The Analysis Toolbox is a collection of model tools for analyzing simulated products from the SCVM and the LSM. Currently, options for four tools have been designed: Performance Model, Forward Model and the Horizontal Wind Model. Only the Performance Model and a data file conversion model is operational in the DLSM version 4.2.

Performance Model

The Performance Model computes the percentage of time that the simulated DWL line of sight wind measurement was useful for various accuracies in terms of sufficient backscatter (aerosols or molecules), clouds and cirrus clouds through-out the vertical. In the example below, the user is opening an LSM generated line of sight wind file. In the DLSM version 4.2, the Performance Model operates on the original ascii line of sight wind file. In the next version it is planned that the model will use the database format for the LOS winds and the LOS Database  Conversion Tool will need to be run first.

A blue slider bar informs the user of the file opening progress.

Once the file is loaded, The user has 5 Data Menu Options to customize the display product: Data Product, Latitudinal Band, Error Type, Cloud Option and False Alarm Option.

Data Product

There are 4 data product choices in the Performance Model: 

• Line of sight winds not horizontally projected

• Line of sight winds horizontally projected

• U, V Horizontal Winds from lidar point of view

• U, V Horizontal Winds from globe point of view

The line of sight winds horizontally projected is the default choice. Only line of sight wind options are available in the DLSM version 4.

Latitudinal Band 

The user can choose to compute the performance statistics for either the entire globe or for a 10 degree latitudinal band. The global option is the default choice.

Error Type 

There are 3 error type choices in the Performance Model: 

• Target sample volume error - instantaneous los wind variability along the los

• Observation uncertainty - los wind standard deviation along the los

• Potential orthogonal error - los wind standard deviation along the los adjusted for azimuth angle

Cloud Option 

The user can choose to compute the performance statistics for cloud or cloud ignored situations.

False Alarm Option

The user can choose to compute the performance statistics with false alarms or with out false alarms.

Once the data options have been chosen, The user has 2 Plot Menu Options to customize the diagram: Change Y-axis and change to a black and white plot. In the DLSM version 4.2, only the Black and White conversion option is available.

To generate the performance diagram, the user should click the View Plot button.

The header file that contains the DLSM inputs for the generated line of sight wind file can be viewed, as shown below, by clicking the View Header Information button.

Run Forward Model

The Forward Model linearly interpolates the nature run atmosphere's horizontal wind components to the latitude, longitude and time of the simulated DWL line of sight wind and given the DWL geometry, computes the "true" line of sight wind. The Forward Model is not available in the DLSM version 4.2.

Run Horizontal Wind Component Model

The Horizontal Wind Component Model computes the U and V horizontal wind components from the DWL line-of-sight velocities either by the Multi-Paired Algorithm (MPA) or a Least Squares technique. 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. The LSM Horizontal Wind Output Products (LEVEL 2) are listed in the table 6.

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 Horizontal Wind Component Model is not available in the DLSM version 4.2.

 

© Copyright 1995-2005, Simpson Weather Associates, Inc.

Last Updated: 02/07/2007