MODIS Collection 5 Active Fire Product User's Guide Version ... - FAO

Satellite‘O’ = Terra‘Y’ = Aqua‘C’ = combined Terra/AquaM?D14C??Temporal Resolution‘M’ = monthly‘8’ = 8 daysSpatial Resolution‘H’ = 0.5˚‘Q’ = 0.25˚Figure 9: MODIS CMG fire product naming prefix (ESDT) convention.4.4.4 Climate Modeling Grid NavigationForward navigation. Given the latitude and longitude (in degrees) of a point on the Earth’s surface,the image coordinates (x,y) of the 0.5 ◦ CMG grid cell containing this point are computed as follows:y = floor((90.0 - latitude) / 0.5)x = floor((longitude + 180.0) / 0.5),where floor is the floor function, e.g., floor(2.2) = 2. These equations yield image coordinatessatisfying the inequalities 0 ≤ x ≤ 719, 0 ≤ y ≤ 319, which are appropriate for programminglanguages using zero-based array indexing such as C and IDL; for languages using one-based arrayindexing (e.g. Fortran, MATLAB) add 1.Inverse navigation. Given coordinates (x,y) of a particular grid cell in the 0.5 ◦ CMG fire products,the latitude and longitude (in degrees) of the center of the grid cell may be computed as follows:latitude = 89.75 - 0.5 × ylongitude = -179.75 + 0.5 × xHere, x and y are again zero-based image coordinates; for one-based image coordinates first subtract1 from both x and y.31