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MeteoSwiss Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with 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 1 Federal Office of Meteorology and Climatology MeteoSwiss, CH-1530 Payerne, Switzerland. 2 Institute for Atmospheric and Climate Science, ETH Zurich, CH-8057-Zurich, Switzerland. 3 Meteolabor AG, CH-8620 Wetzikon, Switzerland.

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Page 1: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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.

Page 2: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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:

Page 3: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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

Page 4: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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

Page 5: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

Radiation Measurements on Radiosondes

Pyranometer and Pyrgeometer measuring downward fluxes

Pyranometer and Pyrgeometer measuring upward fluxes

Page 6: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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

LDRLUR

Page 7: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

LDR_nLNR_nLUR_nT_n

Night flight: 23 Sep 2011, UT21:20

Longwave Radiation Profiles during the Night

Page 8: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

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

Page 9: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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

Page 10: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

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

Page 11: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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

Page 12: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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

Page 13: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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

Page 14: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

Solar Radiation Error during the Day

WMO China, Day results

Page 15: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

- 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

Page 17: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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

Page 18: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

Radiation Error on Temperature

Page 19: MeteoSwiss Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss Thermal and solar radiation errors on air temperature measured with

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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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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

Radiation Error Correction during Day

WMO China, Day results

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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

Summary: Radiation Error Night and Day

Night Day

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Rolf Philipona Federal Office of Meteorology and Climatology MeteoSwiss

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