Determining lightning polarity (positive or negative) by raw signal processing?
Determining the polarity is easy in theory. What we need are a couple of stations where we now the parameters.

Here's that what you can do:

1. Select a stroke which is not too far and not too close (i.e. 100 - 300km) to your station. Too close one may cause some interference, too far might be a reflection.
a) The signal shape should be some sort of a single spike and not too weak. Don't use signals of GREEN stations.
b) The accuracy of the stroke should be good, let's say < 1km.
c) The signal should include an e-field channel and two horizontal H-field channels.
d) Check other stations signal of the stroke which have similar distances. They should be very similar shape.
d) Save the signal!

2. Search for the stroke in another archive like
a) Germany:
b) USA:
c) For other regions you can check the latest 60 minutes here
--> Double check whether the selected stroke is really the one of the signal.

3. Try to match these parameters with your signals:
a) The strokes polarity should always match the polarity of the spike in the E-field channel (either always equal, or always the opposite). If you also consider the directions, you can check the H-field antennas as well (see first post).
b) The current should be propotional of the spikes amplitude multiplied with gain on equal distances from stroke to station.
c) The type (cloud to ground or intra cloud) might have some influence on the shape of the signal.

4. Post your results here.

After we have some results, we can implement algorithms to compute those parameters. Then signals of other stations can be used as well, as their antenna parameters can be calculated from the calibrated stations.

It is also possible to recompute past events again and again to improve all the algorithms. But we have to record them manually. For example, I have world wide signal data from 2017-08-18 15:00 UTC +6 hours which is around 60GB.

It is important not to change any antenna positions/directions or filter settings since you've recorded the signals.

Note: All this can take some long time! I hope that we can implement some of the things from above within the next months, but I can not guarantee it.
Stations: 538, 672, 1534, 1555, 1696, 1712, 2034, 2219

Messages In This Thread
RE: Determining lightning polarity (positive or negative) by raw signal processing? - by Tobi - 2017-08-21, 08:28

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