Abstract. After the successful launch of Aeolus, which is the first
spaceborne wind lidar developed by the European Space Agency (ESA), on 22 August 2018, we deployed several ground-based coherent Doppler wind lidars
(CDLs) to verify the wind observations from Aeolus. By the simultaneous wind
measurements with CDLs at 17 stations over China, the Rayleigh-clear and
Mie-cloudy horizontal-line-of-sight (HLOS) wind velocities from Aeolus in
the atmospheric boundary layer and the lower troposphere are compared with
those from CDLs. To ensure the quality of the measurement data from CDLs and
Aeolus, strict quality controls are applied in this study. Overall, 52
simultaneous Mie-cloudy comparison pairs and 387 Rayleigh-clear comparison
pairs from this campaign are acquired. All of the Aeolus-produced Level 2B (L2B) Mie-cloudy HLOS wind and Rayleigh-clear HLOS wind and CDL-produced HLOS wind are compared
individually. For the inter-comparison result of Mie-cloudy HLOS wind and
CDL-produced HLOS wind, the correlation coefficient, the standard deviation,
the scaled mean absolute deviation (MAD) and the bias are 0.83, 3.15 m s−1, 2.64 m s−1 and −0.25 m s−1, respectively, while the y=ax
slope, the y=ax+b slope and the y=ax+b intercept are 0.93,
0.92 and −0.33 m s−1. For the Rayleigh-clear
HLOS wind, the correlation coefficient, the standard deviation, the scaled
MAD and the bias are 0.62, 7.07 m s−1, 5.77 m s−1 and −1.15 m s−1, respectively, while the y=ax slope, the
y=ax+b slope and the y=ax+b intercept are 1.00, 0.96 and
−1.2 m s−1. It is found that the standard
deviation, the scaled MAD and the bias on ascending tracks are lower than
those on descending tracks. Moreover, to evaluate the accuracy of Aeolus HLOS
wind measurements under different product baselines, the Aeolus L2B
Mie-cloudy HLOS wind data and L2B Rayleigh-clear HLOS wind data under
Baselines 07 and 08, Baselines 09 and 10, and Baseline 11 are compared against the
CDL-retrieved HLOS wind data separately. From the comparison results, marked misfits between the wind data from Aeolus Baselines 07 and 08 and wind data from
CDLs in the atmospheric boundary layer and the lower troposphere are found.
With the continuous calibration and validation and product processor
updates, the performances of Aeolus wind measurements under Baselines 09 and 10
and Baseline 11 are improved significantly. Considering the influence of
turbulence and convection in the atmospheric boundary layers and the lower
troposphere, higher values for the vertical velocity are common in this
region. Hence, as a special note, the vertical velocity could impact the
HLOS wind velocity retrieval from Aeolus.