<_Note>Nodes prefixed with a _ are not valid SPASE, but are included for debugging. Values prefixed with a x_ are not valid SPASE but may considered for addition for completeness. 2.6.1 <_MasterURL>https://cdaweb.gsfc.nasa.gov/pub/software/cdawlib/0JSONS/icon_l2-2_mighti_vector-wind-green_00000000_v01.json (from all.xml) spase://NASA/NumericalData/ICON/MIGHTI/L2/Vector/Green/PT30S <_ResourceID>Source: https://github.com/rweigel/cdawmeta-spase/blob/main/ResourceID.json MIGHTI - Cardinal Vector Winds <_ResourceName>Source: Master/CDFglobalAttributes/Logical_source_description 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. <_Description>Source: Master/CDFglobalAttributes/TEXT <_Acknowledgement>Source: Master/CDFglobalAttributes/Acknowledgement <_Rights> SPDX Creative Commons Zero v1.0 Universal https://spdx.org/licenses/CC0-1.0.html https://spdx.org/licenses/ http://icon.ssl.berkeley.edu/Instruments/MIGHTI ICON MIGHTI MIGHTI Cardinal Vector Winds (DP 2.2) <_Note>URL also in all.xml. Using master. Additional information on ICON https://icon.ssl.berkeley.edu/ ICON spacecraft Homepage. <_Note>Source: InformationURL.json Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI): instrument design and calibration https://doi.org/10.1007/s11214-017-0358-4 Space Science Reviews, 212(1-2), pp.553-584. DOI: 10.1007/s11214-017-0358-4 <_Note>Source: InformationURL.json ICON MIGHTI Cardinal Vector Winds (DP 2.2) https://doi.org/10.48322/vtce-7y29 <_DOI>Source: https://github.com/rweigel/cdawmeta-spase/blob/main/DOI.json <_AccessInformation>Source: https://github.com/rweigel/cdawmeta-spase/blob/main/AccessInformation.json 2019-12-06T00:00:00Z 2022-11-25T00:00:00Z <_TemporalDescription>Generated from all.xml/@timerange_start and all.xml/@timerange_stop <_ObservedRegion>Source: https://github.com/rweigel/cdawmeta-spase/blob/main/ObservedRegion.json <_ProcessingLevel>Processing level is not available in the master file; it should be there instead of, say, https://github.com/rweigel/cdawmeta-spase/blob/main/ProcessingLevel.json spase://SMWG/Instrument/ICON/MIGHTI Dopplergram spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/CDAWeb. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL HTTPS from SPDF https://cdaweb.gsfc.nasa.gov/pub/data/icon/l2/l2-2_mighti_vector-wind-green In CDF via HTTP from CDAWeb icon_l2-2_mighti_vector-wind-green_%Y%m%d_v06r000.nc %Y ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN CDF spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/CDAWeb. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL FTPS from SPDF ftps://cdaweb.gsfc.nasa.gov/pub/data/icon/l2/l2-2_mighti_vector-wind-green In CDF via HTTP from CDAWeb icon_l2-2_mighti_vector-wind-green_%Y%m%d_v06r000.nc %Y ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN CDF spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/CDAWeb. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL CDAWeb Web Service https://cdaweb.gsfc.nasa.gov/WebServices/ Instructions for using web services to access this dataset an other other metadata and options for CDAWeb datasets. The ProductKey here corresponds to the query parameter 'dataset' in the tables at the AccessURL in a dataset-related request can be made. ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN CDF CSV GIF NetCDF PNG PS PDF XML x_Script.IDL x_Script.Python Text.ASCII x_WAV spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/CDAWeb. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL CDAWeb Web Service user interface https://cdaweb.gsfc.nasa.gov/cgi-bin/eval2.cgi?index=sp_phys&dataset=ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN Web service user interface for this product. CDF GIF PDF Text.ASCII x_WAV spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/CDAWeb. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL CDAWeb Python Script https://cdaweb.gsfc.nasa.gov/WS/cdasr/1/dataviews/sp_phys/datasets/ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN/clientLibraryExample/ ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN Web service that generates a Python script to access this product. x_Script.IDL x_Script.Python spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/SSCWeb. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL 4D Orbit Viewer https://sscweb.gsfc.nasa.gov/4dorbit/?sc=ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN Web Service to this product. HTML spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/CDAWeb and the HAPI project. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL CDAWeb HAPI Server https://hapi-server.org/servers/#server=CDAWeb&dataset=ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN Web Service to this product using the HAPI interface. CSV JSON Binary spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/CDAWeb and the HAPI project. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL CDAWeb HAPI Script in Multiple Languages https://hapi-server.org/servers/#server=CDAWeb&dataset=ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN&return=script ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN Web Service user interface that generates scripts in IDL, Javascript, MATLAB, Python, Autoplot, curl, wget to access this product. See https://hapi-server.org/servers/api for the API. x_Script.IDL x_Script.Javascript x_Script.MATLAB x_Script.Python x_Script.Autoplot x_Script.curl x_Script.wget spase://SMWG/Repository/NASA/GSFC/SPDF Online Open SPDF/CDAWeb and the HAPI project. Please also acknowledge the data producer: T. J. Immel at UC Berkeley>SSL HAPI visualizations https://hapi-server.org/plot/?server=https://cdaweb.gsfc.nasa.gov/hapi&dataset=ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN&format=gallery ICON_L2-2_MIGHTI_VECTOR-WIND-GREEN Web Service that generates plots. See https://hapi-server.org/plot/ for the API. PNG PDF SVG Ionospheric Connection Explorer (from all.xml/observatory/description/@short) Michelson Interferometer for Global High-resolution Thermospheric Imaging (from all.xml/instrument/description/@short) Space Physics (from Master/CDFglobalAttributes/Discipline) Ionospheric Science (from Master/CDFglobalAttributes/Discipline) ICON (from Master/CDFglobalAttributes/Source_name) Ionospheric Connection Explorer (from Master/CDFglobalAttributes/Source_name) DP22 (from Master/CDFglobalAttributes/Data_type) Data Product 2.2: Cardinal Vector Winds (from Master/CDFglobalAttributes/Data_type) MIGHTI (from all.xml/instrument/@ID) Earth.NearSurface.Atmosphere Earth.NearSurface.Ionosphere time_epoch Epoch_cdf CATDESC: 'time_inboard'. Notes not in Master CDF: 'The units are the units in CDF files. For other web services, this variable is may be represented as a time string.' seconds since 1970-01-01 00:00:00 Scalar Temporal Time Epoch_Full Master CDF CATDESC: 'Sample time, midpoint of A and B measurements. Number of msec since Jan 1, 1970.'. Master CDF VAR_NOTES: 'See the notes for the variable Epoch. This variable is the same as Epoch but contains a second dimension, which captures the small (30-60 second) variation of time with altitude. For most applications this is expected to be negligible, and Epoch can be used instead of this variable. Also see the variable Time_Delta, which contains the difference between the MIGHTI-A and MIGHTI-B times that contributed to each point. Epoch_Full contains the average time.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' ms -1 84 Altitude ICON_L22_Altitude Master CDF CATDESC: 'WGS84 altitude of each wind sample'. Master CDF VAR_NOTES: 'A one-dimensional array defining the altitude dimension of the data grid (the other dimension being time). Altitude is defined using the WGS84 ellipsoid.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' km 9.96921e+36 84 Fringe Amplitude ICON_L22_Fringe_Amplitude Master CDF CATDESC: 'Fringe Amplitude'. Master CDF VAR_NOTES: 'An approximate volume emission rate (VER) profile in arbitrary units, estimated by combining MIGHTI-A and MIGHTI-B data. Technically this is not the VER, but rather the amplitude of the fringes, which has a dependence on thermospheric temperature and background emission. Thus, it does not truly represent volume emission rate. However, it is a useful proxy. The units are arbitrary, as the fringe amplitudes are not calibrated. See also variables Fringe_Amplitude_Relative_Difference, Fringe_Amplitude_A, and Fringe_Amplitude_B.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' arb 9.96921e+36 84 Fringe Amplitude Error ICON_L22_Fringe_Amplitude_Error Master CDF CATDESC: 'Error in the fringe amplitude estimate'. Master CDF VAR_NOTES: 'The statistical (1-sigma) error in the fringe amplitude estimate, propagated from error in the MIGHTI-A and MIGHTI-B inversions. The units are arbitrary, as the fringe amplitudes are not absolutely calibrated. Systematic errors, such as those arising from airglow gradients or cross-calibration, are not included in this variable, but are probably the dominant source of total error.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' arb 9.96921e+36 84 Latitude ICON_L22_Latitude Master CDF CATDESC: 'WGS84 latitude of each wind sample'. Master CDF VAR_NOTES: 'A two-dimensional array defining the latitude of the two-dimensional data grid. The latitude varies only slightly (a few deg) with altitude, but this variation is included. Latitude is defined using the WGS84 ellipsoid. It should be noted that while a single latitude value is given for each point, the observation is inherently a horizontal average over many hundreds of kilometers.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' deg 9.96921e+36 84 LST ICON_L22_Local_Solar_Time Master CDF CATDESC: 'Local solar time of each wind sample'. Master CDF VAR_NOTES: 'Local solar time at each point in the grid, calculating using the equation of time.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' hour 9.96921e+36 84 Longitude ICON_L22_Longitude Master CDF CATDESC: 'WGS84 longitude of each wind sample'. Master CDF VAR_NOTES: 'A two-dimensional array defining the longitude (0-360 deg) of the two-dimensional data grid. In the initial implementation, the longitude is constant with altitude, but this may change in the future to capture the slight (few deg) variation with altitude. Longitude is defined using the WGS84 ellipsoid. It should be noted that while a single longitude value is given for each point, the observation is inherently a horizontal average over many hundreds of kilometers.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' deg 9.96921e+36 84 MgFA Wind ICON_L22_Magnetic_Field_Aligned_Wind Master CDF CATDESC: 'Magnetic field-aligned component of the wind'. Master CDF VAR_NOTES: 'The component of the wind in the direction of the magnetic field line, assuming vertical winds are negligible. This variable is calculated by taking the geographic zonal and meridional wind (the primary data products in this file) and expressing the wind vector in a local magnetic coordinate system defined using the Python package OMMBV (https://github.com/rstoneback/OMMBV). The coordinate system used here is orthogonal and is identical to the coordinate system used to express the ion drifts in the ICON IVM data product 2.7 (i.e., the variables ICON_L27_Ion_Velocity_Meridional, ICON_L27_Ion_Velocity_Zonal, and ICON_L27_Ion_Velocity_Field_Aligned).'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Mag Lat ICON_L22_Magnetic_Latitude Master CDF CATDESC: 'Magnetic quasi-dipole latitude of each wind sample'. Master CDF VAR_NOTES: 'A two-dimensional array defining the magnetic quasi-dipole latitude of the two-dimensional data grid. The latitude varies only slightly (a few deg) with altitude, but this variation is included. It should be noted that while a single latitude value is given for each point, the observation is inherently a horizontal average over many hundreds of kilometers. Quasi-dipole latitude and longitude are calculated using the fast implementation developed by Emmert et al. (2010, doi:10.1029/2010JA015326) and the Python wrapper apexpy (doi.org/10.5281/zenodo.1214207). '. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' deg 9.96921e+36 84 Mag Lon ICON_L22_Magnetic_Longitude Master CDF CATDESC: 'Magnetic quasi-dipole longitude of each wind sample'. Master CDF VAR_NOTES: 'A two-dimensional array defining the magnetic quasi-dipole longitude of the two-dimensional data grid. The longitude varies only slightly (a few deg) with altitude, but this variation is included. It should be noted that while a single longitude value is given for each point, the observation is inherently a horizontal average over many hundreds of kilometers. Quasi-dipole latitude and longitude are calculated using the fast implementation developed by Emmert et al. (2010, doi:10.1029/2010JA015326) and the Python wrapper apexpy (doi.org/10.5281/zenodo.1214207). Quasi-dipole longitude is defined such that zero occurs where the geodetic longitude is near 285 deg east (depending on latitude).'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' deg 9.96921e+36 84 MgMerWind ICON_L22_Magnetic_Meridional_Wind Master CDF CATDESC: 'Magnetic meridional component of the wind'. Master CDF VAR_NOTES: 'The component of the wind in the magnetic meridional direction, assuming vertical winds are negligible. This variable is calculated by taking the geographic zonal and meridional wind (the primary data products in this file) and expressing the wind vector in a local magnetic coordinate system defined using the Python package OMMBV (https://github.com/rstoneback/OMMBV). The magnetic meridional unit vector is orthogonal to the magnetic field line but within the plane of the magnetic meridian (defined by the apex of the field line and its footpoint). At the magnetic equator, the meridional direction points up, while away from the equator it has a poleward component (north in the northern hemisphere, south in the southern hemisphere). Note that in some ion-neutral coupling models, a definition of magnetic meridional is often used that is horizontal (i.e., perpendicular to gravity) and generally northward. The definition used here is perpendicular to B and thus has primarily a vertical component at ICON latitudes. Note also that the definition of magnetic meridional and zonal used here differs from quasi-dipole and apex coordinate bases. The coordinate system used here is orthonormal and is identical to the coordinate system used to express the ion drifts in the ICON IVM data product 2.7 (i.e., the variables ICON_L27_Ion_Velocity_Meridional, ICON_L27_Ion_Velocity_Zonal, and ICON_L27_Ion_Velocity_Field_Aligned).'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 MgZon Wind ICON_L22_Magnetic_Zonal_Wind Master CDF CATDESC: 'Magnetic zonal component of the wind'. Master CDF VAR_NOTES: 'The component of the wind in the magnetic zonal direction, assuming vertical winds are negligible. This variable is calculated by taking the geographic zonal and meridional wind (the primary data products in this file) and expressing the wind vector in a local magnetic coordinate system defined using the Python package OMMBV (https://github.com/rstoneback/OMMBV). At the magnetic equator, the zonal direction points horizontally, while away from the equator it can have a slightly vertical component. Note that the definition of magnetic meridional and zonal used here differs from quasi-dipole and apex coordinate bases. The coordinate system used here is orthonormal and is identical to the coordinate system used to express the ion drifts in the ICON IVM data product 2.7 (i.e., the variables ICON_L27_Ion_Velocity_Meridional, ICON_L27_Ion_Velocity_Zonal, and ICON_L27_Ion_Velocity_Field_Aligned).'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Meridional Wind ICON_L22_Meridional_Wind Master CDF CATDESC: 'Meridional component of the horizontal wind. Positive Northward.'. Master CDF VAR_NOTES: 'The zonal (positive eastward) and meridional (positive northward) winds are the primary data product in this file. They are defined on a grid with dimensions of time and altitude, spanning 24 hours and nominally 90-300 km (150-300 km for the red channel). The altitude, time, latitude and longitude corresponding to each point in the grid are given by other variables in this file. It should be noted that while each measurement is ascribed to a particular latitude, longitude, altitude, and time, it is actually an average over many hundreds of kilometers horizontally and 2.5-30 kilometers vertically (depending on the binning). It also assumes stationarity over the 5-8 minutes between the MIGHTI-A and B measurements used for each point. See Harding et al. [2017, doi:10.1007/s11214-017-0359-3] for a more complete discussion of the inversion algorithm. Knowledge of the 'zero wind phase' is needed for any instrument using Doppler shifts to determine winds. The zero wind phase is defined as the measured interference fringe phase that corresponds to the rest wavelength of the emission. For this initial data release, the zero wind phase has been determined by comparing a 60-day average of MIGHTI data to a 60-day average of the empirical Horizontal Wind Model 2014 (HWM14, Drob et al., 2015, doi:10.1002/2014EA000089), which is a fit to decades of previous wind measurements. At each time and location of a MIGHTI measurement, the MIGHTI measurement is simulated by integrating HWM14 along the line of sight, weighted by the observed volume emission rate as determined by the measured fringe amplitude profile. The 60-day-average difference between the measured and simulated phases is taken as the zero wind phase. This is done separately for each sensor (A and B), for each color (red and green), for each mode (day and night), and for each row (i.e., each altitude). This approach to determining the zero wind phase is analogous to the approach taken for the UARS/HRDI instrument (Hays et al., 1992, doi:10.1016/0032-0633(92)90119-9), which assumed that a long-term average of the meridional wind is zero. Although the long-term average altitude profile is constrained to match HWM14 in this initial MIGHTI data release, measured variations in time, latitude, longitude, and from day to day are retained using this approach. A future data release will leverage ICON's unique 'zero wind' 'maneuver' to determine an independent zero wind phase.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Meridional Wind Prec 1-Day ICON_L22_Meridional_Wind_Accuracy Master CDF CATDESC: 'Accuracy of the meridional wind estimate.'. Master CDF VAR_NOTES: '['Various sources of error in MIGHTI winds are quantified with 1-sigma estimates and organized by their temporal persistence. These error sources are nearly uncorrelated with each other and can thus be added in quadrature. Users are encouraged to contact the MIGHTI team for assistance with error propagation.', 'The "Accuracy" variable quantifies the error introduced by the zero-wind phase estimate. It is strongly correlated across time lags of days to weeks and becomes increasingly decorrelated for time lags longer than 2 precession cycles (96 days). This error is estimated from the discrepancy between various techniques of determining the zero-wind phase. This error source is irrelevant for most users studying perturbations from the mean (e.g., tides, waves), but may be important for studies of zonal mean winds, point comparisons with other data sets, and seasonal/long-term trends thereof. Errors are moderately correlated across small altitude gaps. Errors in day mode and night mode are nearly uncorrelated, implying there could be different offsets for day mode and night mode. This could be important for error propagation of odd-numbered migrating tides (e.g., DW1).']'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Meridional Wind Error ICON_L22_Meridional_Wind_Error Master CDF CATDESC: 'Error in the meridional wind estimate.'. Master CDF VAR_NOTES: 'The statistical (1-sigma) error in the meridional wind, propagated from the error in the L2.1 (line-of-sight wind) files. This is usually dominated by shot noise in the detectors, but also includes the effects of dark and read noise, as well as calibrations errors (e.g., the zero wind calibration), and spacecraft pointing error (which affects the uncertainty in removing the spacecraft velocity from the observed velocity). Other systematic errors or biases may exist (e.g., the effect of gradients along the line of sight) which are not included in this variable.Errors in daily calibrations may create systematic patterns in winds that are constant for an entire 24 hour period (00:00 - 23:59 UT) but change from day to day.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Meridional Wind Prec 1-Day ICON_L22_Meridional_Wind_Precision_1_Day Master CDF CATDESC: '1-day precision in the meridional wind estimate.'. Master CDF VAR_NOTES: '['Various sources of error in MIGHTI winds are quantified with 1-sigma estimates and organized by their temporal persistence. These error sources are nearly uncorrelated with each other and can thus be added in quadrature. Users are encouraged to contact the MIGHTI team for assistance with error propagation.', 'The "1 Day" error variable quantifies the error introduced by daily calibrations, which is correlated for an entire 24-hour period (00:00 - 23:59 UT). This is estimated from the magnitude of fluctuations in the daily-averaged phase, propagated through the inversion. Errors in day mode and night mode are nearly uncorrelated. For studies pertaining to atmospheric tidal modes that combine data from many days, this error can be treated as uncorrelated across time.']'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Merid Wind Prec 1-Sample ICON_L22_Meridional_Wind_Precision_1_Sample Master CDF CATDESC: '1-sample precision in the meridional wind estimate.'. Master CDF VAR_NOTES: '['Various sources of error in MIGHTI winds are quantified with 1-sigma estimates and organized by their temporal persistence. These error sources are nearly uncorrelated with each other and can thus be added in quadrature. Users are encouraged to contact the MIGHTI team for assistance with error propagation.', 'The "1 sample" error variable quantifies errors that are uncorrelated from one exposure to the next, dominated by shot and dark noise in the detectors. The correlation time of this error source is 30-60 seconds (i.e., the measurement cadence). The reported error is estimated from the fringe intensity and background. This is the recommended variable to use for analyses of wind fluctuations within a single day and a single altitude (e.g., gravity waves). Because the Level 2.2 data include interpolation of Level 2.1 data, some correlation remains between consecutive samples. Errors are slightly correlated across small altitude gaps as a result of the inversion.']'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Merid Wind Prec Low Sig ICON_L22_Meridional_Wind_Precision_Low_Signal_Effect Master CDF CATDESC: 'Low-signal precision in the meridional wind estimate.'. Master CDF VAR_NOTES: '['Various sources of error in MIGHTI winds are quantified with 1-sigma estimates and organized by their temporal persistence. These error sources are nearly uncorrelated with each other and can thus be added in quadrature. Users are encouraged to contact the MIGHTI team for assistance with error propagation.', 'The "Low Signal Effect" error variable quantifies the error introduced by the imperfect correction for the signal-dependent phase shift, which is an effect seen in atmospheric and calibration-lamp fringes where the phase of the fringes is biased at very low signal levels. This is under investigation but could be caused by a charge trapping effect in the CCD. A correction has been implemented based upon the empirical relationship between measured phase and signal level of the calibration lamps for the first ~30 months of the mission. However, especially for cases with low signal levels, this correction is uncertain. The uncertainty in the resulting winds is estimated from the signal level and reported in this variable. It is likely to be correlated across samples nearby in time and space, but the correlation between different channels (red and green), sensors (MIGHTI-A and MIGHTI-B), and operating modes (Day and Night) is not known. Depending on the analysis being used, it could be treated as a systematic error or as a statistical error. Where this uncertainty is large, caution is recommended. For example, for winds in the core science region (90-105 km altitude), the magnitude of the correction is small or zero, but data in the red channel during the night and twilight are subject to a large correction (many tens of m/s) and the uncertainty is correspondingly large. A goal for future releases is to characterize and correct this effect more accurately.']'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Orbit Node ICON_L22_Orbit_Node Master CDF CATDESC: 'ICON orbit ascending/descending flag'. Master CDF VAR_NOTES: 'A flag indicating whether ICON is in the ascending (0) or descending (1) part of the orbit. For some grid points, samples from MIGHTI-A are on the descending part of the orbit, while samples from MIGHTI-B are ascending. In these cases an interpolated value is used (between 0 and 1).'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' 9.96921e+36 84 Orbit Number ICON_L22_Orbit_Number Master CDF CATDESC: 'ICON orbit number'. Master CDF VAR_NOTES: 'The ICON orbit number corresponding to each grid point. This is usually an integer, but when samples from two different orbits are used, an interpolated (fractional) value is used.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' 9.96921e+36 84 Relative VER ICON_L22_Relative_VER Master CDF CATDESC: 'Relative volume emission rate'. Master CDF VAR_NOTES: 'The volume emission rate (VER) obtained by averaging the VER from MIGHTI-A and MIGHTI-B, which is obtained by scaling the fringe amplitude by a calibration factor, as described in Data Product 2.1. Pre-flight calibrations and on-orbit comparisons with ground-based instruments are used to determine the best possible calibration. The fringe amplitude has a dependence on temperature, which is corrected using the MSIS model. Because the on-orbit calibration is uncertain, and because the MSIS temperature correction is not perfect, caution should be exercised when absolute calibration is required, or when precise comparisons are being made between samples at very different temperatures. Please contact the MIGHTI team before performing any studies that require absolute calibration. The statistical (1-sigma) error for this variable is provided in the variable ICON_..._Relative_VER_Error, though it is expected that systematic calibration errors dominate the total error.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' ph/cm^3/s 9.96921e+36 84 Relative VER Error ICON_L22_Relative_VER_Error Master CDF CATDESC: 'Error in VER estimate (statistical)'. Master CDF VAR_NOTES: 'The statistical (1-sigma) error in the relative VER estimate, propagated from error in the MIGHTI-A and MIGHTI-B inversions. This error arises mostly from shot noise. Importantly, it is expected that systematic errors (e.g., calibration errors) dominate the total error, but they are not included in this variable.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' ph/cm^3/s 9.96921e+36 84 SZA ICON_L22_Solar_Zenith_Angle Master CDF CATDESC: 'Solar zenith angle of each wind sample'. Master CDF VAR_NOTES: 'Angle between the vectors towards the sun and towards zenith, for each point in the grid.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' deg 9.96921e+36 84 Time Delta ICON_L22_Time_Delta Master CDF CATDESC: 'Difference between MIGHTI-A and B times contributing to each point'. Master CDF VAR_NOTES: 'To determine the cardinal wind at each point, a MIGHTI-A line-of-sight wind is combined with a MIGHTI-B line-of-sight wind from several minutes later. This variable contains this time difference for every point. During standard operations (LVLH Normal), this variable should be positive, but can potentially become negative during conjugate operations or when ICON is observing to the south (LVLH Reverse).'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' s 9.96921e+36 84 Time ICON_L22_UTC_Time Master CDF CATDESC: 'Sample time, average of A and B measurements.'. Master CDF VAR_NOTES: 'This variable is the same as Epoch but is formatted as a human-readable string. Missing grid points are labeled with empty strings.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' VER Quality ICON_L22_VER_Quality Master CDF CATDESC: 'A quantification of the VER data quality, from 0 (Bad) to 1 (Good)'. Master CDF VAR_NOTES: 'A quantification of the overall quality of the VER data. While the intent is that the XXX_VER_Error variable accurately characterizes the statistical error in the VER data, it is possible that systematic errors are present, or that the statistical error estimation is not accurate. If it is suspected that this is the case, the quality will be less than 1.0. If the data are definitely unusable, the quality will be 0.0 and the sample will be masked. Users should exercise caution when the quality is less than 1.0. Currently, the quality can take values of 0 (Bad), 0.5 (Caution), or 1 (Good).'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' 1=good 9.96921e+36 84 Wind Quality ICON_L22_Wind_Quality Master CDF CATDESC: 'A quantification of the wind data quality, from 0 (Bad) to 1 (Good)'. Master CDF VAR_NOTES: 'A quantification of the overall quality of the wind data. While the intent is that the XXX_Wind_Error variable accurately characterizes the statistical error in the wind data, it is possible that systematic errors are present, or that the statistical error estimation is not accurate. If this is suspected to be the case, the quality will be less than 1.0. If the data are definitely unusable, the quality will be 0.0 and the sample will be masked. Users should exercise caution when the quality is less than 1.0. Currently, the quality can take values of 0 (Bad), 0.5 (Caution), or 1 (Good).'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' 1=good 9.96921e+36 84 Zonal Wind ICON_L22_Zonal_Wind Master CDF CATDESC: 'Zonal component of the horizontal wind. Positive Eastward.'. Master CDF VAR_NOTES: 'The zonal (positive eastward) and meridional (positive northward) winds are the primary data product in this file. They are defined on a grid with dimensions of time and altitude, spanning 24 hours and nominally 90-300 km (150-300 km for the red channel). The altitude, time, latitude and longitude corresponding to each point in the grid are given by other variables in this file. It should be noted that while each measurement is ascribed to a particular latitude, longitude, altitude, and time, it is actually an average over many hundreds of kilometers horizontally and 2.5-30 kilometers vertically (depending on the binning). It also assumes stationarity over the 5-8 minutes between the MIGHTI-A and B measurements used for each point. See Harding et al. [2017, doi:10.1007/s11214-017-0359-3] for a more complete discussion of the inversion algorithm. Knowledge of the 'zero wind phase' is needed for any instrument using Doppler shifts to determine winds. The zero wind phase is defined as the measured interference fringe phase that corresponds to the rest wavelength of the emission. For this initial data release, the zero wind phase has been determined by comparing a 60-day average of MIGHTI data to a 60-day average of the empirical Horizontal Wind Model 2014 (HWM14, Drob et al., 2015, doi:10.1002/2014EA000089), which is a fit to decades of previous wind measurements. At each time and location of a MIGHTI measurement, the MIGHTI measurement is simulated by integrating HWM14 along the line of sight, weighted by the observed volume emission rate as determined by the measured fringe amplitude profile. The 60-day-average difference between the measured and simulated phases is taken as the zero wind phase. This is done separately for each sensor (A and B), for each color (red and green), for each mode (day and night), and for each row (i.e., each altitude). This approach to determining the zero wind phase is analogous to the approach taken for the UARS/HRDI instrument (Hays et al., 1992, doi:10.1016/0032-0633(92)90119-9), which assumed that a long-term average of the meridional wind is zero. Although the long-term average altitude profile is constrained to match HWM14 in this initial MIGHTI data release, measured variations in time, latitude, longitude, and from day to day are retained using this approach. A future data release will leverage ICON's unique 'zero wind maneuver' to determine an independent zero wind phase.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Zonal Wind Prec 1-Day ICON_L22_Zonal_Wind_Accuracy Master CDF CATDESC: 'Accuracy of the zonal wind estimate.'. Master CDF VAR_NOTES: '['Various sources of error in MIGHTI winds are quantified with 1-sigma estimates and organized by their temporal persistence. These error sources are nearly uncorrelated with each other and can thus be added in quadrature. Users are encouraged to contact the MIGHTI team for assistance with error propagation.', 'The "Accuracy" variable quantifies the error introduced by the zero-wind phase estimate. It is strongly correlated across time lags of days to weeks and becomes increasingly decorrelated for time lags longer than 2 precession cycles (96 days). This error is estimated from the discrepancy between various techniques of determining the zero-wind phase. This error source is irrelevant for most users studying perturbations from the mean (e.g., tides, waves), but may be important for studies of zonal mean winds, point comparisons with other data sets, and seasonal/long-term trends thereof. Errors are moderately correlated across small altitude gaps. Errors in day mode and night mode are nearly uncorrelated, implying there could be different offsets for day mode and night mode. This could be important for error propagation of odd-numbered migrating tides (e.g., DW1).']'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Zonal Wind Error ICON_L22_Zonal_Wind_Error Master CDF CATDESC: 'Error in the zonal wind estimate.'. Master CDF VAR_NOTES: 'The statistical (1-sigma) error in the zonal wind, propagated from the error in the L2.1 (line-of-sight wind) files. This is usually dominated by shot noise in the detectors, but also includes the effects of dark and read noise, as well as calibrations errors (e.g., the zero wind calibration), and spacecraft pointing error (which affects the uncertainty in removing the spacecraft velocity from the observed velocity). Other systematic errors or biases may exist (e.g., the effect of gradients along the line of sight) which are not included in this variable.Errors in daily calibrations may create systematic patterns in winds that are constant for an entire 24 hour period (00:00 - 23:59 UT) but change from day to day.'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Zonal Wind Prec 1-Day ICON_L22_Zonal_Wind_Precision_1_Day Master CDF CATDESC: '1-day precision in the zonal wind estimate.'. Master CDF VAR_NOTES: '['Various sources of error in MIGHTI winds are quantified with 1-sigma estimates and organized by their temporal persistence. These error sources are nearly uncorrelated with each other and can thus be added in quadrature. Users are encouraged to contact the MIGHTI team for assistance with error propagation.', 'The "1 Day" error variable quantifies the error introduced by daily calibrations, which is correlated for an entire 24-hour period (00:00 - 23:59 UT). This is estimated from the magnitude of fluctuations in the daily-averaged phase, propagated through the inversion. Errors in day mode and night mode are nearly uncorrelated. For studies pertaining to atmospheric tidal modes that combine data from many days, this error can be treated as uncorrelated across time.']'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Zonal Wind Prec 1-Sample ICON_L22_Zonal_Wind_Precision_1_Sample Master CDF CATDESC: '1-sample precision in the zonal wind estimate.'. Master CDF VAR_NOTES: '['Various sources of error in MIGHTI winds are quantified with 1-sigma estimates and organized by their temporal persistence. These error sources are nearly uncorrelated with each other and can thus be added in quadrature. Users are encouraged to contact the MIGHTI team for assistance with error propagation.', 'The "1 sample" error variable quantifies errors that are uncorrelated from one exposure to the next, dominated by shot and dark noise in the detectors. The correlation time of this error source is 30-60 seconds (i.e., the measurement cadence). The reported error is estimated from the fringe intensity and background. This is the recommended variable to use for analyses of wind fluctuations within a single day and a single altitude (e.g., gravity waves). Because the Level 2.2 data include interpolation of Level 2.1 data, some correlation remains between consecutive samples. Errors are slightly correlated across small altitude gaps as a result of the inversion.']'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84 Zonal Wind Prec Low Sig ICON_L22_Zonal_Wind_Precision_Low_Signal_Effect Master CDF CATDESC: 'Low-signal precision in the zonal wind estimate.'. Master CDF VAR_NOTES: '['Various sources of error in MIGHTI winds are quantified with 1-sigma estimates and organized by their temporal persistence. These error sources are nearly uncorrelated with each other and can thus be added in quadrature. Users are encouraged to contact the MIGHTI team for assistance with error propagation.', 'The "Low Signal Effect" error variable quantifies the error introduced by the imperfect correction for the signal-dependent phase shift, which is an effect seen in atmospheric and calibration-lamp fringes where the phase of the fringes is biased at very low signal levels. This is under investigation but could be caused by a charge trapping effect in the CCD. A correction has been implemented based upon the empirical relationship between measured phase and signal level of the calibration lamps for the first ~30 months of the mission. However, especially for cases with low signal levels, this correction is uncertain. The uncertainty in the resulting winds is estimated from the signal level and reported in this variable. It is likely to be correlated across samples nearby in time and space, but the correlation between different channels (red and green), sensors (MIGHTI-A and MIGHTI-B), and operating modes (Day and Night) is not known. Depending on the analysis being used, it could be treated as a systematic error or as a statistical error. Where this uncertainty is large, caution is recommended. For example, for winds in the core science region (90-105 km altitude), the magnitude of the correction is small or zero, but data in the red channel during the night and twilight are subject to a large correction (many tens of m/s) and the uncertainty is correspondingly large. A goal for future releases is to characterize and correct this effect more accurately.']'. Notes not in Master CDF: 'The time index (the ISTP DEPEND_0 variable) for this parameter is Epoch_cdf.' m/s 9.96921e+36 84