To understand the relationship between turbid water and coral damage caused by the heavy rain disaster at the end of October 2010 in Amami-Oshima, Kagoshima Prefecture, Japan, turbid water and coral damage distributio...To understand the relationship between turbid water and coral damage caused by the heavy rain disaster at the end of October 2010 in Amami-Oshima, Kagoshima Prefecture, Japan, turbid water and coral damage distribution monitoring was attempted using satellite imagery and a diving survey immediately after the disaster. ALOS AVNIR-2 images (spatial resolution: 10 m) on October 6 (before the disaster), October 24, October 30, and October 31 (after the disaster) were obtained as satellite data in 2010. The red-silt deposition index (RSI) map based on the method by Nadaoka and Tamura (1992) was also created. Moreover, a diving survey was conducted via the spot check method on December 18, 2010. As a result, comparison between the high turbidity (RSI) areas estimated using AVNIR-2 data and the coral damage areas judging from the field survey was considered relatively light. It is shown that satellite data such as AVNIR-2 can be a powerful tool to monitor damage distribution of coral reefs after heavy rain.展开更多
In this study, we estimated the growth area of aquatic macrophytes that have expanded spontaneously in Lake Shinji, located in eastern Shimane Prefecture, Japan, using Terra satellite Advanced Spaceborne Thermal Emiss...In this study, we estimated the growth area of aquatic macrophytes that have expanded spontaneously in Lake Shinji, located in eastern Shimane Prefecture, Japan, using Terra satellite Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Visible and near infrared ASTER data from April, August, and September 2012 were used. The water depth at which ASTER can detect submersed aquatic macrophytes using in situ spectral reflectance of aquatic macrophytes and a bio-optical model was also examined. As a result, when the threshold value of a normalized difference vegetation index (NDVI) was set to 0, only aquatic macrophytes up to a depth of approximately 10 cm could be detected. The growth area of aquatic macrophytes detected by NDVI from ASTER data was in relatively good agreement with the growth area as observed by aerial photography.展开更多
This study discusses the fusion of chlorophyll-a (Chl.a) estimates around Tachibana Bay (Nagasaki Prefecture, Japan) obtained from MODIS and GOCI satellite data. First, the equation of GOCI LCI was theoretically calcu...This study discusses the fusion of chlorophyll-a (Chl.a) estimates around Tachibana Bay (Nagasaki Prefecture, Japan) obtained from MODIS and GOCI satellite data. First, the equation of GOCI LCI was theoretically calculated on the basis of the linear combination index (LCI) method proposed by Frouin et al. (2006). Next, assuming a linear relationship between them, the MODIS LCI and GOCI LCI methods were compared by using the Rayleigh reflectance product dataset of GOCI and MODIS, collected on July 8, July 25, and July 31, 2012. The results were found to be correlated significantly. GOCI Chl.a estimates of the finally proposed method favorably agreed with the in-situ Chl.a data in Tachibana Bay.展开更多
文摘To understand the relationship between turbid water and coral damage caused by the heavy rain disaster at the end of October 2010 in Amami-Oshima, Kagoshima Prefecture, Japan, turbid water and coral damage distribution monitoring was attempted using satellite imagery and a diving survey immediately after the disaster. ALOS AVNIR-2 images (spatial resolution: 10 m) on October 6 (before the disaster), October 24, October 30, and October 31 (after the disaster) were obtained as satellite data in 2010. The red-silt deposition index (RSI) map based on the method by Nadaoka and Tamura (1992) was also created. Moreover, a diving survey was conducted via the spot check method on December 18, 2010. As a result, comparison between the high turbidity (RSI) areas estimated using AVNIR-2 data and the coral damage areas judging from the field survey was considered relatively light. It is shown that satellite data such as AVNIR-2 can be a powerful tool to monitor damage distribution of coral reefs after heavy rain.
文摘In this study, we estimated the growth area of aquatic macrophytes that have expanded spontaneously in Lake Shinji, located in eastern Shimane Prefecture, Japan, using Terra satellite Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Visible and near infrared ASTER data from April, August, and September 2012 were used. The water depth at which ASTER can detect submersed aquatic macrophytes using in situ spectral reflectance of aquatic macrophytes and a bio-optical model was also examined. As a result, when the threshold value of a normalized difference vegetation index (NDVI) was set to 0, only aquatic macrophytes up to a depth of approximately 10 cm could be detected. The growth area of aquatic macrophytes detected by NDVI from ASTER data was in relatively good agreement with the growth area as observed by aerial photography.
文摘This study discusses the fusion of chlorophyll-a (Chl.a) estimates around Tachibana Bay (Nagasaki Prefecture, Japan) obtained from MODIS and GOCI satellite data. First, the equation of GOCI LCI was theoretically calculated on the basis of the linear combination index (LCI) method proposed by Frouin et al. (2006). Next, assuming a linear relationship between them, the MODIS LCI and GOCI LCI methods were compared by using the Rayleigh reflectance product dataset of GOCI and MODIS, collected on July 8, July 25, and July 31, 2012. The results were found to be correlated significantly. GOCI Chl.a estimates of the finally proposed method favorably agreed with the in-situ Chl.a data in Tachibana Bay.
