3. In the bottom section of the NDOP configuration window, specify the output resolution
by specifying the characteristics of the grid.
The NDOP product produces wind vectors on a 3D grid.
a. Specify the Range Span.
The Range Span is the distance in km from the center of the projection, east to the
edge of the projection, analogous to a radar range.
It is specified in the named projection. If you are not using a Projection Name, type
the range.
A max range of about 4 times the baseline length is typical.
b. Specify the Range Grid.
The Range Grid is an integer that specifies the number of points in the output array
representing the Range Span.
c. For the Height Span, specify a maximum and minimum height (km).
d. Specify the Height Grid.
The resolution is then calculated from:
Height Res = (Max Height - Min Height) / (Height Grid - 1)
The Resolution (Res) is a display-only field calculated from:
Range Res = (Range Span) / (Range Grid)
In the example, the Range Span is 40 and the grid is 16, therefore the resolution is
2.5 km (1.6 mi). The actual number of points in the output array that is made by NDOP
depends on the aspect ratio of the projection, which may not be square.
For a square projection and a grid specification of 16, the output array would be
32 × 32.
4. In the bottom section of the NDOP configuration window, specify Min Crossing Angle.
This is the minimum crossing angle that is used. The recommended value is 20°. The
same value is used by the algorithm to specify the maximum crossing angle, that is, the
max crossing angle = 180 - Min Crossing Angle.
5. If needed, enable Make Diagnostic.
When enabled, the NDOP product makes additional velocity CAPPI products, with
product names NDOP_CAPPI_#. These are the input data used by NDOP.
5.5.3
NDOP Display and Algorithm
The following example is an actual NDOP display showing the low-level (1 km) winds for a
projection 40 km (24.9 mi) across using two S-band radar systems.
2)
2) Courtesy of the Hong Kong Observatory
Chapter 5 – Configuring and Scheduling Optional IRIS Products
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