Last Update: March 13, 1998

Number: JOP072

Submitted: October 23, 1997

Philip Judge, HAO, NCAR, Boulder CO, USA.
Bruce Lites, HAO, NCAR, Boulder CO, USA.
Ted Tarbell, Lockheed
Mats Carlsson, Viggo Hansteen, Oivind Wikstol, University of Oslo, Norway
Klaus Wilhelm, Lindau
Richard Harrison, RAL
Joe Gurman, NASA GSFC.
Rock Bush, Stanford



We propose an extension/modification of JOPs 20 and 46 and several chromospheric dynamics campaigns to take advantage of the unique spatial and temporal resolution of the TRACE instrument. It is likely that this can be run during the TRACE "30 day plan". UPDATE: Currently this is planned for the week of 11 May 1998, especially 16, 17 May. TRACE/SUMER observing sequences are attached.

Scientific Justification

The basic physical processes in the solar chromosphere, transition region and corona are very complex. These plasmas are controlled by magnetic fields emerging from beneath the photosphere and which are driven at the base by convective motions. Neither the nature of the driving motions or the response of the plasma is adequately constrained by currently available observation or by numerical simulation, except in the very simplest cases whose reality must be seriously doubted on observational and physical grounds. Thus, one must continue to turn to observation for further insight into these regions of the Sun's atmosphere. Spectral data of the chromosphere, transition region and corona from many instruments indicate that dynamical processes, both resolved and unresolved in space and time, are critical to the formation and interpretation of such data and are central to the coronal and chromospheric heating problems. Theoretical considerations of viable heating mechanisms support this viewpoint. SOHO data from JOP20, JOP46 and other studies have revealed interesting dynamical evolution of emission lines in "quiet" regions on timescales down to 10 seconds or so, for lines formed in the chromosphere, transition region and corona (e.g., Judge, Carlsson, Wilhelm 1997; Hansteen 1997; Judge 1997). Analysis of these data, primarily from SUMER, CDS, EIT, MDI, is beginning to yield new insights into heating mechanisms. Detailed analysis will require numerical simulations of gas dynamics in flux tubes protruding into the corona. These difficult (radiation- magneto- hydrodynamic) calculations are currently at a basic level of development, but progress has been made. 1D radiation hydrodynamic (and reduced magneto-hydrodynamic) simulations can be made (Carlsson & Stein 1997) accounting for a consistent NLTE treatment of the radiation field and constituent atoms. In 2D, MHD simulations are possible in simple magnetic topologies with a self consistent NLTE treatment in optically thin plasmas. Realistic simulations of the dynamic evolution of the spectra, albeit in simple geometries, will soon be brought to bear on the interpretation of these data. Observations with the TRACE instrument can provide vital additional information through the higher spatial and temporal resolution than is available with EIT. Based upon SUMER timeseries data, it is clear that EIT misses a substantial fraction of important time variations in the transition region and chromosphere that occur on timescales of 10 or so seconds instead of a minute. TRACE also will provide valuable rapid imaging data of the UV continuum and the Ly alpha and C IV regions whose spatio-temporal behavior cannot be explored in the same way with the SOHO instruments which require rastering. Although the instruments all have pixel sizes orders of magnitude larger than the energy dissipation scale lengths, the combination of SUMER with MDI, CDS, TRACE and ground based data (see below) should provide the clearest picture yet of the nature of the dynamic evolution of plasmas in response to photospheric driving motions, that will probably not be surpassed for the forseeable future.

Observations Requested

As well as a high spatial resolution, TRACE has the unique capability of acquiring imaging data over significant areas of the solar disk at a cadence on the order of 10 seconds, a factor of 3 better than is possible with EIT. We wish to obtain TRACE images at the highest rate of cadence together with SUMER, CDS, MDI data running at their respective highest cadences. Each time series should be at least an hour, and even longer to permit co-alignment from maps constructed using the rotation of the Sun (see below). We would choose quiet Sun and active region targets close to disk center. Sunspots would have a higher priority for reasons of co-alignment (below). We have modified existing SUMER sequences from JOP20, JOP46 to match the TRACE sequence written by one of us (T. Tarbell). Both are listed below. We propose to observe the C IV line region with TRACE, and the O VI/ C II/ O I/ continuum region with SUMER (the C IV region is too weak in SUMER, and our experience shows that C IV and O VI should behave in similar manner). These will be augmented with MDI magnetic field and velocity data, and with vector magnetograph data from Sac Peak obtained with the Advanced Stokes Polarimeter (ASP). Ca II H line data will also be acquired with the ASP together with slit jaw images. Our main difficulty will be to co-align data acquired with SUMER without E-W mapping capability, to the TRACE, Sac Peak and MDI magnetogram data. To be successful co-alignment must be achieved to better than the width of the SUMER point spread function which is 1 arcsecond. Two techniques can be used for this. The most reliable is to use the SUMER rear slit camera to observe white light images every few minutes. This requires observation of the passage of a sunspot, together with associated plage. The less reliable technique involves constructing a map from a longer SUMER timeseries, using the known solar rotation rate to map the quiet Sun in the E-W direction. Experience has shown us that MDI/SUMER can always be co-aligned to better than 2-3 arcseconds with this method, but to do substantially better is difficult, probably because MDI looks at photospheric magnetic fields but SUMER sees low/ middle chromospheric emission- these are not expected to co-align except on coarser scales. Both methods will provide substantial accumulated counts, so targets for this JOP, if run, should be chosen carefully. The sequences below should allow accurate co-alignment of TRACE and SUMER data using the C IV (TRACE) and O VI (SUMER) maps. SUMER and MDI/Sac Peak data will be co-aligned through rears slit camera observations of sunspots (if available) and using the UV continuum formed deep in the chromosphere for comparison with Sac Peak Ca II and magnetic field data. Attached below is a justification for adopting telemetry sub-mode 4, giving SUMER a high telemetry rate for a short period, to enhance our ability to obtain accurate co-alignment as well as more useful data. MDI should be run in the high resolution mode. CDS should use sequences run previously for JOP20 and JOP46. References: Carlsson, M., Stein, R.F., 1997 ApJ Hansteen, V., 1997, Proc. Oslo SOHO workshop. Judge, P., Carlsson, M. Wilhelm K., 1997 , ApJL, in press. Judge, P., 1997, Proc. Oslo SOHO workshop.

(During TRACE's 30 day plan)

Observations have been requested from Sacramento Peak for the period 11 May- 17 May. MDI should operate in high resolution mode, returning Doppler and magnetograms as rapidly as possible. EIT and CDS are not required in this campaign SOHO Telemetry submode 4 has been requested for 16 and 17 May 1998, and these days should have highest weight when planning. JUSTIFICATION FOR TELEMETRY SUBMODE 4 We would like to obtain co-aligned timeseries data with SUMER, TRACE, and Sac Peak (Advanced Stokes Polarimeter [ASP]) to look for chromospheric, transition region and coronal responses to changes in the photospheric magnetic and velocity fields in the quiet Sun, and weak active regions. Earlier work with SUMER, MDI and ASP have shown that the more data we have to try to co-align, the more accurate the co-aligment is-- it has been very difficult for us to obtain co-alignment of these data to better than +/- 2 arcseconds, using SUMER's 120 arsecond long slit. This error is larger than the width of the SUMER and ASP slits. Thus, if we can use a long slit with SUMER (300 arcseconds), we will obtain more data with which to co-align as well as obtaining more data to analyze, improving statistics considerably. With 20KB/sec, we can run SUMER at a cadence of 7 seconds per 50 wavelength pixel window without filling memory. We would operate with 3 or 4 such windows.


The following SUMER sequence uses a 20KB/s telemetry rate and loads 3 Mbyte into SUMER's on-board memory. The study is centered around item 2, a 127 minute timeseries with 25 second cadence and rotational compensation. Either side is a three window timeseries of 76 minute duration without compensation, thereby producing maps, and the whole timeseries is sandwiched between two full spectral frames. The wavelengths windows to be observed (for item 2) are: O I .... 1041.69 Angstroem C II .... 1035.80 Angstroem CONT .... 1047.00 Angstroem O VI .... 1038.00 Angstroem This list contains the continuum formed in the lower- middle chromosphere (near 1Mm height above the photosphere), O I lines near 1.5Mm, C II lines formed in the lower transition region and O VI formed in the middle transition region. Item Description 0. Full frame 1. 3 window timeseries, 25sec exposures, no tracking => map, dur=77min 2. 4 window timeseries, 25sec exposures, tracking, dur=127 min 3. 3 window timeseries, 25sec exposures, no tracking => map, dur=77min 4. Full frame total duration = 285 minutes Parameter List for SUMER Study: j72_o1039_mem Item # 2 ------------------------------------------------- You have selected (Irrelevant points are not listed.): 1. Interruption or flag mode: Interruption by ground command. 2. Slit 2 with 1*300 arcsec^2. 3. Point to QUIET SUN SOHO roll angle: 0.00000 deg 4. Solar rotation: Standard compensation. 5. Binning (spectral) = 1 (spatial) = 1 6. Compression: 5. Quasilog_min_max (0.92 s). Flat-field correction: OFF 7. Reference pixel 1: 724 on detector B Ion(s) in band 1: O I .... 1041.69 Angstroem C II .... 1035.80 Angstroem CONT .... 1047.00 Angstroem O VI .... 1038.00 Angstroem Spectral window(s) (pixel): 50 8. Image format: Format #8 (50*360, B1); 4 time(s) 9. Spectrohelio mode: Spectrohelio 3 Scans back and forth. Integration time: 25.0000 s Step size: 0.00000 arcsec or 0 units. Image number: 1.00000 17. Your selection requires a mean telemetry rate of: 23.0400 kbit/s Available bitrate: 20.0000 kbit/s This item will run for approximately: 126.689 minutes and will cover a solar area defined by 300 px time(s) 0.00000 arcsec Note that the memory monitoring and the run times are not very accurate. The run times just give the total exposure times with a margin of 1%, but the grating focus adjust time is included. More detailed information can be provided by the SUMER Simulator. All items up to now will run for approximately: 205.734 minutes You will use for this item: 2.95124 MB out of which 0.00000 MB are for uncompressed images. You will have used in total: 2.95124 MB out of which 0.00000 MB are for uncompressed images.


//name:TDT.trfast.useq //description: Fast fluctuations in the transition region //revision: 2 //status: draft //date: 19971126 //keywords: 53: Transition Region, 47: Spicules, 55: Waves //ID: //Type: main program //Target: top1 //Termination: by interrupt //Telemetry: TBD // Original by Charles Kankelborg, called CCK.rapid.partial.1600plus.useq // Fast time series of 1600, with 1550 & 1700 every 52 sec, EUV every 7 mins. // 256 x 1024 field in center of CCD in UV, 1024 x 1024 centered in EUV // Check for flare in EUV (full frame) & 1600 (partial frame) // If flare flag is detected, take only fast UV frames, no EUV // Add safeframe, full EUV frames, 2.25 sec cadence $type:main // define sequence type $PRI=0; // lower priority to allow interrupts $FEF=0; // reset the flare flag resetaec; target(top1); set_target_list(top1); call(STD.CCDsafe_init); // initialize CCD safety check //setup frames: darks and EUV AEC set_frame_list( tdt.trdark1, tdt.trdark1, tdt.trdark2, tdt.trdark3 ); $L0 = 3; while($L0--) { execute_list(0s,0s,@saa_pause); } set_frame_list( cjs.stdaecfull171, cjs.stdaecfull195 ); $L0 = 3; while($L0--) { execute_list(0s,0s,@saa_pause); } while(1) { // run until interrupted $L1 = 8; // 8 reps @50s ~ 8 min. while($L1--) { $L0 = 16; // 16 reps @2.25s = 36s delay(1); // reset delay time while($L0--) { if ($FEF) frame(tdt.trfast1600AEC); else frame(tdt.trfast1600); delay(45); // 2.25s cadence } frame(tdt.trfast1700); frame(tdt.trfast1550); } if ($saa ==0) safeframe(cjs.stdaecfull171); // not in SAA if ($saa ==0) safeframe(cjs.stdaecfull195); target(top1); } return 0;