A spatial heterodyne Raman spectrometer (SHRS) is a variant of a Michelson interferometer where the mirrors in a Michelson are replaced with stationary diffraction gratings. Instead of generating an interferogram in the time domain, as in the case of a Michelson interferometer, the SHRS interferogram is generated in the spatial domain as a superposition of two-dimensional cosinusoidal spatial fringes. The spatial interferogram is recorded by an intensified charge-coupled device (ICCD) camera, and the Raman spectrum is recovered by taking the Fourier transform of the spatial interferogram. In the modified SHRS utilized in the present work, a λ/10 mirror has replaced one of the diffraction gratings. This alteration has a few effects. First, the ICCD records a greater number of photons because photons are not lost into unused diffraction orders. Second, the spectral bandpass of the modified SHRS has been doubled allowing the measurement of Raman spectra from 100-4000 cm-1. In this work, the authors present Raman spectra of organic compounds taken at remote distances of 19 meters with this modified SHRS.
{"title":"Modified spatial heterodyne Raman spectrometer for remote-sensing analysis of organics","authors":"M. Egan, Shiv k. Sharma, T. Acosta-Maeda","doi":"10.1117/12.2324834","DOIUrl":"https://doi.org/10.1117/12.2324834","url":null,"abstract":"A spatial heterodyne Raman spectrometer (SHRS) is a variant of a Michelson interferometer where the mirrors in a Michelson are replaced with stationary diffraction gratings. Instead of generating an interferogram in the time domain, as in the case of a Michelson interferometer, the SHRS interferogram is generated in the spatial domain as a superposition of two-dimensional cosinusoidal spatial fringes. The spatial interferogram is recorded by an intensified charge-coupled device (ICCD) camera, and the Raman spectrum is recovered by taking the Fourier transform of the spatial interferogram. In the modified SHRS utilized in the present work, a λ/10 mirror has replaced one of the diffraction gratings. This alteration has a few effects. First, the ICCD records a greater number of photons because photons are not lost into unused diffraction orders. Second, the spectral bandpass of the modified SHRS has been doubled allowing the measurement of Raman spectra from 100-4000 cm-1. In this work, the authors present Raman spectra of organic compounds taken at remote distances of 19 meters with this modified SHRS.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125253204","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}
T. Refaat, M. Petros, U. Singh, C. Antill, Teh-Hwa Wong, R. Remus, K. Reithmaier, Jane Lee, S. Bowen, B. Taylor, Angela M. Welters, Anna Noe, S. Ismail
Atmospheric water vapor and carbon dioxide are important greenhouse gases that significantly contribute to the global radiation budget on Earth. A 2-micron triple-pulse, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric carbon dioxide and water vapor concentration measurements using direct detection was developed at NASA Langley Research Center. This active remote sensing instrument provides an alternate approach with significant advantages for measuring atmospheric concentrations of the gases. A high energy pulsed laser transmitter approach coupled with sensitive receiver detection provides a high-precision measurement capability by having a high signal-to-noise ratio. This paper presents the concept, development, integration and testing of the 2-micron triple-pulse IPDA. The integration includes the various IPDA transmitter, receiver and data acquisition subsystems and components. Ground and airborne testing indicated successful operation of the IPDA lidar.
{"title":"Airborne direct-detection 2-μm triple-pulse IPDA lidar integration for simultaneous and independent atmospheric water vapor and carbon dioxide active remote sensing","authors":"T. Refaat, M. Petros, U. Singh, C. Antill, Teh-Hwa Wong, R. Remus, K. Reithmaier, Jane Lee, S. Bowen, B. Taylor, Angela M. Welters, Anna Noe, S. Ismail","doi":"10.1117/12.2324785","DOIUrl":"https://doi.org/10.1117/12.2324785","url":null,"abstract":"Atmospheric water vapor and carbon dioxide are important greenhouse gases that significantly contribute to the global radiation budget on Earth. A 2-micron triple-pulse, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric carbon dioxide and water vapor concentration measurements using direct detection was developed at NASA Langley Research Center. This active remote sensing instrument provides an alternate approach with significant advantages for measuring atmospheric concentrations of the gases. A high energy pulsed laser transmitter approach coupled with sensitive receiver detection provides a high-precision measurement capability by having a high signal-to-noise ratio. This paper presents the concept, development, integration and testing of the 2-micron triple-pulse IPDA. The integration includes the various IPDA transmitter, receiver and data acquisition subsystems and components. Ground and airborne testing indicated successful operation of the IPDA lidar.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123620027","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}
S. Papandrea, Yoshitaka Jin, E. Collini, L. Mingari, Hernan Ciminari, J. L. Bali, M. A. Salles, A. Barbero, P. Ristori, L. Otero, J. Salvador, B. Barja, T. Nishizawa, A. Shimizu, N. Sugimoto, A. Mizuno
In the southern South America, various types of aerosols have been observed including biomass burning aerosols from the Amazon region, flying ashes from the volcanic eruptions coming from the Andean Volcanic Belt, mineral dust from the Patagonian Desert, and air pollution aerosols from urban areas. To monitor such aerosols continuously, we developed a lidar observation network in Argentina and Chile. Eight lidars were installed in Argentina and one in Punta Arenas, Chile. Backscattering signals are measured at three wavelengths: 355, 532, and 1064 nm. Eight of those instruments are measuring depolarization ratio at 355 and 532 nm to detect non-spherical aerosols. In addition, four lidars are equipped Ramans channels and two high-spectral-resolution channels to measure backscattering and extinction coefficients quantitatively. Lidar operation, data analysis, and products release are implemented within the South American Environmental Risk Management Network (SAVER-Net) system, which was developed by a trinational project among Japan, Argentina, and Chile. Using lidar data, hazard information on the aerosol type and extinction coefficient at low altitude is provided for public in a near real time. In addition, plume height and qualitatively concentration for volcanic ashes are estimated. The information on volcanic ashes may be effectively used for advising aircraft landing and departing when volcanic eruptions occurs.
{"title":"Aerosol monitoring with a lidar observation network in the southern South America","authors":"S. Papandrea, Yoshitaka Jin, E. Collini, L. Mingari, Hernan Ciminari, J. L. Bali, M. A. Salles, A. Barbero, P. Ristori, L. Otero, J. Salvador, B. Barja, T. Nishizawa, A. Shimizu, N. Sugimoto, A. Mizuno","doi":"10.1117/12.2324774","DOIUrl":"https://doi.org/10.1117/12.2324774","url":null,"abstract":"In the southern South America, various types of aerosols have been observed including biomass burning aerosols from the Amazon region, flying ashes from the volcanic eruptions coming from the Andean Volcanic Belt, mineral dust from the Patagonian Desert, and air pollution aerosols from urban areas. To monitor such aerosols continuously, we developed a lidar observation network in Argentina and Chile. Eight lidars were installed in Argentina and one in Punta Arenas, Chile. Backscattering signals are measured at three wavelengths: 355, 532, and 1064 nm. Eight of those instruments are measuring depolarization ratio at 355 and 532 nm to detect non-spherical aerosols. In addition, four lidars are equipped Ramans channels and two high-spectral-resolution channels to measure backscattering and extinction coefficients quantitatively. Lidar operation, data analysis, and products release are implemented within the South American Environmental Risk Management Network (SAVER-Net) system, which was developed by a trinational project among Japan, Argentina, and Chile. Using lidar data, hazard information on the aerosol type and extinction coefficient at low altitude is provided for public in a near real time. In addition, plume height and qualitatively concentration for volcanic ashes are estimated. The information on volcanic ashes may be effectively used for advising aircraft landing and departing when volcanic eruptions occurs.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129680456","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}
Characteristics of the atmospheric low-frequency oscillation on the drought process during the flood season (May to September) in eastern part of the northwest China are analyzed using the NCEP/NCAR reanalysis data and conventional surface precipitation data. Results show the low-frequency characteristics of the southward and eastward propagation in the middle and high latitudes, and the divergence airflow over eastern part of the northwest China during the drought. Drought event occurs during propagation of the low-frequency north wind and before convergence of the north and south airflows. The drought process mainly occurs in the negative phase of relative vorticity low-frequency oscillation and in the positive phase of the OLR low-frequency oscillation, i.e., in the period of relatively weak convection. A method based on the atmospheric Low-Frequency diagnosis was used to predict the meteorological drought event in eastern part of the northwest China. The forecast results are promising on the meteorological drought event during the flood season from 2010 to 2017.
{"title":"Application of atmospheric low-frequency oscillation on meteorological drought forecast in Eastern part of the Northwest China","authors":"Jianying Feng, Yuanpu Liu, Zhilan Wang","doi":"10.1117/12.2324833","DOIUrl":"https://doi.org/10.1117/12.2324833","url":null,"abstract":"Characteristics of the atmospheric low-frequency oscillation on the drought process during the flood season (May to September) in eastern part of the northwest China are analyzed using the NCEP/NCAR reanalysis data and conventional surface precipitation data. Results show the low-frequency characteristics of the southward and eastward propagation in the middle and high latitudes, and the divergence airflow over eastern part of the northwest China during the drought. Drought event occurs during propagation of the low-frequency north wind and before convergence of the north and south airflows. The drought process mainly occurs in the negative phase of relative vorticity low-frequency oscillation and in the positive phase of the OLR low-frequency oscillation, i.e., in the period of relatively weak convection. A method based on the atmospheric Low-Frequency diagnosis was used to predict the meteorological drought event in eastern part of the northwest China. The forecast results are promising on the meteorological drought event during the flood season from 2010 to 2017.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"444 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122720906","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}
N. Guo, Yaling Lu, Yingyun Cheng, Yiping Li, S. Sha, Wang Wei, Jie Zheng
The monthly precipitation and temperature data，soil moisture data and NDVI data from 1981 to 2010 in Eastern Gansu were used to analyze the temperature, precipitation, soil moisture and drought change in this area. The results show that: 1) The climate in Eastern Gansu appeared a significant warming trend, and the temperature increase was extremely significant in spring, summer, autumn and winter. Among them, the spring temperature increase was the largest with the rate of 0.82 °C/10a. 2) The annual precipitation has experienced a process of high-low-high in the past 30 years. Among them precipitation in spring continued to decrease, while other seasons showed increase tendency in the 21st century after a decline in the last 10 years of the 20th century. 3) The soil moisture in the whole layer (10-100cm) in spring showed a significant downward trend, especially in the surface layer. During the growth season, the water storage capacity of the whole layer of soil decreased significantly. 4) The frequency and extent of drought events in Eastern Gansu experienced a change of low-high-low process. The lowest period of drought occurred in the 1980s and the highest period occurred in the 1990s. The frequency and extent in the first 10 years of this century declined. 5) The spring drought occurred most frequently and strongest intensity in the past 30a. AVI has a good consistency with CI and soil moisture on the monitoring of drought process, but the volatility is higher.
{"title":"Climate change and its impact on drought in Eastern Gansu rainfed agricultural area in Northwest China in the last thirty years","authors":"N. Guo, Yaling Lu, Yingyun Cheng, Yiping Li, S. Sha, Wang Wei, Jie Zheng","doi":"10.1117/12.2324652","DOIUrl":"https://doi.org/10.1117/12.2324652","url":null,"abstract":"The monthly precipitation and temperature data，soil moisture data and NDVI data from 1981 to 2010 in Eastern Gansu were used to analyze the temperature, precipitation, soil moisture and drought change in this area. The results show that: 1) The climate in Eastern Gansu appeared a significant warming trend, and the temperature increase was extremely significant in spring, summer, autumn and winter. Among them, the spring temperature increase was the largest with the rate of 0.82 °C/10a. 2) The annual precipitation has experienced a process of high-low-high in the past 30 years. Among them precipitation in spring continued to decrease, while other seasons showed increase tendency in the 21st century after a decline in the last 10 years of the 20th century. 3) The soil moisture in the whole layer (10-100cm) in spring showed a significant downward trend, especially in the surface layer. During the growth season, the water storage capacity of the whole layer of soil decreased significantly. 4) The frequency and extent of drought events in Eastern Gansu experienced a change of low-high-low process. The lowest period of drought occurred in the 1980s and the highest period occurred in the 1990s. The frequency and extent in the first 10 years of this century declined. 5) The spring drought occurred most frequently and strongest intensity in the past 30a. AVI has a good consistency with CI and soil moisture on the monitoring of drought process, but the volatility is higher.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125866502","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}
Photosynthesis available radiation (PAR) that makes primary producers to compose carbon compounds is the energy source of carbon circulation at the ocean. In these days, global scale PAR is efficiently observed from satellite remotesensing with low cost and high resolution. Here, Geostationary Ocean Color Imager (GOCI) which is geostationary orbit sensor is used to estimate daily PAR at smaller scale area for decreasing influence of diurnal variation such as cloud. GOCI daily PAR is estimated using PAR model based on Plane-parallel theory and compared with in-situ data observed during year of 2015 at two stations that has turbid and clear ocean area, respectively. Each band image of GOCI L1B data and solar altitude data are input data for PAR model to estimate daily PAR. Correlation coefficient between GOCI daily PAR and in-situ daily PAR is 0.98 and root-mean-square error (RMSE) is 4.50 Ein/m2 /day. To correct underestimated GOCI daily PAR, correction equation is developed from linear regression between GOCI daily PAR and in-situ daily PAR observed during clear sky condition days. RMSE of GOCI daily PAR which corrected with correction equation is decreased to 3.08 Ein/m2 /day and seasonal bias between GOCI and in-situ daily PAR is decreased, too. Validation is carried out with in-situ daily PAR observed during year of 2016. Correlation coefficient is 0.98 and RMSE is 2.69 Ein/m2 /day. Estimating GOCI daily PAR is expected to make accurate daily PAR by reducing meteorological element and regional error.
{"title":"Estimating GOCI daily PAR and validation","authors":"D. Hwang, Jong-Kuk Choi, J. Ryu, R. Frouin","doi":"10.1117/12.2500061","DOIUrl":"https://doi.org/10.1117/12.2500061","url":null,"abstract":"Photosynthesis available radiation (PAR) that makes primary producers to compose carbon compounds is the energy source of carbon circulation at the ocean. In these days, global scale PAR is efficiently observed from satellite remotesensing with low cost and high resolution. Here, Geostationary Ocean Color Imager (GOCI) which is geostationary orbit sensor is used to estimate daily PAR at smaller scale area for decreasing influence of diurnal variation such as cloud. GOCI daily PAR is estimated using PAR model based on Plane-parallel theory and compared with in-situ data observed during year of 2015 at two stations that has turbid and clear ocean area, respectively. Each band image of GOCI L1B data and solar altitude data are input data for PAR model to estimate daily PAR. Correlation coefficient between GOCI daily PAR and in-situ daily PAR is 0.98 and root-mean-square error (RMSE) is 4.50 Ein/m2 /day. To correct underestimated GOCI daily PAR, correction equation is developed from linear regression between GOCI daily PAR and in-situ daily PAR observed during clear sky condition days. RMSE of GOCI daily PAR which corrected with correction equation is decreased to 3.08 Ein/m2 /day and seasonal bias between GOCI and in-situ daily PAR is decreased, too. Validation is carried out with in-situ daily PAR observed during year of 2016. Correlation coefficient is 0.98 and RMSE is 2.69 Ein/m2 /day. Estimating GOCI daily PAR is expected to make accurate daily PAR by reducing meteorological element and regional error.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130421358","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}
F. Fitzpatrick, J. Rudd, Michael Albert, Kent Puffenburger, T. Schum, Slava Litvinovitch, D. Jones, F. Hovis
A long-lived UV laser is an enabling technology for several high-priority, space-based lidar instruments. These include a next generation cloud and aerosol lidar that incorporates a UV channel, a direct detection 3-D wind lidar, and an ozone differential absorption lidar (DIAL) system. To advance the TRL of UV lasers we have designed and built a High Energy UV Demonstrator (HEUVD) that has increased output power and space-qualifiable packaging and that is mechanically robust, thermally-stable, and fully conductively cooled. Contamination control processes and optical coatings have been chosen that are compatible with multi-billion shot lifetimes. The diode pumped laser contains an essentially polymer free internal module that houses the third harmonic generator and beam expansion optics. When operated at 150 Hz the laser has demonstrated 275 mJ per pulse at 1064 nm, second harmonic conversion efficiencies of 70%, and third harmonic conversion efficiencies of 45%, thus meeting the 355 nm 100 mJ/pulse goal with margin. We have successfully completed a full power 532 nm life test, a half power (50 mJ/pulse) UV lifetest, and a full power (100 mJ/pulse @ 150 Hz) lifetest. These tests have validated the importance and success of our approach to contamination control for achieving a long-lived UV laser. They also resurfaced the need for the qualification of the pump laser diodes and more attention to the external optics in a UV lidar system.
{"title":"Lifetime testing of a 355-nm, space-qualifiable laser","authors":"F. Fitzpatrick, J. Rudd, Michael Albert, Kent Puffenburger, T. Schum, Slava Litvinovitch, D. Jones, F. Hovis","doi":"10.1117/12.2325015","DOIUrl":"https://doi.org/10.1117/12.2325015","url":null,"abstract":"A long-lived UV laser is an enabling technology for several high-priority, space-based lidar instruments. These include a next generation cloud and aerosol lidar that incorporates a UV channel, a direct detection 3-D wind lidar, and an ozone differential absorption lidar (DIAL) system. To advance the TRL of UV lasers we have designed and built a High Energy UV Demonstrator (HEUVD) that has increased output power and space-qualifiable packaging and that is mechanically robust, thermally-stable, and fully conductively cooled. Contamination control processes and optical coatings have been chosen that are compatible with multi-billion shot lifetimes. The diode pumped laser contains an essentially polymer free internal module that houses the third harmonic generator and beam expansion optics. When operated at 150 Hz the laser has demonstrated 275 mJ per pulse at 1064 nm, second harmonic conversion efficiencies of 70%, and third harmonic conversion efficiencies of 45%, thus meeting the 355 nm 100 mJ/pulse goal with margin. We have successfully completed a full power 532 nm life test, a half power (50 mJ/pulse) UV lifetest, and a full power (100 mJ/pulse @ 150 Hz) lifetest. These tests have validated the importance and success of our approach to contamination control for achieving a long-lived UV laser. They also resurfaced the need for the qualification of the pump laser diodes and more attention to the external optics in a UV lidar system.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121386065","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}
Viktor Feygels, Nicholas M. Johnson, Y. Kopilevich, V. Ramnath, R. Marthouse, J. Wozencraft, H. Duong, C. Macon
Based on the processing of CZMIL data collected in Hawaii during a JALBTCX mission (2013) and in the Pacific for The Ocean Cleanup project (October, 2016), we demonstrate the possibility of reliably estimating the seawater column’s optical properties from lidar waveforms in deep clear (Jerlov class I and IB) waters. With minor improvements to the data processing method previously applied to Florida survey data (2003, 2006, 2012–2017), we estimate the diffuse attenuation coefficient at the wavelength of 532 nm, Kd (532), to be 0.045–0.060 m-1 in both regions. The results are in good agreement with space satellite data for the days of the lidar surveys and with Jerlov’s Kd curves for water classes I and IB.
{"title":"Features of airborne lidar surveys in clear ocean waters using Coastal Zone Mapping and Imaging Lidar (CZMIL)","authors":"Viktor Feygels, Nicholas M. Johnson, Y. Kopilevich, V. Ramnath, R. Marthouse, J. Wozencraft, H. Duong, C. Macon","doi":"10.1117/12.2324749","DOIUrl":"https://doi.org/10.1117/12.2324749","url":null,"abstract":"Based on the processing of CZMIL data collected in Hawaii during a JALBTCX mission (2013) and in the Pacific for The Ocean Cleanup project (October, 2016), we demonstrate the possibility of reliably estimating the seawater column’s optical properties from lidar waveforms in deep clear (Jerlov class I and IB) waters. With minor improvements to the data processing method previously applied to Florida survey data (2003, 2006, 2012–2017), we estimate the diffuse attenuation coefficient at the wavelength of 532 nm, Kd (532), to be 0.045–0.060 m-1 in both regions. The results are in good agreement with space satellite data for the days of the lidar surveys and with Jerlov’s Kd curves for water classes I and IB.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125225564","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}
Wuying Zhang, Chenyi Yang, Qingyun Zhao, Yueqian Cao
The Qilianshan Mountain area is very important for water resources and ecosystem safety of the Northwest China and Qinghai-Tibet Plateau. Satellite remote sensing is the best way to estimate precipitation over this region in the future due to the complex terrain and sparse of ground weather stations. The primary goal of this research is to evaluate the Tropical Rainfall Measuring Mission (TRMM) 3B43 rainfall products during 2008 ~ 2017 over the region, by using the gridded precipitation data and routine ground-based observation data from National Meteorological Information Center (NMIC) of China, combining with the Land Use and Land Cover (LULC, MCD12Q1) and topographic data (SRTM). Results show that accuracy of TRMM precipitation has changed a lot except in winter (arid season). Correlation coefficient of TRMM precipitation against the ground-based observations varies from 0.33 to 0.67, indicating that TRMM product is applicable over the Qilianshan mountain area. Seasonal variation of the relative error is mainly in the northeast and southwest areas. The TRMM rain products are greatly affected by topography, and its overestimations are basically distributed in the valley or trough areas. According to analysis of the land use classification, accuracy of the TRMM precipitation is obviously impacted by the sparse vegetation, evergreen broad-leaved forest and city area.
{"title":"Evaluation of the validation of TRMM data over the region of Qilianshan mountain in Northwest China","authors":"Wuying Zhang, Chenyi Yang, Qingyun Zhao, Yueqian Cao","doi":"10.1117/12.2324651","DOIUrl":"https://doi.org/10.1117/12.2324651","url":null,"abstract":"The Qilianshan Mountain area is very important for water resources and ecosystem safety of the Northwest China and Qinghai-Tibet Plateau. Satellite remote sensing is the best way to estimate precipitation over this region in the future due to the complex terrain and sparse of ground weather stations. The primary goal of this research is to evaluate the Tropical Rainfall Measuring Mission (TRMM) 3B43 rainfall products during 2008 ~ 2017 over the region, by using the gridded precipitation data and routine ground-based observation data from National Meteorological Information Center (NMIC) of China, combining with the Land Use and Land Cover (LULC, MCD12Q1) and topographic data (SRTM). Results show that accuracy of TRMM precipitation has changed a lot except in winter (arid season). Correlation coefficient of TRMM precipitation against the ground-based observations varies from 0.33 to 0.67, indicating that TRMM product is applicable over the Qilianshan mountain area. Seasonal variation of the relative error is mainly in the northeast and southwest areas. The TRMM rain products are greatly affected by topography, and its overestimations are basically distributed in the valley or trough areas. According to analysis of the land use classification, accuracy of the TRMM precipitation is obviously impacted by the sparse vegetation, evergreen broad-leaved forest and city area.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125256407","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}
Ankita Misra, B. Chapron, F. Nouguier, B. Ramakrishnan, M. Yurovskaya
Local changes in specular reflections of visible sunlight on the ocean surfaces can be captured effectively by satellite sensors operating in the visible range of the electromagnetic spectrum. This causes the sun-glint imagery to closely resemble the oceanic images obtained using Synthetic Aperture Radar (SAR) further allowing the identification of the various fine scale structures and patterns of the ocean. Moreover, at relevant spatial resolutions, cloud-free conditions as well as optimum relative positions of the sensor, sun and the wave front it is possible to image ocean waves, wave transformations and refraction patterns using Satellite Sun-glint imagery (SSGI). In the present study, Landsat OLI imagery captured along the coast of Brest, France is used to derive ocean wave characteristics such as wavelength, direction, amplitude and then mapped to better understand the process of wave transformation. The 2D fast Fourier transform technique has been used on Band 5 (NIR, 0.851 - 0.879μm) to derive the wavelength of swell waves in nearshore regions as well as to analyze the wavelength change. Furthermore, owing to the detector configuration of Landsat 8 OLI there is a small time lag between the channel acquisitions. This effectively helps to infer the space-time characteristics of the surface waves using the cross channel correlation between Band 5 and Band 6 subsequently enabling removal of the directional ambiguity associated with the wave spectra obtained from the analysis. The main purpose of this study is to demonstrate the importance of SSGI in deriving relevant coastal information which can be further utilized for bathymetry, surface current and wave motion determinations.
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