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Thermal and s olar r adiation errors o n air temperature

Thermal and s olar r adiation errors o n air temperature m easured w ith upper -air radiosondes. R. Philipona 1 , A. Kräuchi 2 , G. Romanens 1 , G. Levrat 1 , P. Ruppert 3 , E . Brocard 1 , P. Jeannet 1 , D. Ruffieux 1 , B. Calpini 1.

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Thermal and s olar r adiation errors o n air temperature

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  1. Thermal and solar radiation errors on air temperature measuredwith 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.

  2. Motivation Resultsfromthe: WMO Intercomparison of High Quality Radiosonde Systems Yangjiang, 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

  3. Experiments: Atmosphere / Laboratory 1Measurementsof solar and thermal radiationflux profilesthroughtheatmosphere 2Measurementsoftheradiationerror on unshaded andshadedtemperaturesensors in flight 3Measurementsoftheradiationerror on temperature sensorsof different diameters in a vacuumchamber

  4. Radiation Measurements through the Atmosphere SRS-C34 Radiosondes from Meteolabor and CNR 4 Net Radiometer from Kipp and Zonen

  5. Radiation Measurements on Radiosondes Pyranometer and Pyrgeometer measuring downward fluxes Pyranometer and Pyrgeometer measuring upward fluxes

  6. Kiehl and Trenberth Solar and Thermal Radiation Fluxes Satellite Radiation Measurements Solar shortwave Radiation Thermal longwave Rad. LUR LDR LUR LDR SUR SDR 168 Kiehl and Trenberth Surface Radiation Measurements Can we measure radiation profiles through the atmosphere ?

  7. Longwave Radiation Profiles during the Night Night flight: 23 Sep 2011, UT21:20 T_n LUR_n LNR_n LDR_n

  8. Longwave Radiation Profiles during Night and Day Night flight: 23 Sep 2011, UT21:20 Day flight: 23 Sep 2011, UT10:13 and T_n LUR_n LNR_n LDR_n T_d LUR_d LNR_d LDR_d

  9. Kiehl and Trenberth Solar and Thermal Radiation Fluxes Satellite Radiation Measurements Solar shortwave Radiation Thermal longwave Rad. LUR SUR SDR LDR LUR LDR SUR SDR 168 Kiehl and Trenberth Surface Radiation Measurements Can we measure radiation profiles through the atmosphere ?

  10. Shortwave and longwave Radiation Profiles Night flight: 23 Sep 2011, UT21:20 Day flight: 23 Sep 2011, UT10:13 and LUR SUR LDR SDR DIR SDR =+880 W m-2 DIR = 1344 W m-2 LUR_d LDR_d LUR_n LDR_n SUR SDR DIR Poster – P3(7) Philipona, Kräuchi, Brocard, GRL, 2012 doi:10.1029/2012GL052087

  11. Longwave Radiation Error during the Night Night flight: 23 Sep 2011, UT21:20 Longwave Net Radiation on Temperature Sensor Cooling LDR e sT^4 LUR LDR e sT^4 Heating LNR T e sT^4 LUR Cooling LNR • Reducesensor Size • ReducesensorEmissivity • Increasesensor Speed Glenn E. Daniels, JAM, 1968:

  12. Longwave Radiation Error during the Night WMO China, Night results Meteolabor 50m T sensor smallest Size uncertain Emissivity same Speed Cooling Heating Cooling

  13. Longwave Radiation Error during the Night WMO China, Night results All sensorsare too warm Heating All sensorsare toocold Cooling

  14. Solar Radiation Error during the Day WMO China, Day results

  15. Radiation Error during the Day Day flight: 23 Sep 2011, UT10:13 Total Net Radiation on Temperature Sensor sT^4 SUR LDR LUR SDR DIR DIR LDR e sT^4 LNR T e sT^4 LUR LNR SUR Longwave Emission e: (0.05 - 0.3) Shortwave Absorption a: (0.01 - 0.2)

  16. Method to Shade and Unshade • Aluminium plate (brilliant / black) attached to Meteolabor sonde • Temperature sensors on both sides (5cm distance) • Alternately one sensor is exposed to the sun SRS C34 front view Reference sensor T sensor

  17. Radiation Error on Meteolabor temperature sensor 50 micronthermocouple temperaturesensors unshadedandshaded

  18. Radiation Error on Temperature

  19. Radiation Error on Temperature

  20. Radiation Error measured in Vacuum Chamber Experiment withone Meteolabor sonde havingthreethermocouplesensors withwiresof 20m, 50mand 100m 1 Minute on, 1 Minute off P = 5 hPa v = 5 m/s Observatory of Lindenberg Vacuum Chamber Xenon Arc Lamp, Intensity: ~ 1650 Wm-2 P = 10 hPa v = 5 m/s P = 30 hPa v = 5 m/s P = 100 hPa v = 5 m/s P = 300 hPa v = 5 m/s

  21. Radiation Error: Atmosphere / Laboratory Old correction New correction 100m Lab 50m Lab 20m Lab

  22. Radiation Error Correction during Day WMO China, Day results

  23. Summary: Radiation Error Night and Day Night Day

  24. Summary and Conclusions WMO China resultsreferencedtonew Meteolabor T-correction Night Day • More nightexperimentsareneededtoclarify thermal effects • Future WMO intercomparisonsareneededtohelpimproving • radiosonde measurements Thank you for your attention !

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