WSR-88D Radar Coverages

!EXPERIMENTAL!

Last Updated 13, November, 2001

 

 
 

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1. Radar beam blockage maps

The beam blockage map for a single radar was obtained by remapping the OSF  occultation fields onto a Cartesian grid.  The OSF  occultation fields are catagorized values associated with radar beam blockages in the lowest four tilts.  The spatial resolutions of the occultation fields are 0.2o x 1 km  (Timothy O'Bannon,  personal communication).   Table 1.1 shows the occultation values and the corresponding percentage of radar beam blockages.


Table 1.1  Relationship between the catagorized occultation values and the actual amount of beam blockage


 
Catagory
Occultation (%)
0
< 10
1
11-29
2
30-43
3
44-55
4
56-60
5
> 60

 

Below are examples of the lowest tilt (0.5o elevation) blockage maps for  several radars covering the Arizona region. In the maps, different colors represent different amount of blockages (see Table 1.1 and the legend in the maps).

KIWA (Phoenix,  AZ)
KFSX  (Flgstaff,  AZ)
KEMX  (Tucson,  AZ)
KYUX  (Yuma,  AZ)
KESX  (LasVegas,  NV)
KICX  (CedarCity,  UT)
 

The following map shows the coverage of the 0.5o radar tilt in the Arizona region.  It is obtained by mosaicking the unblocked (or, less than 10% blocked) radar beams at 0.5o from the above 6 radars in the Arizona domain. Note that in this map, different colors indicating areas covered by different radars, and the grey areas indicating overlapped radar coverages. The orange "+" symbols indicating the radar locations.

Radar blockage map in Arizona
 
 

The following map shows the coverage of the 0.5o radar tilt in the western United States.  It is obtained by mosaicking the unblocked (or, less than 10% blocked) radar beams at 0.5o from all the radars in the analysis domain. The colors in this map represent number of radars that covering the same location (light blue-1; dark blue-2; dark green-3; light green-4; yellow-5; brown-6; red-7). The orange "+" symbols indicating the radar locations.

Radar blockage map in the western US.
 
 

The following map shows the coverage of the 0.5o radar tilt in the United States.  It is obtained by mosaicking the unblocked (or, less than 10% blocked) radar beams at 0.5o from all the radars in the analysis domain. The colors and symbols are the same as in the above figure.

Radar blockage map in the continental US.
 

2. Three-dimensional effective radar coverage

There are four possible volume scan patterns (VCPs) that are running operationally at each WSR-88D sites.  Table 2.1 list the elevation angles for each VCPs, and Fig.2.1 and Fig.2.2 shows vertical cross sections of the beam geometry for VCP 21 and VCP11.

Table 2.1  Elevation angles (in degrees) for different VCPs' tilts

 
tilt1
tilt2
tilt3
tilt4
tilt5
tilt6
tilt7
tilt8
tilt9
tilt10
tilt11
tilt12
tilt13
tilt14
VCP 11
0.5
1.45
2.4
3.35
4.3
5.2
6.2
7.5
8.7
10.0
12.0
14.0
16.7
19.5
VCP 21
0.5
1.45
2.4
3.35
4.3
6.0
9.9
14.6
19.5
          
VCP 31
0.5
1.45
2.4
3.35
4.3
                  
VCP 32
0.5
1.45
2.4
3.35
4.3

The 3D effective radar coverage is defined as the volume between the center of the lowest, unblocked radar beams and the center of the highest radar beams.  The lowest, unblocked radar beams we are using are those in the hybrid scan (ref: 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).  And the highest beams are those at 19.5o elevation angle.  Hybrid scan files for all the WSR-88D sites in the United States can be obtained from  the WSR-88D Operational Support Facility (OSF) .

3. Two-dimensional effective radar coverage at a constant height above mean sea level

The 2D effective radar coverage at a given height, z0, is defined as a horizontal cross section that cuts through the radar coverage volume at the given height.  Below are examples of the 2D radar coverage in the Arizona region, in the western United States, and in the continental US at 3km and 5km above mean sea level. In these figures, the orange "+" symbols indicate the radar sites and the background grey color indicates regions where there are no effective radar coverage.


Fig.1 Radar coverage at 3km (msl) in the Arizona region.


Fig.2 Radar coverage at 5km (msl) in the Arizona region.

 


Fig.3 Radar coverage at 3km (msl) in the western US.


Fig.4 Radar coverage at 5km (msl) in the western US.

 


Fig.5 Radar coverage at 3km (msl) in the continental US.


Fig.6 Radar coverage at 5km (msl) in the continental US.

4. Two-dimensional effective radar coverage at a constant height above ground level

The 2D effective radar coverage at a certain height, z0, above ground level is defined as a cross section that cuts through the radar coverage volume by a terrain-following plane at the given height above the ground level.  Below are examples of the 2D radar coverage in the western United States and the continental US at 2km and 10km above ground level as well as the associated topography maps.  The topography maps are based on the NCAR 5' (~10km) terrain data set.  In the coverage maps, the orange "+" symbols indicate the radar sites and the background grey color indicates regions where there are no effective radar coverage.   The dark "+" symbols in the topography maps indicate the radar locations.


Fig.7 Radar coverage at 1km (agl) in the continental US.


Fig.8 Radar coverage at 3km (agl) in the continental US.


Fig.9 Radar coverage at 5km (agl) in the continental US.


Fig.10 Radar coverage at 10km (agl) in the continental US.


Fig.11 Terrain height (msl) in the continental US.












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