| The Engineering Research
Center (ERC) for Collaborative Adaptive Sensing of the Atmosphere (CASA),
based at the University of Massachusetts-Amherst, is developing a network
of Doppler radars that scan the lowest level of the atmosphere, where severe
weather forms, to overcome the predictive limitations of the current national
radar system. Therefore, one of the important goals of CASA’s research
on this experimental radar system is a clear demonstration of better detection
of existing severe events than is possible with current technology.
The National Weather Service’s
(NWS’) current state of the art uses single Doppler velocities coupled
with assumptions about the phenomena being observed to infer storm circulation.
Recently CASA has made two major improvements to this approach. First,
the better resolution of the CASA radars brings immediate improvement to
detection of severe weather, especially tornadoes. Further, in conjunction
with this better resolution, CASA researcher have used the full adaptive-sampling
capabilities of the radars to image three-dimensional wind fields within
storms. This capability does not exist in the current NWS system
because these radars are too widely dispersed and are not capable of coordinating
their scans.
CASA designed and deployed
an end-to-end distributed-collaborative adaptive radar network in "Tornado
Alley" in Oklahoma. CASA researchers have been running real time and simulated
real time tests of the system’s value in conjunction with actual NWS forecasters,
through the NWS Experimental Warning Program. When a tornadic storm
hit Anadarko, Oklahoma on May 13, 2009, a CASA forecaster in a real time
experiment was able to issue a “simulated warning” three minutes earlier
than the NWS warning was issued during the actual storm. The current
average lead time of the NWS for tornado warnings is 11 minutes, so a 3-minute
improvement in warning time is significant. Additionally, it is likely
that this detection lead time can be even further improved, since the forecasters
are still learning how to utilize the CASA data, and also the CASA forecaster
did not have available the full suite of CASA-derived products.
The NWS field emergency managers
later noted that this degree of improvement in lead time would give them
a critical advantage in their ability to protect the public. Results
such as this point to the promise of CASA's distributed adaptive technology
to contribute to better, more accurate and timely warnings, thereby saving
lives and enhancing public safety. |
