long term monitoring of total solar irradiance: results ... · total solar irradiance filter...
TRANSCRIPT
Werner Schmutz, PMOD/WRC, Switzerland
Wien, COPUOS, February 9, 2012
Long term monitoring of Total Solar Irradiance:
Results and Challenges
Overview
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• Introduction:� The role of solar forcing is not yet understood
• Results:− 30 years of TSI space observations− Measurement of the absolute value of TSI
• Challenge #1:− Construct a TSI composite over 30 years
• Challenge #2:− Maintain TSI monitoring in the future !
Comparison irradiance forcing with ice ages
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Illustration from Wikipedia
Climate anomalies
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Maunder
Temperature reconstruction
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Uncertainty is large !
Temperature reconstructions
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IPCC radiative forcing
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LOSULevel of Scientific Understanding
!
Results …
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Since 1979 Total Solar Irradiance is measured from space
8
TSI from space experiments
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TIM/SORCE2003 -
x
TSI from space experiments
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4.5 W/m2 difference in the absolute level of TIM/SORCE versus all other experiments
Total Solar Irradiance
Filter Radiometers
PICARD – a French Micro-satellite
PREMOS – SOVAP – SODISMPREMOS – Swiss radiometer on PICARD
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Irradiance calibration
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PREMOS A is the first and so far onlyradiometer in space with a SI-traceable irradiance calibration in vacuum
Traceable to the irradiance calibration facility at LASP in Boulder (TRF)
•PICARD was launched June 15, 2010
•PREMOS first light was July 27th, 2010
The absolute value of the solar constant
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ACRIM scattering correction determined at TRF(with ACRIM witness instrument)
... and the new PREMOS data
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The Solar Constant
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PREMOS/PICARD � The Solar Constant is1361 W/m2
in agreement to the value from TIM/SORCE and (re-characterized) ACRIM3, which both were not SI-traceable calibrated
PICARD: French Micro-Satellite
There are three TSI composites
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TSI-composites normalized
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normalized 2004-2005DIARAD
PMOD, ACRIM
� 0.2 W/m2 / 10-years
Is there a long-term trend?
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Fröhlich 2009, A&AL 501, L27-L30
Could we detect a trend with a composite?
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Requirements for a TSI monitoring
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„Any plan to rely on an unbroken chain of measurements is broken“
o Not only because of a potential gap;o But mainly because of the
continuously increasing uncertainty.
� Accurate absolute measurements are required !
Presence …
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Presently, 4 operational space experiments observing TSI:
- VIRGO (launched 1995)- ACRIM III (launched 2000)- TIM (launched 2003)- PREMOS (launched 2010)
… and future
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Presently, 4 operational space experiments observing TSI:
- VIRGO (launched 1995)- ACRIM III (launched 2000)- TIM (launched 2003)- PREMOS (launched 2010)
...x ?
Several new missions with TSI instruments are in the planning
…
… but no new mission is really approved so far !!
...x ?
...x ?
Thank you for your attention
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PREMOS PICARD