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Heat/cold degree days and Chill hours: Difference between revisions
Heat/cold degree days and Chill hours (view source)
Revision as of 21:24, 30 May 2013
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=Setting the threshold= | =Setting the threshold= | ||
== Heat and Cold Degree Days for NOAA reports == | == Heat and Cold Degree Days for NOAA reports == | ||
[[File:NOAA_Setup_extract.jpg]]The thresholds for '''Heat and Cold Degree days''' are set in the ''NOAA Setup'' option within the ''Configuration'' menu. The picture shows just parts of the setup screen. It allows you to specify the two thresholds in the units you have selected to use in your implementation of Cumulus | [[File:NOAA_Setup_extract.jpg]]The thresholds for '''Heat and Cold Degree days''' are set in the ''NOAA Setup'' option within the ''Configuration'' menu. The picture shows just parts of the setup screen. It allows you to specify the two thresholds (they do not have to be the same, although they are in the picture) in the units you have selected to use in your implementation of Cumulus. | ||
===CAUTION: Think carefully, about what threshold to use | === CAUTION: Think carefully, about what threshold to use === | ||
Cumulus stores your selected threshold values in the '''cumulus.ini''' file within the folder containing your Cumulus software (see [[Cumulus.ini#Section:_NOAA]]). | |||
If you later change the threshold, you will have inconsistencies on your reports: | '''If you later change the threshold, you will have inconsistencies on your reports:''' | ||
* The report will quote the new threshold, but only ''after the time'' you changed the threshold, will | * The report will quote the new threshold, but only ''after the time'' you changed the threshold, will Cumulus calculate the degree day counts based on the new threshold for the minute by minute interrogations of the weather station. | ||
* For the period from ''when you installed'' Cumulus version 1.9.2 ( | * For the period from ''when you installed'' Cumulus version 1.9.2 (this also applies for any earlier days added by 'create missing' with the new version) until day before changing threshold, the integrated figures as stored in [[dayfile.txt]] at the end of the meteorological day are quoted in the report. These counts were integrated on a minute-by-minute basis using the thresholds that existed at the time that the figures were stored in the daily summary log. It is therefore not possible to affect these degree days restrospectively by changing the thresholds. | ||
* For | * For days that were logged before you installed version 1.9.2 (or a later build if you missed out that version), there are no degree day figures in dayfile.txt. The values for the NOAA report are calculated simply by comparing the average daily temperature with the current threshold settings, so in this case any change in the threshold does apply retrospectively for those days although the calculation is inconsistent with later days. | ||
Cumulus 1.9.2 was available as default version from 5th October 2011, or as beta Build 1004 from 21 July 2011. | |||
One option is to manually recalculate an approximate value for each day simply by comparing the average daily temperature with the current threshold settings, making any consequent edits directly | '''Reducing the inconsistencies:''' | ||
* One option is to manually recalculate ''an approximate value'' for each day simply by comparing the average daily temperature with the current threshold settings, making any consequent edits directly in stored files containing past reports. For each degree (° C or ° F) below/above the threshold of the average daily temperature, add/subtract 1 degree-day from the daily figure previously recorded. | |||
The preferred option uses the View menu in Cumulus and the selection to generate new NOAA reports for a month (or year). The new report will not be consistent with the latest thresholds unless you have ''deleted all the 'pre-threshold change' values'' stored on 'dayfile.txt', but there is an option to save the new report (overwriting any previous one if you use the same name). Obviously if you have deleted values, your report will not | * The preferred option uses the View menu in Cumulus and the selection to generate new NOAA reports for a month (or year). The new report will ''not be consistent with the latest thresholds'' unless you have ''deleted all the 'pre-threshold change' values'' stored on 'dayfile.txt', but there is an option to save the new report (overwriting any previous one if you use the same name). Obviously if you have deleted values, your report will be consistent for the whole month, it will not use integrated totals, but simply an approximation based on the average daily temperature. | ||
== Configuring Chill Hours == | == Configuring Chill Hours == | ||