Validation of the ACRIM composite TSI by solar surface magnetic field proxies

Validation of the ACRIM composite TSIby solar surface magnetic field proxies

AGU Session GC22E Tuesday

Dec 4 2012RICHARD C. WILLSON 1

ACRIMSAT/ACRIM3

ACRIM3 TEAM

Dr. Richard C. WillsonPrincipal Investigator

ACRIM

Dr. Nicola ScafettaCo-Investigtor

Duke University & ACRIM







Construction of TSI Long Term Time SeriesThe ACRIM and PMOD TSI Satellite Composites

• A Composite of TSI observations can be constructed using overlapping comparisons

• A TSI database with long term traceability requires ‘bridging’ the ACRIM Gap

• ERB and ERBE comparisons with ACRIM1 and ACRIM2 to bridge the ACRIM Gap result in significantly different TSI trends during solar cycles 21 - 23

• The ACRIM Composite approach 1

ERB, ACRIM1,2 and 3 results published by the experiment science teamsERB comparisons with ACRIM1 and ACRIM2 to bridge the ACRIM GapACRIM3 scale

• The PMOD Composite approach 2

ERB, ACRIM1,ACRIM2 and VIRGO resultsSome ERB and ACRIM1 results altered results to conform with TSI proxy modelsERBE comparisons with ACRIM1 and ACRIM2 to bridge the ACRIM GapVIRGO scale

1 Willson & Mordvinov, GRL 20032 Frohlich & Lean, GRL 1998







Summary of ACRIM Gap bridging Using ERB, ERBE and Solar Magnetic Flux Area (SMFA) 1 Data

• All TSI and solar magnetic data show similar behavior before and after the ‘gap’

• ERB and SMFA data show similar upward trends during the ‘gap’

• ERBE shows a downward trend during the ‘gap’

• ERBE results do not conform to the TSI – magnetic activity paradigm 2 during the ‘gap’

Enhanced UV of solar maxima accelerates TSI sensor degradation ratesThe ‘Gap’ occurred during first exposure of ERBE to solar maximum UV levels

• Conclusion:

ERBE results likely compromised by uncorrected degradation during ‘gap’ERB results most reliable TSI database for bridging the ACRIM ‘gap’

1 Solar Magnetic Flux Area - National Solar Observatory/Kitt Peak Data Archives2 Willson & Hudson, Nature 1991



A Hybrid TSI Composite using aSolar Magnetic Flux Area (SMFA) 1

TSI Proxy Model 2 to bridge the ACRIM ‘Gap’

• ACRIM Gap dilemma: TSI trending during solar cycles 21 - 24

Nimbus7/ERB ACRIM Gap bridge à ACRIM Composite with 0.04 %/decade trendERBS/ERBE ACRIM Gap bridge à PMOD Composite with no significant trend

• SMFA TSI Proxy model provides an independent evaluation of the ACRIM ‘Gap’ issue

• The TSI – magnetic activity paradigm : TSI varies directly as solar magnetic activity

1 Solar Magnetic Flux Area - National Solar Observatory/Kitt Peak Data Archives2 Krivova, et. Al., Astronomy & Astrophysics 2007



Bridging the ACRIM Gap with the SMFA TSI Proxy Model

Comparing ACRIM1 results (black dots)With SMFA TSI proxy model (red lines)

before the ACRiM Gap

Comparing ACRIM2 results (black dots)With SMFA TSI proxy model (red lines)

after the ACRiM Gap

SMFA Proxy Model used to Bridge the ACRIM ‘Gap’

Hybrid ACRIM Composite agrees with the ACRIM Composite trend

during solar cycles 21 – 23



Reconstruction of ACRIM and PMOD TSI Composites

Using the SMFA proxy model (red lines)

to Bridge the ACRIM ‘Gap’

SFMA-ACRIM Composite (top) agrees with the ACRIM Composite trend

during solar cycles 21 – 23

SMFA-PMOD Composite (bottom) agrees with the ACRIM Composite trend during

solar cycles 21 – 23

Conclusion:

The Hybrid Composite results support the ACRIM Composite trend



Documents

Validation of the ACRIM composite TSI by solar surface magnetic field proxies