Well, a big thank you to @Mantis for pointing this out to me in Space weather memes. The post by @Mantis is linked here.

SWPC says that this flare in 2020 was the first m-class flare in years, but I just checked a random day in 2018, and it showed a M class flare.

https://www.swpc.noaa.gov/news/first-m-class-flare-observed-years

Edited October 30, 2024Oct 30 by Zhe Yu
Added information

1 hour ago, Zhe Yu said:

Well, a big thank you to @Mantis for pointing this out to me in Space weather memes. The post by @Mantis is linked here.

SWPC says that this flare in 2020 was the first m-class flare in years, but I just checked a random day in 2019, and it showed a lot of X and M class flares.

https://www.swpc.noaa.gov/news/first-m-class-flare-observed-years

I think you must be mistaken. This was during the last minimum. I just checked the archive and X-Ray flux for that period was around A and B levels.

Edit:  Having checked in more detail I find that the archive shows an M1.17 on 7th Feb 2018, an M1.05 and M1.4 on 6th May 2019 and an M1.19 on 27th May 2020, but bear in mind that these values are higher than they would have been at the time SWPC produced the article since the database has been updated in the meantime.

Edited October 30, 2024Oct 30 by 3gMike
Additional detail

you might be confused... this was during solar minimum where the solar flux didn't exceed A/B levels

1 hour ago, 3gMike said:

I think you must be mistaken. This was during the last minimum. I just checked the archive and X-Ray flux for that period was around A and B levels.

Edit:  Having checked in more detail I find that the archive shows an M1.17 on 7th Feb 2018, an M1.05 and M1.4 on 6th May 2019 and an M1.19 on 27th May 2020, but bear in mind that these values are higher than they would have been at the time SWPC produced the article since the database has been updated in the meantime.

Thank you for your response, I do remember it was solar minimum, and after reading your edit, I looked further in, and seems that SWL redirected me to a date in 2024. Reading a historical note listed below the graph says that they scaled it down by 42%, which would make all the M1 flares listed there in your edit be a smaller C flare. Does GOES-18 (Secondary) do this? I turned on the Secondary line on the graph, and seemed to be scaled down. This showed a C flare instead of the supposed M flare.

7 minutes ago, YourLocalCapybara2 said:

you might be confused... this was during solar minimum where the solar flux didn't exceed A/B levels

There were several M flares in the "several years period" @3gMike listed some:

1 hour ago, 3gMike said:

... Edit:  Having checked in more detail I find that the archive shows an M1.17 on 7th Feb 2018, an M1.05 and M1.4 on 6th May 2019 and an M1.19 on 27th May 2020...

 

i get it now... their "several years" in question is only a year

2 hours ago, Zhe Yu said:

Thank you for your response, I do remember it was solar minimum, and after reading your edit, I looked further in, and seems that SWL redirected me to a date in 2024. Reading a historical note listed below the graph says that they scaled it down by 42%, which would make all the M1 flares listed there in your edit be a smaller C flare. Does GOES-18 (Secondary) do this? I turned on the Secondary line on the graph, and seemed to be scaled down. This showed a C flare instead of the supposed M flare.

There were several M flares in the "several years period" @3gMike listed some:

 

 

1 hour ago, YourLocalCapybara2 said:

i get it now... their "several years" in question is only a year

 

No, that is not correct. The article referred to the period between October 2017 and August 2020 and that was a true indication of the situation at that time. Subsequently, the data was updated to INCREASE the recorded value of flares, which meant that what were previously high end C flares became M flares as I indicated in my response to Zhe Yu

On 10/30/2024 at 7:44 PM, 3gMike said:

No, that is not correct. The article referred to the period between October 2017 and August 2020 and that was a true indication of the situation at that time. Subsequently, the data was updated to INCREASE the recorded value of flares, which meant that what were previously high end C flares became M flares as I indicated in my response to Zhe Yu

oh... so their "several years" were only 3 years, which still doesn't sound like several to me

3 hours ago, YourLocalCapybara2 said:

oh... so their "several years" were only 3 years, which still doesn't sound like several to me

Well, show me the flare that happened "three years ago" before 2020. 2016 was still entering solar minimum, and had no M flares in the second half due to the 42% scaling. And 2015 was the last year they had M flares.

9 hours ago, Zhe Yu said:

Well, show me the flare that happened "three years ago" before 2020. 2016 was still entering solar minimum, and had no M flares in the second half due to the 42% scaling. And 2015 was the last year they had M flares.

2016 had a couple of flares in the second half that would have been M-class even before the correction factor was removed. On Nov 29 of 2016 there were two flares of M1.48 and M1.81 respectively; multiplying these by 0.7 you're still above 1. A good rule of thumb is that any flare which is M1.43 or higher was still an M-flare before the correction factor was removed. 2015 had many such flares.

Perhaps you stopped looking after 2016 because you thought it was "fizzling out" at that point? Not so! In 2017 there was a big resurgence in activity, which isn't untypical for the downslope of the cycles, there's often a burst or two with a big uptick in action. In 2017 there were 44 flares which would have been M-class even before the correction factor was removed, including the two very strong X-flares mentioned in the other thread.

12 hours ago, YourLocalCapybara2 said:

oh... so their "several years" were only 3 years, which still doesn't sound like several to me

Well, I guess you could argue the semantics of "several" being inappropriate there; perhaps "a few" would have been better? In any case it did indeed explicitly refer to ~3 years, since it explicitly reads "since 20 Oct 2017" in the article.

2 hours ago, Philalethes said:

2016 had a couple of flares in the second half that would have been M-class even before the correction factor was removed. On Nov 29 of 2016 there were two flares of M1.48 and M1.81 respectively; multiplying these by 0.7 you're still above 1. A good rule of thumb is that any flare which is M1.43 or higher was still an M-flare before the correction factor was removed. 2015 had many such flares.

Perhaps you stopped looking after 2016 because you thought it was "fizzling out" at that point? Not so! In 2017 there was a big resurgence in activity, which isn't untypical for the downslope of the cycles, there's often a burst or two with a big uptick in action. In 2017 there were 44 flares which would have been M-class even before the correction factor was removed, including the two very strong X-flares mentioned in the other thread.

Well, I guess you could argue the semantics of "several" being inappropriate there; perhaps "a few" would have been better? In any case it did indeed explicitly refer to ~3 years, since it explicitly reads "since 20 Oct 2017" in the article.

Thank you @Philalethes for explaining, I have realised my mistake of not checking the whole of 2017! You are the tour guide to the top of the mountain of achieving inner knowledge of space weather and detail, I wonder where the community would be without you and all the other community regulars and supporters!