Data Assimilation ofWeather Radar and LIDAR for Convection Forecasting and Windshear Alerting in Aviation Applications - Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications - page 543

Perturbation Vertical Velocity
9:54 UTC

5 (m/sec)

2

w-<w>
(m/sec)

1

3
2.4
1.8
1.2
0.6
0
− 0.6
−

0

1.2

1.8
− 2.4
−

−

− 1

3

− 2

− 2 − 1 0 1 2

West - East (km)

Fig. 22.18 4DVAR-analyzed perturbation vertical velocity with the horizontal wind vectors

overlaid

22.5 Concluding Remarks

In this chapter, variational data assimilation algorithms to retrieve the 3-dimensional
wind field from weather radars and LIDAR have been discussed. The retrieval winds
from weather radars show benefits in the analysis of dynamical condition conducive
to intense development of convective storms. The retrieved wind data are also found
to provide positive impacts in resolving the wind flow over low to mid-tropospheric
levels in the non-hydrostatic NWP model (RAPIDS-NHM). Improvements are made
in model simulation of the mesoscale features and dynamics of a severe convective
storm. Furthermore, the novel variational minimization algorithms (3DVAR and
4DVAR) applied to the LIDAR data are found to be very useful to retrieve the
3-dimensional wind flow over the complex terrain near HKIA, for example in study
of low-level windshear effects and even for a gustnado event.

References

Chai T, Lin CL, Newsom RK (2004) Retrieval of microscale flow structures from high-resolution
Doppler data using an adjoint model. J Atmos Sci 61:1500-1520
Chan PW, Shao AM (2007) Depiction of complex airflow near Hong Kong International
Airport using a Doppler LIDAR with a two-dimensional wind retrieval technique. Meteorol
Z 16(5):491-504
Germano M, Piomelli U, Moin P, Cabot WH (1991) A dynamic subgrid-scale eddy viscosity
model. Phys Fluids A 3(7):1760-1765