Characteristics of the GLORIA dataset
Calibrated and geo-located limb-imaging hyperspectral infrared radiance data from the GLORIA POLSTRACC campaign are available in NetCDF format in accordance with the NetCDF CF Metadata Conventions (http://cfconventions.org/).
Due to the NetCDF CF convention, for visualization or data, various tools are publicly available and easily to be adapted (e.g. Panoply https://www.giss.nasa.gov/tools/panoply/download/ or the Python packages ‘netCDF4’ or ‘Xarray’).
As an example, Figure 1 shows a typical radiance spectrum observed by GLORIA.
Together with the main data (the calibrated hyperspectral radiance data) also auxiliary data are provided which are essential for level-1 -> level-2 analysis(retrieval of atmospheric quantities from the calibrated radiances). Below the content of the whole dataset as distributed over sub-directories is listed:
- netCDF files containing row-averaged spectra for the given time stamp
- Abscissa: spectral abscissa for all spectra (in cm-1)
- Radiance: the infrared spectra per pixel row and wave number defined in abscissa (nW cm-2 sr-1 cm).
- Imagpart: imaginary part of the spectra. The spectral noise (NESR) can be estimated from these.
- Further self-explaining variables contain metadata, which may be repeated by the dedicated metadata files (see below)
- Text files containing rows in the measurements, which are not cloud affected according to the cloud filter (explained in the AMT paper)
- Not all spectra have a corresponding cloud_filter file: These files are pre-filtered and not considered for further analysis.
- *.pt Text files with temperature and pressure information interpolated on tangent points from ECMWF operational analysis global fields
- Text files with climatological trace gas profiles from MIPAS-Envisat climatology
- H2O profiles are interpolated from ECMWF operational analysis global fields
- Instrument/aircraft metafiles for all measurements classified as “chemistry mode”
- Altitude/latitude/longitude: GPS information of aircraft position for corresponding measurement
- cubname: internal timestamp of measurement (also used for all other files)
- meastime: UTC timestamp in Unix time (seconds since 1 January 1970)
- meastype: measurement classification (chemistry mode, dynamics mode, calibration, parking)
- opd: optical path difference
- pitch/roll/yaw: Aircraft angles of GLORIA view
- temp_bb1/2: blackbody temperatures (used for calibration)
- same as metadata_atm_chem.nc, but for all measured spectra during this flight (also “dynamics mode” and calibration measurements)
- Extended metafiles, differences explained below:
- id: internal timestamp as string
- time: UTC timestamp in seconds since 1 January 2000
- h_t/lat_t/lon_t: Coordinates of tangent points per pixel row
- elev_deg: Elevation angle per pixel row
- nadir_deg: Elevation angle from nadir direction (per pixel row)
- cld_cia: MIPAS Cloud Index (see Spang et al., 2004) per pixel row, used for cloud filtering
- ele_offset: do not use! Dummy variable!
- Correction for line-of sight/elevation angles for all metadata (explanation see (Johansson et al., 2018). These values should be added to the elevation/nadir angle in elev_dag/nadir_deg.
Disclaimer and contacts
On utilising this data we ask you to provide a proper reference to the data (References as appropriate: see below, acknowledgement: “This data has been provided by the Institut für Energie und Klimaforschung (IEK-7), Forschungszentrum Jülich, Germany, and by the Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany.”) and acknowledge the HEMERA data infrastructure and the data provider in their publications with a sentence like “This project has received support from the European Commission in the frame of the INFRAIA grant 730790-HEMERA”.
We strongly recommend to consult one of the following persons for information on the datasets: Jörn Ungermann <firstname.lastname@example.org>, Peter Preusse <email@example.com>, Felix Friedl-Vallon <firstname.lastname@example.org>, Sören Johansson <email@example.com>, Michael Höpfner <firstname.lastname@example.org>
Johansson, S., et al.: Airborne limb-imaging measurements of temperature, HNO3, O3, ClONO2, H2O and CFC-12 during the Arctic winter 2015/2016: characterization, in situ validation and comparison to Aura/MLS: Characterization, in situ validation and comparison to Aura/MLS, Atmos. Meas. Tech., 11, 4737–4756, https://doi.org/10.5194/amt-11-4737-2018, 2018.
Spang, R., Remedios, J., and Barkley, M.: Colour indices for the detection and differentiation of cloud types in infra-red limb emission spectra, Advances in Space Research, 33, 1041-1047, https://doi.org/10.1016/S0273-1177(03)00585-4, 2004.