1. Validating Models of the Corona and Inner Heliosphere Discussion Leaders Bart Van Der Holst, Peter MacNeice

2. Objective To initiate the design and execution of a program of model validation that would enable users and developers of coronal and inner heliospheric models to better understand the relative strengths and limitations of the codes. Ideally to leave having – identified a set of test problems – settled on a common format for presenting results – agreed on a schedule Getting these was always going to be an extended multi-stage and multi-year process Yesterday we made a solid start!

3. The Process Stage 1 (here) - ‘Buy In’ Stage 2 (here) – Identify the broad outlines of a set of tests Stage 3 (next 6 months) – Define the specific details of each test Stage 4 (6-12 months) – First model runs complete Stage 5 (Year 2) – Refine problem definitions and rerun Stage 6 – Final Report

4. Stage 1 – ‘Buy In’ Well attended and lively debate Unanimous agreement that the goal is worthy Issues all centered on whether it can be completed successfully – Consensus seemed to be yes – if the initial effort doesn’t over-reach Limit the number of test cases Carefully constrain the model input Where possible develop tests around well studied datasets Zoran suggested making this the subject of a SHINE proposal to give the project additional momentum Philosophy of approach – Focus on science rather than space weather based metrics Importance of having multiple metrics for each test case Means to avoid tuning for specific metrics Critical mass of model developers

5. Potential Model Participants Corona – MHD PredSci SWMF Wu et al – NLFFF Wiegelmann et al ?McTiernan et al ?Wheatland et al ?Regnier et al McKay, Yeates, Van Ballegooijen – Potential ?DeRosa and Schrijver Arge et al Inner Heliosphere PredSci SWMF ENLIL ?HAF Wu et al Arge et al Jackson et al Merkin et al

6. Stage 2 – Outline of Test Set Global corona – Full disk EUV and X-ray image reconstruction – Locations of coronal hole boundaries – Size and location of streamer structures – Importance of using multiple lines to avoid over tuning heating functions – Recommended submission of model solution in form of plasma parameters ( ,T,v) and a single ‘forward modeling’ application to be used uniformly for all models – Tests should target both solar max and min – Leonard Strachan identified his UVCS database and its synoptic ,T,v maps as a usable measure of ground truth particularly at solar min – Discussion of need for corrections for scattered light – How to make comparison with observation more quantitative Extract DEM from different classes of features ‘Line cuts’ through emission maps – CoMP Polarization measurements might also be used as metric – Metric should expose alfven profiles in low coronal solutions – Should use magnetogram data from multiple sources V o at 2.3 R o Strachan

7. Stage 2 – Outline of Test Set Inner Heliosphere – IMF and plasma parameters – SIR / CIR structure and location – Importance of testing at range of latitudes – Coupled corona and inner heliosphere may be too ambitious Different coronal models would mean helio components were solving different problems Can we construct a ‘standardized ‘ inner BC that all competing helio models could use? – Heard about the updated UCSD Heliospheric Tomography model and how it could be used to support the test setup Merkin

8. Summary Will probably limit initial effort to two test cases – Static global corona – Ambient helio structure I will set up a communication network to keep this dialogue active In 3 months hope to hold a telecon to propose a specific set of test cases to be defined in greater detail over the following 3 months Expect to continue this working group next year I see no reason why we cannot be reporting results of our first iteration then