Can Reference radiosounding measurements be used to improve historical time series?



Madonna, F.



by Il Nuovo Cimento C (INC) at 2020-10-07



Upper-air radiosounding observations are undoubtedly a primary
data source for the study of climate and for the atmospheric reanalysis. Nevertheless,
historical radiosounding time series are affected by several systematic uncertainties
due to change in the measurement sensors. As an alternative to the few existing
approaches, in the frame of the Copernicus Climate Change Service (C3S), a novel
approach, named RHARM (Radiosounding HARMonization), has been developed
to provide a homogenized dataset of temperature, humidity and wind radiosounding
profiles available from the Integrated Global Radiosonde Archive (IGRA) along with
an estimation of the total uncertainty for each profile. Estimation of uncertainties
has never been developed in previous homogenization algorithms. The homogenization
is carried out for a substantial subset of IGRA radiosounding stations.
Comparisons of trends calculated at 300 hPa over Europe in the period 2000–2018
using ERA5 ECWMF atmospheric reanalysis, IGRA and RHARM datasets show
a good agreement for temperature with mutual differences within 0.05K/da. For
relative humidity, ERA5 shows a trend of −0.7%/da, while the trend for IGRA and
RHARM is of 0.5%/da and 0.8%/da, respectively. The usefulness of comparing,
for the first time, ERA5 and RHARM time series taking advantage of the RHARM
uncertainty is also discussed.




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