Post on 05-Jan-2016
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Ozone Radiometer at 142 GHz:Calibration
Yasmine Calisesi
The Stratospheric Ozone Monitoring Radiometer SOMORA
●Developed by the IAP for MeteoSwiss●Tuned to Ozone at 142.175 GHz●Improved version of the GROMOS instrument●Operated at the IAP since January 2000●Moved to Payerne in June 2002
Somora location in Payerne
SOMORA Quasi-Optics
Rotating Planar MirrorHot Load
ColdLoad
Eccosorb CV-3
IF 7.1 Ghz
T = 310 K
T=77K
Fans PT 100HeatingElement
EccosorbCV-3
PT 100
PolystyreneWindow
SOMORA Hot Load
EccosorbCV-3
SOMORA Cold Load
Dewar Vessel
Packaging Foam Material
Liquid N2
InletGaz-phase N2 exhaust
ExpansionVesselP = 0.4 Bar
Total Power Calibration
coldcoldhotcoldhot
coldskysky TTT
PP
PPT
)(
,1
y
yTTT coldhotrec
0
0
PP
PPy
cold
hot
Temperature Definitions
● Physical Temperature● „Planck“ Brightness Temp.:
T :
TP :
)2
1ln(
1
2
3
Pc
hk
hTP
● In the RJ limit (hkT):
P ÷ T P can be replaced by T in RT model
RJP Tk
PcT :
2 2
2
Example: Planck and RJ emission curves at various frequencies
Brightness Temperature [K]
Conclusions:
● SOMORA: Total power radiometer
● P ÷ T in considered T range Total power calibration formula can be used
● TRJ ≠ T
P Radiative transfer
computed in the units of P