Magnetosphere regions and bow shock: How to find ================================================ Note: The analysator methods here are prototypes and should be adapted and modified as needed. Bow shock --------- Plasma properties for estimating bow shock position: * plasma compression: * :math:`n_p > 2n_{p, sw}` [Battarbee_et_al_2020]_ (Vlasiator) * solar wind core heating: * :math:`T_{core} > 4T_{sw}` [Battarbee_et_al_2020]_ (Vlasiator) * :math:`T_{core} = 3T_{sw}` [Suni_et_al_2021]_ (Vlasiator) * magnetosonic Mach number: * :math:`M_{ms} < 1` [Battarbee_et_al_2020]_ (Vlasiator) **In analysator:** :mod:`regions` has an option to find the bow shock. Default method uses 1.5*solar wind density as limit. Usage example: .. code-block:: python datafile = "vlsvbulkfile.vlsv" outfilen = "bowshock.vlsv" RegionFlags(datafile, outfilen, regions=["bowshock"]) Magnetosheath ------------- properties: * density: * :math:`8 cm^{-3}` [Hudges_Introduction_to_space_physics_Ch_9]_ * temperature: * ion: :math:`150 eV` [Hudges_Introduction_to_space_physics_Ch_9]_ * electron: :math:`25 eV` [Hudges_Introduction_to_space_physics_Ch_9]_ * magnetic field: * :math:`15 nT` [Hudges_Introduction_to_space_physics_Ch_9]_ * plasma :math:`\beta`: * 2.5 [Hudges_Introduction_to_space_physics_Ch_9]_ **In analysator:** :mod:`regions` has an option to find the magnetosheath using bow shock and magnetopause: Usage example: .. code-block:: python datafile = "vlsvbulkfile.vlsv" outfilen = "magnetosheath.vlsv" RegionFlags(datafile, outfilen, regions=["magnetosheath"]) Polar cusps ----------- *Properties:* * plasma density: high density in comparison to solar wind * Ion density :math:`\geq` solar wind ion density [Pitout_et_al_2006]_ (Cluster spacecraft data) * ion energy: * mean ion energy :math:`~2-3 keV` [Pitout_et_al_2006]_ /[Stenuit_et_al_2001]_ * energy flux: * energy flux **In analysator:** :mod:`regions` has an option to find cusps using convex hull of the magnetosphere. Note that the default parameters may catch some dayside cells near the magnetopause and some non-cusp areas inside dayside in addition to cusps. Areas near magnetopause can be excluded for example by only including cells where the SDF is less than e.g. -1 Re. Usage example: .. code-block:: python datafile = "vlsvbulkfile.vlsv" outfilen = "cusps.vlsv" RegionFlags(datafile, outfilen, regions=["cusps"]) Tail lobes ---------- * plasma density: low * below :math:`0.03 cm^{-3}` [Grison_et_al_2025]_ (Cluster spacecraft data) * :math:`0.01 cm^{-3}` [Koskinen_Space_Storms]_ p.38 * less than :math:`0.1 cm^{-3}` [Wolf_Introduction_to_space_physics_Ch_10]_ p.291 * plasma :math:`\beta`: low * typically around :math:`0.05` [Grison_et_al_2025]_ (Cluster spacecraft data) * :math:`3e-3` [Koskinen_Space_Storms]_ p.38 * temperature: * ion temperature :math:`300 eV` [Koskinen_Space_Storms]_ p.38 * electron temperature :math:`50 eV` [Koskinen_Space_Storms]_ p.38 * magnetic field: * :math:`20 nT` [Koskinen_Space_Storms]_ p.38 * open magnetic field lines [Wolf_Introduction_to_space_physics_Ch_10]_ p.291 * strong and stable magnetic field towards the Earth (northern lobe) and away from the Earth (southern lobe) [Coxon_et_al_2016]_ Separated from the plasma sheet by the plasma sheet boundary layer (PSBL) **In analysator:** :mod:`regions` has an option to find tail lobes. Note that the default parameters to find lobes may include some areas from the dayside. Usage example: .. code-block:: python datafile = "vlsvbulkfile.vlsv" outfilen = "lobes.vlsv" RegionFlags(datafile, outfilen, regions=["lobes"]) Low-latitude boundary layer (LLBL) ---------------------------------- Properties: * density: * ion number densities between those of magnetosphere and magnetosheath [Hudges_Introduction_to_space_physics_Ch_9]_ p.267 * temperature * ion temperatures between those of magnetosphere and magnetosheath [Hudges_Introduction_to_space_physics_Ch_9]_ p.267 * unknown field line configuration, probably a mix of open and closed field lines [Hudges_Introduction_to_space_physics_Ch_9]_ p.262 High-latitude boundary layer (HLBL) ----------------------------------- Includes the plasma mantle on the tail side and the entry layer on the dayside Properties: * open magnetic field lines [Hudges_Introduction_to_space_physics_Ch_9]_ p.261 Plasma sheet boundary layer (PSBL) ---------------------------------- The plasma sheet boundary layer is a very thin boundary layer separating the tail lobes from the tail plasma sheet [Koskinen_Johdatus]_ *Properties:* * density: * :math:`0.1 cm^{-3}` [Koskinen_Space_Storms]_ p.38 * temperature: * ion temperature :math:`1000 eV` [Koskinen_Space_Storms]_ p.38 * electron temperature :math:`150 eV` [Koskinen_Space_Storms]_ p.38 * magnetic field: * :math:`20 nT` [Koskinen_Space_Storms]_ p.38 * plasma :math:`\beta` : * :math:`0.1` [Koskinen_Space_Storms]_ p.38 * probably closed magnetic field lines [Wolf_Introduction_to_space_physics_Ch_10]_ p.291 Central plasma sheet -------------------- *Properties:* * density: * :math:`0.3 cm^{-3}` [Koskinen_Space_Storms]_ p.38 * :math:`0.1-1 cm^{-3}` [Wolf_Introduction_to_space_physics_Ch_10]_ p.291 * temperature: hot * ion temperature :math:`4200 eV` [Koskinen_Space_Storms]_ p.38 * electron temperature :math:`600 eV` [Koskinen_Space_Storms]_ p.38 * magnetic field: * :math:`10 nT` [Koskinen_Space_Storms]_ p.38, [Hudges_Introduction_to_space_physics_Ch_9]_ * plasma :math:`\beta`: high * :math:`6` [Koskinen_Space_Storms]_ p.38 * Mostly closed magnetic field lines [Wolf_Introduction_to_space_physics_Ch_10]_ Inner plasma sheet: unusually low plasma beta may exist (e.g., cold tenuous plasma near the neutral sheet after long periods of northward IMF) [Boakes_et_al_2014]_, (Cluster spacecraft data) **In analysator:** :mod:`regions` has an option to find the central plasma sheet. Note that the default parameters may catch some dayside cells in addition to plasma sheet. Usage example: .. code-block:: python datafile = "vlsvbulkfile.vlsv" outfilen = "CPS.vlsv" RegionFlags(datafile, outfilen, regions=["central_plasma_sheet"]) .. automodule:: regions :members: ------------ References .. [Battarbee_et_al_2020] Battarbee, M., Ganse, U., Pfau-Kempf, Y., Turc, L., Brito, T., Grandin, M., Koskela, T., and Palmroth, M.: Non-locality of Earth's quasi-parallel bow shock: injection of thermal protons in a hybrid-Vlasov simulation, Ann. Geophys., 38, 625-643, https://doi.org/10.5194/angeo-38-625-2020, 2020 .. [Suni_et_al_2021] Suni, J., Palmroth, M., Turc, L., Battarbee, M., Johlander, A., Tarvus, V., et al. (2021). Connection between foreshock structures and the generation of magnetosheath jets: Vlasiator results. Geophysical Research Letters, 48, e2021GL095655. https://doi. org/10.1029/2021GL095655 .. [Grison_et_al_2025] Grison, B., Darrouzet, F., Maggiolo, R. et al. Localization of the Cluster satellites in the geospace environment. Sci Data 12, 327 (2025). https://doi.org/10.1038/s41597-025-04639-z .. [Koskinen_Johdatus] Koskinen, H. E. J. (2011). Johdatus plasmafysiikkaan ja sen avaruussovellutuksiin. Limes ry. .. [Koskinen_Space_Storms] Koskinen, H. E. J. (2011). Physics of Space Storms: From the Solar Surface to the Earth. Springer-Verlag. https://doi.org/10.1007/978-3-642-00319-6 .. [Pitout_et_al_2006] Pitout, F., Escoubet, C. P., Klecker, B., and Rème, H.: Cluster survey of the mid-altitude cusp: 1. size, location, and dynamics, Ann. Geophys., 24, 3011–3026, https://doi.org/10.5194/angeo-24-3011-2006, 2006. .. [Coxon_et_al_2016] Coxon,J.C.,C.M.Jackman, M. P. Freeman, C. Forsyth, and I. J. Rae (2016), Identifying the magnetotail lobes with Cluster magnetometer data, J. Geophys. Res. Space Physics, 121, 1436–1446, doi:10.1002/2015JA022020. .. [Hudges_Introduction_to_space_physics_Ch_9] Hudges, W. J. (1995) The magnetopause, magnetotail and magnetic reconnection. In Kivelson, M. G., & Russell, C. T. (Eds.), Introduction to space physics (pp.227-287). Cambridge University Press. .. [Wolf_Introduction_to_space_physics_Ch_10] Wolf, R. A. (1995) Magnetospheric configuration. In Kivelson, M. G., & Russell, C. T. (Eds.), Introduction to space physics (pp.288-329). Cambridge University Press. .. [Boakes_et_al_2014] Boakes, P. D., Nakamura, R., Volwerk, M., and Milan, S. E. (2014). ECLAT Cluster Spacecraft Magnetotail Plasma Region Identifications (2001–2009). Dataset Papers in Science, 2014(1):684305. eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1155/2014/684305 .. [Stenuit_et_al_2001] Stenuit, H., Sauvaud, J.-A., Delcourt, D. C., Mukai, T., Kokubun, S., Fujimoto, M., Buzulukova, N. Y., Kovrazhkin, R. A., Lin, R. P., and Lepping, R. P. (2001). A study of ion injections at the dawn and dusk polar edges of the auroral oval. Journal of Geophysical Research: Space Physics, 106(A12):29619–29631. eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2001JA900060.