Chapter 3 _________________________________________________________ Ozone Calculation
VAISALA_______________________________________________________________________ 91
By setting the background current I
o
= 0, the background current
correction is disabled.
The ASOPOS panel recommends the use of a constant, pressure-
independent I
B2
in the basic equation to determine the ozone partial
pressure throughout the entire vertical profile. Pressure-dependent
background can be done by:
I
O
= (P/P
0
) x I
B2
As a Vaisala equation, this is:
I
BG
= (P/P
0
) x I
O
Pumping Time for 100 ml of Air (t)
The pumping time is measured during sounding preparations. The value
is entered in the ground equipment during sounding preparations.
Measured Airflow Temperature (T
P
)
All sensors use measured values in a Vaisala application.
Pump Efficiency Correction (Cef)
The efficiency of the SPC Model 6A Ozonesonde air sampling pump
decreases with altitude. Calculated ozone partial pressures must,
therefore, be corrected for the efficiency loss. Correcting factors for
Model 6A pumps, with ECC sensor cathodes filled with 2.5 cm
3
sensing solution and 3.0 cm
3
sensing solution, are shown in
, respectively. At pressure level (P) the value of C
ef
is calculated
using linear interpolation as a function of pressure.
NOTE
The ASOPOS panel recommends the use of 3.0 cm
3
only.
