Friday, May 30, 2014

Calling Radar and Precipitation Junkies

One of the more exciting developments over the past few years in my field has been the development of applications that can integrate data from ground-based radars, space-borne radars, precipitation gauges, and other platforms to produce very detailed analyses of the three-dimensional structure of precipitation systems and the accumulation of precipitation on the ground.

One such system, which radar and precipitation junkies can access and play with at, is the Multi-Radar Multi-Sensor System (MRMS) developed as a joint initiative between the National Severe Storms Lab, FAA, National Weather Service, and the University of Oklahoma Cooperative Institute in Mesoscale Meteorological Studies.  The MRMS allows one to examine historical (beginning July 2013) or real-time storms, which is great for both researchers and weather junkies.

Here are a few snippets from the system.  I'll concentrate on a particularly intense lake-effect storm that we examined during the National Science Foundation sponsored Ontario Winter Lake-effect Systems (OWLeS) field campaign this past winter.  An advantage of the MRMS here is the use of both US and Canadian Radars, providing a more complete view of lake-effect precipitation in the Great Lakes Region.

The system also provides what meteorologists call quantitative precipitation estimates, or QPE, which is basically just a spatial map showing the estimated precipitation during a period of interest.  Such estimates are surprisingly difficult to produce.  Radar has the advantage of high resolution in both space and time, but for a variety of reasons, often suffers from large errors.  Gauges typically have better accuracy (but not always), but are often widely spaced.  The MRMS system blends these and other observations to produce a best-of-both-worlds analysis.  The one below is for the 24-hour period during the storm depicted above and shows nicely the highly concentrated snowbands downstream of Lakes Erie and Ontario and the enhancement of precipitation over the Tug Hill Plateau east of Lake Ontario.

Finally, there is the ability to take vertical slices through storms - something I do frequently with some of my toys in the office, but not using multiple radars online.  Here we take a slice through three lake-effect bands showing the deeper, more intense nature of the snowband downstream of Lake Ontario over the Tug Hill Plateau and the weaker bands to the north and south that have persisted well downstream of Lakes Huron and Erie. 

Lake-effect storms are typically quite shallow and that is definitely the case during this event.  Those of you looking to really have fun with this should target severe thunderstorms and you should have even more fun.

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