Long term monitoring of Total Solar Irradiance: Results ... · Total Solar Irradiance Filter...

Werner Schmutz, PMOD/WRC, Switzerland

Wien, COPUOS, February 9, 2012

Long term monitoring of Total Solar Irradiance:

Results and Challenges

Overview

Werner Schmutz 29.2.2012

• 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

Werner Schmutz 39.2.2012

Illustration from Wikipedia

Climate anomalies

Werner Schmutz 49.2.2012

Maunder

Temperature reconstruction

Werner Schmutz 59.2.2012

Uncertainty is large !

Temperature reconstructions

Werner Schmutz 69.2.2012

IPCC radiative forcing

Werner Schmutz 79.2.2012

LOSULevel of Scientific Understanding

!

Results …

Werner Schmutz9.2.2012

Since 1979 Total Solar Irradiance is measured from space

8

TSI from space experiments

Werner Schmutz 99.2.2012

TIM/SORCE2003 -

x

TSI from space experiments

Werner Schmutz 109.2.2012

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

9.2.2012 11

Irradiance calibration

Werner Schmutz 129.2.2012

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

Werner Schmutz 139.2.2012

ACRIM scattering correction determined at TRF(with ACRIM witness instrument)

... and the new PREMOS data

Werner Schmutz 149.2.2012

The Solar Constant

Werner Schmutz 159.2.2012

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

Werner Schmutz 169.2.2012

TSI-composites normalized

Werner Schmutz 179.2.2012

normalized 2004-2005DIARAD

PMOD, ACRIM

� 0.2 W/m2 / 10-years

Is there a long-term trend?

Werner Schmutz 189.2.2012

Fröhlich 2009, A&AL 501, L27-L30

Could we detect a trend with a composite?

Werner Schmutz 199.2.2012

Requirements for a TSI monitoring

Werner Schmutz 209.2.2012

„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 …

Werner Schmutz 219.2.2012

Presently, 4 operational space experiments observing TSI:

- VIRGO (launched 1995)- ACRIM III (launched 2000)- TIM (launched 2003)- PREMOS (launched 2010)

… and future

Werner Schmutz 229.2.2012

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

Werner Schmutz 239.2.2012

PREMOS PICARD