Constant altitude plan position indicator

CAPPI is a special display format for a weather radar. It is the abbreviation of Constant Altitude plan position indicator and is a horizontal, two-dimensional representation of radar measurements at a certain height or altitude. A CAPPI is calculated from several PPI measurements at different elevation angles ( elevation ) and interpolated. On a plan position indicator to the different heights are usually represented by color variations. The radar reflectivity factor Z and rainfall rate R are usually divided into 14 classes and displayed in color.

In a Max CAPPI ( MAXimum - CAPPI ) maxima are shown the data from CAPPI from different heights. The Max CAPPI representation generally serves to provide an overview of the weather patterns. This is done firstly by a vertical maximum projection in a floor plan, the other by horizontal maximum projections from south to north and from west to east side cracks. In the side cracks the lateral scale gives the altitude in km. In a Max CAPPI usually reflectivities are presented.

Another three-dimensional representation ability is called Vol- CAPPI (Volume Constant Altitude plan position indicator). The view is similar to the Max - Cappi, but allows, in contrast to this a unique echo mapping in all three cracks. Above an elevation of the floor plan is (equivalent to a Zonalschnitt, so a side elevation from east to west ) and of the floor plan a cross crack (corresponds to a meridional, ie a side elevation from north to south ) are shown. With the aid of a crosshair can be the positions of these cuts select any.

CAPPI with a Reflektivitätsanzeige a height of 1.5 km from Montreal ( Canada)

Radar intensity classes of a weather radar

  • Meteorological instrument
  • Radar module
  • Abbreviation
162656
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