Quality Controls, Data Gaps and Processing
The Thomson detided product only provides clean and gap filled data with a 15 second boxcar average with 50% overlap. These options are fixed and only shown for consistency and information. For your information, the 50% overlap is not available in any other data products, while regular non-overlap boxcar averaging is widely available. These data product options are presented in greater detail in the following pages, which are available on standard time series scalar data.
Oceans 3.0 API filter: dpo_qualityControl=1&dpo_dataGaps=1&dpo_resample=15
Kaiser-Bessel Filtering Options
This option specifies the window duration of the Kaiser Bessel filter, of which there are two passes. The parameter β of the Kaiser window, which controls the level of the sidelobe, is set to 3 by default. The first pass is a low-pass filter to isolate the tsunami signal. For highly energetic tsunami events such as the 2011 Tohoku tsunami, a 6 hour window duration should be used. For smaller events, such as the 2012 Haida Gwaii earthquake, a shorter window of 2-3 hours can be used. It is important to note that these options should only be chosen to isolate a tsunami signal. The second pass of the Kaiser-Bessel Filter further removes noise from the final output after processing by using a relatively short window duration. If necessary, high-frequency infra-gravity waves can be eliminated from the data by selecting the 6 minute option. In many cases, this is not necessary, and in other cases, a 2 minute window is sufficient. For data with very strong infra-gravity waves, a 20 minute window can be applied. The filtering should only be used if needed since it can distort the tsunami record and lead to the introduction of signal "artifacts". The 'off' option for both passes should be selected for spectral analysis and is the default to allow users to initially see all of the signals before applying additional filtering. The default off option provides the residual (detided), non-filtered data.
Oceans 3.0 API filter: dpo_tsunamiKBfilter1=10800 (other options: 7200, 21600 (window duration in seconds) or 0 for off)
Oceans 3.0 API filter: dpo_tsunamiKBfilter2=360 (other options: 120, 1200 (window duration in seconds) or 0 for off)