Supported variables and data reducers

Reading variables from .vlsv files

Analysator supports reading multiple different types of variables:

• MPIgrid variables
• FSgrid variables
• variables directly available in the data files
• variables generated via receipes from the data file variables (named, somewhat incorrectly, datareducers)

Vlasiator variable naming scheme

In Vlasiator versions before V5, variables were always saved on the DCCRG/MPI/Vlasov grid, and as such, only a single naming scheme was required. With the introduction of Vlasiator V5, variables could also be saved on the FSgrid. When the new ionosphere will be implemented, that can also be saved to on its own grid. To differentiate between the different grids, a naming scheme was introduced where a prefix defines the grid type:

• No prefix: old pre-V5 data
• prefix vg_: Vlasov/MPI/DCCRG grid
• prefix fg_: fieldsolver/FSgrid
• prefix ig_: ionosphere grid

Multipop naming (version 4 onwards)

Some variables are directly connected to a given particle species, with the variable name having a particle species prefix. For example: ´proton/rho´ or proton/vg_rho for V4 and V5 outputs respectively. Note that multipop outputs are always on the Vlasov grid, but still have the vg_ prefix after the particle species name. Some variable such as rho and blocks which are directly connected to particle species are availabe without the population identifier in datafiles from version 3 and earlier.

Vlasiator variable correspondences

The below tables list variable names used in different versions of Vlasiator proper. A blank entry in a corresponding column indicates this variable is not available. Some debugging variables such as field derivatives have been omitted from the table.

FSgrid variables	Corresponding Vlasov grid variable in older versions
fg_b	B
fg_b_background	background_B
fg_b_perturbed	perturbed_B
fg_b_vol	B_vol
fg_e	E
fg_e_hall_??	EXHALL_???_???
fg_e_vol	E_vol
fg_rhom	Rhom
fg_rhoq	Rhoq
fg_v	V
fg_pressure	Pressure
fg_maxdt_fieldsolver	max_fields_dt
fg_rank	FSgrid_rank
fg_amr_level
fg_boundarytype	FSgrid_boundaryType
fg_boundarylayer	Boundary_layer

V5 Vlasov grid variables	Older Vlasov grid variables
vg_rhom	Rhom
vg_rhoq	Rhoq
vg_v	V
vg_pressure	Pressure
	Blocks
vg_b_vol	B_vol
vg_b_background_vol	BGB_vol
vg_b_perturbed_vol	PERB_vol
	E
vg_e_vol	E_vol
vg_e_gradpe	EGRADPE
vg_f_saved	fSaved
vg_maxdt_acceleration	max_v_dt
vg_maxdt_translation	max_r_dt
vg_rank	MPI_rank
vg_loadbalance_weight	LB_weight
vg_boundarytype	Boundary_type
vg_boundarylayer	Boundary_layer
---------------------	--------------------
Per-population variables	Older per-population variables
---------------------	--------------------
populations/vg_rho	populations/rho
populations/vg_v	populations/V
populations/vg_rho_thermal	populations/RhoNonBackstream
populations/vg_rho_nonthermal	populations/RhoBackstream
populations/vg_v_thermal	populations/VNonBackstream
populations/vg_v_nonthermal	populations/VBackstream
populations/vg_effectivesparsitythreshold	populations/EffectiveSparsityThreshold
populations/vg_rho_loss_adjust	populations/rho_loss_adjust
populations/vg_energydensity	populations/EnergyDensity
populations/vg_precipitationdifferentialflux	populations/PrecipitationDiffFlux
populations/vg_maxdt_acceleration	populations/MaxVdt
populations/vg_maxdt_translation	populations/MaxRdt
populations/vg_blocks	populations/Blocks
populations/vg_acceleration_subcycles	populations/acc_subcycles
populations/vg_ptensor_diagonal	populations/PTensorDiagonal
populations/vg_ptensor_offdiagonal	populations/PTensorOffDiagonal
populations/vg_ptensor_nonthermal_diagonal	populations/PTensorBackstreamDiagonal
populations/vg_ptensor_nonthermal_offdiagonal	populations/PTensorBackstreamOffDiagonal
populations/vg_ptensor_thermal_diagonal	populations/PTensorNonBackstreamDiagonal
populations/vg_ptensor_thermal_offdiagonal	populations/PTensorNonBackstreamOffDiagonal
---------------------	-------------------