Jianmao Guo, W. Lu, Ronghua Liu, B. Bi, Guoping Zhang, Jianlin Wang
Determination the regional land surface parameters and components of surface radiation balance over heterogeneous landscape is very important and not an easy problem, in such researches, the utilization of satellite remote sensing is indispensable. In this study, a parameterization method based on Landsat-7 ETM+ data and 22 weather stations data is described for deriving the regional distributions of land surface parameters and components of surface radiation balance over the South Ningxia area. The distribution figs and straight-bar charts of the parameters and components are given out. Further more, the South Ningxia area is classified into five surface types, regional distributions are discussed according to each type. The main results indicate: All the regional distributions are characteristic by their terrain nature and the regional distributions are obvious and regular. The figures of the mountains and rivers are very clear, cause there is a great deal vegetation growing over the mountains and rivers edge. It is seen that the derived regional distributions of land surface parameters and components of surface radiation balance for the whole mesoscale area are in good accordance with the land surface status.
{"title":"Determination of regional land surface parameters and components of surface radiation balance over heterogeneous landscape of South Ningxia by using satellite remote sensing data","authors":"Jianmao Guo, W. Lu, Ronghua Liu, B. Bi, Guoping Zhang, Jianlin Wang","doi":"10.1117/12.678162","DOIUrl":"https://doi.org/10.1117/12.678162","url":null,"abstract":"Determination the regional land surface parameters and components of surface radiation balance over heterogeneous landscape is very important and not an easy problem, in such researches, the utilization of satellite remote sensing is indispensable. In this study, a parameterization method based on Landsat-7 ETM+ data and 22 weather stations data is described for deriving the regional distributions of land surface parameters and components of surface radiation balance over the South Ningxia area. The distribution figs and straight-bar charts of the parameters and components are given out. Further more, the South Ningxia area is classified into five surface types, regional distributions are discussed according to each type. The main results indicate: All the regional distributions are characteristic by their terrain nature and the regional distributions are obvious and regular. The figures of the mountains and rivers are very clear, cause there is a great deal vegetation growing over the mountains and rivers edge. It is seen that the derived regional distributions of land surface parameters and components of surface radiation balance for the whole mesoscale area are in good accordance with the land surface status.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"88 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127998324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yen-Ben Cheng, D. Riaño, P. Zarco-Tejada, S. Ustin
We assessed the capability of AVIRIS and MODIS to estimate canopy water content. Hyperspectral water retrievals with AVIRIS data, EWT, were compared to in situ leaf water content and LAI measurements at a semi-arid site in southeastern Arizona. Retrievals of EWT showed good correlation with field canopy water content measurements. Statistical analysis also suggested that EWT was significant among seven different vegetation communities. Four MODIS indexes derived from band ratios using the reflectance product and were compared to retrievals of EWT with AVIRIS at both the semi-arid site and a temperate conifer forest. Good statistical agreements were found between AVIRIS EWT and all four MODIS indexes at the semi-arid site in savanna shrub communities. Slightly poorer correlations were found at the forest site where water indexes had better correlation to AVIRIS EWT than vegetation indexes. Temporal patterns of the four indexes in all semi-arid vegetation communities except creosote bush and agriculture show distinct seasonal variation and responded to precipitation at the savanna site. Three years of net ecosystem exchange (NEE) data from eddy covariance measurements at the forest site were compared to the time series of MODIS indexes. MODIS water indexes showed similar seasonal patterns to NEE that were strongest during the period of net carbon sequestration. In contrast, the time series of MODIS vegetation indexes did not yield a good relationship to NEE.
{"title":"Canopy water content estimates with AVIRIS imagery and MODIS reflectance products","authors":"Yen-Ben Cheng, D. Riaño, P. Zarco-Tejada, S. Ustin","doi":"10.1117/12.676833","DOIUrl":"https://doi.org/10.1117/12.676833","url":null,"abstract":"We assessed the capability of AVIRIS and MODIS to estimate canopy water content. Hyperspectral water retrievals with AVIRIS data, EWT, were compared to in situ leaf water content and LAI measurements at a semi-arid site in southeastern Arizona. Retrievals of EWT showed good correlation with field canopy water content measurements. Statistical analysis also suggested that EWT was significant among seven different vegetation communities. Four MODIS indexes derived from band ratios using the reflectance product and were compared to retrievals of EWT with AVIRIS at both the semi-arid site and a temperate conifer forest. Good statistical agreements were found between AVIRIS EWT and all four MODIS indexes at the semi-arid site in savanna shrub communities. Slightly poorer correlations were found at the forest site where water indexes had better correlation to AVIRIS EWT than vegetation indexes. Temporal patterns of the four indexes in all semi-arid vegetation communities except creosote bush and agriculture show distinct seasonal variation and responded to precipitation at the savanna site. Three years of net ecosystem exchange (NEE) data from eddy covariance measurements at the forest site were compared to the time series of MODIS indexes. MODIS water indexes showed similar seasonal patterns to NEE that were strongest during the period of net carbon sequestration. In contrast, the time series of MODIS vegetation indexes did not yield a good relationship to NEE.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116044843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The exact knowledge of the spatiotemporal dynamics of crop diseases for an implementation of a site-specific fungicide application is fundamental. Remote sensing is an appropriate tool to monitor the heterogeneity of fungal diseases within agricultural sites. However, the identification of an infection at an early growth stage is essential. This study assesses the potential of multispectral remote sensing for multitemporal analyses of crop diseases. Within an experimental test site near Bonn (Germany) a 6-ha sized plot with winter wheat was created, containing crops with each possible infection stage of three different pathogens. Two multispectral QuickBird images (04/22/2005 and 06/20/2005) and a spectrally resampled HyMap image (05/28/2005) were used to analyse the spatiotemporal dynamic of infection. The data preprocessing comprised a radiometric and a precise geometric correction by using DGPS-measurements that is an important requirement for Precision Agriculture applications. Ground truth data, in particular infection severity, growth stage/height, and spectroradiometer measurements were collected. A decision tree, using mixture tuned matched filtering results and a vegetation index was applied to classify the data (infected and non-infected areas). Classification results were compared to ground truth data. The classification accuracy of the first scene was only 56.8% whereas the scene of 28 May (65.9%) and the scene of 20 June (88.6%) achieved considerably higher accuracies. The results showed that high-resolution multispectral data are generally suitable to detect in-field heterogeneities of vegetation vitality though they are only moderately suitable for early detection of stress factors.
{"title":"Detection of fungal infection in wheat with high-resolution multispectral data","authors":"J. Franke, G. Menz","doi":"10.1117/12.680913","DOIUrl":"https://doi.org/10.1117/12.680913","url":null,"abstract":"The exact knowledge of the spatiotemporal dynamics of crop diseases for an implementation of a site-specific fungicide application is fundamental. Remote sensing is an appropriate tool to monitor the heterogeneity of fungal diseases within agricultural sites. However, the identification of an infection at an early growth stage is essential. This study assesses the potential of multispectral remote sensing for multitemporal analyses of crop diseases. Within an experimental test site near Bonn (Germany) a 6-ha sized plot with winter wheat was created, containing crops with each possible infection stage of three different pathogens. Two multispectral QuickBird images (04/22/2005 and 06/20/2005) and a spectrally resampled HyMap image (05/28/2005) were used to analyse the spatiotemporal dynamic of infection. The data preprocessing comprised a radiometric and a precise geometric correction by using DGPS-measurements that is an important requirement for Precision Agriculture applications. Ground truth data, in particular infection severity, growth stage/height, and spectroradiometer measurements were collected. A decision tree, using mixture tuned matched filtering results and a vegetation index was applied to classify the data (infected and non-infected areas). Classification results were compared to ground truth data. The classification accuracy of the first scene was only 56.8% whereas the scene of 28 May (65.9%) and the scene of 20 June (88.6%) achieved considerably higher accuracies. The results showed that high-resolution multispectral data are generally suitable to detect in-field heterogeneities of vegetation vitality though they are only moderately suitable for early detection of stress factors.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116013893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Temperature vegetation dryness index (TVDI) is a simple and effective methods for drought monitoring. In this study, the statistic characteristics of MODIS-EVI and MODI-NDVI at two different times were analyzed and compared. NDVI reaches saturation in well-vegetated areas while EVI has no such a shortcoming. In current study, we used MODIS-EVI as vegetation index for TVDI. The analysis of vegetation index and land surface temperature at different latitudes and different times showed that there was a zonal distribution of land surface parameters. It is therefore necessary to calculate the TVDI with a zonal distribution. Compared with TVDI calculated for the whole region, the zonal calculation of TVDI increases the accuracy of regression equations of wet and dry edge, improves the correlations of TVDI and measured soil moisture, and the effectiveness of the large scale drought monitoring using remote sensing data.
{"title":"Zonal calculation for large scale drought monitoring based on MODIS data","authors":"Hongjun Li, Li Zheng, Chunqiang Li, Yuping Lei","doi":"10.1117/12.678644","DOIUrl":"https://doi.org/10.1117/12.678644","url":null,"abstract":"Temperature vegetation dryness index (TVDI) is a simple and effective methods for drought monitoring. In this study, the statistic characteristics of MODIS-EVI and MODI-NDVI at two different times were analyzed and compared. NDVI reaches saturation in well-vegetated areas while EVI has no such a shortcoming. In current study, we used MODIS-EVI as vegetation index for TVDI. The analysis of vegetation index and land surface temperature at different latitudes and different times showed that there was a zonal distribution of land surface parameters. It is therefore necessary to calculate the TVDI with a zonal distribution. Compared with TVDI calculated for the whole region, the zonal calculation of TVDI increases the accuracy of regression equations of wet and dry edge, improves the correlations of TVDI and measured soil moisture, and the effectiveness of the large scale drought monitoring using remote sensing data.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114904374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The surface heterogeneity of densely vegetated region is often ignored as its spatial variation doesn't shows so obvious as sparse region. This paper is to examine to which degree the estimation difference with scale change would be. The surface net radiation and related variables between six consecutive scales from 30 to 960 m over a dense grass covered region in Northern China are calculated with a simplified scheme based on Landsat ETM data. The estimation agreements between neighbouring scales are evaluated with the mean absolute percent difference and the index of agreement. The two indices indicated variation is not so obvious and can't determine whether the study area is homogeneous or not. Further analyses of the fraction variation of land covers with scales and the change of related mean variables for individual land cover with scales, reach a consistent result that the major covers with larger patches are more insensitive to scale change than the minor ones with smaller patches. The introduction of land cover information improves detecting the effect of patches with different covers when the surface net radiation is considered.
植被密集区由于其空间变化不像稀疏区那么明显，地表异质性往往被忽视。本文的目的是研究估算值随尺度变化的差异程度。利用基于Landsat ETM数据的简化方案，计算了中国北方茂密草原区30 ~ 960 m 6个连续尺度的地表净辐射及其相关变量。用平均绝对百分比差和一致性指数来评价相邻尺度之间的估计一致性。这两个指标的变化并不明显，不能确定研究区域是否均匀。进一步分析土地覆被随尺度的变化比例和单个土地覆被随尺度的相关平均变量的变化，得到了一致的结果，即斑块较大的大覆盖对尺度变化的不敏感程度高于斑块较小的小覆盖。在考虑地表净辐射的情况下，土地覆盖信息的引入提高了对不同覆盖斑块影响的检测。
{"title":"Scaling characteristics of remotely sensed surface net radiance over densely vegetated grassland in Northern China","authors":"Wenjiang Zhang, Zhiqiang Gao","doi":"10.1117/12.675930","DOIUrl":"https://doi.org/10.1117/12.675930","url":null,"abstract":"The surface heterogeneity of densely vegetated region is often ignored as its spatial variation doesn't shows so obvious as sparse region. This paper is to examine to which degree the estimation difference with scale change would be. The surface net radiation and related variables between six consecutive scales from 30 to 960 m over a dense grass covered region in Northern China are calculated with a simplified scheme based on Landsat ETM data. The estimation agreements between neighbouring scales are evaluated with the mean absolute percent difference and the index of agreement. The two indices indicated variation is not so obvious and can't determine whether the study area is homogeneous or not. Further analyses of the fraction variation of land covers with scales and the change of related mean variables for individual land cover with scales, reach a consistent result that the major covers with larger patches are more insensitive to scale change than the minor ones with smaller patches. The introduction of land cover information improves detecting the effect of patches with different covers when the surface net radiation is considered.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"139 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114434733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Sun, Z. Rong, Cheng Liu, Jingjing Liu, Yan Zhang, Peng Zhang, Xinli Wang, Wei Gao
Field experiments with man-made fires in a forest were conducted to verify fire warning products from satellite remote sensing techniques and to select more effective channels for producing these products. Pine branches and trunks as well as other woods were burned at a designated place in a pine-dominated forest to simulate wild forest fires when a satellite was passing over the sky. Infrared spectral irradiances, visible spectrum, brightness, and temperature were measured concurrently with satellite data at the ground using a medium and near-infrared MOMEM MR154 FT-Spectroradiometer, an infrared thermal imager, and a visible and near-infrared spectroradiometer (ASD FR). The measurements showed two emission peaks in middle infrared band that corresponded exceptionally to the combustion strength. One of the spikes at 4.17 μm reflected the CO emission peak. The other peak spanned through the wavelengths of 4.34-4.76 μm, which exhibited a much stronger response to the fire than the commonly used channel 3.5-4.0 μm for fire monitoring in remote sensing. The results suggest that the wave band 4.34-4.76 μm is probably more sensitive and more effective than the common-used channel for wild fire monitoring using satellite remote sensing techniques. However, the peak of this wavelength band drifted during the burning process, which should be taken into account in channel selection. This band is suitable to determine forest fires. Further studies are needed to use it for retrieving fire strength quantitatively.
{"title":"Spectral characteristics of infrared radiation from forest fires","authors":"H. Sun, Z. Rong, Cheng Liu, Jingjing Liu, Yan Zhang, Peng Zhang, Xinli Wang, Wei Gao","doi":"10.1117/12.679775","DOIUrl":"https://doi.org/10.1117/12.679775","url":null,"abstract":"Field experiments with man-made fires in a forest were conducted to verify fire warning products from satellite remote sensing techniques and to select more effective channels for producing these products. Pine branches and trunks as well as other woods were burned at a designated place in a pine-dominated forest to simulate wild forest fires when a satellite was passing over the sky. Infrared spectral irradiances, visible spectrum, brightness, and temperature were measured concurrently with satellite data at the ground using a medium and near-infrared MOMEM MR154 FT-Spectroradiometer, an infrared thermal imager, and a visible and near-infrared spectroradiometer (ASD FR). The measurements showed two emission peaks in middle infrared band that corresponded exceptionally to the combustion strength. One of the spikes at 4.17 μm reflected the CO emission peak. The other peak spanned through the wavelengths of 4.34-4.76 μm, which exhibited a much stronger response to the fire than the commonly used channel 3.5-4.0 μm for fire monitoring in remote sensing. The results suggest that the wave band 4.34-4.76 μm is probably more sensitive and more effective than the common-used channel for wild fire monitoring using satellite remote sensing techniques. However, the peak of this wavelength band drifted during the burning process, which should be taken into account in channel selection. This band is suitable to determine forest fires. Further studies are needed to use it for retrieving fire strength quantitatively.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124733047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuping Lei, Li Zheng, Y. Shu, Suying Chen, Chunqiang Li
Moderate Resolution Imaging Spectroradiometer (MODIS) data are widely used to compute regional evapotranspiration (ET) at 1000-m spatial resolution. However, due to the fact that the village densities in most counties in North China Plain are higher than 0.5 per km2, the crop ET mapping at 1000-m resolution computed using MODIS data often fails to differentiate the crop field from the residential area, thus resulted in inaccurate ET estimation. In this study, we analyzed relationship between crop ET and MODIS-normalized difference vegetation index (NDVI) and deduced ET equations to calculating winter wheat and summer corn ET from NDVI. The equations were tested using measured data and proved that they are reliable. The equations were applied using MODIS 250 m spatial resolution NDVI and mapped crop ET at 250 m resolution. Compared with ET map from high resolution Landsat, the improved resolution ET map can described the spatial variations of regional crop ET in a similar pattern.
{"title":"Mapping evapotranspiration of wheat and corn using MODIS data with improved resolution","authors":"Yuping Lei, Li Zheng, Y. Shu, Suying Chen, Chunqiang Li","doi":"10.1117/12.680291","DOIUrl":"https://doi.org/10.1117/12.680291","url":null,"abstract":"Moderate Resolution Imaging Spectroradiometer (MODIS) data are widely used to compute regional evapotranspiration (ET) at 1000-m spatial resolution. However, due to the fact that the village densities in most counties in North China Plain are higher than 0.5 per km2, the crop ET mapping at 1000-m resolution computed using MODIS data often fails to differentiate the crop field from the residential area, thus resulted in inaccurate ET estimation. In this study, we analyzed relationship between crop ET and MODIS-normalized difference vegetation index (NDVI) and deduced ET equations to calculating winter wheat and summer corn ET from NDVI. The equations were tested using measured data and proved that they are reliable. The equations were applied using MODIS 250 m spatial resolution NDVI and mapped crop ET at 250 m resolution. Compared with ET map from high resolution Landsat, the improved resolution ET map can described the spatial variations of regional crop ET in a similar pattern.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"163 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123422443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Droughts hazard that occurrs frequently in nature and has a great impact on agriculture. Timely monitoring and assessment of drought conditions are critical to mitigate its effects. By using NOAA/AVHRR satellite data, in current study, we derived the normalized difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI) and land surface temperature (LST), and analyzed the spatial characteristics of vegetation indexes and land surface temperature. The temperature vegetation dryness index (TVDI) was used to monitor the winter wheat drought conditions from March to May of 2005 in the middle-south part of Hebei Province, China. The results showed that SAVI was better than NDVI for representing the winter wheat growth condition in spring. The correlation of soil moisture with TVDI based on SAVI was greater than that of based on NDVI. The analysis of TVDI and soil moisture data from weather stations' measurement demonstrated that a better correlation existed between TVDI and relative humidity of soil at 10cm and 20cm. TVDI therefore can be used as a good indicator for operational drought monitoring.
{"title":"Study on winter wheat drought monitoring by TVDI in Hebei Province","authors":"Chunqiang Li, Hongjun Li","doi":"10.1117/12.678450","DOIUrl":"https://doi.org/10.1117/12.678450","url":null,"abstract":"Droughts hazard that occurrs frequently in nature and has a great impact on agriculture. Timely monitoring and assessment of drought conditions are critical to mitigate its effects. By using NOAA/AVHRR satellite data, in current study, we derived the normalized difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI) and land surface temperature (LST), and analyzed the spatial characteristics of vegetation indexes and land surface temperature. The temperature vegetation dryness index (TVDI) was used to monitor the winter wheat drought conditions from March to May of 2005 in the middle-south part of Hebei Province, China. The results showed that SAVI was better than NDVI for representing the winter wheat growth condition in spring. The correlation of soil moisture with TVDI based on SAVI was greater than that of based on NDVI. The analysis of TVDI and soil moisture data from weather stations' measurement demonstrated that a better correlation existed between TVDI and relative humidity of soil at 10cm and 20cm. TVDI therefore can be used as a good indicator for operational drought monitoring.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114620693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Meiting Hou, R. Mao, Suying Chen, Hongjun Li, Bo‐Lin Wang
Multitemporal remotely sensed data provide an accurate, economical means to analyze the changes in land cover over time. Land cover change in the region of Baiyang Lake that is the biggest freshwater lake in North China effects local eco-environment intensely. Based on the Landsat (TM) data for 1987, 1991, 1996, and 2002, and employing the maximum-likelihood method, the land cover was classified into seven types, farmland, forest land, urban land, village, water body, wetland and bare land. The overall classification accuracies averaged 86% and the Kappa coefficient is 0.75. Then the transition matrix of The LCC was obtained by overlaying land post-classification map. Between 1987 and 2002 the amount of farmland decreased from 63.9% to 58% of the total land area, wetland decreased from 4.5% to 3.3%, while forest land increased from 2.6% to 3.3%, urban land increased from 1.2% to 2.6%, village increased from 26.1% to 29.1%, water body increased from 1.3% to 3.3%, the amount of bare land was unchanged. Land cover change can not take place independently but has certain linkages with the socioeconomic factors and mutations in natural conditions. Precipitation controlled the area of water and wetland, and human practice process restricted conversions of farmland, urban land, village and forest land.
{"title":"The analysis of land cover change in the Baiyang Lake region by multitemporal Landsat remote sensing data","authors":"Meiting Hou, R. Mao, Suying Chen, Hongjun Li, Bo‐Lin Wang","doi":"10.1117/12.680435","DOIUrl":"https://doi.org/10.1117/12.680435","url":null,"abstract":"Multitemporal remotely sensed data provide an accurate, economical means to analyze the changes in land cover over time. Land cover change in the region of Baiyang Lake that is the biggest freshwater lake in North China effects local eco-environment intensely. Based on the Landsat (TM) data for 1987, 1991, 1996, and 2002, and employing the maximum-likelihood method, the land cover was classified into seven types, farmland, forest land, urban land, village, water body, wetland and bare land. The overall classification accuracies averaged 86% and the Kappa coefficient is 0.75. Then the transition matrix of The LCC was obtained by overlaying land post-classification map. Between 1987 and 2002 the amount of farmland decreased from 63.9% to 58% of the total land area, wetland decreased from 4.5% to 3.3%, while forest land increased from 2.6% to 3.3%, urban land increased from 1.2% to 2.6%, village increased from 26.1% to 29.1%, water body increased from 1.3% to 3.3%, the amount of bare land was unchanged. Land cover change can not take place independently but has certain linkages with the socioeconomic factors and mutations in natural conditions. Precipitation controlled the area of water and wetland, and human practice process restricted conversions of farmland, urban land, village and forest land.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123938351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Visible and Infrared Scanner (VIRS) aboard the Tropical Rainfall Measuring Mission (TRMM), launched on 28 November 1997, has two reflected solar bands and three thermal infrared bands. The solar bands are calibrated using an onboard solar diffuser (SD) and the thermal bands are calibrated using an onboard blackbody (BB). Since launch, VIRS has provided more than eight years of on-orbit observations. The five VIRS bands have a close spectral match with corresponding Moderate Resolution Imaging Spectroradiometer (MODIS) bands. MODIS was launched on 18 December 1999 and 4 May 2002 aboard the NASA EOS Terra and Aqua spacecrafts, respectively. In this study, six years of VIRS and MODIS overlapping data are used to examine VIRS long-term calibration stability and consistency. This is particularly useful for the VIRS solar band calibration due to a lack of capability to track the on-orbit SD degradation. To reduce impacts due to scene variations, measurements from simultaneous nadir overpasses (SNOs) for VIRS and MODIS are co-located and aggregated to 30-by-30km areas for inter-comparison. Results show that the VIRS thermal bands maintain a stable calibration. For the two VIRS solar bands at 0.62μm and 1.62μm, the calibrated reflectance values gradually drift higher over the six-year period. The 0.62μm band increases at a rate of 1.1%/yr over the period, compared to an increase of 0.4%/yr for the 1.62μm band.
{"title":"Tracking VIRS/TRMM on-orbit calibration with MODIS","authors":"A. Wu, C. Lyu, X. Xiong, W. Barnes","doi":"10.1117/12.681138","DOIUrl":"https://doi.org/10.1117/12.681138","url":null,"abstract":"The Visible and Infrared Scanner (VIRS) aboard the Tropical Rainfall Measuring Mission (TRMM), launched on 28 November 1997, has two reflected solar bands and three thermal infrared bands. The solar bands are calibrated using an onboard solar diffuser (SD) and the thermal bands are calibrated using an onboard blackbody (BB). Since launch, VIRS has provided more than eight years of on-orbit observations. The five VIRS bands have a close spectral match with corresponding Moderate Resolution Imaging Spectroradiometer (MODIS) bands. MODIS was launched on 18 December 1999 and 4 May 2002 aboard the NASA EOS Terra and Aqua spacecrafts, respectively. In this study, six years of VIRS and MODIS overlapping data are used to examine VIRS long-term calibration stability and consistency. This is particularly useful for the VIRS solar band calibration due to a lack of capability to track the on-orbit SD degradation. To reduce impacts due to scene variations, measurements from simultaneous nadir overpasses (SNOs) for VIRS and MODIS are co-located and aggregated to 30-by-30km areas for inter-comparison. Results show that the VIRS thermal bands maintain a stable calibration. For the two VIRS solar bands at 0.62μm and 1.62μm, the calibrated reflectance values gradually drift higher over the six-year period. The 0.62μm band increases at a rate of 1.1%/yr over the period, compared to an increase of 0.4%/yr for the 1.62μm band.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130045224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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