Sensitivity analysis of wake vortex parameters measured by doppler lidar

In this study, the sensitivity analysis of wake vortex parameters measured by a Doppler lidar is conducted to assess the errors due to the measurement process. To reduce the uncertainty caused by the measurement process as possible, wake vortex parameters along with a surrounding wind field are estimated based on the four-dimensional variational (4D-Var) method assuming a velocity field obtained by the Rosenhead-Burnham-Hallock vortex model. With this approach, vortex parameters are obtained considering the factors such as insufficient resolution in the line-of-sight direction and vortex descent during a laser scan. It is confirmed from numerical experiments that the average circulation is significantly underestimated when it is derived from the lidar measurement, while vortex core radius becomes too large in the lidar measurement. On the other hand, vortex parameters estimated with the help of the 4D-Var method are improved by compensating the errors due to the measurement process.