Fall AGU 2010, San FranciscoDec 17, 2010

Observing the Ionospheric Signature of Ocean Tsunamis

Using GPS Total Electron Content

D. A. Galvan1; A. Komjathy1; M. P. Hickey2; A. Mannucci1

1Ionospheric and Atmospheric Remote Sensing Group, NASA Jet Propulsion Laboratory, California Institute of Technology2Department of Physical Sciences, Embry-Riddle Aeronautical University

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Tsunami-driven Traveling Ionospheric Disturbances(TIDs)

From Artru et al., 2005

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Motivation:Why add ionospheric observations?

• DART buoy system is expensive: • ~$250,000 per buoy to build• DART system cost $12 M to maintain/operate in

2009 (28% of NOAA’s total tsunami-related budget)*

• Buoys are sparsely distributed, temperamental• Data available 84% of time, outages due to harsh weather,

human error*

• GPS Receivers are more abundant, multi-use, low-cost

• Additional means of observing tsunamis over a broader area could help to validate and improve theoretical model predictions, contributing to tsunami early warning system.

*Government Accountability Office (GAO) report, April 2010http://www.gao.gov/cgi-bin/getrpt?GAO-10-490

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Data Type: Total Electron Content (TEC) from International GNSS System (IGS) stations

-30-second TEC data from dual-frequency GPS receivers.-Data processed through Global Ionospheric Mapping (GIM) algorithm at JPL

-For simultaneous bias identification/removal (satellite and receiver),

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Regional Networks

Source: Scripps Orbit and Permanent Array Center (SOPAC) GPS Data Archive, UCSDhttp://sopac.ucsd.edu/cgi-bin/somi4i

5

Source: Japanese GPS Earth Observation Network (GEONET) ArrayOver 1200 stationshttp://terras.gsi.go.jp/gps/geonet_top.html

GEONET Array

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Streaming 1-second data availability

Currently up to 130 stations worldwide providing 1-second realtime data.http://www.gdgps.net/,ftp://cddis.gsfc.nasa.gov/pub/gps/data/highrate

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Methodology

• Estimate arrival time. Use simple 200 m/s projection, model predictions (MOST, Song, etc.)

• Process GPS TEC data JPL GIM software.

• Apply bi-directional band-pass filter: 0.5 – 5 mHz (33.3 – 3 min period)

• Plot filtered TEC as a function of distance/time.

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American Samoa Tsunami 9/29/09 Observed at Hawaii

Rolland et al., 2010 (GRL)Galvan et al., 2011 (submitted)

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American Samoa Tsunami 9/29/09Observed at Hawaii (map plot)

Lat

LonUT Sep 29-30, 2009

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American Samoa Tsunami 9/29/09Real-time 1-second data

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COSMIC as additional resource

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Chile Tsunami 2/27/10Observed at Japan

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Chile Tsunami 2/27/10Observed at Japan

UT Sep 29-30, 2009

Dis

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Theoretical Model Results

Ocean Surface Displacement (m)

Vertical TEC

Spectral full-wave model (SFWM), Hickey et al., 2009, using input wave form from Peltier and Hines, 1976, and period/velocity from DART buoy.

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Hickey Model Compared with Data

FilteredVTEC (TECU)

Universal Time (2/28/2010)

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Summary

• Tsunami-driven TID’s observed via GPS TEC after the American Samoa Tsunami of 9/29/2009 and the Chilean tsunami of 2/27/2010. (Galvan et al., submitted)

• Models predict tsunami-driven TID’s. (Occhipinti et al., 2008; Hickey et al., 2009; Mai and Kiang, 2009).

• Observations: Typically ~0.1 – 0.5 TECU.

• 30-second archived data AND 1-second real-time data available for study, both ground-based and LEO (COSMIC).

• Long-term potential for warning system.

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Acknowledgements

• NASA ROSES Grant # NNH07ZDA001N-ESI(Tsunami Imaging Using GPS Measurements)

• Dr. John LaBrecque (NASA HQ)• Dr. Philip Stephens (JPL)• Dr. Vasily Titov and Dr. Yong Wei (NOAA

Center for Tsunami Research)• Dr. James Foster (University of Hawaii)• Dr. Giovanni Occhipinti (IPGP, France)

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BACKUP SLIDES

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JPL’s GIM Ionosphere Algorithm

• Data-driven vertical TEC maps based on interpolating GPS slant TEC measurements on global scales (1993 – present):• Solar-geomagnetic reference frame• Shell approximation: extended slab (450 km altitude)• Multiple shells (250, 450, & 800 km altitude)• Map slant TEC measurements to equivalent vertical

using obliquity factor• Spatial interpolation: Triangular-grid or Bi-cubic splines

• Temporal smoothing: stochastic Kalman filter– Vertical TEC at each vertex treated as a random walk

parameter• Initialized with Klobuchar, Bent, or IRI95 model• Simultaneously solve for satellite biases (Tgd) and

receiver biases