2011 - Cooperative Institute for Research in Environmental Sciences ...

statistical measurements such as the minimum, maximum,
mean and root-mean-square error (RMSE). These products
are being used to assess the effects of different gridding
algorithms and near-shore morphologic features on the
accuracy of DEMs in areas with varying relief and data
density.
The split-sample computer program is also useful for
determining the optimal gridding algorithm parameters
based on surface relief and data density in order to
minimize DEM interpolation errors. A new addition to
the program will quantify the uncertainty of interpolated
elevations in DEMs using the range of interpolation errors
from the various gridding algorithms at the DEM cellscale.
This will improve our understanding of the spatial
variability of uncertainty introduced by gridding algorithms,
and the propagation of that uncertainty into the
modeling of tsunami inundation. The impacts on coastal
inundation that result from tsunami modeling on divergent
DEMs developed with various gridding algorithms
will be assessed at Crescent City, Calif., using the historic
1964 tsunami event.
Milestone 3. Develop techniques and software to process raw
Deep-ocean Assessment and Reporting of Tsunamis (DART)
data with various time discretization and record lengths
to produce high-quality data sets for climate and tsunami
research.
During FY11, CIRES staff at the NGDC developed a set
of programs for control, validation, processing and visualization
of raw DART data. DART data are of two types:
1) high-resolution 15-second retrospective records and 2)
irregularly sampled real-time transmitted data. The main
purpose of DART data is early detection and warning of
tsunamis in the open ocean. Their real-time use by the
NOAA Tsunami Warning Centers improves the tsunami
forecasts and refines the tsunami source parameters. In
most of the cases, the tsunami signal is about 3-5 percent
of the recorded amplitude, and high precision processing
is required. The instruments are deployed on the ocean
floor for up to 48 months at depths up to 6,000 meters. As
with any scientific instrumentation, various instrument
issues are identified and fixed throughout the data control
and validation processing. The tidal signal that usually
accounts for more than 90-95 percent of the variance of the
DART records is removed by a redesigned and customized
tidal fitting high-precision code. An additional filter
is used to process the residuals that contain the tsunami
signal.
More than 85 archived DART high-resolution records
are processed and available on the NGDC website. This
unique data set of long-term observations is used by researchers,
hazard managers and many other users all over
the world. We have also processed the real-time DART
data from the Chilean Feb. 27, 2010, and Tohoku March 11,
2011, earthquakes and tsunamis, and posted them on the
NGDC website.
Milestone 4. Enhance online and offline access and delivery
of hazards data.
CIRES staff at the NGDC have improved data discovery
and access to hazards data. New map services and interactive
maps have been created using ArcGIS Server and
the ArcGIS JavaScript API. The interactive maps feature
90 CIRES Annual Report 2011
Figure 3: Screen grab of interactive DART event page describing the
March 11, 2011, Tohoku tsunami. Map depicts earthquake location,
tsunami travel times and locations of DART buoys in the northern
Pacific Ocean. Inset shows processed DART data for the two closest
stations, with clear recordings of the earthquake (on left) and subsequent
tsunami (to the right).
Figure 4: The Natural Hazards Viewer, an ArcGIS Server interactive map
provides access to NGDC’s historical Natural Hazards database. Shown
are observations of the March 11, 2011, tsunami along Japan’s coast.
increased usability, improved performance and enhanced
cartography.
The NGDC Natural Hazards database can be explored
using a powerful new interactive map interface (http://
maps.ngdc.noaa.gov/viewers/hazards) that integrates
historical tsunami events, tsunami observations, significant
earthquakes, volcanic eruptions and water-level data
from open-ocean buoys and coastal tide gauges.
Discovery of and access to coastal DEMs at NGDC
(http://www.ngdc.noaa.gov/mgg/coastal/coastal.
html) have also been enhanced using the Grails database
framework. DEM search pages now include interactive
maps depicting spatial coverage of the DEMs, along with
shaded-relief visualizations. An RSS subscription feed announces
the latest releases and updates.
The new map services are accessible via standard Open
Geospatial Consortium (OGC) protocols such as WMS
and WFS, which can be consumed by a variety of clients
both inside and outside NGDC.