Project Selection - Sibeck Postdoc

By Nithin Sivadas

21st September 2020

Deciding between projects

Considering the higher potential utility and my personal interest (and acknowledging the possible difficulty), we could pick Project idea 3 and 4. Both could potentially help the X-ray and UVI imagers of SMILE (and perhaps even STORM). A demonstration of the 3D capabilities of a tomographic reconstruction, might add to the case for the selection of STORM - to provide real-time 3D tomographic reconstruction in tandem with SMILE. More details of the project ideas follow.

Idea 1: Exploring magnetosheath parameters with existing satellite data$^1$

Verify or validate models of ion species concentrations and X-ray emissions from its charge-exchange in the magnetosheath using in siute measurements from Cluster/ MMS plasma composition analyzers.

Utility:

Allows us to validate existing models of charge-exchange with data

Questions that this project can address:

What are the statistical thickness, density, and location of the magnetosheath and how does it vary with solar wind parameters?

How consistent are the current models with respect to these measurements?

Success criteria:

Construct estimates of the magnetosheath parameters using in situ measurements of different ion species.

Pros:

Data is available through MMS HPCA instrument.

Stein is working on it - so there is expertise that is invested in the project.

The success of the project is independent of the mission success.

Cons:

Not necessarily first author

Best case outcome does not necessarily heavily add value to the overall mission.

If we should discover that HPCA can measure multiple charged Oxygen, then a study showing how it varies with solar wind features has value. (ACE Observations were used to do this. So added value is to see what it looks like in the mangetosheath, as opposed to L1.)

*Archaeology data - on AMPTE program, CCE - charge composition explorer, George Glockler - Univ of Maryland. Lynn Kistler was a student. Some obligation to archive to NASA.

*Marcos - sub-solar sheath as any location within 2RE of the sun-earth line between the magnetopause and bow shock. Expect, highest densities of solar wind. He will evaluate density there with input solar wind parameters.

Idea 2: Conjugate measurements of magnetopause & ionosphere$^2$

Observe magnetically conjugate signatures of localized features in the magnetopause, such as Flux Transfer Events (FTE). Or use ground-based instruments such as superDarn data with spacecraft crossings, to explore the motion of the boundaries (magnetopause and polar-cap).

Utility:

Allows us to connect reconnection signatures from the magnetosphere to the ground..

Questions that this project can address:

What triggers bursty reconnection?

Whether or when turbulence triggers FTE?

Whether or when intrinsic magnetopause instabilities triggers FTEs?

Success criteria:

Pros:

Data available through MMS, THEMIS, ground instruments

Toshi has extensively worked on this, therefore t here is an expert

Can shed light on specific localized reconnection phenomena

Demonstrate M-I coupling for the

Cons:

Idea 3: Solar wind drivers of magnetospheric dynamcis$^3$

Using canonical correlation analysis on solar wind parameters to evaluate which combination of parameters can provide the best estimate of certain magnetospheric effects of interests. For example: 1) magnetoapuse location, 2) polar cap size, and 3) auroral precipitaiton flux. We will carry this out using satellite measurements of the above quantities in combination with OMNI database.

Utility:

Understand from data

what controls reconnection, and
what external parameters affect the magnetosphere and its different properties

For example: Understand how the magnetopause distances vary with solar wind input .

Questions this project can address:

What are the IMF conditions favoring day-side reconnection?
What combination of parameters contribute most to the magnetopause location and reconnection rate?

Success criteria:

Identify the right combination of input indices that become good predictors of certain magnetospheric parameters

Identify a physical explanation for the kind of functional relationship between the solar wind parameters and magnetospheric parameter

Pros:

Data mostly available through OMNI and existing spacecraft

Allows for a systems level understanding of the drivers and its direct effects on the global magnetosphere

Success is mission independent

Preliminary work carried out for the NPP proposal development

Cons:

Limited by the available data

Other people have worked on this topic before

We need to discuss what data set we need to use. [We need to elaborate]. Find a large relevant data base, and input solar wind, and magnetosphere state parameter - and then get more out of it.

*Parameters that are available - in situ measurements. Always seen as a snapshot, we do not get the time history. There is an error in the estimate (which is perhaps hard to get). Trouble tracking it with time/ continuously.

Auroral oval - get it from AMPERE, IMAGE, ground-magnetometers, FUV imager - on IMAGE, or POLAR
Ring current - measured by ground-magnetometer; sequences of ENA images from IMAGE
[Jim Slaven & Holzer- AE over time, Petrinec/ Yongli Wang/Sibeck; Original starting database is noisy - tagging an hour average of solar wind with an instantaneous crossing. Global MHD model perhaps can be used?]
[Patrick Newel - auroral precipitation flux (and intensity); Radar - is hard; Field-aligned currents - Brian Anderson, Iridium & AMPERE; Kong Liou APL Polar Data; Steve Milan - oval varies as a function of solar wind input; ground magnetometer - AMY, Aaron Ridley, Gang Lou]

*Find magnetospheric states that are similar, so Tomography can be done on those snapshots

Field aligned currents - magnetopause erosion; observable through magnetopause location; large accessible database, and is continuous.

*Action item: Project plan, Data sets needed, Likely outcome

Idea 4: Magnetosheath Tomography$^4$

Developing a tomographical algorithm to reconstruct the 3-D dimensional shape of the magnetosheath based on soft X-ray images of the magnetosheath from SMILE/ STORM spacecrafts from different vantage points at different times.

Utility:

A technique that allows us to construct 3D (statistical/average) images of the magnetopause for specific solar wind parameters

(Observe average spatial extent of reconnection signatures across horizontal and vertical direction?)

Questions this project can address:

Is the day-side reconnection steady or unsteady?
What are the IMF conditions favoring reconnection on equatorial or polar magnetosphere?
Does plasma beta, radial IMF, and solarwind velocity have a role in determining reconnection?
How good are our current model in simulating the 3D structure of the magnetosphere?
What SW parameters contribute most to the magnetopause location, share, and reconnection rate?
How does the magnetopause structure relate to the internal dynamics of the magnetosphere - like the size and strength of the precipitation, and auroral oval.

Pros:

A novel technique

Has the potential to add great value to the mission

Cons:

The statistical method of tomographical reconstruction could have a lot of uncertainty/ error, rendering the output useless

Practical success depends on the successful operation and launch of SMILE or STORM

Challenging to develop/ outside of direct expertise

*Anders Jorgensen- SMILE: Run an MHD simulation, extract information from the simulation. Michael Collier - circular orbit, SW interaction is steady, how much of that orbit do you need observations from to reconstruct the tomography. Hyunju Connor. Gonzalo - extract exosphere information from IBEX, TWIN.

Useful mindmaps

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