I was curious to see how SID numbers increase over the solar cycle period. So plotted total SID numbers from jan 2008 to march 2012 using AAVSO SID database. What I get is here in the attahment:
Looks like we're on the same trend per NOAA's solar cycle 24 progression charts. At one time our SID data was submitted to NOAA but I think now that's not the case.
If you pull all the AAVSO SID submissions from the NGDC ftp site:
and graph the duration (from start to end) of the SIDs going back to 1958 this is what it looks like. You can see the last 3 solar cycles in there, I think.
Thanks for the graph. It's looking interesting. Does this graph correlate with the solar cycle prediction graph? Or can we predict the solar cycle by graphing this SID number increasing and decreasing? I see the graph is not smooth where the mean sunspot number graph shows a smooth curve. But it is clear about the solar activity rising and falling from the SID graph.
I was looking to the NGDC SID data. I found in some months there is no data in the database. i.e. from May to December of 1998 there is no data. But AAVSO database has it. Again AAVSO database and NGDC database do not have same records of SID number.
In the mean time I plotted a graph started from January, 1996 to May, 2012 based on NGDC database. Look at the attachment. The second graph represents the yearly averaged number of SID from 1996 to 2011.
Is there any alternative source of NGDC SID database except from Ametures?
Tarif Rashid Santo(A133)
To my knowledge the data stored at NGDC does have contributions to the SID database from other professional observatories all over the world, although, most seem to be amateur stations: ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/Sudden_Ionospheric_Disturbances/sid_stations
Since most of NOAA's interest was from 1957 (after Sputnik) on it is interesting to read about how it started: ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/Sudden_Ionospheric_Disturbances/1README.TXT
I think the NGDC data make more sense when you look all the way back to 1958. In this graph attached, you can see how the solar cycles show up from 1960 - 1990 , then it seems a decision was made to compare the SID events to the GOES satellite: http://en.wikipedia.org/wiki/GOES_8
This seems to have made a big difference in 'variability' of the SID event data. The AAVSO still compares all SID submissions to the GOES satellites (GOES 15 now).
Is this a good idea?