Current and Future Solar Observing Missions

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Current and Future Solar Observing Missions

• Tom Woods
• LASP / University of Colorado
• lttom.woods_at_lasp.colorado.edugt

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Outline

• Introduction to the Sun and Useful Definitions
• Possible repeat of some information in previous
  talks
• Brief History of Solar Observations
• Ground-based observations prior to space era
  (1600-1950)
• Early solar observations from space (1950-1995)
• Current Solar Observing Missions (1995-2007)
• Solar physics (imaging) missions
• Solar irradiance measurements
• LASPs Solar Influence Group and Their
  Contributions
• Future Solar Observing Missions (2008 and beyond)
• Solar physics (imaging) missions
• Solar irradiance measurements
• Homework Assignment

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Introduction to the Sun and Useful Definitions
4
The Sun
5
Radiance versus Irradiance
I(?)

• Spectral Radiance, I(?), is the intensity from a
  small region on the Sun
• Energy units of W / m2 / nm / steradian
• Spectral Irradiance, E(?), is the solar radiance
  integrated over the solar disk
• Also called Solar Spectral Irradiance (SSI)
• Sometimes called the full-disk radiation
• Energy units of W / m2 / nm
• Often normalized to 1.0 AU distance
• Total Spectral Irradiance (TSI) is the
  integration of the solar spectral irradiance over
  all wavelengths
• Sometimes called the solar constant
• Energy units of W / m2
• Often normalized to 1.0 AU distance

E(?)
6
Layers of the Solar Atmosphere

• Corona
• Outer layer - hot, low density
• 0.5 - 10 MK
• Transition Region
• Thin transition layer for temperature rise,
  plasma, and LTE
• 10,000 K -gt 500,000 K
• neutral -gt plasma
• LTE -gt non-LTE
• Chromosphere
• Warmer layer
• Photosphere
• Surface layer
• temperature 5700 K
• x 1000 less dense that air
• Convection Zone
• Upper 1/3 of Sun
• Solar dynamo
• Source of magnetic activity

REF Lean, A.R.A.A., 1997
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UV Emissions are from Different Solar Layers
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Solar Variability at Different Wavelengths

• Various images of the sun from SOHO showing solar
  activity
• Full-disk images
• B/W visible light from MDI showing sunspots
• Red Green EUV images from EIT showing active
  regions and flares
• Off-disk images
• LASCO coronagraph showing streamers of particles
  and coronal mass ejections (CMEs)

movie from SOHO web site figures from J. Lean
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Sources of Solar Variability (surface features)

• Harvey and White (Solar Phys., 1999) defined
  surface features based primarily on magnetic
  structures
• Quiet Sun (QS) quiet regions whose radiances are
  usually assumed to be constant, but SOHO-SUMER
  observations have proven this concept wrong for
  the EUV and FUV emissions (Schühle et al., 2000,
  AA)
• Sunspot (SS) dark regions that appear in the
  photosphere (effects irradiance gt 260 nm)
• Faculae (F) bright regions in the visible (gt 260
  nm)
• Active region (AR) very bright regions in the UV
  - above the sunspots also called plage
• Active network (AN) slightly bright regions in
  the UV (similar to faculae)
• Quiet network (QN) even less bright regions in
  the UV
• Coronal hole (CN) dark regions in the corona
  emissions

Ca II K line 6/03/1992
Features Map
Example of identifying surface features from a
solar image

• Black quiet-Sun
• Purple active network
• Lined active region (AR)
• White brightest AR

REF Worden et al., Ap J, 1998.
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Brief History of Solar Observations
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Ground-based Observations (1600-1950)
The sunspot record is the longest ( 400 years)
direct solar observation.
REF http//www.hao.ucar.edu/Public/education/spTi
meline.html
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Spörer's Law of Sunspot Migration
Spörers relationship of sunspot latitude with
solar cycle activity
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Early Detections of Solar Flares

• Routine scientific observations of the Sun began
  soon after the discovery of the telescope in the
  early 1600s
• Stephen Gary observed flash in sunspot on Dec.
  27, 1705
• Richard C. Carrington noted visible light flare
  on Sept. 1, 1859 while making routine sunspot
  observation
• Brightening started at points A B
• Brightening flowed along sunspot
• Disappeared at points C D
• Lasted for a few minutes
• Drawing from Carrington (M.N.R.A.S, 20, 13, 1860).

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Early Space Observations (1950-1995)

• Orbiting Solar Observatory (OSO) series
  1962-1978
• OSO-1 1962
• OSO-2 1965
• OSO-3 -4 1967
• OSO-5 6 1969
• OSO-7 1971
• OSO-8 1975

1950
1960
1970
1980
1990
2000
Sounding Rockets 1947-now
Skylab
Yohkoh (Japan)
Solar Maximum Mission
Orbiting Solar Observatory 8 missions
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Skylab - 8 Solar Instruments - 1973
corona, coronal holes, bright points, chromospheri
c (active) network, loops, spicules, polar
plumes, prominences
REF http//history.nasa.gov/SP-402/ A New Sun
The Solar Results From Skylab
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Solar Maximum Mission (SMM) - 1980

• 4 solar imaging instruments

corona, coronal holes, bright points,
flares, coronal mass ejections (CME), chromospheri
c evaporation
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Yohkoh (Japanese) Solar Observatory - 1991

• 4 solar imaging instruments

corona, coronal holes, bright points, arcades,
flares, magnetic reconnection
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Solar Physics Critical Questions - 1995

• Coronal Heating Process
• What heats up the corona to 2 MK?
• Nanoflares
• Nature of Solar Flares
• What causes solar flares and coronal mass
  ejections?
• Magnetic reconnection in the corona
• Origin of the Sunspot Cycle
• What is the basic physical principles that drive
  the 11-year solar cycle (22-year magnetic cycle)?
• Dynamo (magnetic field dynamics) at base of
  convection zone
• Missing Neutrinos
• Why is the number of neutrinos observed about a
  factor of 2 less than predicted?
• Discovery of muon neutrino oscillations, and
  thereby neutrino mass

REF http//solarscience.msfc.nasa.gov/
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Previous Solar Irradiance Measurements

• SSI
• Visible GOME
• MUV Nimbus, SBUV, SME, UARS, GOME
• FUV OSO, AE-E, SME, UARS
• XUV/EUV SOLRAD, AE-E, GOES, SNOE

• TSI
• ERB/ERBE
• SMM ACRIM
• UARS ACRIM
• SOHO VIRGO

• Solar Irradiance Questions
• What is the solar cycle variability in the
  XUV/EUV, visible, and infrared ranges?
• What are the long-term (decade-century) changes
  in the TSI and SSI?
• What are the spectral variations during flares?

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Composite Time Series Important for Climate Change

• Issues in combining data sets
• Calibration differences
• Instrument degradation issues
• Gaps between measurements
• Factor of 2 difference is found at times in the
  UV range

REF Woods et al., JGR, 2000
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Are Solar Minima All the Same?

• Understanding long-term solar forcing on climate
  change depends on understanding how the solar
  cycle minima are changing
• Some assume NONE
• Paleo-climate requires SOME
• VIRGO composite shows small change, if any,
  between SC 22 min.
• But ACRIM composite shows large increase

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Current Solar Observing Missions (1995-2007)
REF http//www.lmsal.com/solarsites.html
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Current Solar Physics Missions

• Solar and Heliospheric Observatory (SOHO)
• Transition Region Coronal Explorer (TRACE)
• Reuven Ramaty High Energy Solar Spectroscopic
  Imager (RHESSI)
• Solar-B (Japan) - renamed Hinode
• Solar-Terrestrial RElations Observatory (STEREO)
• GOES Solar X-ray Imager (SXI)
• CORONAS-F (Russia)

TRACE
Hinode (Solar-B)
SOHO
STEREO 2 S/C
RHESSI
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SOHO Helioseismology, Corona, Solar Wind

• In orbit about Sun-Earth Lagrangian point (L1)
• 9 solar instruments, 3 particle instruments

Helioseismology (surface oscillations used for
imaging the interior of the Sun) Back-side
solar imaging Corona Dynamics Global Waves
(after large flares) Solar Wind and CMEs
(particle outflow from the Sun)
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TRACE High Spatial Resolution Imaging

• SMEX with single instrument telescope with EUV
  and FUV filters
• High spatial resolution 0.5 arc-sec per pixel
• High time cadence 5 sec usually (lt 1 sec
  sometimes)
• Not full-disk imager 8 x 8 arc-min region

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RHESSI Hard X-ray Solar Imaging

• SMEX with single instrument hard X-ray
  telescope
• Study high-energy processes of flares

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Hinode (Solar-B) Dynamic Magnetic Fields

• Japanese solar mission with 3 instruments
• Advanced instruments for vector magnetic fields,
  coronal X-ray full-disk imaging, and coronal EUV
  long-slit (spectral) imaging
• Very high spatial resolution (0.2 arc-sec) for
  magnetic field imaging

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STEREO Stereographic Imaging of CMEs

• 4 instrument suites on two identical spacecraft
• 2 different locations provides first ever
  stereographic imaging of CMEs

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Current Solar Irradiance Measurements

• NOAA SBUV (200-400 nm) and XRS (2 X-ray bands
  0.05-0.8 nm)
• SOHO SEM (2 EUV bands 0.1-50 nm)
• SOHO VIRGO (TSI)
• TIMED SEE (0.1-194 nm)
• SORCE (TSI, 0.1-27 nm and 115-2400 nm)

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SOHO Irradiance Measurements

• SOHO SEM 2 EUV bands
• Transmission grating with Si photodiodes, 15-sec
  cadence
• 1st order 26-34 nm and 0th order 0.1-50 nm
• SOHO VIRGO TSI
• 2 instruments PMO6V and DIARAD

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NOAA Irradiance Measurements

• POES SBUV
• Ozone spectrometer
• Daily (calibration) solar measurements from 200
  nm to 400 nm
• Mg II core-to-wing ratio - important
  chromospheric proxy
• GOES XRS
• 2 soft x-ray photometers, 0.05-0.4 nm and
  0.1-0.8 nm
• Reference for X-ray flare classification
• eXtreme, Medium class
• small C, B, A
• 3-sec cadence, but only 1-min and 5-min data
  available

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TIMED SEE Measures Solar VUV Irradiance
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Example TIMED SEE Time Series

• New measurements of the solar EUV irradiance time
  series are providing new results on the solar
  variations, especially important for shortward of
  115 nm where daily measurements have not been
  made since 1981 (the EUV Hole).

REF Woods et al., JGR, 2005.
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SORCE Measures TSI and SSI
REF SORCE, Solar Phys., 2005.
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TSI Record Relies on Continuity
Satellite measurements of TSI have been made
since 1978. Current TSI measurements are from
SOHO VIRGO, ACRIMSAT, and SORCE TIM.
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Solar Variability versus Wavelength

• SORCE solar rotation (27-day) variability
  consistent with UARS results
• UARS REF2002 Woods and Rottman, 2002
• Variability longward of 400 nm is consistent with
  average temperature change of the Planck function

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11-Yr Solar Cycle Variability in Energy Units

• Although relative (ratio) variability is small in
  the visible, the visible variations dominate in
  energy units
• About 50 of the energy change is from the
  visible
• UV and IR contribute about equally to the
  remaining variations in energy

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LASPs Solar Influence Group and Their
Contributions
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LASP Organization Chart
LASP Director - D. Baker LASP Admin. Dir. - C.
Himes
Color Definitions Laboratory Division Group
Assoc. Dir. - Technical T. Woods
Assoc. Dir. - Science B. Jakosky
Administration Division C. Himes
Engineering Division M. McGrath
MOIS (Operations) Division W. Possel
Science Division B. Jakosky
Earth Atmos. Group Lead - C. Randal
Mechanical Group Lead - H. Reed
Accountant Group Lead - A. Perez de Tejada
Operations Group Lead - S. Ryan
Planetary Group Lead- B. Jakosky
Electrical Group Lead - J. Westfall
Planning Group Lead - K. Griest
Admin. Support Group Lead - C. Himes
Solar Influence Group Lead - T. Woods
Data System Group Lead - C. Pankratz
RA/QA Group Lead - T. Taylor
Computer Group Lead - G. Schut
Space Plasma Group Lead - R. Ergun
Assembly Group Lead - S. Bramer
E/PO Group Lead - E. CoBabe-Ammann
Calibration Group Lead - G. Drake
Flight S/W Group Lead - G. Tate
Program Managers Group Lead - M. McGrath
System Engineers Group Lead - M. McGrath
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Solar Influence Group
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Future Solar Observing Missions (2008 and beyond)
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Outstanding Questions in Solar Research

• New Research Initiatives from The Sun to the
  Earth - and Beyond (2005)
• What physical processes are responsible for
  coronal heating and solar wind acceleration, and
  what controls the development and evolution of
  the solar wind in the innermost heliosphere?
• What determines the magnetic structure of the Sun
  and its evolution in time, and what physical
  processes determine how and where magnetic flux
  emerges from beneath the photosphere?
• What is the physics of explosive energy release
  (e.g., flares, CMEs) in the solar atmosphere, and
  how do the resulting heliospheric disturbances
  evolve in space and time?
• What is the physical nature of the outer
  heliosphere, and how does the heliosphere
  interact with the galaxy?
• How do the changes in solar irradiance relate to
  the evolving solar magnetic field, and how do
  these irradiance changes affect the short-term
  space weather operations and the long-term
  climate changes?
• Areas of Research
• Solar Interior
• Quiet Sun
• Active Sun
• Solar Wind / Heliospheric Processes
• Solar Irradiance

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Future Solar Physics Missions

• NASA
• SDO 2009 - HMI, AIA, EVE for helioseismology ,
  EUV images, EUV irradiance
• Glory TIM 2009 - TSI
• Solar Probe mission to the Sun !
• NOAA
• GOES SXI and SUVI are solar imagers
• GOES XRS and EUVS are X-ray and EUV solar
  irradiance instruments
• NPOESS TSIS for TSI and SSI
• ESA
• Space Station solar irradiance instruments
  (SOVIM, SOLSPEC, SOLACES)
• French PICARD 2008 - first solar diameter
  measurements from satellite
• Solar Orbiter
• Other Missions
• Russian CORONAS-PHOTON 2007
• French-Chinese SMESE 2010
• Chinese KuaFu 2012
• Japan, South Korea, India, Canada, Taiwan,
  Brasil, and potentially others are also
  considering future solar missions

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NOAA Taking Over Solar Irradiance Monitoring
Solar Radiation and Climate Experiment
(SORCE) 2003 to 2010 or longer Solar Irradiance
TSI, 0.1-27 nm, 115-2700 nm
2005
2010
2015
2020
TIMED 2001 to 2010 or longer Solar EUV
Irradiance 0.1-190 nm
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SDO is Ultimate Flare Mission

• SOHO, TIMED, and SORCE (and previous missions)
  have observed hundreds of flares but the
  information is incomplete
• Observations of single, small region on Sun
  (SOHO)
• Observations of single wavelength at time (SOHO,
  SORCE)
• Observations with limited time coverage
• Duty cycle low (TIMED - 3, but simultaneous
  spectral coverage)
• Time cadence slow (SORCE 5-min to 100-min)
• NASA SDO mission addresses these issues with
  full-disk solar images, complete EUV spectral
  coverage, 10-sec cadence, and 100 duty cycle
• HMI vector magnetogram images
• AIA full-disk EUV images
• EVE EUV irradiance at 0.1 nm spectral resolution
• Launch planned for January 2009
• Web site http//sdo.gsfc.nasa.gov/

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Visit LASP Clean Room to see EVE and TIM
Instruments
SDO EVE EUV Variability Experiment
Glory TIM Total Irradiance Monitor
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Homework Assignment
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Solar H I Lyman-? Emission Line

• The bright hydrogen (H I) Lyman-? emission line
  at 121.57 nm is an important solar emission for
  both solar physics and solar-terrestrial
  atmospheric research.
• What is the atomic transition (configurations)
  for the Lyman-? line?
• See NIST Atomic Spectral Database web site
  http//physics.nist.gov/PhysRefData/ASD/
• How many LASP instruments measured the solar
  Lyman-? emission line?
• See LASPs Interactive Solar Irradiance
  Datacenter (LISIRD) http//lasp.colorado.edu/lis
  ird/
• How much does the solar Lyman-? emission vary
  over the 11-year solar cycle?
• One can estimate the variations by using the
  Composite Lyman Alpha link on the LISIRD web
  site to view the solar Lyman-? time series.