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Improvements in Weather Radar – Dual-Polarization

Apr 09, 2012

Tags:Dr. Grey,Dr. Klotzbach,Earthquake,East Pacific,El Nino,Hurricane Irene,Hurricane Outlook,Hurricane Prediction,Hurricane Season 2011,Hurricane Season 2012,HUrricane Season Update,La Nina,Meteorology,Polar Vortex,Tropical,Tropics,Weather,Winter

Taking place now through early 2013, a major upgrade to the WSR-88D Doppler Radar network will be completed by the National Weather Service, promising significant improvements in near-term forecasting and warning technology across the United States.

The advanced technology is called dual-polarization (or dual-pol) radar. Up until now, conventional radar could only detect the horizontal dimension of particles in the air. Dual-pol radar will detect both horizontal and vertical dimensions and yield a much better estimate of the size, shape, and composition of precipitation particles. Armed with this new information, forecasters will be better equipped to obtain the following:

Better estimates of total precipitation
Better identification of precipitation type, rain, snow, sleet or mixtures
A more exact location of the rain/snow line
A more clearly defined hail core and updraft core in thunderstorms
Better detection of airborne debris associated with tornadoes
Easier determination of hazardous icing conditions for aircraft operations
Better identification of snow levels in higher terrain
Better ability to distinguish between precipitation and non-precipitation objects (ground clutter and biological targets)

Some limitations, as with current radar technology, will continue. In particular degradation in data quality due to distance from the radar antenna or storms lining up along a single radial from the antenna and “filling” the radar beam will continue. However, the benefits cited above are expected to vastly improve short term forecasting and warnings. For example, forecasters should have much better confidence in locating the transition line between rain and snow, estimating the amount of snowfall, determining the risk of flooding, distinguishing between heavy rain and hail, and confirming the presence of a tornado. With respect to the last item, dual-pol radar may allow the NWS to enhance tornado warnings with information signaling a more dire prediction of significant or catastrophic damage.

Only well after the national upgrade is complete will all of the benefits of this newly deployed technology be realized. It is seen as an exciting time for meteorologists and forecasters. For the general public it is also a very positive development with the expectation of improved warnings, and more reliable near term forecasts. Check with your local National Weather Service office for information on when you may see dual polarization in your area (or if it is available already).

Rod Gonski, Jeremy Gilchrist

Source: NOAA

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