Hands-on session : Analyzing Cluster data near the Earth's bow shock

AMDA :

Introduction on CDPP

http://amda.cdpp.eu

30 accounts:  asperaw01   to   asperaw30        (pass : toulouse)

Request accounts : amda@irap.omp.eu

If you use AMDA/CDPP, note the System Use Policy :
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Thank you for acknowledging the use of AMDA in publications with wording like "Data analysis was performed with the AMDA science analysis system provided by the Centre de Données de la Physique des Plasmas (CDPP) supported by CNRS, CNES, Observatoire de Paris and Université Paul Sabatier, Toulouse."
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Documents : TP.pdf
+ manuals AMDA.pdf, TOPCAT.pdf, 3Dview.pdf
+ http://userpages.irap.omp.eu/~vgenot/M2/Chocs15.pdf    for more details on shocks

θBn : angle between the magnetic field and the normal to the shock
– Quasi-perpendicular shocks : θBn> 45° → steeper, more laminar (waves confined in the plane of the shock)
– Quasi-parallel shocks : θBn< 45° → highly turbulent (waves propagate along the magnetic field)

Plot

Icon Plot : "f(x)=" at lower left 
Plot windows ("Informations" everywhere)

In Workspace explorer / resources
AMDA database > Cluster > Cluster 1

Sweep with mouse on a data folder indicates the available time interval and the description

=> drag  CIS-HIA > ion moments > density, |v|, temperature total
FGM > 4 sec (spin) >  |b|, b_gse
(Bgse = solar ecliptic, organises data better near the stationary bow shock on Earth-Sun line ; Bgsm organises data better near the Earth)

Optionally
CIS-HIA > PA/energy distribution > ion flux:2D pa/energy
and in the window "Selected element options" to the right
PA(deg) :  (anode) 8 : [90.00, 101.25]-101	Energy (eV) All

Time selection > Interval > 2001/04/15 03:49:00 → 2001/04/15 03:59:00

Plot	=>  SW to the right, Msheath to the left of the jump, shock is Quasi-// (maybe)

Request name : Plot1  =>   Save All Tabs => saved in Workspace > operations

Close plot window (can be restored)

Create parameter

Icon Create/Modify parameter : "pencil" at lower left 

Magnetic pressure   B^2/2µo

In Workspace > resources, Sweep with mouse on a parameter gives its unit

Construct parameter
Tools for Parameter Construction > Calculator, Constants (SI), Functions

c1_btot*c1_btot/(2*@mu_0)/1e9

Parameter name : Pmag, Time step : 4 sec, Units: nPa

Save => in Workspace > resources > Derived parameters

Add in Plot manager

Modify Plot 1, add CIS-HIA > ion moments > pressure total
on the same panel as Pmag

(one can pile up plots on each other in the Plot manager)

=> Pmag << Ptot

Idem: build Pth = nkT

c1_hia_dens*1e6*@k*c1_hia_t*@eV2K*1e9

and add on pressure plot

Idem: build Pdyn = nmV^2/2

c1_hia_dens*1e6*@m_p*c1_hia_v(0)*c1_hia_v(0)*1e6*1e9/2

and add on pressure plot

=> Pmag < (Pth = pressure total) < Pdyn

Sum the 3 pressures and Plot => variations across the shock

Redo Pdyn with Vx  (v(0))

Save Plot 2

Data mining

Icon Data mining : "magnifier" lower left

How to identify a shock ?

Create parameter dv, 60 sec, km/s/s, Descr: dv/dt	        deriv_(c1_hia_vtot)

Plot v & dv

Option : overplot on dv the parameter
dvs = deriv_(smooth_(c1_hia_vtot,16))	4 sec     km/s/s
=> more noisy 

Shock detection :  in the window Data minig, condition
deriv_(c1_hia_vtot)>1.5      or     ws_dv>1.5	60 sec, name
on the same interval as above

save request  => choc1, in operations / data mining

Do search => Data mining results => Edit/Save
(sometimes in jobs, if large data set)

name = res_choc0 => Save  => resources > Time tables > My time tables

Interval of 2 min (= 2 x 60 sec) around the condition
(if several intervals => list)

We re-use Plot 1   in Operations

Time table or Catalog > drag  res_choc0
=> too narrow interval

(if list of intervals : Plot > Next for next interval)

To enlarge the plot window => click res_choc0

Window Manage Time Tables

Extend 3 min (on each side)		Apply		Merge intervals (if several)

Save => res_choc1

Idem for   2001/02/12 00:00:00  =>  2001/02/15 00:00:00

plotting in addition Cluster 1 > Ephemeris > orbit > xyz_gse

shocks, Earth CA (rapid in/out = ?? MS inflates/deflate)

Plot 2001/02/12 00:00:00 => 2001/02/13 16:00:00 

2 shocks

Search problem  ? => lacks abs in  condition on dv

abs(deriv_(c1_hia_vtot))>1.5	=> choc2

Option : apply to all april 2001

Option : Rankine-Hugoniot relations across shock

TopCat :

Intro TopCat / VO ; tool to import & manipulate (plots statistics) various data

download TopCat from http://www.star.bris.ac.uk/~mbt/topcat/#install

launch topcat  =>  yellow disk at top (or bottom in windows or linux) => indicates that the SAMP connection (that allows dialog between application, messages and data exchanges between applications and/or web sites) is open

Page AMDA, lower right: "samp connexion" button, click, ok => Icon in topcat et reciprocally in AMDA => both are connected

In AMDA: 

Download Data :  bottom center

In  Workspace > resources   get parameters :

Cluster ephemeris   xyz_gse, + parameters to plot, B, V, N

File structure : all in one file, Sampling time : 4 sec, File format : VOTable
+ in Time table => res_choc2

=> send via SAMP to ... TopCat, that receives an AMDA Table

In TopCat:

Button Display column metadata (top)
select xyz_gse and explode in scalars
Plot 2D (Plane plotting window)

Plot B vs V => 2 groups of points

Select each group with the contour tool, reclick
New subset name (SW, Msh) => add subset

Main TopCat window
Button Sigma = statistics (values, can be saved to disk...) for each subset

3D View :

http://3dview.cdpp.eu   launch => lava web start

3DView   (open, ctrl-click if pb)

File	>  New scene, then in the window

File  > Manage scene

Select the data
	Cluster 1
	Start time : 2001/02/12 00:00:00
	Stop time : 2001/02/13 16:00:00
	Step 1800 s, GSE
Ok
Go

Science > Models

Bow shock > Add selected data to 3D scene   (bottom)
Magnetopause > Add to scene 

Interoperability > AMDA login
Science > Remote data (Impex)  >   connects to AMDA

Observational data > Cluster 1 > FGM > ...  > add to scene
Time Tables > AMDA > Private > res_choc2

Plot observations : 

In the main window : Go
Science > Scene controls => toggle option displays (boundary crossings, etc.)
Options > Preferences > Trajectory > Display > Full ...

Explore possibilities

Option: study all february 2001 ...