Decadal Cycles in the Sun, Sun-like
Stars, and
Earth’s Climate System
Meeting Introduction
Tom Woods
LASP / University of Colorado
tom.woods@lasp.colorado.edu
Organizers
Bob Cahalan, Greg Kopp, Judith Lean,
Wes Lockwood, Vikram Mehta, Peter Pilewskie,
Tom Woods, Vanessa George
1
Five Themes for Meeting
1. Solar Irradiance Cycles
– Session 1, Tue 9/13 (11-year solar cycle)
– Session 5, Thur 9/15 (27-day solar rotation)
2. Comparative Sun-Star Cycles
– Session 3, Wed 9/14
3. Climate System Decadal Variability
– Session 2, Wed 9/14
4. Climate Sensitivity and Global Energy Imbalance
– Session 4, Thur 9/15
5. Modeling and Forecasting Solar Cycles and
Climate Impacts
– Session 6, Fri 9/16
2
Key Questions for Meeting
• What can we learn about decadal climate response and
climate sensitivity using the solar cycle as a wellspecified external radiative forcing?
• What is current understanding of the amplitude of solar
spectral variability and the response of the Earth’s
atmosphere and climate system?
• How does total solar irradiance vary over the solar cycle
and what are the implications for climate modeling to
recent refinements in its magnitude?
• How do comparisons with Sun-like stars improve our
understanding of solar variability?
• How can solar and climate models be advanced to
better reproduce decadal variability and improve
forecast capabilities?
3
Workshop Logistics
• Oral Presenters
– PC / Mac available: Office / Acrobat / Keynote (Mac only)
– Please provide presentation in advance (during breaks)
• Poster Session on Wednesday 3:50 – 5:30 PM with Reception
– 4’ x 6’ (1.2 m x 1.8 m) area assigned per poster
– Posters are up all week
– Poster Organizer: Marty Snow
• Need Help?
– Vanessa George can help with registration, hotel, and local questions
– Workshop Organizers: Bob Cahalan, Greg Kopp, Judith Lean, Wes
Lockwood, Vikram Mehta, Peter Pilewskie, Tom Woods, and Vanessa George
• Group Meals
– Lunches provided Tuesday, Wednesday, and Thursday
– Field trip and Science Dinner on Thursday afternoon / evening
• Internet – Wireless = meeting (not hhonors)
– User: hiltonsedona Password: Sedona
4
SORCE Fieldtrip & Science Dinner – Thursday, Sept. 15
Lowell Observatory
Flagstaff, AZ
Tickets: $50 (includes transportation
up scenic Oak Creek Canyon,
observatory admission, and a
wonderful reception and dinner).
Hilton front lobby entrance –
Buses load: 3:20 p.m.
Buses depart: 3:30 p.m.
See Vanessa by 2:00 pm today to
get your ticket. Please join us!
5
SORCE: A Mission of Solar Irradiance for Climate Research
• SORCE Measurements
– Total Solar Irradiance (TSI)
– Solar Spectral Irradiance (SSI)
http://lasp.colorado.edu/sorce/
• 0.1-27 nm and 115-2400 nm
– Daily cadence for data products
• Relations to Earth Science Research
– Critical measurement for solar forcing of
climate change
– Important measurements for radiative forcing,
dynamics, and photochemistry for atmospheric
studies
• SORCE Mission
– Launched January 25, 2003; now in extended
mission (NASA Senior Review this year)
– Instruments are in excellent condition
– Spacecraft is working very well but has limitedlife components (battery and reaction wheels)
SORCE aging spacecraft has had 4 safehold / contingency mode events since
last SORCE Meeting in May 2010. Most recent one was last week (9/6/2011).
6
Threat for TSI Climate Record Gap
• Glory launch failure on March 4, 2011 is threat to the 35-year total
solar irradiance (TSI) climate record
– SOHO, ACRIMSat, SORCE are old missions with limited life concerns
– Picard PREMOS is currently overlapping with SORCE and is intended
for a 2 year mission.
– It is not clear that JPSS TSIS will be launched soon enough to overlap
with SORCE.
7
SORCE Three Reaction Wheels are doing OK
• Reaction Wheel #3 experienced high friction in 2008 and
is now not being used for SORCE attitude control
Nominal 4-wheel control
RW#3
Anomaly
4-wheel control with bad wheel
Nominal 3-wheel control
SORCE Pointing Requirement: ≤ 1 arcmin
is still being met with 3-wheel control
8
SORCE life is likely limited by battery performance
• Ni-H Batteries have shown steady degradation since 2009
• Because of battery performance, we now cycle SIM, SOLSTICE,
and XPS on and off for each orbit, but have TIM on continuously.
TIM only
TIM & SIM-A
TIM & 2 SIM
Battery performance
trending indicates a
useful life until 2016
9
SORCE Data Products
• TIM TSI and SOLSTICE and XPS SSI data products are
released daily
– http://lasp.colorado.edu/sorce/ for SORCE products
– http://lasp.colorado.edu/lisird/ for other solar data sets
• SIM SSI (250-2400 nm) is routinely processed but have
not been released since October 2010
– Shifts in SIM due to thermal hysteresis during the spacecraft safehold
events is requiring the development of improved processing
algorithms for SIM
– Frequent (every orbit) power cycling of SIM causes wider thermal
swings than normal operations, so some of the SIM algorithms need
to be updated for this new operating mode of SIM
– It could be a year before the SIM revised algorithms are ready for reprocessing and having routine releases of the SIM data products
10
UARS Re-entry expected this month
• NASA predicts late September for UARS re-entry
– NASA solar irradiance observations continued on with ACRIMSat & SORCE
• Google UARS Re-entry countdown page is at:
– http://sites.google.com/site/uarsreentry/home
Upper Atmosphere Research Satellite (UARS)
Launched on Sept. 15, 1991. Operated until Dec. 2005.
UARS Solar Irradiance Instruments
ACRIM-II (TSI)
SUSIM (UV SSI)
SOLSTICE (UV SSI)
UARS being deployed from Space Shuttle
11
UARS made many, many contributions…
• For example, the UARS measurements are a critically
important part of the TSI and SSI climate records and
for providing solar cycle variation results for solar cycle
22 and 23.
ACRIM TSI
SOLSTICE & SUSIM SSI
(H I Lyman-α composite as example)
12