Measure the latent heat flux parameters. Include latent heat of evaporation of water and call it λ (lambda). Include evapo-transpiration rate and call it Ε. These two components together are associated with latent heat flux (λΕ).
Write down the following formula: λΕ= λ*1/ {(1/ga) + (1/gs)} * (qs (Ts)-qa (Ta))
This is the basic formula for calculating latent heat flux. Each variable is equally important in solving the equation. The "ga" represents the aerodynamic conductance while "gs" is a variable for surface conductance of water. In atmospheric sciences, "ga" and "gs" variables are always expressed in meter per second. The λ is the representation of latent heat of evaporation of water. This variable is in joules per kilogram. The "qs" is a variable for vapor concentration and will be measured in kilogram per meter cube. Similarly variable "qa" represents the vapor concentration of air and is measured in kilogram per meter cubed. Variable "Ts" and "Ta" represents the surface temperature and air temperature respectively. For maintaining consistency with other variables these values should be measured in Kelvin. If the measurement is in Celsius add 273 to the Celsius values.
Solve for λΕ using simple algebra. The resulting value of latent heat flux will be in joule per meter, square per second or watt per meter squared.