# Presentation: 540625

## Radar Reflectivity Quality Control and 3-D Mosaic (and ideas for eventual use of data in WRF GSI)4 January 2005

## Code Functionalities

- Input of Level-2 data (single radar compatible)
- Regrid raw radar volume scan to 1° x 1 km spherical grid
- Produce “hybrid scan” of base reflectivity to address beam-blockage issues
- Perform QC
- Produce 1 km cartesian grid from QC’d data

## Terrain-based
Assuming normal propagation
Using high-resolution DEM data
Calculate occultation based on radar power density
Create a “hybrid scan” lookup table
3D radar fields structure-based
Vertical reflectivity gradients
Horizontal reflectivity structure
PURPOSE:  To remove non-precipitation echoes 

- Assuming normal propagation
- Using high-resolution DEM data
- Calculate occultation based on radar power density
- Create a “hybrid scan” lookup table
**3D radar fields structure-based**
- Vertical reflectivity gradients
- Horizontal reflectivity structure
**PURPOSE:  To remove non-precipitation echoes **

- Reflectivity QC Techniques

## Terrain Based QC

- All reflectivity bins below a terrain-based hybrid scan (O’Bannon, 1997*) are removed.  The hybrid scan bins are the lowest ones which meet the following criteria:
- * Bottom of the bin must clear the ground by at least 50m (500ft for ROC).
- * Less than 50% power blockage at any shorter range bin in the same radial.

- *** ****O'Bannon, 1997: Using a 'terrain-based’ hybrid scan to improve WSR-88D precipitation estimates. *****Preprints, The 28th International Conference on Radar Meteorology*****, September 7-12, 1997,  506-507**

**Notes:**
An description of the terrain-based hybrid scan.  This 2D polar grid hybrid scan lookup table is used in our QC software to remove residual ground clutter.

## New Hybrid Scans Using High-resolution Terrain

- Beam geometry vs. terrain

- Power density distribution & beam blockage

**Notes:**
An example for our QC procedure (after). Also show buttons of single radar products.

## Structure-based QC:  Possible Non-precipitation echoes

| Echo |
| --- |
| Ground/Sea Clutter |
| Sun strobe |
| Chaff |
| Clear air returns |
| Birds and insects |
| Electronic interferences |
| Non-precip clouds |

## Reflectivity QC Variables

- Reflectivity Structure: KFWS, 4/20/1995,  04:53Z

## Some Notes...

- SIGN and Texture are very similar
- Median is similar to raw reflectivity
- Vertical gradient is very useful, especially at close ranges

## QC Decisions

- A reflectivity datum is removed if P_nonpcp > P_thresh

**Notes:**
A list of parameters and variables used in the radar echo classifier.

## Reflectivity QC

**Before**

**After**

- KFWS 1995-04-20.0453Z

## Reflectivity QC

**Before**

**After**

- KFWS 1995-04-20.1850Z

## Reflectivity QC

**Before**

**After**

- KTLX 2002-10-18.1246Z

## Future Use of Reflectivity Datain 

- GSI

- CWB/FSL/NSSL Project Review

- Oct. 13-17, 2003

## Separate “cloud analysis” system
Use Z-R/Z-M relationships to diagnose hydrometeor concentrations
Nudge vertical momentum via 3-D divergence constraint 
Variational approach to w component
Nudge (I know, bad word) to maintain rh/latent heat release to support w-component
Similar to FSL’s Hot Start and CAPS ADAS cloud analysis

- Use Z-R/Z-M relationships to diagnose hydrometeor concentrations
- Nudge vertical momentum via 3-D divergence constraint
- Variational approach to w component
- Nudge (I know, bad word) to maintain rh/latent heat release to support w-component
- Similar to FSL’s Hot Start and CAPS ADAS cloud analysis

## 

Eventually:  define error covariance matrices (?) for use of reflectivity in a “true” 3-D sense (not a diabatic or nudging technique, per se)

FIRST THINGS FIRST:  MOSAIC/QC package running operationally at NCEP

- Eventually:  define error covariance matrices (?) for use of reflectivity in a “true” 3-D sense (not a diabatic or nudging technique, per se)
- FIRST THINGS FIRST:  MOSAIC/QC package running operationally at NCEP