Campbell Scientific Bowen Ratio Instrumentation - Manual (Page 29)

Section 4. Calculating Fluxes Using SPLIT
4-3
TABLE 4.2-1. Input Values for Flux Calculations
VARIB. VALUE UNITS DESCRIPTION
CP 1.01 kJ/(kg K) Specific heat of air
CW 4190.0 J/(kg K) Specific heat of water
CS* 840.0 J/(kg K) Specific heat of dry soil (estimate)
EW** 2450.0 kJ/kg Latent heat of vaporization at 20°C
P* 87.18 kPa Atmospheric pressure, measure or
calculate for elevation
T** 1200 s Output interval
D** 0.08 m Depth to flux plates
BD* 1200 kg/m 3 Soil bulk density, must be
measured for site
W vol-H2O/bulk
vol-soil Soil water content, volume basis,
measured by the CS615
F W/m 2 Soil heat flux measured at 8 cm.
S W/m 2 Heat stored, calculated from soil
heat capacity and measured change
in temperature
G W/m 2 Soil heat flux at surface (F+S)
RN W/m 2 Net radiation, measured
BR — Bowen ratio
LE W/m 2 Latent heat flux
H W/m 2 Sensible heat Flux
0.622 Molecular weight of
water/molecular weight of air.
* These values are for a particular site. Correct values must be entered for the
site under study.
** These values may need to change if the program or installation is changed.