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Changes for page AusPass Data

Last modified by robert on 2026/02/12 14:01
From version 15.3
edited by robert
on 2026/01/16 11:29
Change comment: There is no comment for this version
To version 19.1
edited by robert
on 2026/01/16 12:23
Change comment: There is no comment for this version

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... ... @@ -48,11 +48,11 @@
48 48  
49 49  = SmartSolo Node Polarity Issues =
50 50  
51 -There has been a lot of confusion about the polarity of the IGU-16HR (1C and 3C) data, as well as the BD3C-5 data over the years.
51 +There has been a lot of confusion about the polarity of the IGU-16HR (1C and 3C) data, as well as the BD3C-5 data over the years. We now believe we know what's going on with certainty.
52 52  
53 53  (% class="box errormessage" %)
54 54  (((
55 -ALL IGU-16HR channels have negative polarity relative to "standard" FDSNXML convention (positive down = -90 degrees, positive north = 0 degrees, positive east = 90 degrees). Freshly exported data requires a -1 multiplier relative to be "correct" relative to what you're likely expecting.
55 +ALL IGU-16HR channels have **negative** polarity relative to "standard" FDSNXML convention (e.g., positive down = -90 degrees, positive north = 0 degrees, positive east = 90 degrees). Freshly exported data requires a -1 multiplier to ALL channels to be "correct" relative to what you're likely expecting.
56 56  )))
57 57  
58 58  (% class="box infomessage" %)
... ... @@ -60,18 +60,13 @@
60 60  BD3C-5 channels are "normal" and consistent with usual high gain seismometers. These sensors do not require any polarity flips.
61 61  )))
62 62  
63 -After much consternation was have finally tested this ourselves in a controlled environment, and have also consulted various agencies. We are now certain the above notices to be correct.
63 +After much consternation was have finally tested this ourselves in a controlled environment and are now certain the above notices to be correct. Other researchers have demonstrated the same:
64 64  
65 -[[Arrivals showing the polarity of various instrument types (courtesy of the China Earthquake Administration). Note that the IGU-HR3C are inverted relative to the BD3C and CMG40T. >>image:Weixin Image_20260115150150_19_1185.png||alt="Arrivals showing various sensors. The HR3C channels are inverted."]]
65 +[[Arrivals showing the polarity of various instrument types (courtesy of the China Earthquake Administration). Note that the IGU-16HR3C (labelled HR3C) are inverted relative to the BD3C and CMG40T. >>image:Weixin Image_20260115150150_19_1185.png||alt="Arrivals showing various sensors. The HR3C channels are inverted."]]
66 66  
67 -In[[ late 2023 it was discovered>>https://epic.earthscope.org/content/smartsolo-archives-flipped-polarity-igu-16hr-3c-5hz]] that the vertical Z channel of **the IGU-16HR short period **SmartSolo nodes is actually inverted relative to the standard expectation of "positive up" (vertical axis dip = -90). EarthScope's solution was to add a -1 multiplier to the //response data.// Because we have a much smaller volume of this data to fix, and far less of it already distributed prior to this announcement, we have opted to do the opposite; e.g. we invert the //raw data// because the data is what is wrong; not the response.
67 +As of December 2025, all waveform data on AusPass are now corrected.
68 68  
69 -**In late 2025 we also discovered that the horizontal (N and E) channels are ALSO flipped! Data downloaded before Friday 5 December 2025 is affected- multiply your DH[NE] channels by -1 if you have already downloaded them.**
69 +Previously it was understood that only the "Z" channel data on the IGU-16HRs was incorrect. It is unclear how other agencies handle this, so for that reason we do not advise mixing up response information from what is provided on AusPass. It is possible that other groups account for this by adding a multiplier in the metadata and not by editing the waveform data.
70 70  
71 -Until very recently we also thought that the BD3C-5 "broadband" nodes had inverted data by default, but now understand that their raw exported data has the correct polarity.
72 72  
73 -{{warning}}
74 -Do not mix up EarthScope's or the IRIS-NRL node response data with those available at AusPass. Theirs could be inverted relative to our data! In general we have low confidence in the information provided but can confirm that our metadata is at least "pretty close".
75 -{{/warning}}
76 -
77 77