Average temperature - Revision history

Sfws: /* Calculation */

2021-06-27T11:11:04Z

Calculation

← Older revision		Revision as of 11:11, 27 June 2021
Line 1:		Line 1:

			= Cumulus approach =

			Please see [[Meteorological day]] for discussion about WMO standard way to calculate average temperature from sum of minimum in previous 12 hours and maximum in subsequent 12 hours, divided by two.

	== Calculation ==		== Calculation ==
	The average temperature for the day, is calculated by Cumulus using samples of the temperature taken at 1-minute intervals (sometimes called the 'integration method'). (This assumes Cumulus is running continuously, if it has just been restarted, for some station types Cumulus will use the temperatures stored at the console logging interval for the period since Cumulus previously ran). Each minute the new measurement is added onto the accumulator ''Total'' and increments by one the counter ''Samples'' in the [[today.ini]] log file.		The average temperature for the day, is calculated by Cumulus 1 using samples of the temperature taken at 1-minute intervals (sometimes called the 'integration method'). (This assumes Cumulus is running continuously, if it has just been restarted, for some station types Cumulus will use the temperatures stored at the console logging interval for the period since Cumulus previously ran). Each minute the new measurement is added onto the accumulator ''Total'' and increments by one the counter ''Samples'' in the [[today.ini]] log file.

			For MX, the sampling may be every second.

	== Cumulus outputs ==		== Cumulus outputs ==

Sfws: /* Annual NOAA report */ add hyphen

2021-02-15T15:11:12Z

Annual NOAA report: add hyphen

← Older revision		Revision as of 15:11, 15 February 2021
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	'''Annual summary line:'''		'''Annual summary line:'''
	The [https://library.wmo.int/doc_num.php?explnum_id=4166 WMO guidlines] say that for a climatic normal over an annual or seasonal period, the mean you quote should be the average of the monthly means you calculated for international exchanged products, but allow "National Meteorological and Hydrological Services [to] weight monthly normals by the number of days in the month when calculating the ~~multimonth~~ normal". In other words, within a nation you can report annual averages calculated using integrated daily means. If you are calculating climate norms for international publication you average the individual months. Put another way, within a nation you can add all the daily average temperature values you have and divide by the number of days (part or full year); for publishing climate norms you add all the monthly average temperatures you have for a past year and divide by 12.		The [https://library.wmo.int/doc_num.php?explnum_id=4166 WMO guidlines] say that for a climatic normal over an annual or seasonal period, the mean you quote should be the average of the monthly means you calculated for international exchanged products, but allow "National Meteorological and Hydrological Services [to] weight monthly normals by the number of days in the month when calculating the multi-month normal". In other words, within a nation you can report annual averages calculated using integrated daily means. If you are calculating climate norms for international publication you average the individual months. Put another way, within a nation you can add all the daily average temperature values you have and divide by the number of days (part or full year); for publishing climate norms you add all the monthly average temperatures you have for a past year and divide by 12.

	For Cumulus users looking at complete ''past years'' the difference between the two approaches just sometimes shows small discrepancies, and those are partly because of the way Cumulus does its rounding of each daily figure, rather than just rounding final figure. For the ''current year'', (or any past year if you have missing days in that year) especially in Northern Hemisphere Spring, the difference between approaches is seen because February and April have fewer days than January, March, and May, and when you look at a report the current month may have even fewer days. e.g. on 7 March one approach divides by 3, the other by 66 in a non-leap year (31+28+6 completed days, if none missing) leading to discrepancies, but in the same year on 1 April the first approach is still dividing by 3, but the second approach is dividing by 90. The latter shows little discrepancy because 30 (the 90 quoted divided by the 3 quoted) days is a reasonable average length for a month. So for good practical reasons, annual averages calculated from daily averages are good for Cumulus web pages as they are not skewed by missing days nor by incomplete months.		For Cumulus users looking at complete ''past years'' the difference between the two approaches just sometimes shows small discrepancies, and those are partly because of the way Cumulus does its rounding of each daily figure, rather than just rounding final figure. For the ''current year'', (or any past year if you have missing days in that year) especially in Northern Hemisphere Spring, the difference between approaches is seen because February and April have fewer days than January, March, and May, and when you look at a report the current month may have even fewer days. e.g. on 7 March one approach divides by 3, the other by 66 in a non-leap year (31+28+6 completed days, if none missing) leading to discrepancies, but in the same year on 1 April the first approach is still dividing by 3, but the second approach is dividing by 90. The latter shows little discrepancy because 30 (the 90 quoted divided by the 3 quoted) days is a reasonable average length for a month. So for good practical reasons, annual averages calculated from daily averages are good for Cumulus web pages as they are not skewed by missing days nor by incomplete months.

Sfws: /* Annual NOAA report */ add mention of possible missing days - see https://cumulus.hosiene.co.uk/viewtopic.php?f=27&t=17856#p138447

2020-03-09T11:02:07Z

Annual NOAA report: add mention of possible missing days - see https://cumulus.hosiene.co.uk/viewtopic.php?f=27&t=17856#p138447

← Older revision		Revision as of 11:02, 9 March 2020
Line 15:		Line 15:
	The [https://library.wmo.int/doc_num.php?explnum_id=4166 WMO guidlines] say that for a climatic normal over an annual or seasonal period, the mean you quote should be the average of the monthly means you calculated for international exchanged products, but allow "National Meteorological and Hydrological Services [to] weight monthly normals by the number of days in the month when calculating the multimonth normal". In other words, within a nation you can report annual averages calculated using integrated daily means. If you are calculating climate norms for international publication you average the individual months. Put another way, within a nation you can add all the daily average temperature values you have and divide by the number of days (part or full year); for publishing climate norms you add all the monthly average temperatures you have for a past year and divide by 12.		The [https://library.wmo.int/doc_num.php?explnum_id=4166 WMO guidlines] say that for a climatic normal over an annual or seasonal period, the mean you quote should be the average of the monthly means you calculated for international exchanged products, but allow "National Meteorological and Hydrological Services [to] weight monthly normals by the number of days in the month when calculating the multimonth normal". In other words, within a nation you can report annual averages calculated using integrated daily means. If you are calculating climate norms for international publication you average the individual months. Put another way, within a nation you can add all the daily average temperature values you have and divide by the number of days (part or full year); for publishing climate norms you add all the monthly average temperatures you have for a past year and divide by 12.

	For Cumulus users looking at complete ''past years'' the difference between the two approaches just sometimes shows small discrepancies, and those are ~~mainly~~ because of the way Cumulus does its rounding of each daily figure, rather than just rounding final figure. For the ''current year'', especially in Northern Hemisphere Spring, the difference between approaches is seen because February and April have fewer days than January, March, and May, and when you look at a report the current month may have even fewer days. e.g. on 7 March one approach divides by 3, the other by 66 in a non-leap year (31+28+6 completed days) leading to discrepancies, but in the same year on 1 April the first approach is still dividing by 3, but the second approach is dividing by 90. The latter shows little discrepancy because 30 (the 90 quoted divided by the 3 quoted) days is a reasonable average length for a month.		For Cumulus users looking at complete ''past years'' the difference between the two approaches just sometimes shows small discrepancies, and those are partly because of the way Cumulus does its rounding of each daily figure, rather than just rounding final figure. For the ''current year'', (or any past year if you have missing days in that year) especially in Northern Hemisphere Spring, the difference between approaches is seen because February and April have fewer days than January, March, and May, and when you look at a report the current month may have even fewer days. e.g. on 7 March one approach divides by 3, the other by 66 in a non-leap year (31+28+6 completed days, if none missing) leading to discrepancies, but in the same year on 1 April the first approach is still dividing by 3, but the second approach is dividing by 90. The latter shows little discrepancy because 30 (the 90 quoted divided by the 3 quoted) days is a reasonable average length for a month. So for good practical reasons, annual averages calculated from daily averages are good for Cumulus web pages as they are not skewed by missing days nor by incomplete months.

	From Cumulus ''Version 3.4.4 - Build 3068'' onwards the figures shown at the bottom of the columns in this first table on the annual report shows the '''more accurate annual average calculated from adding all the daily averages and dividing by number of days'''. For Cumulus 1.9.4 (and Cumulus MX up to and including build 3067), the annual averages shown at the bottom of the annual NOAA report do not use these integrated daily means, instead '''the yearly average is calculated by adding all the months and then dividing by the number of months'''.		From Cumulus ''Version 3.4.4 - Build 3068'' onwards the figures shown at the bottom of the columns in this first table on the annual report shows the '''more accurate annual average calculated from adding all the daily averages and dividing by number of days'''. For Cumulus 1.9.4 (and Cumulus MX up to and including build 3067), the annual averages shown at the bottom of the annual NOAA report do not use these integrated daily means, instead '''the yearly average is calculated by adding all the months and then dividing by the number of months'''.

Sfws: /* Alternatives */ Minor tweaking

2020-03-09T10:34:50Z

Alternatives: Minor tweaking

← Older revision		Revision as of 10:34, 9 March 2020
Line 20:		Line 20:

	== Alternatives ==		== Alternatives ==
	~~This~~ ~~offers~~ an ~~alternative~~ to the simple mean of the highest and lowest temperatures of the day, ~~and~~ can give a 'better' average in cases where the high or low temperature occurred for a relatively short period, so could skew the ~~simple~~ average. To compare the two, select ''This period'' from the '''view''' menu and by default it will show both the integrated mean and simple mean temperatures for yesterday when you click '''Update display'''.		An alternative ''average temperature'' figure, sometimes seen, is the simple mean of the ''highest'' and ''lowest temperatures'' of the day. The intregated mean using all measurements can give a 'better' average especially in cases where the high or low temperature occurred for a relatively short period, so could skew the simpler extremity-based average. To compare the two, select ''This period'' from the '''view''' menu and by default it will show both the integrated mean and simple extremity-based mean temperatures for one day, yesterday, when you click '''Update display'''.

	Note that statistically, a median temperature could be used to avoid such skewing, this would require holding all the individual measurements for a day, ranking them in order of magnitude and quoting the central value in that list - Cumulus does not retain the every minute individual values and cannot calculate median. If you wanted to compare daily median and daily mean, you would need to analyse the monthly log file with an external package.		Note that '''statistically''', a median temperature could be used to avoid such skewing, this would require holding all the individual measurements for a day, ranking them in order of magnitude and quoting the central value in that list - Cumulus does not retain the every minute (timing can vary by weather station type) individual values and cannot calculate median. If you wanted to compare daily median and daily mean, you would need to analyse the monthly log file with an external package. Medians are not used by meteorologists.

	[[Category:Terminology]]		[[Category:Terminology]]

Sfws: /* Cumulus outputs */ Tidying

2020-03-09T10:27:33Z

Cumulus outputs: Tidying

← Older revision		Revision as of 10:27, 9 March 2020
Line 3:		Line 3:

	== Cumulus outputs ==		== Cumulus outputs ==
	At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of '''Total''' over '''Samples''' in the ~~old~~ today.ini and the same average is written to [[dayfile.txt]]. The integrated mean temperature for each day is also output to the monthly NOAA style report row for the last line (which is yesterday's date). Integrated average temperatures are ~~thus~~ available as [[webtags]] for today and yesterday~~. For past days they~~ ~~are found in the [[dayfile~~.~~txt]].~~		At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of '''Total''' over '''Samples''' in the [[today.ini\|previous today.ini]] and the same average is written to [[dayfile.txt\|the daily log file line representing that last complete day]]. The integrated mean temperature for each day is also output to the monthly NOAA style report row for the last line (which is yesterday's date). For past days they are found in the [[dayfile.txt]]. Integrated average temperatures are also made available as [[webtags]] for today (<#avgtemp>) and yesterday (<#avgtempY>).

			=== Monthly NOAA report ===
	The average of these daily intregated means for the whole month is shown at the bottom of the monthly NOAA style report, and the lowest, actual, and highest of these integrated daily mean for each month are output to the annual NOAA style report. Providing Cumulus is in continuous operation, so the number of measurements in the calculation is the same for every day, the average of integrated daily means over a month is mathematically the same as an integrated mean for the whole month.
			This report shows the figures taken from [[dayfile.txt\|daily summary log file]] for each day, so in the "Mean Temp" column it is reporting the same integrated average temperature (not the average of daily maximum and daily minimum). The value at the bottom of the column is the monthly average and that is in accordance with [https://library.wmo.int/doc_num.php?explnum_id=4166 WMO guidance] that says a monthly mean is calculated as "The mean of the daily values throughout the month". Obviously, prior to the end of the month it is mean-so-far! Providing Cumulus is in continuous operation, so the number of measurements in the daily calculation is the same for every day, the average of integrated daily means over month-so-far or whole past month is mathematically the same as an integrated mean calculated from all readings read by Cumulus whether this is for a part current month or for a whole past month.

			=== Annual NOAA report ===
	The annual averages shown at the bottom of the annual NOAA report do not use these integrated daily means, instead they simply add up the figures in that column. '''Thus, the way that Cumulus 1.9.4 (and Cumulus MX up to and including build 3067) works out all of the annual averages is arithmetrically wrong (the discrepancy varies through the year but is highest in March/April (because February has fewer days). The yearly average is calculated by adding all the months and then dividing by the number of months. Arithmetrically, the most accurate average is from adding all individual readings and dividing by number of readings (this what Cumulus does in the [[today.ini]] file that holds sum and number of readings. The NOAA reports however read from the [[dayfile.txt\|daily log]] so a more accurate annual average can be calculated from adding all the daily averages and dividing by number of days (which is what newer CM builds do).'''
			'''Each monthly line'''
			This report shows temperature in its first table, each line shows values calculated from [[dayfile.txt\|daily summary log file]],with columns for lowest, average, and highest of those integrated daily mean. For each month line, looking at the corresponding monthly table you can find the same figures. Another column gives the departure from normal; the normal mean temperature is defined for each month on the NOAA setup part of the Cumulus initial configuration, and the annual report takes the immediate preceding (mean) column, subtracts the figure you entered as the normal and shows the difference. Since the monthly mean is calculated in accordance with WMO guidelines, and the normal figure should be, the difference is also in compliance.

			'''Annual summary line:'''
			The [https://library.wmo.int/doc_num.php?explnum_id=4166 WMO guidlines] say that for a climatic normal over an annual or seasonal period, the mean you quote should be the average of the monthly means you calculated for international exchanged products, but allow "National Meteorological and Hydrological Services [to] weight monthly normals by the number of days in the month when calculating the multimonth normal". In other words, within a nation you can report annual averages calculated using integrated daily means. If you are calculating climate norms for international publication you average the individual months. Put another way, within a nation you can add all the daily average temperature values you have and divide by the number of days (part or full year); for publishing climate norms you add all the monthly average temperatures you have for a past year and divide by 12.

			For Cumulus users looking at complete ''past years'' the difference between the two approaches just sometimes shows small discrepancies, and those are mainly because of the way Cumulus does its rounding of each daily figure, rather than just rounding final figure. For the ''current year'', especially in Northern Hemisphere Spring, the difference between approaches is seen because February and April have fewer days than January, March, and May, and when you look at a report the current month may have even fewer days. e.g. on 7 March one approach divides by 3, the other by 66 in a non-leap year (31+28+6 completed days) leading to discrepancies, but in the same year on 1 April the first approach is still dividing by 3, but the second approach is dividing by 90. The latter shows little discrepancy because 30 (the 90 quoted divided by the 3 quoted) days is a reasonable average length for a month.

			From Cumulus ''Version 3.4.4 - Build 3068'' onwards the figures shown at the bottom of the columns in this first table on the annual report shows the '''more accurate annual average calculated from adding all the daily averages and dividing by number of days'''. For Cumulus 1.9.4 (and Cumulus MX up to and including build 3067), the annual averages shown at the bottom of the annual NOAA report do not use these integrated daily means, instead '''the yearly average is calculated by adding all the months and then dividing by the number of months'''.

	== Alternatives ==		== Alternatives ==

Sfws: /* Cumulus outputs */ Expanding re NOAA report annual averages with reference to Cumulus MX builds up to 3067

2020-03-08T16:38:49Z

Cumulus outputs: Expanding re NOAA report annual averages with reference to Cumulus MX builds up to 3067

← Older revision		Revision as of 16:38, 8 March 2020
Line 3:		Line 3:

	== Cumulus outputs ==		== Cumulus outputs ==
	At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of '''Total''' over '''Samples''' in the old today.ini and the same average is written to [[dayfile.txt]]. The integrated mean temperature for each day is also output to the monthly NOAA style report. Integrated average temperatures are available as [[webtags]] for today and yesterday.		At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of '''Total''' over '''Samples''' in the old today.ini and the same average is written to [[dayfile.txt]]. The integrated mean temperature for each day is also output to the monthly NOAA style report row for the last line (which is yesterday's date). Integrated average temperatures are thus available as [[webtags]] for today and yesterday. For past days they are found in the [[dayfile.txt]].

	The average of these daily intregated means for the whole month is shown at the bottom of the monthly NOAA style report and the lowest, actual, and highest of these ~~averages of~~ integrated daily mean for each month are output to the annual NOAA style report. Providing Cumulus is in continuous operation, so the number of measurements in the calculation is the same for every day, the average of integrated daily means over a month is mathematically the same as an integrated mean for the whole month.		The average of these daily intregated means for the whole month is shown at the bottom of the monthly NOAA style report, and the lowest, actual, and highest of these integrated daily mean for each month are output to the annual NOAA style report. Providing Cumulus is in continuous operation, so the number of measurements in the calculation is the same for every day, the average of integrated daily means over a month is mathematically the same as an integrated mean for the whole month.

			The annual averages shown at the bottom of the annual NOAA report do not use these integrated daily means, instead they simply add up the figures in that column. '''Thus, the way that Cumulus 1.9.4 (and Cumulus MX up to and including build 3067) works out all of the annual averages is arithmetrically wrong (the discrepancy varies through the year but is highest in March/April (because February has fewer days). The yearly average is calculated by adding all the months and then dividing by the number of months. Arithmetrically, the most accurate average is from adding all individual readings and dividing by number of readings (this what Cumulus does in the [[today.ini]] file that holds sum and number of readings. The NOAA reports however read from the [[dayfile.txt\|daily log]] so a more accurate annual average can be calculated from adding all the daily averages and dividing by number of days (which is what newer CM builds do).'''

	== Alternatives ==		== Alternatives ==

Sfws: /* Cumulus outputs */ Clarifying monthly figures

2013-07-02T08:02:42Z

Cumulus outputs: Clarifying monthly figures

← Older revision		Revision as of 08:02, 2 July 2013
Line 3:		Line 3:

	== Cumulus outputs ==		== Cumulus outputs ==
	At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of Total over Samples in the old today.ini and the same average is written to [[dayfile.txt]]. ~~Integrated average temperatures are available as [[webtags]] (but only for today and yesterday), the~~ integrated mean temperature for each day ~~and~~ ~~the month as a whole is~~ output to the monthly NOAA style report, ~~and~~ ~~the~~ ~~lowest,~~ ~~actual,~~ ~~and~~ ~~highest integrated mean temperature~~ for ~~each~~ ~~month~~ ~~are output to the annual NOAA style report~~.		At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of '''Total''' over '''Samples''' in the old today.ini and the same average is written to [[dayfile.txt]]. The integrated mean temperature for each day is also output to the monthly NOAA style report. Integrated average temperatures are available as [[webtags]] for today and yesterday.

			The average of these daily intregated means for the whole month is shown at the bottom of the monthly NOAA style report and the lowest, actual, and highest of these averages of integrated daily mean for each month are output to the annual NOAA style report. Providing Cumulus is in continuous operation, so the number of measurements in the calculation is the same for every day, the average of integrated daily means over a month is mathematically the same as an integrated mean for the whole month.

	== Alternatives ==		== Alternatives ==

Sfws: /* Cumulus outputs */ add link to webtags

2013-07-01T07:40:42Z

Cumulus outputs: add link to webtags

← Older revision		Revision as of 07:40, 1 July 2013
Line 3:		Line 3:

	== Cumulus outputs ==		== Cumulus outputs ==
	At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of Total over Samples in the old today.ini and the same average is written to [[dayfile.txt]]. Integrated average temperatures are available as webtags (but only for today and yesterday), the integrated mean temperature for each day and the month as a whole is output to the monthly NOAA style report, and the lowest, actual, and highest integrated mean temperature for each month are output to the annual NOAA style report.		At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of Total over Samples in the old today.ini and the same average is written to [[dayfile.txt]]. Integrated average temperatures are available as [[webtags]] (but only for today and yesterday), the integrated mean temperature for each day and the month as a whole is output to the monthly NOAA style report, and the lowest, actual, and highest integrated mean temperature for each month are output to the annual NOAA style report.

	== Alternatives ==		== Alternatives ==

Sfws: Adding mention of how Cumulus outputs average temperature

2013-07-01T07:24:18Z

Adding mention of how Cumulus outputs average temperature

← Older revision		Revision as of 07:24, 1 July 2013
Line 1:		Line 1:
			== Calculation ==
	The average temperature for the day~~, as recorded in the [[dayfile.txt]]~~, is calculated by Cumulus using samples of the temperature taken at 1-minute intervals (sometimes called the 'integration method'). (This assumes Cumulus is running continuously, if it has just been restarted, for some station types Cumulus will use the temperatures stored at the console logging interval for the period since Cumulus previously ran). Each minute the new measurement is added onto the accumulator ''Total'' and increments by one the counter ''Samples'' in the [[today.ini]] log file. ~~At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of Total over Samples in the old today.ini.~~		The average temperature for the day, is calculated by Cumulus using samples of the temperature taken at 1-minute intervals (sometimes called the 'integration method'). (This assumes Cumulus is running continuously, if it has just been restarted, for some station types Cumulus will use the temperatures stored at the console logging interval for the period since Cumulus previously ran). Each minute the new measurement is added onto the accumulator ''Total'' and increments by one the counter ''Samples'' in the [[today.ini]] log file.

			== Cumulus outputs ==
⚫	This offers an alternative to the simple mean of the highest and lowest temperatures of the day, and can give a 'better' average in cases where the high or low temperature occurred for a relatively short period, so could skew the simple average. To compare the two, select ''This period'' from the '''view''' menu and by default it will show both the integrated mean and simple mean temperatures for yesterday when you click '''Update display'''. Although average temperatures are not available as webtags, the integrated mean temperature for each day is output to the monthly NOAA style report, and the highest and lowest integrated mean temperature for each month are output to the annual NOAA style report.
			At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of Total over Samples in the old today.ini and the same average is written to [[dayfile.txt]]. Integrated average temperatures are available as webtags (but only for today and yesterday), the integrated mean temperature for each day and the month as a whole is output to the monthly NOAA style report, and the lowest, actual, and highest integrated mean temperature for each month are output to the annual NOAA style report.

⚫	Note that statistically, a median temperature could be used, this would require holding all the individual measurements for a day, ranking them in order of magnitude and quoting the central value in that list ~~(again this means extreme values have less skewing effect)~~ - Cumulus does not retain the every minute individual values and cannot calculate median. If you wanted to compare daily median and daily mean, you would need to analyse the monthly log file with an external package.

			== Alternatives ==
		⚫	This offers an alternative to the simple mean of the highest and lowest temperatures of the day, and can give a 'better' average in cases where the high or low temperature occurred for a relatively short period, so could skew the simple average. To compare the two, select ''This period'' from the '''view''' menu and by default it will show both the integrated mean and simple mean temperatures for yesterday when you click '''Update display'''.

		⚫	Note that statistically, a median temperature could be used to avoid such skewing, this would require holding all the individual measurements for a day, ranking them in order of magnitude and quoting the central value in that list - Cumulus does not retain the every minute individual values and cannot calculate median. If you wanted to compare daily median and daily mean, you would need to analyse the monthly log file with an external package.

	[[Category:Terminology]]		[[Category:Terminology]]

Sfws: added reference to NOAA style reports

2013-06-01T07:06:45Z

added reference to NOAA style reports

← Older revision		Revision as of 07:06, 1 June 2013
Line 1:		Line 1:
	The average temperature for the day, as recorded in the [[dayfile.txt]], is calculated by Cumulus using samples of the temperature taken at 1-minute intervals (sometimes called the 'integration method'). (This assumes Cumulus is running continuously, if it has just been restarted, for some station types Cumulus will use the temperatures stored at the console logging interval for the period since Cumulus previously ran). Each minute the new measurement is added onto the accumulator ''Total'' and increments by one the counter ''Samples'' in the [[today.ini]] log file. At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of Total over Samples in the old today.ini.		The average temperature for the day, as recorded in the [[dayfile.txt]], is calculated by Cumulus using samples of the temperature taken at 1-minute intervals (sometimes called the 'integration method'). (This assumes Cumulus is running continuously, if it has just been restarted, for some station types Cumulus will use the temperatures stored at the console logging interval for the period since Cumulus previously ran). Each minute the new measurement is added onto the accumulator ''Total'' and increments by one the counter ''Samples'' in the [[today.ini]] log file. At rollover, the ''AvgTemp'' field in [[yesterday.ini]] holds the final integrated mean calculated by the quotient of Total over Samples in the old today.ini.

	This offers an alternative to the simple mean of the highest and lowest temperatures of the day, and can give a 'better' average in cases where the high or low temperature occurred for a relatively short period, so could skew the simple average. To compare the two, select ''This period'' from the '''view''' menu and by default it will show both the integrated mean and simple mean temperatures for yesterday when you click '''Update display'''.		This offers an alternative to the simple mean of the highest and lowest temperatures of the day, and can give a 'better' average in cases where the high or low temperature occurred for a relatively short period, so could skew the simple average. To compare the two, select ''This period'' from the '''view''' menu and by default it will show both the integrated mean and simple mean temperatures for yesterday when you click '''Update display'''. Although average temperatures are not available as webtags, the integrated mean temperature for each day is output to the monthly NOAA style report, and the highest and lowest integrated mean temperature for each month are output to the annual NOAA style report.

	Note that statistically, a median temperature could be used, this would require holding all the individual measurements for a day, ranking them in order of magnitude and quoting the central value in that list (again this means extreme values have less skewing effect) - Cumulus does not retain the every minute individual values and cannot calculate median. If you wanted to compare daily median and daily mean, you would need to analyse the monthly log file with an external package.		Note that statistically, a median temperature could be used, this would require holding all the individual measurements for a day, ranking them in order of magnitude and quoting the central value in that list (again this means extreme values have less skewing effect) - Cumulus does not retain the every minute individual values and cannot calculate median. If you wanted to compare daily median and daily mean, you would need to analyse the monthly log file with an external package.