Joint Polarization Experiment

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Joint Polarization Experiment
Beamwidth
0.95°[2]
Range460km
Diameter8.51 m
Azimuth0-360°
Elevation-1°— 20°
Power750 kW

The Joint Polarization Experiment (JPOLE) was a test for evaluating the performance of the

hydrometeor, and quantities that have fallen.[3]

History

During the years preceding JPOLE, the

dual polarization for a weather radar, with staff Dusan S. Zrnic and Alexander V. Ryzhkov. In July 2000, the first planning meeting for JPOLE was held at the National Severe Storms Laboratory
(NSSL), and it was determined that the project would take place in two stages:

  • The multi-season
    dual polarization
    data collection using a specially modified NEXRAD from spring 2002;
  • a second, more intense observation campaign starting in the spring of 2003 with several instruments (other radars,
    dual polarization
    concept operationally and to demonstrate the cost/benefit of the NEXRAD network modification. In addition, the second phase has made scientific advances in the field.

Description

JPOLE was introduced using a

horizontal polarization and a vertical polarization.[4] The signals were sent to the antenna by two waveguides and could simultaneously transmit the two signals and furthermore receive the echoes returned by the precipitation in the emitted or orthogonal planes.[5]

In general, most

horizontal polarization, we can note a difference of several characteristics between these returns:[6]

Differential Reflectivity

If the targets have a flattened shape, by sampling with two waves [of which one is of

vertical polarization
(V) and the other horizontal (H)], we obtain stronger intensities returning the horizontal axis. On the other hand, if the orthogonal returns are equal, this indicates a round target. This is called differential reflectivity, or ().

Correlation Coefficient

The radar beam probes a larger or smaller volume depending on the characteristics of the transmitting antenna. What comes back is the average of the waves reflected by the individual targets within the volume. Since the targets can change position in time relative to each one another, the intensity of the V and H waves remains constant only if the targets maintain homogeneity. The intensity ratio between the H and V channels returning from successive samples is called the correlation coefficient () and therefore gives an idea of the homogeneity, or lack thereof, of the targets in the volume surveyed.

Differential Phase Shift

The phase of the wave changes as it passes through media of varying densities. By comparing the phase change rate of the return wave with the distance, the

specific differential phase
can help sample the quantity of material traversed.[7] Unlike the differential reflectivity, correlation coefficient, which are both dependent on reflected power, differential phase is a "propagation effect." The range derivative of differential phase, specific differential phase, can be used to localize areas of strong precipitation/attenuation.

References

  1. ^ "NOAA NEXt-Generation RADar (NEXRAD) Products - Data.gov". catalog.data.gov.
  2. ISBN 978-0-309-08466-6
    .
  3. S2CID 1619558
    .
  4. ^ Service, US Department of Commerce, NOAA, National Weather. "Contact Us". www.weather.gov.{{cite web}}: CS1 maint: multiple names: authors list (link)
  5. doi:10.1175/bams-86-6-809
    .
  6. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2016-03-03. Retrieved 2018-08-22.{{cite web}}: CS1 maint: archived copy as title (link)
  7. ^ "Polarimetric Radar Page". www.cimms.ou.edu. Archived from the original on 2018-08-22. Retrieved 2018-08-22.
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