Monthly mean hemispheric sunspot numbers:

Time range: 1/1992 - last elapsed month (provisional values)

Data description:
Monthly mean North/South sunspot numbers obtained by taking a simple arithmetic mean of the daily North/South sunspot numbers over all days of each calendar month. Each sunspot group is counted in one of the hemispheres based on its heliographic latitude. NB: Hemispheric numbers are always normalized to the corresponding total monthly mean sunspot number (cf. file monthssn.dat)

Error values:
For total numbers, the monthly standard deviation of individual data is derived from the daily values by:
sigma(m)=sqrt(SUM(N(d)*sigma(d)^2)/SUM(N(d)))
where sigma(d) is the standard deviation for a single day and N(d) is the
number of observations for that day.
For hemispheric values, the errors are derived from daily values by:
sigma(m)=sqrt(SUM(sigma(d)^2)/Nobs)
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TXT
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Filename: SN_m_hem_V2.0.txt
Format: plain ASCII text

Contents:
Column 1-2: Gregorian calendar date
- Year
- Month
Column 3: Date in fraction of year for the middle of the corresponding month
Column 4: Monthly mean total sunspot number.
Column 5: North monthly mean sunspot number.
Column 6: South monthly mean sunspot number.
Column 7: Monthly mean standard deviation of total sunspot number data
Column 8: Monthly mean standard deviation of North sunspot number data
Column 9: Monthly mean standard deviation of South sunspot number data
Column 10: Number of observations used to compute the monthly mean total sunspot number.
Column 11: Number of observations for the monthly mean North sunspot number (not used yet)
Column 12: Number of observations for the monthly mean South sunspot number (not used yet)
Column 13: Definitive/provisional marker. A blank indicates that the monthly mean values are definitive. A '*' symbol indicates that the monthly values are still provisional and are subject to a possible revision (Usually the last 3 to 6 months)

Line format [character position]:
- [1-4] Year
- [6-7] Month
- [9-16] Decimal date
- [19-23] Monthly total sunspot number
- [25-29] Monthly north sunspot number
- [31-35] Monthly south sunspot number
- [38-42] Standard deviation (Total)
- [44-48] Standard deviation (North)
- [50-54] Standard deviation (South)
- [57-60] Number of observations (Total)
- [62-65] Number of observations (North)
- [67-70] Number of observations (South)
- [72] Definitive/provisional indicator

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CSV
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Filename: SN_m_hem_V2.0.csv (adapted for import in spreadsheets)
The separator is the semicolon ';'.

Format: Comma Separated values
Contents:
Column 1-2: Gregorian calendar date
- Year
- Month
Column 3: Date in fraction of year for the middle of the corresponding month (day 15)
Column 4: Monthly mean total sunspot number.
Column 5: North monthly mean sunspot number.
Column 6: South monthly mean sunspot number.
Column 7: Monthly mean standard deviation of total sunspot number data
Column 8: Monthly mean standard deviation of North sunspot number data
Column 9: Monthly mean standard deviation of South sunspot number data
Column 10: Number of observations for the monthly mean total sunspot number.
Column 11: Number of observations for the monthly mean north sunspot number (not used yet)
Column 12: Number of observations for the monthly mean south sunspot number (not used yet)
Column 13: Definitive/provisional marker. '1' indicates that the value is definitive. '0' indicates that the value is still provisional.