Abstract
Shipborne wind observations by a coherent Doppler lidar (CDL) have been
conducted to study the structure of the marine atmospheric boundary layer
(MABL) during the 2014 Yellow Sea campaign. This paper evaluates
uncertainties associated with the ship motion and presents the correction
methodology regarding lidar velocity measurement based on modified 4-Doppler
beam swing (DBS) solution. The errors of calibrated measurement, both for the
anchored and the cruising shipborne observations, are comparable to those of
ground-based measurements. The comparison between the lidar and radiosonde
results in a bias of −0.23 ms−1 and a standard deviation of 0.87 ms−1 for the wind speed measurement,
and 2.48, 8.84° for the wind direction. The biases of horizontal wind speed and random
errors of vertical velocity are also estimated using the error propagation
theory and frequency spectrum analysis, respectively. The results show that
the biases are mainly related to the measuring error of the ship velocity and
lidar pointing error, and the random errors are mainly determined by the
signal-to-noise ratio (SNR) of the lidar backscattering spectrum signal. It
allows for the retrieval of vertical wind, based on one measurement, with
random error below 0.15 ms−1 for an appropriate SNR threshold and bias
below 0.02 ms−1. The combination of the CDL attitude correction system
and the accurate motion correction process has the potential of continuous
long-term high temporal and spatial resolution measurement for the MABL
thermodynamic and turbulence process.
Citation
ID:
246751
Ref Key:
zhai2018atmosphericshipborne