Product Resolution and Display Range

Returned power, velocity, and spectrum width are assigned at 250 m (0.25 km, 0.13 nm) range resolution, which is the best possible. These base data are assigned a memory address, or "bin", that corresponds to a range resolution of 250 m (0.25 km, 0.13 nm). Depending on the elevation angle, the range bin dimensions are either 0.25 km (250 m) by 1 degree or 0.25 km (250 m) by 0.5 degree. All the WSR-88D products are built from these range bins. The WSR-88D product range resolutions are 0.25 km (250 m, 0.13 nm), 0.50 km (500 m, 0.27 nm), 1 km (1000 m, 0.54 nm), 2 km (2000 m, 1.1 nm), and 4 km (4000 m, 2.2 nm). The WSR-88D product azimuthal resolutions are either 1 degree or 0.5 degree.

Table 1 contains standard WSR-88D product range resolution conversion values.

Table 1: Range Resolutions

There are two fundamental types of base data resolution. The first is the legacy resolution, which has been available since the WSR-88D was initially deployed. Legacy resolution base data are 1 km by 1 degree for reflectivity and 0.25 km by 1 degree for velocity and spectrum width. There are also lower resolution base products built from the legacy resolution base data. The second is super resolution (or super-res), which is available at lower elevation angles and is 0.25 km by 0.5 degree for reflectivity, velocity, and spectrum width. Section 5-6 demonstrates the difference between legacy and super-res base data, as well as the construction techniques for lower resolution base products.

Base data are displayable out to a certain range from the radar. Both legacy and super-res base reflectivity are available to a display range of 248 nm. For velocity and spectrum width, legacy resolution products are available to a display range of 124 nm, while super-res products go out to 162 nm.

Table 2 contains standard WSR-88D product display range conversion values.

Table 2: Display Ranges

The data levels or precision of the WSR-88D products are of three types: 3-bit, 4-bit, and 8-bit. A 3-bit product has 8 data levels, a 4-bit product has 16 data levels, and an 8-bit product has 256 data levels. Table 3 shows AWIPS D-2D color bars associated with 8-bit reflectivity (top), 4-bit reflectivity (middle), and 3bit spectrum width (bottom), which area the three types of data levels for WSR-88D products.

Table 3: Data Levels

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