meteoswiss rolf philipona federal office of meteorology and climatology meteoswiss thermal and solar...
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Thermal and solar radiation errorson air temperature
measured with upper-air radiosondes
R. Philipona1, A. Kräuchi2, G. Romanens1, G. Levrat1, P. Ruppert3, E. Brocard1, P. Jeannet1, D. Ruffieux1, B. Calpini1
1Federal Office of Meteorology and Climatology MeteoSwiss, CH-1530 Payerne, Switzerland.2Institute for Atmospheric and Climate Science, ETH Zurich, CH-8057-Zurich, Switzerland.
3Meteolabor AG, CH-8620 Wetzikon, Switzerland.
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Motivation
WMO Intercomparison of High Quality Radiosonde SystemsYangjiang, China, 12 July - 3 August 2010
Night Day
J. Nash, T. Oakley, H. Vömel, LI Wei, WMO/TD-No. 1580, 2011
Reinvestigation of Meteolabor radiation correction
Results from the:
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Experiments: Atmosphere / Laboratory
1 Measurements of solar and thermal radiation flux profiles through the atmosphere
2 Measurements of the radiation error on unshaded and shaded temperature sensors in flight
3 Measurements of the radiation error on temperature sensors of different diameters in a vacuum chamber
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
SRS-C34 Radiosondes from Meteolabor and CNR 4 Net Radiometer from Kipp and Zonen
Radiation Measurements through the Atmosphere
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Radiation Measurements on Radiosondes
Pyranometer and Pyrgeometer measuring downward fluxes
Pyranometer and Pyrgeometer measuring upward fluxes
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Solar shortwave Radiation
Kiehl and Trenberth
SUR
Thermal longwave Rad.
Kiehl and Trenberth
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Solar and Thermal Radiation Fluxes
LDRLURSDR
Can we measure radiation profiles through the atmosphere ?
Surface Radiation Measurements
Satellite Radiation Measurements
LDRLUR
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LDR_nLNR_nLUR_nT_n
Night flight: 23 Sep 2011, UT21:20
Longwave Radiation Profiles during the Night
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Night flight: 23 Sep 2011, UT21:20 Day flight: 23 Sep 2011, UT10:13and
LDR_dLNR_dLUR_dT_dLDR_nLNR_nLUR_nT_n
Longwave Radiation Profiles during Night and Day
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Solar shortwave Radiation
Kiehl and Trenberth
SUR
Thermal longwave Rad.
Kiehl and Trenberth
168
Solar and Thermal Radiation Fluxes
LDRLURSDR
Can we measure radiation profiles through the atmosphere ?
Surface Radiation Measurements
Satellite Radiation Measurements
LDRLURSUR SDR
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LDRLUR SUR DIRSDR
Shortwave and longwave Radiation Profiles
LUR_d
SUR
LUR_n
DIRSDR
LDR_d
LDR_n
Night flight: 23 Sep 2011, UT21:20 Day flight: 23 Sep 2011, UT10:13and
SDR =+880 W m-2 DIR = 1344 W m-2
Poster – P3(7) Philipona, Kräuchi, Brocard, GRL, 2012 doi:10.1029/2012GL052087
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Longwave Radiation Error during the Night
Longwave Net Radiation on Temperature Sensor
Night flight: 23 Sep 2011, UT21:20
T
LNR
LURLDRT^4
LDR
LURCooling
Heating
T^4
T^4
LNR
Glenn E. Daniels, JAM, 1968:• Reduce sensor Size• Reduce sensor Emissivity• Increase sensor Speed
Cooling
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Longwave Radiation Error during the Night
Cooling
Heating
WMO China, Night resultsMeteolabor
50T sensor
smallest Size
uncertain Emissivity
same Speed
Cooling
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Longwave Radiation Error during the Night
Cooling
Heating
All sensors are too cold
All sensors are too warm
WMO China, Night results
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Solar Radiation Error during the Day
WMO China, Day results
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Radiation Error during the Day
Day flight: 23 Sep 2011, UT10:13
DIR
SUR
T
LDR
LURT^4
T^4
LNR
LDR LURT^4SUR DIRSDR
LNR
Longwave Emission : (0.05 - 0.3)
Shortwave Absorption : (0.01 - 0.2)
Total Net Radiation on Temperature Sensor
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- Aluminium plate (brilliant / black) attached to Meteolabor sonde
- Temperature sensors on both sides (5cm distance)
- Alternately one sensor is exposed to the sun
Referencesensor
Method to Shade and Unshade
SRSC34SRSC34
front view
T sensor
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Radiation Error on Meteolabor temperature sensor
50 micron thermocouple temperature sensors unshaded and shaded
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Radiation Error on Temperature
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Radiation Error on Temperature
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
P = 5 hPav = 5 m/s
P = 10 hPav = 5 m/s
P = 300 hPav = 5 m/s
P = 100 hPav = 5 m/s
P = 30 hPav = 5 m/s
Radiation Error measured in Vacuum Chamber
Observatory of Lindenberg Vacuum Chamber Xenon Arc Lamp, Intensity: ~ 1650 Wm-2
Experiment with one Meteolabor sondehaving three thermocouple sensorswith wires of 20, 50 and 100
1 Minute on, 1 Minute off
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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss
Radiation Error: Atmosphere / Laboratory
Old correction New correction
20 Lab
50 Lab
100 Lab
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Radiation Error Correction during Day
WMO China, Day results
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Summary: Radiation Error Night and Day
Night Day
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Night Day
Summary and Conclusions
Thank you for your attention !
• Future WMO intercomparisons are needed to help improving radiosonde measurements
WMO China results referenced to new Meteolabor T-correction
• More night experiments are needed to clarify thermal effects