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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0063

Magneto-acoustic shocks in the chromosphere and UV variability+Hinode Observations in Support of MOTH-II  South Pole Observations

plan term


@ @


 name : Finsterele, Haberreiter, Kosovichev, Sekii, Jefferies
McIntosh, Jefferies, Fleck, Straus, Murhy, De Pontieu, Finsterle
@  e-mail : wolfgang[at]pmodwrc.ch

contact person in HINODE team

 name : Sekii
@  e-mail : sekii[at]solar.mtk.nao.ac.jp

 abstract of observational proposal
We propose to establish a physical connection between photospheric magnetic fields and the variability of solar UV intensity based on magneto-acoustic shocks produced by leaking p modes in magnetic regions. Based on multi-height Doppler and magnetic field measurements the amplitudes of upward traveling waves in the p-mode frequency range will be determined. As the pressure and density of the plasma decreases along the wave path pressure fluctuations of the wave can no longer be considered infinitesimal and hence the wave crest is significantly accelerated due to the temperature increase induced by the wave itself. This eventually leads to the formation of a shock front, i.e. a quasi non-linear increase of pressure and temperature. The shock front continues to travel upwards while dissipating its energy and thus heating the plasma. Numerical simulations of wave propagation and radiative transfer will be used to estimate the effect of such magneto-acoustic shocks on the UV emitting layers. The goal is to better understand the short-term (minutes) as well as long-term (decades, solar cycle) variability of UV irradiance. The result of such a simplified simulation is shown in Figure 1. Here, pure pressure waves were assumend and magnetic forces were neglected.

Motivating Science: The Magneto-Optical filter at Two Heights (MOTH) experiment has played an crucial role in our understanding of magnetoatmospheric (MA) waves and their interaction with the ever changing magnetic field  (e.g., Jefferies et al. 2006, ApJL, 648, 151) by simultaneously observing Doppler signals at two "heights" in the solar chromosphere. Throughout January 2008 the second MOTH experiment will be deployed at South Pole Station and will observe simultaneous magnetograms and Dopplergrams of the full solar disk in K I (7770) and Na I D1 (5896) at ~2.5 arcsecond spatial and 10s temporal resolution. This truly unique dataset, especially when combined with SOT, will allow us to explore the dynamics of the quiet chromosphere over the whole disk including high-impact investigations of potential p-mode and (~1mHz) internal gravity waves (Straus et al. 2007, Submitted to Science, November 2007 - available on request) coupling to Alfvenic motions that are now being abundantly observed in the chromosphere and corona (Tomczyk et al. 2007, Science, 317, 1192; De Pontieu et al. 2007, Science, 318, 1574). We also hope to measure the energy flow through the "acoustic portals" that are driven by relentless magneto-convection (cf. the excitation of fibrils and mottles, e.g., De Pontieu et al. 2007, ApJ, 655, 624).

 request to SOT
Hinode: SOT/NFI Mg Ib 517.3 high-cadence (10 – 60 sec) Doppler-grams near disk center, preferably in active region. Daily photospheric vector magnetograms (SOT/SP fast map 160h of the same area).

Joint Hinode/SOT observations will provide fantastic observational detail for MOTH-II - allowing the potential combination of wave and magnetic field evolution at granular and supergranular scales. By choosing a limb and disk target with modest length timeseries (~4hrs in length) we will be able to address a broad range of chromospheric wave phenomena (including those mentioned above) and get a new (more accurate) multi-point estimate of the wave energy flux in and through the quiet chromosphere. To this end we request a Hinode/SOT campaign with two targets (one at disk center and another at a determined limb position, possibly including polar coronal holes) that are repeated as often as possible throughout the MOTH-II observing period although one observation of each type will suffice.

Solar Optical Telecope

1.  NFI:  [2x2 pixel binning (~0.3" resolution) using <1kx1k of detector]
    - Halpha 6562.8 Dopplergrams at approx. (+- 204 mA) at 20s cadence [on
         disk - wave phenomena typically have ~3-5min periods]
       - Halpha 6562.8 Dopplergrams at approx. (+- 408 mA) at 20s cadence [for
         limb study - horizontal coupling, straws and  spicules]
    - Na I D 5890.6 Dopplergrams at approx. (+- 156 mA) at 20s cadence
    - Mg I b Dopplergrams at approx. (+- 114 mA) at 20s cadence
- Each sequence should be started and finished with both a Mg Ib and Na
         ID magnetogram
note: SOT Na ID magnetograms can be "calibrated" by MOTH II magnetograms of the same line].

2.  BFI:  [2x2 pixel binning (~0.3" resolution) using <1kx1k of detector]
- Ca II H imaging with relatively long exposure (~300ms) to enhance
         appearance of dynamic "straws" at a cadence of ~10s.
- Would like one sequence of Ca IIH [at the limb].
- Removal of this element for on disk will give better NFI cadence [by
         ~3s] and be able to run sequences longer.

3.  SP: Fast Maps [0.32" spatial resolution]. The SP map will be used to infer
   the field topology through inversions and extrapolations.
   - Repeated rapid rastering of target region at ~0.32" spatial resolution with
     step size of (0.32").

*NFI - obtain one disk center sequence with at least two positions in the wings of Mg I B (+- TBD),  and or Na 1 D (+- TBD), for more accurate determination of wave energy flux through chromosphere. This alone would be a truly unique observation.

 request to XRT
Special Considerations:  Plans for coordination with EIS and XRT will be developed with the relevant planners. There is potential that the CoMP instrument will be deployed at Haleakala Solar Observatory in time to support the these observations and provide wave context in the corona.

 request to EIS
Extreme-Ultraviolet Imaging Spectrometer

 - 2 repeated rasters of target region "HPW004_QS_RAST_120m" at start and end of
- for one hour of each targeted run do "IUU_QS_SNS_001" sit and stare at the
   image center of SOT/XRT

Special Considerations:  Plans for coordination with EIS and XRT will be developed with the relevant planners. There is potential that the CoMP instrument will be deployed at Haleakala Solar Observatory in time to support the these observations and provide wave context in the corona.

 other participating instruments
MOTH-II (South Pole): Full-disk high-cadence (10 sec) simultaneous dopplergrams and line-of-sight magnetograms in K I 769.9 (photosphere) and Na I D2 589.0 (low chromosphere).
MDI: Full-disk dopplergrams and line-of-sight magnetograms in Ni I 676.8 (photosphere)

MOTH-II Observations: MOTH-II is likely to begin observing around January 20th 2008 [almost continuously] for approximately two weeks.

Duration: We request that sequences of this type be run for between 1 and 2 hours per day of MOTH-II observations in combination/support of HOP63.

Target: Disk Center [Topology & Energy Flux] or Limb [Transverse Motion Coupling] Studies

FOV: As large as possible to retain cadence of ~10-20s  and be at least of dimension 100"x100"

Other Considerations :
- Combination with HOP63
- We wish to cycle through the 3 prime Doppler observations [Halpha, Na and Mg], one in each individual observation, where each observation also havs a Mg and Na magnetogram before and after time series for reference. Alternating Halpha (+- 204 mA) and (+- 408 mA) when pointed at disk center and the limb respectively although we would like at least one sequence of Halpha(+- 408 mA) at disk center. The inclusion or not  of Ca II H [SOT/BFI] at the limb can be decided by the planner but we would like at least one sequence [with reduced cadence] at the limb with this observation - NONE of the disk center observations should have this element.

Jan 14, 2007 - modifications of BFI/NFI based on discussions with Ted Tarbell.
Jan 16, 2007 - inclusion of HOP63 lead Finsterle
Jan 16, 2007 - Comments from B. Lites and T. Tarbell on SP resolution and NFI
               wavelength selection

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