"As solar activity ramps up (multiple X/near-X solar flares this week), we must be *cautious* on drawing comparisons to the last decade. If these flares happened 5 years ago, they wouldn’t have made it into the top flare category. A thread:
GOES-14 & 15 defined flares from 2010-2020, covering the previous solar maximum. However, upon launch of these satellites, a calibration discrepancy was discovered between GOES-14/15 and ALL prior GOES X-ray detectors, so old GOES-1 to 13 data were adjusted to account for this.
HOWEVER. Upon launch of GOES-16, it was announced that the older calibration had been correct (and GOES-14/15 were not). So in 2020, NOAA announced a recalibration to their dataset, increasing all prior flare classes by 42%!!! (Divide by 0.7). A massive change.
This huge difference CANNOT be understated. If this week’s X1 flares had happened before 2020, they’d have been categorised an M7 flare. In fact, a flare today would need to be X4.2, in order to have been called an X-flare just five years ago.
Taking this into account: we’ve had 31 X-class flares this solar cycle (since 2022). Under the previous calibration (used last solar cycle), we’d have only TWO(!!!). This is a MASSIVE discrepancy, that must be considered in qualitative and quantitative comparisons."
Full thread:
https://twitter.com/RyanJFrench/status/1787108955065352197
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