Validation of the Aeolus L2B Rayleigh winds and ECMWF short‐range forecasts in the upper troposphere and lower stratosphere using Loon super pressure balloon observations

Rennie, Michael
Žagar, Nedjeljka

Pinol Sole, Montserrat
Straume, Anne Grete
Antifaev, James
Candido, Salvatore
Carver, Robert
Fehr, Thorsten
von Bismarck, Jonas
Hünerbein, Anja

Deneke, Hartwig

DOI: https://doi.org/10.1002/qj.4391
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11666
Žagar, Nedjeljka; 4 Meteorological Institute Universität Hamburg Hamburg Germany
Pinol Sole, Montserrat; 5 ESA–ESTEC European Space Research and Technology Centre Noordwijk the Netherlands
Straume, Anne Grete; 5 ESA–ESTEC European Space Research and Technology Centre Noordwijk the Netherlands
Antifaev, James; 6 Loon Mountain View California USA
Candido, Salvatore; 6 Loon Mountain View California USA
Carver, Robert; 6 Loon Mountain View California USA
Fehr, Thorsten; 5 ESA–ESTEC European Space Research and Technology Centre Noordwijk the Netherlands
von Bismarck, Jonas; 1 ESA–ESRIN Centre for Earth Observation Frascati
Hünerbein, Anja; 2 Leibniz Institute for Tropospheric Research Leipzig Germany
Deneke, Hartwig; 2 Leibniz Institute for Tropospheric Research Leipzig Germany
Abstract
The novel Aeolus satellite, which carries the first Doppler wind lidar providing profiles of horizontal line‐of‐sight (HLOS) winds, addresses a significant gap in direct wind observations in the global observing system. The gap is particularly critical in the tropical upper troposphere and lower stratosphere (UTLS). This article validates the Aeolus Rayleigh–clear wind product and short‐range forecasts of the European Centre for Medium‐Range Weather Forecasts (ECMWF) with highly accurate winds from the Loon super pressure balloon network at altitudes between 16 and 20 km. Data from 229 individual balloon flights are analysed, applying a collocation criterion of 2 hr and 200 km. The comparison of Aeolus and Loon data shows systematic and random errors of -0.31 and 6.37 m·s-1, respectively, for the Aeolus Rayleigh–clear winds. The horizontal representativeness error of Aeolus HLOS winds (nearly the zonal wind component) in the UTLS ranges from 0.6–1.1 m·s-1 depending on the altitude. The comparison of Aeolus and Loon datasets against ECMWF model forecasts suggests that the model systematically underestimates the HLOS winds in the tropical UTLS by about 1 m·s-1. While Aeolus winds are currently considered as point winds by the ECMWF data assimilation system, the results of the present study demonstrate the need for a more realistic HLOS wind observation operator for assimilating Aeolus winds.
Subjects
Aeolusdata assimilation
ECMWF forecasts
HLOS winds
Loon
super pressure balloon observations
systematic and random errors