1. 3 rd RSIH&SWA Workshop – Morelia, Mexico – 20 October 2015 IPS Cross-Analyses M.M. Bisi (Mario.Bisi@stfc.ac.uk) (1), E. Aguilar-Rodriguez (2), and The world-wide IPS community.. (1) RAL Space, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, OX11 0QX, England, UK (2) Instituto de Geofisica, Unidad Michoacan, UNAM, Mexico

2. Outline  Why?  Original Plan  Ad-hoc Modified Plan  Where are we?  Open Discussions

3. Why?

4. Why (1)  IPS is a powerful tool for investigating coronal and heliospheric outflow; this includes ambient, co-rotating, and transient flows.  There are multiple active IPS analysis suites in use world wide with different methodologies in getting to, and in presenting, the end data products such as velocity(ies), g-levels, non-radial flow angles, relative densities, etc…  There are both single-station and multi-station analyses methods where the results from the two are not always the same.  There are formal fitting methods as well as geometrical methods to be able to get to the end results.

5. Why (2)  IPS is hugely under-exploited by the greater Heliophysics community and part of that is people’s lack of understanding of the data products, and how they are obtained, that IPS is able to provide to them.  Some great example of exploitation thus far include multi- technique studies (visible-light combined with IPS), driving MHD models (including comparisons with the outer heliosphere), tomographic methods, and studies using IPS from different frequencies and different systems to track features right through the inner heliosphere (at least to the Earth and Mars); but much more could be achieved.

6. Why (3)  For multi-site methods, two or more observing sites are used to simultaneously observe the same radio source where the geometry is sufficient to have the parallel baseline roughly aligned to that of the plasma outflow.  There is typically a cross-correlation analyses undertaken where velocity estimates are given based on the peak position in time lag of the cross-correlation function and the parallel baseline length.  Additional formal fitting to multiple spectra have been used in the past to be able to obtain more fundamental parameter values such as the axial ratio, alpha, density ratios, etc…

7. Why (4)  For single-site analyses, there are several different approaches based around the fitting of the IPS power spectrum where the position of the Fresnel knee gives an indication of the outflow velocity.  However, there are not uniform methods to produce power spectra (as became evident at the Nagoya 2013 meeting) and also no uniform method (although based in principle on solving the same IPS equation, but with so many different parameter assumptions in different cases by different observatories) to obtain velocity values.  Producing g-level values also seems to have differences.

8. Why (5)  End result is often different values of parameters for very similar/identical plasma regimes with no complete understanding of how, where, or why these differences came about – hence the need for some form of cross-analyses of methods and perhaps some cross-calibration of results (certainly from single- to multi- site approaches); tomographic methods where multiple data sources are subsumed into one single tomographic output account for some of the discrepancies due to best-fitting of the data to a model, but not for all…

9. Original Plan

10. Original Plan (1)  Share well-known (to the observer) IPS time-series data for several good IPS sources over a few days (perhaps five sources over three days of observing – needn’t be consecutive).  A description of how the time series is formatted (e.g. time- series sampled at 100Hz for 15 minutes of data observing J0318+164 using XXXXX observatory/station with an arbitrary amplitude scale in YYYYY binary format including ZZZZZ lines of header, etc…).  Each active analyses suite would then be used on each of the different data sets to produce power spectra, velocity/g-level values, cross-correlation functions, etc…, accordingly.

11. Original Plan (2)  A DropBox was set up for sharing the data and data descriptions and then for sharing all the analyses on each of the sets of data.  Then a comparison at this workshop (today) would be undertaken in looking at the differences/similarities in how the power spectra are ‘looking’, and also in how the results compare – at least for velocity as a starting point (with g-level also considered for sites and analyses tools where this is a capability).  All of this would be undertaken for each INDIVIDUAL observation in the hope of forming a larger picture of where things stand between the different observing methods.

12. Ad-hoc Modified Plan

13. Modifications  A time period of May 2013 was taken as something to work on.  Concentration of observations with 3C48 was suggested.  Not all sites have data from that period of that radio source during that period – and so not all sites have participated due to the above thinking.

14. Where are we?

15. Where are we? (1)  From looking at the DropBox (Sunday 18 October 2015) only BSA (Pushchino) and MEXART made data available in the expected format with a readme, STELab also supplied much data but no explanation of the data, and ORT (Ooty) and KSWC provided data in different formats with no explanation for the latter.  There were no good/well-studies data available from EISCAT for 3C48 during May 2013, and no LOFAR data at all for 3C48 during May 2013 (although some unstudied observations from April 2013 still).  UTR-2 and China data availabilities are unknown.

16. Where are we? (2)  Do we need some time here now to concentrate on this study/project and is it something really of interest to the world- wide IPS community?  If so, then all is not lost and we should ensure that today and throughout this workshop we plan accordingly to ensure this activity is completed effectively, and we can then learn from each other the differences/similarities and perhaps the good and bad ways to go about providing end data products to each other as well as to the wider Heliophysics community.  This study is important to the IPSCDFv1.0 and to its usefulness/ reliability for the non-IPS end user/scientist as well as in the validation of IPS for use in space-weather-related activities.

17. Open Discussions

18.  Over to you all… Open Discussions