1 Manual measurement 0 002182 Transmissometer system (base < 25 m) 2 002182 2014-09-03T09:54:00.782Z Transmissometer system (base > 25 m) 1 002182 Missing value 15 002182 Forward scatter system 3 002182 Backscatter system 4 002182 Others 14 002182 Visibility measurement system