spase://CNES/NumericalData/CDPP-AMDA/SWARM-B/TII/swarmb-tii-all

Calibrated

ftp://swarm-diss.eo.esa.int

EFI TII Cross-Track Flow Data

Calibrated

ElectricField

Earth.Magnetosphere

Data coverage is not continuous. Starting in 2014 EFI TII operations have been limited to a small number of orbits per day. Experience has shown that daily rest periods have the effect of stabilizing the TII imaging performance. Effort has been made to remove background levels on an orbital timescale. Significant non-geophysical offsets can remain, however, and the TII team urges caution in interpreting flow variations spanning time-scales larger than a few to 10s of minutes. Horizontal flow data flagged calibration level 2 are for the most part suitable for research and publication. The flagging algorithm currently does not perform as well for the vertical flow measurements. The EFI team continues to work on improving the flagging algorithm, and solicits and welcomes feedback from the scientific community on the data quality. Because along-track flow is assumed to be the satellite speed (~7.6 km/s), real flow variations in the along-track direction will appear in the cross-track direction when the angle between the ram flow and the satellite x-axis is non-zero. Apparent variations typically not exceeding 100 – 200 m/s in the cross-track flow due to large-amplitude along-track flow variations can be expected mainly at high latitudes. 2 Hz ion cross-track flow speed : * vy_ion - horizontal flow speed in co-rotating frame. Positive values are to the right, facing forward * vz_ion - vertical flow speed in co-rotating frame. Positive values are downward. * v_corot - Co-rotation signal. Can be added to viy to get approximate horizontal cross-track component of ion velocity in inertial frame of reference. Electric field : * ex - component parallel to along-track direction in co-rotating frame. Calculated from -vxB assuming along-track ion velocity component is zero * ey - component in cross-track horizontal direction in co-rotating frame. Positive values are to the right facing forward. Calculated from -vxB assuming along-track ion velocity component is zero. * ez - component in cross-track vertical direction in co-rotating frame. Positive values are downward. Calculated from -vxB assuming along-track ion velocity component is zero. Flags : Three quality flags are included for each measurement: vy_qual, vz_qual, and e_qual represent approximate data quality for the y and z components of ion velocity and all components of electric field, respectively. Because electric field is derived from both y and z components of ion velocity, qe is effectively the logical ‘AND’ of the other two flags. The flag meanings are as follows : * -1: ion flow measurements lie outside the nominal measurement range of +- 4 km/s; this encompasses both anomalous measurements and large, geophysical flows. * 0: calibration level 0; do not use in scientific publications except for research into TII imaging anomaly, calibration and validation studies. * 1: calibration level 1: may contain significant uncorrected biases; the data are often of good quality. * 2: calibration level 2: horizontal flows are generally of good quality with reasonable baselines; vertical flows may still contain large variations not of geophysical origin.