生物质燃烧排放大量烟雾和温室气体对于全球气候变化有显著影响,而准确及时地提取火烧迹地面积对于火灾补救、植被恢复、估算大气排放至关重要。中分辨率成像光谱仪MODIS较高的时间分辨率可以快速获取全球每日的火烧迹地产品,但对于小...生物质燃烧排放大量烟雾和温室气体对于全球气候变化有显著影响,而准确及时地提取火烧迹地面积对于火灾补救、植被恢复、估算大气排放至关重要。中分辨率成像光谱仪MODIS较高的时间分辨率可以快速获取全球每日的火烧迹地产品,但对于小型和破碎度高的火烧迹地的遗漏率比较高。据此,本研究融合MODIS与Landsat-8 OLI(Operational Land Imager陆地成像仪)的时空优势,提出了基于地表反射率数据集支持的火烧面积提取算法。首先,使用MODIS地表反射率产品MOD09GA构建燃烧日期前后在红、绿、蓝、近红外和短波红外的先验地表反射率数据集。然后,采用自适应遥感图像时空融合算法(Spatial and Temporal Adaptive Reflectance Fusion Model,STARFM)以及线性拟合的方法对MODIS与Landsat-8地表反射率数据进行空间和光谱一致化处理。最后,运用自动阈值的方法厘定火烧区域的最佳阈值。此外,通过选取4个不同的燃烧规模样地/样区验证了该算法的火烧迹地面积提取准确率在75%以上。本研究将MODIS的高时间分辨率和Landsat-8的高空间分辨率的优势结合,既解决了单独使用MODIS对小型、破碎度高的火烧迹地提取不足的问题,也验证了基于地表反射率数据集的算法对于火烧迹地实时提取能力。展开更多
Recent satellite data analysis has provided improved data sets relevant to the surface energy budget in the Arctic Ocean. In this paper, surface radiation properties in the Arctic Ocean obtained from the Surface Radia...Recent satellite data analysis has provided improved data sets relevant to the surface energy budget in the Arctic Ocean. In this paper, surface radiation properties in the Arctic Ocean obtained from the Surface Radiation Budget（SRB3.0） and the International Satellite Cloud Climatology Project（ISCCP-FD） during 1984– 2007 are analyzed and compared. Our analysis suggests that these datasets show encouraging agreement in basin-wide averaged seasonal cycle and spatial distribution of surface albedo; net surface shortwave and all-wave radiative fluxes; and shortwave, longwave, and all-wave cloud radiative forcings. However, a systematic large discrepancy is detected for the net surface longwave radiative flux between the two data sets at a magnitude of ~ 23 W m–2, which is primarily attributed to significant differences in surface temperature, particularly from April to June. Moreover, the largest difference in surface shortwave and all-wave cloud radiative forcings between the two data sets is apparent in early June at a magnitude of 30 W m–2.展开更多
文摘生物质燃烧排放大量烟雾和温室气体对于全球气候变化有显著影响,而准确及时地提取火烧迹地面积对于火灾补救、植被恢复、估算大气排放至关重要。中分辨率成像光谱仪MODIS较高的时间分辨率可以快速获取全球每日的火烧迹地产品,但对于小型和破碎度高的火烧迹地的遗漏率比较高。据此,本研究融合MODIS与Landsat-8 OLI(Operational Land Imager陆地成像仪)的时空优势,提出了基于地表反射率数据集支持的火烧面积提取算法。首先,使用MODIS地表反射率产品MOD09GA构建燃烧日期前后在红、绿、蓝、近红外和短波红外的先验地表反射率数据集。然后,采用自适应遥感图像时空融合算法(Spatial and Temporal Adaptive Reflectance Fusion Model,STARFM)以及线性拟合的方法对MODIS与Landsat-8地表反射率数据进行空间和光谱一致化处理。最后,运用自动阈值的方法厘定火烧区域的最佳阈值。此外,通过选取4个不同的燃烧规模样地/样区验证了该算法的火烧迹地面积提取准确率在75%以上。本研究将MODIS的高时间分辨率和Landsat-8的高空间分辨率的优势结合,既解决了单独使用MODIS对小型、破碎度高的火烧迹地提取不足的问题,也验证了基于地表反射率数据集的算法对于火烧迹地实时提取能力。
基金supported by the National Basic Research Program of China(2011CB30970)the National Natural Science Foundation of China(41176169 and 40930848)
文摘Recent satellite data analysis has provided improved data sets relevant to the surface energy budget in the Arctic Ocean. In this paper, surface radiation properties in the Arctic Ocean obtained from the Surface Radiation Budget（SRB3.0） and the International Satellite Cloud Climatology Project（ISCCP-FD） during 1984– 2007 are analyzed and compared. Our analysis suggests that these datasets show encouraging agreement in basin-wide averaged seasonal cycle and spatial distribution of surface albedo; net surface shortwave and all-wave radiative fluxes; and shortwave, longwave, and all-wave cloud radiative forcings. However, a systematic large discrepancy is detected for the net surface longwave radiative flux between the two data sets at a magnitude of ~ 23 W m–2, which is primarily attributed to significant differences in surface temperature, particularly from April to June. Moreover, the largest difference in surface shortwave and all-wave cloud radiative forcings between the two data sets is apparent in early June at a magnitude of 30 W m–2.
