I have measured the transpiration rate of chickpea leaves by IRGA meter expressed as mmole/m2/sec. we have also measured evapotranspiration by water balance method. Now, i we want to measure Transpiration/Evapotranspiration ratio, we need to convert the units of transpiration from mmole/m2/sec to mm, as ET is measured in mm unit. How can we do it?
T = mmole/m2/sec = mmole/1000mmˆ2/sec
So T x 1000mmˆ2/sec = mmole
And 1000mmˆ2/sec = mmole/T
Then 1000mmˆ2 = mmole x sec/T
And mmˆ2 = mmole x sec/T/1000
Therefore mm = square root of mmole x sec/T/1000
So you can work out mm for each set of mmole, time and transpiration parameter values groups :)
@Andrew Paul McKenzie Pegman is this the write way to calculate? The transpiration measured by IRGA meter is expressed as mmole/m2/sec whereas the evapotranspiration measured by water balance method is in mm of water.the conversion you showed is not justified and correct.
The evapotranspiration rate is normally expressed in millimeters (mm) per unit time in a definite area, usually mm day-1. (https://www.fao.org/3/X0490E/x0490e04.htm)
Assuming that 1 mol water is 18 mL (https://www.thoughtco.com/how-much-water-is-a-mole-608527)
1 mmol m-2 s-1 = 0.018 mL m-2 s-1 = 0.018*3600 mL m-2 h-1 = 64.8 mL m-2 h-1 = 64.8*24/1000 L m-2 day-1 = 1.5552 L m-2 day-1
1.5552 L = 1.5552*10-3 m3 – this quantity will be distributed in 1 m2, that means a height of 1.5552*10-3 m, i.e. we will have 1.5552 mm per day.