1. Solar Wind Structure from Pseudostreamers: Connecting Remote and in situ Observations
Nicholeen Viall
NASA/GSFC
In collaboration with : Larry Kepko, Angelos Vourlidas, Spiro Antiochos, Sue Lepri, Aleida Higginson, and Jon Linker

2. Connecting the Sun to the Heliosphere
Pseudostreamer and helmet streamer
Which solar structures become structures in the Heliosphere?
Success with large-scale (e.g. CIRs; CMEs), but less so on mesoscales.

3. Success indirectly linking solar structures to heliosphere (in situ) with mesoscales
~tens of minutes up to a few hours/100s Mm up to a few thousand Mm radial length scale
‘small’ – compared to current heliospheric imager resolution and in situ composition measurements
‘large’ – compared to turbulence (‘mesoscale’-> generally larger than the inertial range) and Earth’s magnetosphere/space weather
Rouillard Once Made direct connection
Parker Solar Probe and Solar Orbiter will finally give a DIRECT link of these mesoscale structures

4. Is the HCS/Helmet streamer a special boundary where mesoscale structures are injected into an otherwise steady solar wind?
S-web says there are other locations where magnetic reconnection ought to be injecting structures
Our/others’ previous in situ solar wind work says there are other locations [e.g. Viall et al. 2008]
We see periodic proton density structures in 70-80% of slow solar wind, suggesting that such structures are a substantial component of the ssw. If this is true, then we should see proton density structures (with compositional changes confirming solar source) not only at the HCS crossing, but other places as well.

5. PFSS as viewed by STEREO A
August 2008
HCS is aimed south of Earth; pseudostreamer is aimed north
PFSS as viewed by STEREO A
That eclipse image from first slide and spiro

6. Images and in situ data show pseudostreamer continually releases ‘blobs’/‘puffs’/structured solar wind
Still circumstantial; indirect

7. HI1 images show pseudostreamer continually releases ‘blobs’/‘puffs’/ solar wind structures
DeForest processed HI1 – on STEREO/SECCHI webpage

8. 250 km/s (Faster ones are 400 km/s)
Time-distance plots show continuous release of structures from pseudostreamer
250 km/s (Faster ones are 400 km/s)
Like Jmaps

9. 250 km/s (Faster ones are 400 km/s)
Time-distance plots show continuous release of transient structures from pseudostreamer
250 km/s (Faster ones are 400 km/s)

10. In situ, Wind/ACE observe a stream interface, many slow
In situ, Wind/ACE observe a stream interface, many slow wind structures, and no HCS
Ace C & O
Ace C6+/C5+ Charge State
14 days without a HCS
Slow wind shows highly structured proton density, alpha, carbon, oxygen, charge state - solar source
T sector
A sector
Two traces are 3DP and SWE

11. Two-day zoom-in shows series of ~2.5 hour structures
Alphas and C and O track one another with similar ~2.5 hr variation: structures are from solar source
Typical hour cadence would have lead to false conclusion of steady solar wind
Define boundaries based on compositional changes

12. Magnetic reconnection releases coronal loops with different heating histories
Composition boundaries generally correspond to B field tangential discontinuities and rotations, but not in a predictable orientation- i.e. not Alfven waves or waves between flux tube (see also Viall et al alpha event; Laming poster)
Two heat flux drop outs in the train of periodic density structures are signs of connectivity changes to very long field lines (e.g. through interchange rxn; Chollet et al. Pagel et al)
Laming talk

13. In situ Event Maps to Complex S-web Arcs- Not the HCS
Predictive Science Inc

14. Prediction for Parker Solar Probe and Solar Orbiter: There is no such thing as ‘the steady solar wind’
No such thing as steady solar wind, just like in magnetosphere they learned (with better data) that there is no such thing as steady magnetospheric convection. Magnetic fields always store and then release energy.
PSP and SO will finally be able to make DIRECT link between solar source and heliospheric structures
Key is to get high time resolution composition/alphas + modeling
Take away 1
Crooker et al.

15. Structures from the Sun drive dynamics in Earth’s magnetic field.
Quasi-periodic reconnection at the Sun directly drives oscillations in Earth’s Magnetosphere (4 days later)
Here’s the kicker: this event was observed in magnetosphere 18 years ago… initially they thought it was internal dynamics. (we know CMEs impact earth, but not small guys). The Earth was fully analyzed 15 years ago and shown to be SW (still not sure if it came from Sun though) Finally with STEREO and some new data processing techniques to pull out the smaller guys, able to connect the dots.

16. Solar Wind Structures Formed at Sun through Reconnection
Proton density changes coincide with changes in composition– solar origin
Specially processed, high time resolution ACE composition; typical resolution averages over these structures, and leads to incorrect interpretation of ‘steady’ slow solar wind
Heat flux and B field changes associated with structures (one structure in the train is a flux rope!) this indicates magnetic reconnection (S-web)
We observed perdiocid density structures in situ
Note ‘periodic’ = characteristic time scale, these are not waves
Kepko, Viall, Antiochos, Lepri,
Kasper, Weberg 2016

17. Connecting helmet streamer structures and in situ structures in the Heliospheric Current Sheet
In situ at 1 AU
Last year studies
Viall & Vourlidas 2015
Kepko, Viall, Antiochos, Lepri,
Kasper, Weberg 2016
Left –STEREO images of helmet streamers creating density structures
Indirect (not even from same time) link of Helmet streamer-> HCS structures

18. Indirect link solar structures with structures in solar wind hitting Earth.
Current observational gap
Get full information about temperutature, density, velocity, magnetic field, energetic particles, composition

19. Solar wind structures drive dynamics in Earth’s magnetic field.
Understanding the dynamic space environment in general –these waves come all the way down to the ground - specifically Radiation Belts

20. These dynamics may have just the right timescales (ULF waves) to fill and drain Earth’s Van Allen Belts and provide ‘preconditioning’.

21. ‘Small Things Can do Big Damage’
Small Blackholes
Small Dogs
Small Kids
Small Carpenter Ants
Small Hail
‘Small’ Structures from the Sun-
which are constantly emitted-
can have big, cumulative, impacts on Earth (terrestrial planets in general)
Small leaks
Take awat 2 Even though this structure and variability is small compared to CMEs…they can still have a big impact on Earth and the space environment. Constant barrage; thunderstorms of spaceweather

22. Extra

23. PFSS as viewed by STEREO A
Images and PFSS show HCS is depressed and aimed south of Earth; pseudostreamer directed north of Earth
PFSS as viewed by STEREO A
So what exactly are we mapped to at 1 AU?