiency model (i.e. EC-LUE) to evaluate the spatial-temporal patterns of GPP and the effect of environmental variables on QTP. In general, EC-LUE model performed well in predicting GPP at different time scale over QTP. Annual GPP over the entire QTP ranged from 575 to 703 Tg C, and showed a significantly increasing trend from 1982 to 2013. However, there were large spatial heterogeneities in long-term trends of GPP. Throughout the entire QTP, air temperature increase had a greater influence than solar radiation and precipitation (PREC) changes on productivity. Moreover, our results highlight the large uncertainties of previous GPP estimates due to insufficient parameterization and validations. When compared with GPP estimates of the EC-LUE model, most Coupled Model Intercomparison Project (CMIP5) GPP products overestimate the magnitude and increasing trends of regional GPP, which potentially impact the feedback of ecosystems to regional climate changes. 相似文献
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基于千米格网的区域城市土地开发适宜性评价 总被引:1,自引:0,他引:1
本文选择黑龙江省哈大齐地区(哈尔滨-大庆-齐齐哈尔)为研究案例,在区域尺度上基于千米地理格网进行了城市土地开发适宜性的评价。在明确评价指标选取原则的基础上,结合研究区实际,从自然适宜性、生态重要性、开发潜力性和政策调控性4个方面建立了区域城市土地开发适宜性评价方法体系,并采用主成分分析法进行了适宜性评价。结果表明,哈尔滨、大庆和齐齐哈尔城市核心和周边地区为最适宜或适宜开发区,面积占4.67%,该结论可直接为区域规划和主体功能区规划提供空间决策参考。 相似文献
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In the studies reteted to surface energy balance, satellite data provides important inputs for estimating regional surface albedo and evapotranspiration. The paper describes the use of satellite data in determining the surface emissivity over heterogeneous a’reas by taking Normalized Difference Vegetation Index (NDVI) as modulating parameter at pixel resolution. The estimated emissivity values have been used to find the surface temperature at the pixel scale. Landsat-TM-visible, NIR, TIR bands data and some ground meteorological data have been used in an energy balance model for estimating surface albedo and evapotranspiration. The ET values derived from the model are in good agreement with the values obtained with. ‘CENTURY MODEL’ and ground observations over the area, suggesting the possible use of this approach fot regional scale studies on evapotranspiration. 相似文献