Coronal Hole Boundary Working Group: Work Plan
To: E.
Antonucci, J. Geiss, J. Raymond, P. Riley, R. von Steiger, T. H. Zurbuchen
CC: L.A.
Fisk, G. Gloeckler, J. Kohl
Coronal hole boundaries are being studied
using a combined set of UVCS and SWICS (Ulysses and ACE) data. The connection
between solar and heliospheric data is performed using 3D-MHD simulations to
account for stream-stream interactions in the heliosphere.
The
following scientific question are identified in decreasing level of priority:
1. Coronal boundaries
in composition and density: Identify boundaries in the solar wind and the
corona.
How sharp are they
? Why are they so sharp ?
2. Determine degree of
super-radial expansion.
Dynamics ?
Systematic variations and sub-structure in coronal hole ?
3. How is the solar
wind accelerated.
Constrain solar
wind models using UVCS data.
These
questions should be considered in the context of more general questions such as
A. Cause of the FIP
effect, difference between fast and slow wind.
B. The He/H in the
Outer Convective Zone (OCZ) compared with the slow solar wind.
It will be addressed using the following data-sets:
UVCS:
n
kinetic properties (speed, temperatures)
n
O/H ratios
n
other compositional ratios such as Si/O
n
Electron density
n
speed profiles
The UVCS team will produce synoptic Carrington maps and/or
global maps (or other suitable data-formats). We will start with relatively coarse
spatial resolution and go to more sophisticated data-products as time proceeds.
SWICS:
n
differential speeds, non-thermal temperature distributions
n
Elemental ratios (Si/O, O/H, ..)
n
Ionic compositions (O7+/O6+, C6+/C5+,…)
SWICS data will be mapped back to these maps using the MHD
codes.
This will be addressed using the following methods.
n
SWICS data will be ordered and averaged according to
equivalent expansion level. MHD data may be used for this.
n
UVCS will look at coronal hole boundary effects such as
suggested by SWICS.
n
Simple analytical models will be created/revisited in
connection with large-scale MHD models to characterize fundamental constraints
for over-expansions.
n
The expansion constraints from coronal measurements from
magnetic field data will be revisited.
We will
use the same data as for Question #1.
This will be addressed using the following methods.
n
The MHD model, with improved energy equation is tested
using UVCS electron data and radial velocity profiles.
The study will be performed using the following time-periods.
|
Period at the Sun |
In situ |
Description |
|
|
|
|
|
CR 1912-1918 |
July 96 - January 97 |
Solar minimum. Penetrate boundary from fast wind. Ulysses and UVCS. |
|
CR 1922-1924 |
April 97 - June 97 |
Penetrate boundary from slow wind. Ulysses and high-resolution UVCS |
|
CR 1948-1949 |
April 26 99 - June 99 |
Isolated coronal holes. ACE, Ulysses and high-resolution UVCS. |
The first
part of the work will concentrate on the first time-period, 2nd
priority is the 2nd time-period.
|
When |
Who |
What |
|
|
|
|
|
Soon |
Ruedi von Steiger |
Create WWW page at ISSI where information/data can be accessed.
Inform team. |
|
|
Thomas Zurbuchen |
Correct/distribute the workplan. Put Posner et al paper
on WWW. |
|
|
Pete Riley |
Put some detailed code information on WWW. |
|
August 1st |
Ruedi/Thomas |
SWICS data on WWW |
|
|
Ester Antonucci/John Raymond |
UVCS data, first cut on WWW. Ester: dynamics maps; John:
composition maps (or, according to decision between Ester & John). |
|
|
Pete |
Simulation results, at least partly, available on WWW. |
|
September 1st |
All |
First study completed |
|
|
Thomas/Ruedi |
AGU abstract submitted after teleconference. |
|
March 1st |
All |
2nd time-period completed, 1st
time-period completed at better, revised quality. |
|
March 2nd - March 5th |
All |
Working group meeting at ISSI in Bern. |
|
|
|
|
n All data will be exchanged in IDL, read-routines will be made available.
n Information will be exchanged using a WWW page provided by Ruedi von Steiger at ISSI.