MODIS/Aqua Surface Reflectance Daily L2G Global 500m SIN Grid NRT

The MODIS/Aqua Surface Reflectance Daily L2G Global 500m SIN Grid Near Real Time (NRT) product, short name MYD09GHK, is a seven-band product computed from the MODIS Level 1B land Bands 1-7. The product is an estimate of the surface spectral reflectance for each band as it would have been measured at ground level if there were no atmospheric scattering or absorption. The correction scheme includes corrections for the effect of atmospheric gases, aerosols, and thin cirrus clouds; it is applied to all Level 1B pixels that pass the Level 1B quality control. The correction uses Band 26 to detect cirrus clouds, the approach used in MYD04 and MYD05 for water vapor, aerosol correction, and NCEP for ozone; the best available climatology data are used if the MODIS water vapor, aerosol, or ozone products are unavailable. The Level 2G surface reflectance product is the input for the generation of several land products: 8-day Surface Reflectance, Vegetation Indices (VIs), Bidirectional Reflectance Distribution Function (BRDF), thermal anomaly, snow/ice, and Fraction of Photosynthetically Active Radiation/Leaf Area Index (FPAR/LAI).

MODIS/Aqua地表反射率每日L2G全球500米SIN网格近实时（NRT）产品，简称MYD09GHK，是一种由MODIS第1B级陆地波段1-7计算得到的七波段产品。该产品是对每个波段地表光谱反射率的估计，假定在无大气散射或吸收的情况下，该反射率若在地面测量将得到。校正方案包括对大气气体、气溶胶和薄 cirrus 云影响进行校正；该校正应用于所有通过第1B级质量控制的第1B级像素。校正使用波段26检测 cirrus 云，该方法与MYD04和MYD05中用于水汽、气溶胶校正以及NCEP中用于臭氧校正的方法相同；如果MODIS水汽、气溶胶或臭氧产品不可用，则使用最佳可用的气候学数据。第2G级地表反射率产品是生成多个陆地产品的输入：8日地表反射率、植被指数（VIs）、双向反射分布函数（BRDF）、热异常、雪/冰和光合有效辐射/叶面积指数（FPAR/LAI）的比例。