What is this?

[mizunomizuno]

Could someone explain this? What happened?
It happeded on 6th September.
This wasn't a typhoon. The typhoon was below.

[Gkikas LGPZ]

@mizunomizuno
Is a test pattern.
This is a specific signal that is either sent from the radar to test the transmitter hardware, or which is injected directly into the receiver to check receive performance.
The signals they use don't look anything like normal radar signals, as they want to check the performance in all directions at once.

Probably, radar technicians were performing maintenance but neglected to take the data stream offline, so the system uploaded the test pattern.

[idefix37]

@Gkikas-LGPZ
It’s even better to have the enlightened opinion of a specialist ! I’ve learn something today !

[Yves70]

@Gkikas-LGPZ
Very interesting info, thanks !

[mizunomizuno]

@Gkikas-LGPZ

Thank you for information.

It was fun to imagine what the clouds were like and what was like when it happened.