In situ observations of meteorological variables from the Integrated Global Radiosounding Archive and the Radiosounding Harmonization dataset from 1978 onward

This catalogue entry provides access to vertical profiles of standard meteorological variables. It includes two archives.
The first is version 2 of the Integrated Global Radiosounding Archive (IGRA) from 1978 which incorporates global
radiosounding profiles of temperature, humidity and wind from a large number of data sources,
which is 30% larger than the previous version 1. IGRA v2 is the result of quality assurance procedures applied to the
radiosoundings data which can be grouped into eight categories: fundamental “sanity” checks, checks on the plausibility
and temporal consistency of surface elevation, internal consistency checks, checks for the repetition of values,
checks for gross position errors in ship tracks, climatology-based checks, checks on the vertical and temporal
consistency of temperature, and data completeness checks. No uncertainty estimation for the IGRA data is available.
The second is the Radiosounding HARMonization (RHARM) dataset where values of temperature,
relative humidity and wind are homogenized to remove systematic effects (such as change in the measurement sensors,
solar radiation biases, sonde time-lag, calibration drifts, station relocation etc.) at 700 IGRA radiosounding stations
and radiosoundings from ships.
RHARM includes twice daily (0000 and 1200 UTC) radiosonde data at the mandatory levels (listed below).
At levels with pressure lower than 10 hPa, homogenized temperatures are not provided because of the paucity of available
observations and the issues affecting the measurements at those levels.
Relative humidity homogenization and data provision are limited to 250 hPa owing to pervasive sensor
performance issues at greater altitudes.
Moreover, an estimation of the measurement uncertainty is provided for each value of the time series.
The radiosounding significance levels are also homogenized per interpolation along with the corresponding uncertainties.
The RHARM dataset thus inherits the IGRA quality assurance procedures, and additional quality checks are then applied,
performing tests on physical plausibility, accuracy of the homogenization (bias adjustment), presence of outliers, and coherency check
for the homogenization applied at the significant levels.
The IGRA dataset is provided by NOAA's National Centers for Environmental Information (NCEI) also through the IGRA data portal.
The RHARM dataset has been specifically developed for the Copernicus Climate Change Service (C3S).
The dataset can be downloaded as NetCDF files (CDM-Obs-Core, see documentation) or as comma-separated values (CSV) files.