Data format

File formats

TEXT

Space-delimited text file, directly compatible with SWMF input readers. Header includes a title line with date range and units, a #COORDINATES command naming the frame the file was exported in (GSM, or GSE/SM when selected) with the Earth orbital-motion state on the same line, a column-name line with five time columns, and a #START marker.

MIDL Ballistic 32Re, 2024-05-01 to 2024-05-31 (nT, km/s, cm^-3, K)

#COORDINATES
GSM                     Earth orbital motion EXCLUDED

year month day hour minute Bx By Bz Ux Uy Uz rho T B_interp Ux_interp Uyz_interp rho_interp T_interp
#START
2024 05 01 00 00    -7.10     1.19    -9.69   -407.90     -3.13    -20.15   13.0870    28235.0    0    1    1    1    1
2024 05 01 00 01    -7.08     1.23    -9.66   -406.90      1.00    -13.91   13.3750    30180.0    0    0    0    0    0

Merged data files at L1 include additional columns for satellite position and source attribution:

MIDL L1 (Merged at Closest Satellite Location) L1, 2024-05-01 to 2024-05-31 (nT, km/s, cm^-3, K, Re)

#COORDINATES
GSM                     Earth orbital motion EXCLUDED

year month day hour minute Bx By Bz Ux Uy Uz rho T X B_source Ux_source Uyz_source rho_source T_source B_interp Ux_interp Uyz_interp rho_interp T_interp
#START
2024 05 01 00 00     5.32    2.14   -8.91   -450.20    15.30    -8.50    2.3400   85142.0 235.41 2 13 13 13 13    0    0    1    0    0

CSV

Standard comma-separated values with a single header row. Timestamps in ISO 8601.

timestamp,Bx,By,Bz,Ux,Uy,Uz,rho,T,B_interp,Ux_interp,Uyz_interp,rho_interp,T_interp
2024-05-01T00:00:00,5.32,2.14,-8.91,-450.2,15.3,-8.5,2.34,85000.0,0,1,1,1,1

CSV files for L1 include the same additional columns:

timestamp,Bx,By,Bz,Ux,Uy,Uz,rho,T,X,B_source,Ux_source,Uyz_source,rho_source,T_source,B_interp,Ux_interp,Uyz_interp,rho_interp,T_interp
2024-05-01T00:00:00,5.32,2.14,-8.91,-450.2,15.3,-8.5,2.34,85000.0,235.41,2,13,13,13,13,0,0,1,0,0

Missing values

nan in TEXT format. Empty string (between commas) in CSV format.

Coordinate system

Vectors are stored in GSM. x points Earth → Sun, z is the projection of the magnetic dipole perpendicular to x, y completes the right-handed system. GSE (z perpendicular to the ecliptic) and SM (z along the dipole axis) are available through the download-page selector and the Python client.

GSE / SM rotation

GSM is the native frame of every published file. Selecting GSE or SM rotates B_x, B_y, B_z, U_x, U_y, U_z in your browser using per-minute angle files published alongside the data (data/{YYYY}/{MM}/{YYYYMM}_angles.csv with columns gsm_gse_angle_deg ψ and dipole_tilt_deg μ, IGRF-based). GSE and GSM share the sunward x axis; GSM and SM share the y axis:

GSM → GSE (angle ψ):                 GSM → SM (angle μ):
  Bx_gse = Bx_gsm                        By_sm = By_gsm
  By_gse = cosψ·By_gsm − sinψ·Bz_gsm     Bx_sm = cosμ·Bx_gsm − sinμ·Bz_gsm
  Bz_gse = sinψ·By_gsm + cosψ·Bz_gsm     Bz_sm = sinμ·Bx_gsm + cosμ·Bz_gsm

The same rotation is applied to U. Each 1-minute sample is rotated with that minute's instantaneous frame orientation, so a time series in GSE/SM reflects the slowly turning frame, not a single fixed rotation. Scalars (ρ, T), the source and interpolation-flag columns, and the L1 X column (GSM propagation metadata by definition) are never rotated. Directly fetched monthly CSVs are always GSM.

Earth orbital motion

For most applications, including Earth-centered magnetosphere models such as SWMF, the solar wind velocity as seen from Earth is the physically correct input, so MIDL restores the orbital motion by default on the download page and in the Python client: Earth's tangential orbital velocity is 29.78 km/s on average, ranging seasonally from 29.29 km/s at aphelion (early July) to 30.29 km/s at perihelion (early January), and is added along +y_GSE. In GSM it lands in both U_y and U_z through the per-minute ψ rotation: ΔU_y = cosψ·V_E, ΔU_z = −sinψ·V_E. U_x is left as-is: the convention is only known to remove the tangential component, so Earth's ±0.50 km/s radial speed is not re-added. Untick the option (or pass orbital_motion=False) for convention-frame velocities, e.g. for direct comparison with OMNI or CDAWeb products.

The download page's “Include Earth’s orbital motion” checkbox applies the seasonally exact correction in your browser, and the Python client (v1.1.1+, on by default) does the same in any output frame:

midl.load("2024-05-10", "2024-05-11", "L1", coords="GSE")  # orbital_motion=True is the default

The choice is stamped in ds.attrs["orbital_motion"] and stated on every exported .dat header's #COORDINATES line as Earth orbital motion included or Earth orbital motion EXCLUDED. The monthly archive CSVs hosted on this site and the real-time tier keep the convention (motion removed); the correction is applied at download/load time.

Propagation targets

Real-Time tier (MIDL-RT)

The Real-Time page serves a preliminary tier built from NOAA/SWPC's real-time solar wind stream, refreshed every minute under realtime/. It differs from the monthly definitive dataset: sources are currently SOLAR-1, ACE and IMAP (no WIND, which has no real-time broadcast; IMAP appears here before it joins the archival product), telemetry is not cross-calibrated, and only SOLAR-1 provides vector plasma; ACE and IMAP contribute scalar speed, density and temperature. Real-time intervals are superseded by the definitive product as monthly processing catches up; the two tiers are never mixed silently.

Rows younger than 3 hours are live (look-ahead filtering still open; values may change), rows 3–27 hours old are settled but still preliminary, and older rows are sealed. Payload filenames change every generation; always resolve them through realtime_manifest.json rather than hard-coding.