Line-of-Sight Wind Products The LSM computes along track and cross track winds at the shot location using the
input horizontal wind components,
platform inclination (or heading)
and the sampling scale uncertainties that are obtained by using a random Gaussian
distribution around the turbulence profiles.
Once line-of-sight uncertainties are computed from the
signal-to-noise models, the LSM computes the simulated line-of-sight wind
velocity as
Vlos = (Uhwc × cos(ß) + Vhwc × sin(ß)) × cos(Q) + Wvwc × sin(Q) + LOSunc
where
Vlos - the line-of-sight wind velocity (m/s)
Uhwc - the cross track wind velocity at the shot location (m/s)
Vhwc - the along track wind velocity at the shot location (m/s)
Wvwc - the vertical velocity at the shot location (m/s)
Q - the elevation angle (rad)
ß - the azimuth scanning angle (rad)
LOSunc - the line-of-sight uncertainty (m/s).
For the consensus signal-to-noise model, if the lidar shot is a false alarm, the LSM computes the line-of-sight wind velocity using a random white noise value and the velocity maximum window as
Vlos = (RD - 0.5) × 2 × Vmax
where
Vlos - the line-of-sight wind velocity (m/s)
RD - a random value (0-1)
Vmax - the velocity maximum window (m/s)
The LSM Line-of-Sight output products (LEVEL 1) are listed in the table below
| Platform latitude (deg) |
| Platform Longitude (deg) |
| Time of LOS wind (sec) |
| Azimuth scan of the LOS wind (deg) |
| Platform heading (deg) |
| Platform altitude (km) |
| Nadir scan angle (deg) |
| Number of LOS atmospheric levels |
| Latitude of the LOS wind for each altitude (deg) |
| Longitude of the LOS wind for each altitude (deg) |
| Altitude of the LOS wind (km) |
| Elevation angle for each altitude (deg) |
| Backscatter medium (aerosol,opaque cloud,thick ci,thin ci) for each altitude |
| Shot passed consensus indicator for each altitude |
| Shot failed consensus indicator for each altitude |
| Shot false alarm indicator for each altitude |
| Cross track wind at shot location for each altitude (m/s) |
| Vertical Velocity for each altitude (m/s) |
| Sampling scale uncertainty in U of the LOS wind for each altitude (m/s) |
| Sampling scale uncertainty in V of the LOS wind for each altitude (m/s) |
| Sampling scale uncertainty in W of the LOS wind for each altitude (m/s) |
| Pulse scale uncertainty in U of the LOS wind for each altitude (m/s) |
| Pulse scale uncertainty in V of the LOS wind for each altitude (m/s) |
| Pulse scale uncertainty in W of the LOS wind for each altitude (m/s) |
| Instantaneous uncertainty in U of the LOS wind for each altitude (m/s) |
| Instantaneous uncertainty in V of the LOS wind for each altitude (m/s) |
| Instantaneous uncertainty in W of the LOS wind for each altitude (m/s) |
| Line-of-sight uncertainty of the LOS wind for each altitude (m/s) |
| Consensus line-of-sight uncertainty of the LOS wind for each altitude (m/s) |
| Line-of-sight instantaneous uncertainty of the LOS wind for each altitude (m/s) |
| Aerosol backscatter for each altitude (m-1 sr-1) |
| Molecular attenuation for each altitude (km-1) |
| Wideband SNR for each altitude (db) |
| Range to LOS wind for each altitude (km) |
| True line-of-sight wind velocity for each altitude (m/s) |
| Simulated laser line-of-sight wind velocity for each altitude (m/s) |
The LSM uses either the Multi-Paired Algorithm (MPA) or a Least Squares technique (Press et al., 1986) to compute the U and V horizontal wind components from the laser line-of-sight velocities. Horizontal wind components are computed with one of three different models: High Resolution model, Grid Area Model using the MPA and Grid Area Model using the Least Squares model. Sampling and measurement errors are computed for each horizontal wind model.
High Resolution Method
The high resolution method uses the MPA to match the closest aft line-of-sight shot with the closest forward line-of-sight shot to produce a simulated horizontal U, V wind product. Each shot pair is weighted by angular separation, distance between shots and SNR.
MPA Grid-Based Method
The MPA Grid-Based Method uses the MPA to match all aft line-of-sight shots with all forward line-of-sight shots in the user defined grid area cell size to produce a simulated horizontal U, V wind product. Each shot pair is weighted by angular separation, distance between shots and the lower SNR.
Least-Squares Grid-Based Method
The least squares model performs a least squares fit to the lidar shots within the user’s defined grid area to produce SNR weighted U and V horizontal wind components (Press et al., 1986).
The LSM Horizontal Wind Output Products (LEVEL 2) are listed in the table below.
| This page managed by Sidney A. Wood | Last modified: 21 Feb. 1998 |