The MODIS/Terra Geolocation Angles Daily L2G Global 1km SIN Grid Day Near Real Time (NRT), short name MODMGGAD, product contain information on solar illumination and instrument viewing geometry angles. These data can be used to model the geometric relationship and distance between the area of the Earth's surface imaged, the sun, and the sensor. This is often required to perform atmospheric corrections, or to convert or calibrate spectral data to known (absolute) radiance or reflectance units.MODMGGAD files are used as input to higher-level products such as MODIS Surface Reflectance (MOD09). Geometric information for each sensor observation is stored on a geolocated grid with Level-2 geophysical parameters stored as Level-2G (gridded) products. The multiple observations stored in the L2G grids are examined by the Level-3 processes to extract only the most relevant observations per grid cell.