Derek N. Fuller, J. P. Rickgauer, S. Grimes, P. Jardine, D. Anderson, Douglas E. Smith
The bacteriophage φ29 portal motor is capable of packaging the φ29, 19.3 Kbp, genome to high density into its preformed capsid. The packaging process must overcome the forces due to confining the highly negative charge of the DNA to a small volume, as well as the forces due to bending the DNA on length scales smaller than one persistence length. Both of these energetic considerations can be modulated by the ionic nature of the buffer DNA packaging occurs in. To measure the effects of DNA charge shielding on the packaging process, we studied the dynamics of DNA packaging by optical tweezers in a variety of different ionic conditions. We looked at the effects monovalent, divalent, and trivalent cations have on the motor function and its dependence on external force and, we observed the rate of DNA packaging at nominal force as a function of capsid filling. Specifically, we varied the concentrations of Na+, Mg+2, and cobalt hexamine in the solution bathing the bacteriophage during packaging to see what effects, if any, these cations have. From these measurements, we present an inferred internal force as a function of percent filling of the bacteriophage capsid in a variety of ionic environments. Preliminary analysis suggests the ionic environment can modulate internal pressure, with the presence of higher valence cations better shielding the packaged DNA resulting in lower internal pressures.
{"title":"Dependence of bacteriophage φ29 DNA packaging on ionic conditions studied by optical tweezers manipulation of single DNA molecules","authors":"Derek N. Fuller, J. P. Rickgauer, S. Grimes, P. Jardine, D. Anderson, Douglas E. Smith","doi":"10.1117/12.682097","DOIUrl":"https://doi.org/10.1117/12.682097","url":null,"abstract":"The bacteriophage φ29 portal motor is capable of packaging the φ29, 19.3 Kbp, genome to high density into its preformed capsid. The packaging process must overcome the forces due to confining the highly negative charge of the DNA to a small volume, as well as the forces due to bending the DNA on length scales smaller than one persistence length. Both of these energetic considerations can be modulated by the ionic nature of the buffer DNA packaging occurs in. To measure the effects of DNA charge shielding on the packaging process, we studied the dynamics of DNA packaging by optical tweezers in a variety of different ionic conditions. We looked at the effects monovalent, divalent, and trivalent cations have on the motor function and its dependence on external force and, we observed the rate of DNA packaging at nominal force as a function of capsid filling. Specifically, we varied the concentrations of Na+, Mg+2, and cobalt hexamine in the solution bathing the bacteriophage during packaging to see what effects, if any, these cations have. From these measurements, we present an inferred internal force as a function of percent filling of the bacteriophage capsid in a variety of ionic environments. Preliminary analysis suggests the ionic environment can modulate internal pressure, with the presence of higher valence cations better shielding the packaged DNA resulting in lower internal pressures.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116407946","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}
We present results from a p-n junction device physics model for GaInP/GaAs/GaInAsP/GaInAs four junction solar cells. The model employs subcells whose thicknesses have an upper bound of 5μm and lower bound of 200nm, which is just above the fully depleted case for the assumed doping of NA = 1 x 1018 cm-3 and ND = 1 x 1017 cm-3. The physical characteristics of the cell model include: free carrier absorption, temperature and doping effects on carrier mobility, as well as recombination via Shockley-Read-Hall recombination from a single midgap trap level and surface recombination. Upper bounds on cell efficiency set by detailed balance calculations can be approached by letting the parameters approach ideal conditions. However whereas detailed balance calculations always benefit from added subcells, the current matching requirements for series connected p-n multi-junctions indicate a minimum necessary performance from an added subcell to yield a net increase in overall device efficiency. For the four junction cell considered here, optimizing the subcell thickness is an important part of optimizing the efficiency. Series resistance limitations for concentrator applications can be systematically explored for a given set of subcells. The current matching limitation imposed by series connection reduces efficiency relative to independently-connected cells. The overall trend indicates an approximately 5% drop in efficiency for series connected cells relative to identical independently connected cells. The series-connected devices exhibit a high sensitivity to spectral changes and individual subcell performance. If any single subcell within the series-connected device is degraded relative to its optimal design, the entire device is severely hindered. This model allows complex heterostructure solar cell structures to be evaluated by providing device physics-based predictions of performance limitations.
{"title":"p-n junction heterostructure device physics model of a four junction solar cell","authors":"Melissa J. Griggs, B. Kayes, H. Atwater","doi":"10.1117/12.680793","DOIUrl":"https://doi.org/10.1117/12.680793","url":null,"abstract":"We present results from a p-n junction device physics model for GaInP/GaAs/GaInAsP/GaInAs four junction solar cells. The model employs subcells whose thicknesses have an upper bound of 5μm and lower bound of 200nm, which is just above the fully depleted case for the assumed doping of NA = 1 x 1018 cm-3 and ND = 1 x 1017 cm-3. The physical characteristics of the cell model include: free carrier absorption, temperature and doping effects on carrier mobility, as well as recombination via Shockley-Read-Hall recombination from a single midgap trap level and surface recombination. Upper bounds on cell efficiency set by detailed balance calculations can be approached by letting the parameters approach ideal conditions. However whereas detailed balance calculations always benefit from added subcells, the current matching requirements for series connected p-n multi-junctions indicate a minimum necessary performance from an added subcell to yield a net increase in overall device efficiency. For the four junction cell considered here, optimizing the subcell thickness is an important part of optimizing the efficiency. Series resistance limitations for concentrator applications can be systematically explored for a given set of subcells. The current matching limitation imposed by series connection reduces efficiency relative to independently-connected cells. The overall trend indicates an approximately 5% drop in efficiency for series connected cells relative to identical independently connected cells. The series-connected devices exhibit a high sensitivity to spectral changes and individual subcell performance. If any single subcell within the series-connected device is degraded relative to its optimal design, the entire device is severely hindered. This model allows complex heterostructure solar cell structures to be evaluated by providing device physics-based predictions of performance limitations.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126582659","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}
Keith E. Gregorczyk, B. Kimball, J. Carlson, A. Pembroke, K. Kempa, Z. Ren, C. Yelleswarapu, T. Kempa, G. Benham, Y. Wang, Wenzhi Li, A. Herczynski, J. Rybczynski, D. Rao
The optical properties of periodic and nonperiodic arrays of aligned multiwalled carbon nanotubes are presented. Experimental analysis indicates a complex optical response that is attributed to both the individual carbon nanotube scatterers and also to the array ensembles. These studies indicate that by controlling the geometry and spacing of the arrays, it is possible to create structures that respond very strongly to specific wavelengths or bands of wavelengths. Structures such as these may form the basis for numerous applications in energy conversion. This would include highly efficient solar energy conversion as well as sensitive, finely tuned detectors that can respond to predetermined wavelength bands ranging from the ultraviolet to the infrared region. Experimental, theoretical and modeled results are discussed as they apply to these applications. Challenges and issues are discussed.
{"title":"The complex optical response of arrays of aligned multiwalled carbon nanotubes","authors":"Keith E. Gregorczyk, B. Kimball, J. Carlson, A. Pembroke, K. Kempa, Z. Ren, C. Yelleswarapu, T. Kempa, G. Benham, Y. Wang, Wenzhi Li, A. Herczynski, J. Rybczynski, D. Rao","doi":"10.1117/12.680765","DOIUrl":"https://doi.org/10.1117/12.680765","url":null,"abstract":"The optical properties of periodic and nonperiodic arrays of aligned multiwalled carbon nanotubes are presented. Experimental analysis indicates a complex optical response that is attributed to both the individual carbon nanotube scatterers and also to the array ensembles. These studies indicate that by controlling the geometry and spacing of the arrays, it is possible to create structures that respond very strongly to specific wavelengths or bands of wavelengths. Structures such as these may form the basis for numerous applications in energy conversion. This would include highly efficient solar energy conversion as well as sensitive, finely tuned detectors that can respond to predetermined wavelength bands ranging from the ultraviolet to the infrared region. Experimental, theoretical and modeled results are discussed as they apply to these applications. Challenges and issues are discussed.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122188045","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}
Suying Chen, Xiying Zhang, Silong Chen, Pei Dong, Hongyong Sun
Minimizing soil evaporation is a key element in improving water use efficiency in dry areas. Experiments were conducted in the winter wheat field during 2004-2005 to compare effects of different row spacing on soil evaporation. A model to estimate soil evaporation was developed based on the experimental data. The reference crop evapotranspiration (ET0) was estimated by the Penman-Montieth equation, and the factors affecting evaporation under crop canopy were divided into both the radiation item (ETs1) and the aerodynamics item (ETs2) according to the degree of crop canopy coverage (fc). The simulation equation for actual evaporation, combining with soil moisture parameter, was established in this paper. In this study, a light meter was utilized to measure fc, which replaced leaf are index (LAI) in evaporation estimation. In comparison with the measured evaporation by micro-lysimeters (ML) in four row spacing: 7.5 cm, 15 cm, 22.5 cm and 30 cm, tested in a randomized block design, the simulated daily evaporation had root mean square errors (RMSE) of 0.22 mm, 0.24 mm, 0.25 mm 0.26 mm and a bias of 0.01 mm, 0.02 mm, -0.08 mm, -0.03 mm respectively. Results showed that using canopy coverage factor to replace leaf area index could effectively estimate soil evaporation.
{"title":"Simulation of soil evaporation under different ground coverage with semi-empirical models","authors":"Suying Chen, Xiying Zhang, Silong Chen, Pei Dong, Hongyong Sun","doi":"10.1117/12.682846","DOIUrl":"https://doi.org/10.1117/12.682846","url":null,"abstract":"Minimizing soil evaporation is a key element in improving water use efficiency in dry areas. Experiments were conducted in the winter wheat field during 2004-2005 to compare effects of different row spacing on soil evaporation. A model to estimate soil evaporation was developed based on the experimental data. The reference crop evapotranspiration (ET0) was estimated by the Penman-Montieth equation, and the factors affecting evaporation under crop canopy were divided into both the radiation item (ETs1) and the aerodynamics item (ETs2) according to the degree of crop canopy coverage (fc). The simulation equation for actual evaporation, combining with soil moisture parameter, was established in this paper. In this study, a light meter was utilized to measure fc, which replaced leaf are index (LAI) in evaporation estimation. In comparison with the measured evaporation by micro-lysimeters (ML) in four row spacing: 7.5 cm, 15 cm, 22.5 cm and 30 cm, tested in a randomized block design, the simulated daily evaporation had root mean square errors (RMSE) of 0.22 mm, 0.24 mm, 0.25 mm 0.26 mm and a bias of 0.01 mm, 0.02 mm, -0.08 mm, -0.03 mm respectively. Results showed that using canopy coverage factor to replace leaf area index could effectively estimate soil evaporation.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"67 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":"133775500","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}
Research has shown that remote sensing in both the optical and microwave domain has the capability of estimating vegetation water content (VWC). Though lower in spatial resolution than MODIS optical bands, AMSR-E microwave measurements are typically less affected by clouds, water vapor, aerosol or solar illumination, making them complementary to MODIS real time measurements over regions of clouds and haze. In this study we explored a wavelet based approach for combining vegetation water content observations derived from higher spatial resolution MODIS and lower spatial resolution AMSR-E microwave measurements. Regression analysis between AMSR-E VWC and spatially aggregated MODIS NDII (Normalized Difference Infrared Index) was first used to scale MODIS NDII to MODIS VWC products. Our approach for combining information from the two sensors resorts to multiresolution wavelet decomposition of MODIS VWC into a set of detail images and a single approximation image at AMSR-E resolution. The substitution method of image fusion is then undertaken, in which the approximation image is replaced by AMSR-E VWC image, prior to using inverse wavelet transform to construct a merged VWC product. The merged VWC product thus has information from both MODIS and AMSR-E measurements. The technique is applied over low vegetation regions in Texas grasslands to obtain merged VWC products at intermediate resolutions of ~1.5km. Apart from offering a way to calibrate MODIS VWC content products to AMSR-E observations, the technique has the potential for downscaling AMSR-E VWC to higher spatial resolution over moderately cloudy or hazy regions where MODIS reflective bands become contaminated by the atmosphere. During such situations when contaminated MODIS signals cannot be used to obtain the wavelet detail images, MODIS detail images from a preceding time step is used to downscale the current AMSR-E VWC to higher resolutions. This approach of using detail images from the recent past would be justified if the detail images containing the high frequency components of the image change slowly. Correlation analysis of detail images from consecutive time steps shows that this is approximately true, at-least for the low spatial resolution detail images. Our approach yields accuracy of around 77% on the average over the selected study region and temporal period. This technique thus has the potential for ensuring the data continuity of high spatial resolution VWC products, a requirement essential for fire risk monitoring.
{"title":"Combining MODIS and AMSR-E-based vegetation moisture retrievals for improved fire risk monitoring","authors":"S. Dasgupta, J. Qu","doi":"10.1117/12.681147","DOIUrl":"https://doi.org/10.1117/12.681147","url":null,"abstract":"Research has shown that remote sensing in both the optical and microwave domain has the capability of estimating vegetation water content (VWC). Though lower in spatial resolution than MODIS optical bands, AMSR-E microwave measurements are typically less affected by clouds, water vapor, aerosol or solar illumination, making them complementary to MODIS real time measurements over regions of clouds and haze. In this study we explored a wavelet based approach for combining vegetation water content observations derived from higher spatial resolution MODIS and lower spatial resolution AMSR-E microwave measurements. Regression analysis between AMSR-E VWC and spatially aggregated MODIS NDII (Normalized Difference Infrared Index) was first used to scale MODIS NDII to MODIS VWC products. Our approach for combining information from the two sensors resorts to multiresolution wavelet decomposition of MODIS VWC into a set of detail images and a single approximation image at AMSR-E resolution. The substitution method of image fusion is then undertaken, in which the approximation image is replaced by AMSR-E VWC image, prior to using inverse wavelet transform to construct a merged VWC product. The merged VWC product thus has information from both MODIS and AMSR-E measurements. The technique is applied over low vegetation regions in Texas grasslands to obtain merged VWC products at intermediate resolutions of ~1.5km. Apart from offering a way to calibrate MODIS VWC content products to AMSR-E observations, the technique has the potential for downscaling AMSR-E VWC to higher spatial resolution over moderately cloudy or hazy regions where MODIS reflective bands become contaminated by the atmosphere. During such situations when contaminated MODIS signals cannot be used to obtain the wavelet detail images, MODIS detail images from a preceding time step is used to downscale the current AMSR-E VWC to higher resolutions. This approach of using detail images from the recent past would be justified if the detail images containing the high frequency components of the image change slowly. Correlation analysis of detail images from consecutive time steps shows that this is approximately true, at-least for the low spatial resolution detail images. Our approach yields accuracy of around 77% on the average over the selected study region and temporal period. This technique thus has the potential for ensuring the data continuity of high spatial resolution VWC products, a requirement essential for fire risk monitoring.","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":"115773739","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}
Much attention has been paid to terrain effects on planetary scale. Few works have addressed these impacts at finer scales. In this study, the terrain effect on a backflow weather occurred over North China during December 22 to 23, 2002 was investigated using the Pennsylvania State University-NCAR Fifth-Generation Mesoscale Model (MM5), version 3. Numerical simulation results show that the mountains in the western North China play a very important role in the backflow precipitation. The cold air from North East Plain was obstructed by the Taihang Mountain. The flat topography of the plain reduced the thickness of the cold air, its vertical velocity, and the intenseness of the precipitation. The results indicate that the cold air was accumulated in the windward of the mountain. This accumulation resulted in increased thickness of the cold air. Humid air could climb up to the top and amplify the precipitation.
{"title":"Numerical simulation of terrain effects in a backflow event that occurred over North China","authors":"Shoubao Zhang, P. Guo, Yingxin Zhang","doi":"10.1117/12.674004","DOIUrl":"https://doi.org/10.1117/12.674004","url":null,"abstract":"Much attention has been paid to terrain effects on planetary scale. Few works have addressed these impacts at finer scales. In this study, the terrain effect on a backflow weather occurred over North China during December 22 to 23, 2002 was investigated using the Pennsylvania State University-NCAR Fifth-Generation Mesoscale Model (MM5), version 3. Numerical simulation results show that the mountains in the western North China play a very important role in the backflow precipitation. The cold air from North East Plain was obstructed by the Taihang Mountain. The flat topography of the plain reduced the thickness of the cold air, its vertical velocity, and the intenseness of the precipitation. The results indicate that the cold air was accumulated in the windward of the mountain. This accumulation resulted in increased thickness of the cold air. Humid air could climb up to the top and amplify the precipitation.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"108 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":"124144433","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}
With the rapid socio-conomic development and urbanization acceleration, obvious changes of land use have happened every year in Chongqing. The concerns on the land use dynamic monitoring and assessment by policy makers are rising. The overall objectives of this study are to monitor and examine the major determinants of land use changes of core urban districts in Chongqing. Based on the land use survey information derived from airscapes in 2005, as well as that in 1996 and the land use update data from 1997 to 2004, the land use dynamic database of core urban districts in Chongqing is built, then the land use dynamic analysis is carried out. It shows that the built up area has risen 27.6 percent and cultivated land has decreased 27.5 percent from 1996 to 2005. In this study, a system of econometric model on the changes of built up area and cultivated land has been developed, it was empirically estimated based on remote sensing data of land use and a unique set of data collected by authors on economic development and policies that have driven land use pattern changes of core urban districts in Chongqing. The results of this study indicate that economy growth, urbanization acceleration, the regional development and functional zone policy are key factors that have been driving land use changes of core urban districts in Chongqing. The paper concludes with a set of policy recommendations on harmonizing Chongqing's urban development and cultivated land protection.
{"title":"Land use dynamic monitoring and assessment of core urban districts in Chongqing","authors":"Lifen Zhu, Yongzhong Tian","doi":"10.1117/12.681558","DOIUrl":"https://doi.org/10.1117/12.681558","url":null,"abstract":"With the rapid socio-conomic development and urbanization acceleration, obvious changes of land use have happened every year in Chongqing. The concerns on the land use dynamic monitoring and assessment by policy makers are rising. The overall objectives of this study are to monitor and examine the major determinants of land use changes of core urban districts in Chongqing. Based on the land use survey information derived from airscapes in 2005, as well as that in 1996 and the land use update data from 1997 to 2004, the land use dynamic database of core urban districts in Chongqing is built, then the land use dynamic analysis is carried out. It shows that the built up area has risen 27.6 percent and cultivated land has decreased 27.5 percent from 1996 to 2005. In this study, a system of econometric model on the changes of built up area and cultivated land has been developed, it was empirically estimated based on remote sensing data of land use and a unique set of data collected by authors on economic development and policies that have driven land use pattern changes of core urban districts in Chongqing. The results of this study indicate that economy growth, urbanization acceleration, the regional development and functional zone policy are key factors that have been driving land use changes of core urban districts in Chongqing. The paper concludes with a set of policy recommendations on harmonizing Chongqing's urban development and cultivated land protection.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"96 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":"117315653","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}
Hirokazu Yamamoto, H. Yoshioka, H. Murakami, A. Ono, Y. Honda
Japan Aerospace Exploration Agency (former NASDA) has successfully launched a new Advanced Earth Orbiting Satellite (ADEOS-II) aboard an H-2A booster on December 14, 2002. ADEOS-II is designed to monitor global climactic change through researches of the Earth's environment. GLI, which is one of five sensors, has high potential for vegetation monitoring, and it will contribute to the future satellite sensor. GLI has 23 channels in VNIR which include 380nm channel, 6 channels in SWIR, and 7 channels in MTIR. And this sensor has two kinds of spatial resolution, which are 1km and 250m. GLI 380nm channel is very unique channel, which can be sensitive for aerosol over land. GLI land higher level processing includes precise geometric correction, 16-day composite, atmospheric correction, and vegetation index (NDVI and EVI). However, GLI atmospheric correction for land is conducted for only Rayleigh scattering and Ozone absorption. Therefore, this atmospherically corrected NDVI is affected by aerosol over land. On the other hand, 380nm data has the capability of removal of aerosol over the land. The difference between TOA NDVI and the new NDVI subtracted 380nm can be a function of optical thickness of aerosol. This paper shows that the evaluation of aerosol correction over the land by using GLI 380nm reflectance.
{"title":"The possibility of aerosol correction over land using ADEOS-II GLI 380nm reflectance","authors":"Hirokazu Yamamoto, H. Yoshioka, H. Murakami, A. Ono, Y. Honda","doi":"10.1117/12.680368","DOIUrl":"https://doi.org/10.1117/12.680368","url":null,"abstract":"Japan Aerospace Exploration Agency (former NASDA) has successfully launched a new Advanced Earth Orbiting Satellite (ADEOS-II) aboard an H-2A booster on December 14, 2002. ADEOS-II is designed to monitor global climactic change through researches of the Earth's environment. GLI, which is one of five sensors, has high potential for vegetation monitoring, and it will contribute to the future satellite sensor. GLI has 23 channels in VNIR which include 380nm channel, 6 channels in SWIR, and 7 channels in MTIR. And this sensor has two kinds of spatial resolution, which are 1km and 250m. GLI 380nm channel is very unique channel, which can be sensitive for aerosol over land. GLI land higher level processing includes precise geometric correction, 16-day composite, atmospheric correction, and vegetation index (NDVI and EVI). However, GLI atmospheric correction for land is conducted for only Rayleigh scattering and Ozone absorption. Therefore, this atmospherically corrected NDVI is affected by aerosol over land. On the other hand, 380nm data has the capability of removal of aerosol over the land. The difference between TOA NDVI and the new NDVI subtracted 380nm can be a function of optical thickness of aerosol. This paper shows that the evaluation of aerosol correction over the land by using GLI 380nm reflectance.","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":"129283463","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}
Lingli Wang, J. Qu, J. Xiong, X. Hao, Yong Xie, N. Che
Snow cover is one of the sensitive indicators of global climate change. Numerous studies have shown the importance of accurate measurements of snow cover. The Moderate Resolution Imaging Spectroradiometer (MODIS) is well suited to the measurement of snow cover because snow characteristically has high reflectance in the MODIS Visible (VIS) and low reflectance in the MODIS Shortwave Infrared (SWIR) wavelengths, a characteristic that allows for snow detection by a normalized ratio of VIS and SWIR bands. The automated MODIS snow-mapping algorithm uses at-satellite reflectance in MODIS VIS band 4 (0.545-0.565 μm) and SWIR band 6 (1.628-1.652 μm) to calculate the Normalized Difference Snow Index (NDSI). Aqua MODIS band 7 (2.105-2.155 μm) instead of band 6 has been used to calculate NDSI, in response to band 6 striping problem caused by non-functional or noisy detectors. In our early study, a feasible algorithm to map Aqua MODIS band 6 based on the relationship between Terra MODIS bands 6 and 7 has been developed and validated. This algorithm has been used to retrieve Aqua MODIS band 6. Aqua MODIS NDSI values computed from Aqua MODIS observed band 6, simulated band 6, and observed band 7 are used to map snow based on current MODIS snow algorithm, respectively. Snow coverage mapped using NDSI computed from observed band 6 is regarded as a standard snow product, comparison and analysis are performed between snow mapping using NDSI computed from simulated band 6 and observed band 7. This paper will investigate the measurement continuity between Terra and Aqua MODIS snow coverage products, and propose another alternative for Aqua MODIS NDSI retrieval. Our approach for monitoring snow coverage is valuable to keep the continuity and consistency for MODIS snow products.
积雪是全球气候变化的敏感指标之一。许多研究表明，精确测量积雪的重要性。中分辨率成像光谱仪(MODIS)非常适合测量积雪，因为雪在MODIS可见光波段(VIS)具有高反射率，而在MODIS短波红外波段(SWIR)具有低反射率，这一特性允许通过VIS和SWIR波段的归一化比例进行雪探测。自动MODIS积雪制图算法利用MODIS VIS波段4 (0.545 ~ 0.565 μm)和SWIR波段6 (1.628 ~ 1.652 μm)的卫星反射率计算归一化差雪指数(NDSI)。Aqua MODIS波段7 (2.105-2.155 μm)代替波段6用于计算NDSI，以响应由非功能或噪声探测器引起的波段6条带问题。在前期研究中，我们基于Terra MODIS 6和7波段之间的关系，开发并验证了一种可行的Aqua MODIS 6波段映射算法。该算法已用于Aqua MODIS波段6的检索。利用Aqua MODIS第6观测带、第6模拟带和第7观测带计算的NDSI值分别基于当前MODIS积雪算法进行积雪制图。将利用观测波段6计算NDSI绘制的积雪覆盖度作为标准积雪产品，将模拟波段6计算NDSI绘制的积雪覆盖度与观测波段7进行对比分析。本文将研究Terra和Aqua MODIS积雪覆盖产品之间的测量连续性，并提出Aqua MODIS NDSI反演的另一种替代方案。我们的积雪覆盖监测方法对保持MODIS积雪产品的连续性和一致性具有重要价值。
{"title":"A preliminary study of Aqua/MODIS snow coverage continuity with simulated band 6","authors":"Lingli Wang, J. Qu, J. Xiong, X. Hao, Yong Xie, N. Che","doi":"10.1117/12.680953","DOIUrl":"https://doi.org/10.1117/12.680953","url":null,"abstract":"Snow cover is one of the sensitive indicators of global climate change. Numerous studies have shown the importance of accurate measurements of snow cover. The Moderate Resolution Imaging Spectroradiometer (MODIS) is well suited to the measurement of snow cover because snow characteristically has high reflectance in the MODIS Visible (VIS) and low reflectance in the MODIS Shortwave Infrared (SWIR) wavelengths, a characteristic that allows for snow detection by a normalized ratio of VIS and SWIR bands. The automated MODIS snow-mapping algorithm uses at-satellite reflectance in MODIS VIS band 4 (0.545-0.565 μm) and SWIR band 6 (1.628-1.652 μm) to calculate the Normalized Difference Snow Index (NDSI). Aqua MODIS band 7 (2.105-2.155 μm) instead of band 6 has been used to calculate NDSI, in response to band 6 striping problem caused by non-functional or noisy detectors. In our early study, a feasible algorithm to map Aqua MODIS band 6 based on the relationship between Terra MODIS bands 6 and 7 has been developed and validated. This algorithm has been used to retrieve Aqua MODIS band 6. Aqua MODIS NDSI values computed from Aqua MODIS observed band 6, simulated band 6, and observed band 7 are used to map snow based on current MODIS snow algorithm, respectively. Snow coverage mapped using NDSI computed from observed band 6 is regarded as a standard snow product, comparison and analysis are performed between snow mapping using NDSI computed from simulated band 6 and observed band 7. This paper will investigate the measurement continuity between Terra and Aqua MODIS snow coverage products, and propose another alternative for Aqua MODIS NDSI retrieval. Our approach for monitoring snow coverage is valuable to keep the continuity and consistency for MODIS snow products.","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":"134427855","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. Yimit, M. Ayup, G. Wang, Hongyan Luo, Dilber Ebeidulla
Populus euphratica (P. euphratica), at Tarim Nature Reserve, growing in their natural habitat represents a valuable resource for elucidating mechanism of acclimation to environmental constraints. P. euphratica is a salt-tolerant tree species growing in saline semi-arid areas. It is one of the stress-tolerance and desert-grown species. Therefore, the P. euphratica has been treated as main protecting object and the Tarim Nature Reserve is one of two P. euphratica Reserves in China. The nature reserve is located in the middle reach of the Tarim River, Xinjiang. It is not only the world's largest intact and unfrequented area of Populus euphratica forests, but also plays great significant role in maintaining the ecological balance of the Tarim Basin. However, the Populus euphratica Nature Reserve's eco-environment is getting more and more degenerated due to the human activities in recent years. This paper analyzed the ecological frangible factors and their influence mechanisms on the nature reserve eco-system stability using 3S technologies. The results showed the eco-environmental condition of P. euphratica is fragile and the ability of insisting on the artificial influence is weak because of the harsh climate, topographical conditions, and human irrational water use and land resources. The shortage and exhaustion of surface water, as well as descending of groundwater depth, make Populus euphratica forests deteriorating. The protecting strategies are suggested in this paper according to the research analyses.
{"title":"P. euphratica ecosystem fragility and protecting strategy on Tarim P. euphratica Nature Reserve in Xinjiang","authors":"H. Yimit, M. Ayup, G. Wang, Hongyan Luo, Dilber Ebeidulla","doi":"10.1117/12.684944","DOIUrl":"https://doi.org/10.1117/12.684944","url":null,"abstract":"Populus euphratica (P. euphratica), at Tarim Nature Reserve, growing in their natural habitat represents a valuable resource for elucidating mechanism of acclimation to environmental constraints. P. euphratica is a salt-tolerant tree species growing in saline semi-arid areas. It is one of the stress-tolerance and desert-grown species. Therefore, the P. euphratica has been treated as main protecting object and the Tarim Nature Reserve is one of two P. euphratica Reserves in China. The nature reserve is located in the middle reach of the Tarim River, Xinjiang. It is not only the world's largest intact and unfrequented area of Populus euphratica forests, but also plays great significant role in maintaining the ecological balance of the Tarim Basin. However, the Populus euphratica Nature Reserve's eco-environment is getting more and more degenerated due to the human activities in recent years. This paper analyzed the ecological frangible factors and their influence mechanisms on the nature reserve eco-system stability using 3S technologies. The results showed the eco-environmental condition of P. euphratica is fragile and the ability of insisting on the artificial influence is weak because of the harsh climate, topographical conditions, and human irrational water use and land resources. The shortage and exhaustion of surface water, as well as descending of groundwater depth, make Populus euphratica forests deteriorating. The protecting strategies are suggested in this paper according to the research analyses.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"38 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":"122705680","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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