  A performance measure for a DART tsunami buoy network has been developed. The
measure is based on a statistical analysis of simulated forecasts of wave
heights outside an impact site and how much the forecasts are degraded in
accuracy when one or more buoys are inoperative. The analysis uses simulated
tsunami height time series collected at each buoy from selected source segments
in the Short-term Inundation Forecast for Tsunamis (SIFT) database and involves
a set for 1000 forecasts for each buoy/segment pair at sites just offshore of
selected impact communities. Random error-producing scatter in the time series
is induced by uncertainties in the source location, addition of real oceanic
noise, and imperfect tidal removal. Comparison with an error-free standard
leads to root-mean-square errors (RMSEs) for DART buoys located near a
subduction zone. The RMSEs indicate which buoy provides the best forecast
(lowest RMSE) for sections of the zone, under a warning-time constraint for the
forecasts of 3 hrs. The analysis also shows how the forecasts are degraded
(larger minimum RMSE among the remaining buoys) when one or more buoys become
inoperative. The RMSEs also provide a way to assess array augmentation or
redesign such as moving buoys to more optimal locations. Examples are shown for
buoys off the Aleutian Islands and off the West Coast of South America for
impact sites at Hilo HI and along the U.S. West Coast (Crescent City CA and
Port San Luis CA). A simple measure (coded green, yellow or red) of the current
status of the network's ability to deliver accurate forecasts is proposed to
flag the urgency of buoy repair.
