Detection of the 2010 Chilean tsunami using satellite altimetry

Abstract

Abstract. Tsunamis are difficult to detect and measure in the open ocean because the wave amplitude is much smaller than it is closer to shore. An effective early warning system, however, must be able to observe an impending tsunami threat far away from the shore in order to provide the necessary lead-time for coastal inhabitants to find safety. Given the expansiveness of the ocean, sensors capable of detecting the tsunami must also have very broad areal coverage. The 2004 Sumatra-Andaman tsunami was definitively detected in the open ocean from both sea surface height and sea surface roughness measurements provided by satellite altimeters. This tsunami, however, was exceptionally strong and questions remain about the ability to use such measurements for the detection of weaker tsunamis. Here we study the 2010 Chilean tsunami and demonstrate the ability to detect the tsunami in the open ocean. Specifically, we analyze the utility of filtering in extracting the tsunami signal from sea surface height measurements, and, through the use of statistical analyses of satellite altimeter observations, we demonstrate that the 2010 Chilean tsunami induced distinct and detectable changes in sea surface roughness. While satellite altimeters do not provide the temporal and spatial coverage necessary to form the basis of an effective early warning system, tsunami-induced changes in sea surface roughness can be detected using orbiting microwave radars and radiometers, which have a broad surface coverage across the satellite ground track.

Could satellite altimetry have improved early detection and warning of the 2011 Tohoku tsunami?

“…To extract the tsunami signal from the background ocean variability in the SSH measurements, the filtering technique introduced in Hamlington et al [2011] is implemented. This filtering technique is based on the method developed by Gower [2007]consisting of subtracting a smoothed average (9‐second boxcar filter) of SSH measured on the same pass of the cycles before and after the tsunami cycle.…”

“…Additionally, recent studies have demonstrated the ability to detect a tsunami in the open ocean through changes in the sea surface characterized by the radar backscattering strength at nadir, σ 0 [ Godin et al , 2009; Hamlington et al , 2011]. To determine if σ 0 variations were induced by the 2011 Tohoku tsunami, we perform statistical randomization tests to compare data with and without the tsunami present.…”

“…To determine if σ 0 variations were induced by the 2011 Tohoku tsunami, we perform statistical randomization tests to compare data with and without the tsunami present. Further details of these randomization tests are included in Hamlington et al [2011] and section 3 of the .…”

“…SSH measurements were used by a number of authors to study the properties of the Sumatra‐Andaman tsunami (see). More recently, the comparatively weaker 2010 Chilean tsunami has been positively detected in SSH measurements [ Hamlington et al , 2011]. Studies have also shown that the tsunami signal can be detected in the open ocean from satellite altimeter measurements of sea surface roughness [ Godin et al , 2009; Hamlington et al , 2011].…”

Assessment of GNSS-based height data of multiple ships for measuring and forecasting great tsunamis

“…As one of other offshore measurements, satellite altimetry has been well known to detect significant tsunamis (Gower 2004;Hamlington et al 2011;Song et al 2012), and its nearreal-time use has been also investigated (Hamlington et al 2012). GNSS-reflectometry using numerous GNSS satellites and LEO satellites may also be a promising technique for detecting offshore tsunamis over vast areas of ocean in a relatively short time interval (Stosius et al 2010).…”