ICON explores the boundary between Earth and space (the ionosphere) to understand the physical connection between our world and the immediate space environment around us. Visit http://icon.ssl.berkeley.edu for more details.

Determined via a non-linear least squares fit of RPA currents to the Whipple equation

Ion density uses measured currents and co-rotating atmosphere to determine density.

Ion temperature determined using a best fit of RPA measurements to Whipple equation.

Temperature is obtained by assuming single temperature value for all plasma.

Ion velocity relative to co-rotation along geomagnetic field lines. Positive along the main field vector.   Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame to express the observed vector along a geomagnetic basis. 

Ion velocity along local magnetic meridional direction, perpendicular to geomagnetic field and within local magnetic meridional plane. The local meridional vector maps to vertical at the magnetic equator, positive is up.   Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame to express the observed vector along a geomagnetic basis. 

Cross-track velocity is relative to co-rotation and in the instrument frame. Positive-x is normal to IVM aperture plane and in the direction of satellite motion. Velocity obtained through fitting of RPA currents to the Whipple equation to get a measure of the total along track ion velocity as observed within the instrument. Signals produced by the motion of the spacecraft and the rotation of the Earth are removed to produce this result. Mean offset of -0.0 added by R. A. Heelis.

Cross-track velocity is relative to co-rotation and in the instrument frame. Positive-y points generally southward when the instrument is pointed along the ram direction. Velocity obtained through conversion of arrival angles measured by the DM into a cross track velocity using trigonometry. Signals produced by the motion of the spacecraft and the rotation of the Earth are removed to produce this result. Mean offset of -0.0 added by R. A. Heelis.

Cross-track velocity is relative to co-rotation and in the instrument frame. Positive-z is directed towards nadir (Earth). Velocity obtained through conversion of arrival angles measured by the DM into a cross track velocity using trigonometry. Signals produced by the motion of the spacecraft and the rotation of the Earth are removed to produce this result. Mean offset of -0.0 added by R. A. Heelis.

Ion velocity relative to co-rotation along the magnetic zonal direction, normal to local magnetic meridional plane and the geomagnetic field (positive east). The local zonal vector maps to purely horizontal at the magnetic equator. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame to express the observed vector along a geomagnetic basis. 

Raw ion velocity determined using a best fit of RPA measurements to the Whipple equation.

This is the total ion velocity along normal direction into the RPA, including s/c motion.

Total observed ion velocity along instrument cross-track direction, reported in the instrument frame. The translation of DM measured angles to ion velocities uses knowledge of the ram velocity of the plasma and the electric potential of the instrument aperture relative to the ambient plasma, both of which are provided by the RPA. 

Total observed ion velocity along instrument cross-track direction, reported in the instrument frame. The translation of DM measured angles to ion velocities with no RPA corrections. 

The meridional unit vector is perpendicular to the geomagnetic field and maps along magnetic field lines to vertical at the magnetic equator, where positive is up. The unit vector is expressed here in the IVM coordinate system, where x is along the IVM boresight, nominally along ram when in standard pointing. Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

The meridional unit vector is perpendicular to the geomagnetic field and maps along magnetic field lines to vertical at the magnetic equator, where positive is up. The unit vector is expressed here in the IVM coordinate system, where Y = Z x X, nominally southward when in standard pointing, X along ram. Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

The meridional unit vector is perpendicular to the geomagnetic field and maps along magnetic field lines to vertical at the magnetic equator, where positive is up. The unit vector is expressed here in the IVM coordinate system, where Z is nadir pointing (towards Earth), when in standard pointing, X along ram. Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

Plasma potential relative to instrument aperture plane - determined using a best fit to RPA measurements.

Incident plasma will have some potential to the IVM aperture plane. The aperture plane voltage matches that of a conductor allowed to float electrically with respect to the spacecraft. The flux of ions (driven by s/c motion) must be balanced by the flux of electrons (driven by electron temperature). The value of the aperture plane potential evolves naturally to limit the collection of electrons such the net flux is zero.

The field-aligned vector points along the geomagnetic field, with positive values along the field direction, and is expressed here in the IVM instrument frame. The IVM-x direction points along the instrument boresight, which is pointed into ram for standard operations.Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

The field-aligned vector points along the geomagnetic field, with positive values along the field direction. The unit vector is expressed here in the IVM coordinate system, where Y = Z x X, nominally southward when in standard pointing, X along ram. Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

The field-aligned vector points along the geomagnetic field, with positive values along the field direction, and is expressed here in the IVM instrument frame. The IVM-Z direction points towards nadir when IVM-X is pointed into ram for standard operations.Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

The zonal vector is perpendicular to the local magnetic field and the magnetic meridional plane. The zonal vector maps to purely horizontal at the magnetic equator, with positive values pointed generally eastward. This vector is expressed here in the IVM instrument frame.The IVM-x direction points along the instrument boresight, which is pointed into ram for standard operations.Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

The zonal vector is perpendicular to the local magnetic field and the magnetic meridional plane. The zonal vector maps to purely horizontal at the magnetic equator, with positive values pointed generally eastward. The unit vector is expressed here in the IVM coordinate system, where Y = Z x X, nominally southward when in standard pointing, X along ram. Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

The zonal vector is perpendicular to the local magnetic field and the magnetic meridional plane. The zonal vector maps to purely horizontal at the magnetic equator, with positive values pointed generally eastward. This vector is expressed here in the IVM instrument frame.The IVM-Z direction points towards nadir when IVM-X is pointed into ram for standard operations.Calculated using the corresponding unit vector in ECEF and the orientation of the IVM also expressed in ECEF (sc_*hat_*).

If the magnetic torquers are active during any part of the measurement, it is recorded as active for whole measurement. Decoded from spacecraft housekeeping file: ICON_L0_Spacecraft_Housekeeping-MTB_2020-03-05_v01r000.CSV

Data is from predictive ephemeris. 0 = spacecraft in Sun, 1 = spacecraft in Earth Shadow.

Binary Coded Integer Describing Space Environment Region of Space Craft

Standarized for several missions, not all codes are relevant for ICON where  1: Earth Shadow 2: Lunar Shadow 4: Atmospheric Absorption Zone 8: South Atlantic Anomaly 16: Northern Auroral Zone 32: Southern Auroral Zone 64: Periapsis Passage 128: Inner & Outer Radiation Belts 256: Deep Plasma Sphere 512: Foreshock Solar Wind 1024: Solar Wind Beam 2048: High Magnetic Field 4096: Average Plasma Sheet 8192: Bowshock Crossing 16384: Magnetopause Crossing 32768: Ground Based Observatories 65536: 2-Day Conjunctions 131072: 4-Day Conjunctions 262144: Time Based Conjunctions 524288: Radial Distance Region 1 1048576: Orbit Outbound 2097152: Orbit Inbound 4194304: Lunar Wake 8388608: Magnetotail 16777216: Magnetosheath 33554432: Science 67108864: Low Magnetic Latitude 134217728: Conjugate Observation

Binary Coded Integer where  1: LVLH Normal Mode 2: LVLH Reverse Mode 4: Earth Limb Pointing 8: Inertial Pointing 16: Stellar Pointing 32: Attitude Slew 64: Conjugate Maneuver 128: Nadir Calibration 256: Lunar Calibration 512: Stellar Calibration 1024: Zero Wind Calibration 2048-32768: SPARE

Quasi-dipole magnetic latitude of the spacecraft position.  These values are obtained from passing the geodectic latitudes, longitudes, and altitudes from ICON_ANCILLARY_IVM_LATITUDE, ICON_ANCILLARY_IVM_LONGITUDE, and ICON_ANCILLARY_IVM_ALTITUDE into apexpy Python module. For details on apexpy see: https://apexpy.readthedocs.org/

Quasi-dipole magnetic longitude of the spacecraft position.  These values are obtained from passing the geodectic latitudes, longitudes, and altitudes from ICON_ANCILLARY_IVM_LATITUDE, ICON_ANCILLARY_IVM_LONGITUDE, and ICON_ANCILLARY_IVM_ALTITUDE into apexpy Python module. For details on apexpy see: https://apexpy.readthedocs.org/

Drift meter quality flag. 0 - Good data. 1 - Data may have artifacts due to s/c operations. 2 - Data temporarily removed for photoemission. 3 - Not enough O+ to measure arrival angle. 

Status flag for RPA.  0 - All RPA parameters are good. Ion temperatures correspond to both O+ and H+.  1 - Ram Ion Velocities are not good. Other parameters good. Plasma is presumed to be co-rotating when fitting RPA curves that have an insufficient quantity of O+. Ion temperatures correspond to H+ only.  2 - Geophysical outputs may be impacted by spacecraft operations.

ISO 9601 FORMATted UTC timestamp (at middle of reading).  Time is generated from the time-code at byte 1015 of the IVM packet minus the time sync at byte 1019 of the IVM packet. This is the GPS time at the start of the integration period. The integration period is assumed to be 4 seconds so the center time is 2 seconds after that. The formula is (time-code * 1000ms) + 2000ms - (16 * time sync / 1000) in GPS milliseconds then converted to UTC time. See the UTD 206-024 Rev A document.  Time may be delayed by up to 10 ms due to FSW polling delay.  Maximum time is ~2150 UTC and minimum time is ~1970 UTC.

Milliseconds since 1970-01-01 00:00:00 UTC at start of reading.  Time is generated from the time-code at byte 1015 of the IVM packet minus the time sync at byte 1019 of the IVM packet. This is the GPS time at the start of the integration period. The integration period is assumed to be 4 seconds so the center time is 2 seconds after that. The formula is (time-code * 1000ms) + 2000ms - (16 * time sync / 1000) in GPS milliseconds then converted to UTC time. See the UTD 206-024 Rev A document.  Time may be delayed by up to 10 ms due to FSW polling delay.  Maximum time is ~2150 UTC and minimum time is ~1970 UTC.

Milliseconds since 1970-01-01 00:00:00 UTC at end of reading.  Time is generated from the time-code at byte 1015 of the IVM packet minus the time sync at byte 1019 of the IVM packet. This is the GPS time at the start of the integration period. The integration period is assumed to be 4 seconds so the center time is 2 seconds after that. The formula is (time-code * 1000ms) + 2000ms - (16 * time sync / 1000) in GPS milliseconds then converted to UTC time. See the UTD 206-024 Rev A document.  Time may be delayed by up to 10 ms due to FSW polling delay.  Maximum time is ~2150 UTC and minimum time is ~1970 UTC.

Milliseconds since 1980-01-06 00:00:00 TAI (coincident with UTC) at middle of reading.

Milliseconds since 1980-01-06 00:00:00 TAI (coincident with UTC) at middle of reading.  Time is generated from the time-code at byte 1015 of the IVM packet minus the time sync at byte 1019 of the IVM packet. This is the GPS time at the start of the integration period. The integration period is assumed to be 4 seconds so the center time is 2 seconds after that. The formula is (time-code * 1000ms) + 2000ms - (16 * time sync / 1000) in GPS milliseconds then converted to UTC time. See the UTD 206-024 Rev A document.  Time may be delayed by up to 10 ms due to FSW polling delay.  Maximum time is ~2150 UTC and minimum time is ~1970 UTC.

Binary Coded Integer where  1: Earth Day View 2: Earth Night View 4: Calibration Target View 8: Off-target View 16: Sun Proximity View 32: Moon Proximity View 64: North Magnetic Footpoint View 128: South Magnetic Footpoint View 256: Science Data Collection View 512: Calibration Data Collection View 1024: RAM Proximity View 2048-32768: SPARE  Activity is what the spacecraft was commanded to do while status is the spacecraft's natural state of operations. This means that activity should always be used over status if they differ, but will almost always be the same.

Binary Coded Integer where:  1: Earth Day View 2: Earth Night View 4: Calibration Target View 8: Off-target View 16: Sun Proximity View 32: Moon Proximity View 64: North Magnetic Footpoint View 128: South Magnetic Footpoint View 256: Science Data Collection View 512: Calibration Data Collection View 1024: RAM Proximity View 2048-32768: SPARE  Activity is what the spacecraft was commanded to do while status is the spacecraft's natural state of operations. This means that activity should always be used over status if they differ, but will almost always be the same.

Altitude of North Footpoint of Geomagnetic Line at 150 km from IGRF

Altitude location of the magnetic footpoint in the Northern Hemisphere at 150 km. These data were interpolated using a tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

ECEF X-Component of Field Aligned Drift Direction at Northern Footpoint

At the northern footpoint this is the x-component of the unit vector for field aligned ion drifts expressed in the ECEF frame.

ECEF Y-Component of Field Aligned Drift Direction at Northern Footpoint

At the northern footpoint this is the y-component of the unit vector for field aligned ion drifts expressed in the ECEF frame.

ECEF Z-Component of Field Aligned Drift Direction at Northern Footpoint

At the northern footpoint this is the z-component of the unit vector for field aligned ion drifts expressed in the ECEF frame.

Latitude of North Footpoint of Geomagnetic Line at 150 km from IGRF

Latitude location of the magnetic footpoint in the Northern Hemisphere at 150 km. These data were interpolated using a tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

Longitude of North Footpoint of Geomagnetic Line at 150 km from IGRF

Longitude location of the magnetic footpoint in the Northern Hemisphere at 150 km. These data were interpolated using a tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

Velocity along local magnetic meridional direction, perpendicular to geomagnetic field and within local magnetic meridional plane, field-line mapped to northern footpoint. The meridional vector is purely vertical at the magnetic equator, positive up. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the magnetic footpoint. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d). 

Calculated value of quasi-dipole latitude of northern footpoint from IGRF.

Calculated value of quasi-dipole longitude of northern footpoint from IGRF

ECEF X-Component of Meridional Drift Direction at Northern Footpoint

At the northern footpoint this is the x-component of the unit vector for meridional ion drifts expressed in the ECEF frame.

ECEF Y-Component of Meridional Drift Direction at Northern Footpoint

At the northern footpoint this is the y-component of the unit vector for meridional ion drifts expressed in the ECEF frame.

ECEF Z-Component of Meridional Drift Direction at Northern Footpoint

At the northern footpoint this is the z-component of the unit vector for meridional ion drifts expressed in the ECEF frame.

Velocity along local magnetic zonal direction, perpendicular to geomagnetic field and the local magnetic meridional plane, field-line mapped to northern footpoint. The zonal vector is purely horizontal when mapped to the magnetic equator, positive is generally eastward. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the northern footpoint. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d). 

ECEF X-Component of Zonal Drift Directrion at Northern Footpoint

At the northern footpoint this is the x-component of the unit vector for zonal ion drifts expressed in the ECEF frame.

ECEF Y-Component of Zonal Drift Directrion at Northern Footpoint

At the northern footpoint this is the y-component of the unit vector for zonal ion drifts expressed in the ECEF frame.

At the northern footpoint this is the z-component of the unit vector for zonal ion drifts expressed in the ECEF frame.

Altitude of South Footpoint of Geomagnetic Line at 150 km from IGRF

ECEF X-Component of Field Aligned Drift Direction at Southern Footpoint

At the Southern footpoint this is the x-component of the unit vector for field aligned ion drifts expressed in the ECEF frame.

ECEF Y-Component of Field Aligned Drift Direction at Southern Footpoint

At the Southern footpoint this is the y-component of the unit vector for field aligned ion drifts expressed in the ECEF frame.

ECEF Z-Component of Field Aligned Drift Direction at Southern Footpoint

At the Southern footpoint this is the z-component of the unit vector for field aligned ion drifts expressed in the ECEF frame.

Latitude of South Footpoint of Geomagnetic Line at 150 km from IGRF

Latitude location of the magnetic footpoint in the Southern Hemisphere at 150 km. These data were interpolated using a tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

Longitude of South Footpoint of Geomagnetic Line at 150 km from IGRF

Longitude location of the magnetic footpoint in the Southern Hemisphere at 150 km. These data were interpolated using a tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

Velocity along local magnetic meridional direction, perpendicular to geomagnetic field and within local magnetic meridional plane, field-line mapped to southern footpoint. The meridional vector is purely vertical at the magnetic equator, positive up. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the magnetic footpoint. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d). 

Calculated value of quasi-dipole latitude of southern footpoint from IGRF

Calculated value of quasi-dipole longitude of southern footpoint from IGRF

ECEF X-Component of Meridional Drift Direction at Southern Footpoint

At the Southern footpoint this is the x-component of the unit vector for meridional ion drifts expressed in the ECEF frame.

ECEF Y-Component of Meridional Drift Direction at Southern Footpoint

At the Southern footpoint this is the y-component of the unit vector for meridional ion drifts expressed in the ECEF frame.

ECEF Z-Component of Meridional Drift Direction at Southern Footpoint

At the Southern footpoint this is the z-component of the unit vector for meridional ion drifts expressed in the ECEF frame.

Velocity along local magnetic zonal direction, perpendicular to geomagnetic field and the local magnetic meridional plane, field-line mapped to southern footpoint. The zonal vector is purely horizontal when mapped to the magnetic equator, positive is generally eastward. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the southern footpoint. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d). 

At the Southern footpoint this is the x-component of the unit vector for zonal ion drifts expressed in the ECEF frame.

At the Southern footpoint this is the y-component of the unit vector for zonal ion drifts expressed in the ECEF frame.

At the Southern footpoint this is the z-component of the unit vector for zonal ion drifts expressed in the ECEF frame.

X-component of the magnetic field from IGRF at the spacecarft position, expressed in the ECEF frame.

Y-component of the magnetic field from IGRF at the spacecarft position, expressed in the ECEF frame.

Z-component of the magnetic field from IGRF at the spacecarft position, expressed in the ECEF frame.

Velocity along local magnetic meridional direction, perpendicular to geomagnetic field and within local magnetic meridional plane, field-line mapped to apex/magnetic equator. The meridional vector is purely vertical at the magnetic equator, positive up. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the magnetic equator. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d). 

Velocity along local magnetic zonal direction, perpendicular to geomagnetic field and the local magnetic meridional plane, field-line mapped to apex/magnetic equator. The zonal vector is purely horizontal when mapped to the magnetic equator, positive is generally eastward. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the magnetic equator. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d). 

Component of Earth's corotation velocity vector projected into the IVM instrument axes by taking the dot product of the corotation vector with the instrument's axes and multiplying the Y and Z components by negative 1 (but not the X component by convention).