How do scientists measure global temperature average?

The temperature data of the land is obtained by measuring the temperature of the air above the surface of the land and the measurements are mostly made by the meteorological stations. Floats and ships are mostly used for sea surface temperature measurements. From time to time, data from satellites can also be included in the calculations.

There are three centers measuring average global temperature in the world and these centers use different data analysis methods. These are HadCRUT, the data obtained by the UK National Meteorological Center (Met Office) and the University of East Anglia, NASA GLISS, where the data obtained by the NASA Goddard Space Research Center are evaluated, and the NOAA NCDC, which evaluates the data obtained by the US National Oceanic and Atmospheric Authority.