Which SI unit of measurement should be used for vertical axis?

Kelvin is the SI unit for measurement of X axis. Kelvin is a unit of measure used to measure temperature base on the absolute scale. It is commonly used to measure the color temperature of the light like fluorescent lamp, bulb, etc. It is also used to indicate how noisy a certain electronic is. The symbol of Kelvin is K. here are the conversion formula of Kelvin to F, C and Rankine

=> C = [K] - 273.15

=> R = [K] x 9/5

=> F = [K] x 9/5 - 459.67