Day changing time

[Sammytom1234]

Hi everyone just a couple of quick questions in regards to what time cumulus rolls over to the next day. The local melbourne bom sites all use rainfall to 9am and there minimum and maximum temperture also restarts at about 8pm therefore it is impossible to compare data with nearby stations what are some reasonable solutions to help compare data and possiblly change my times to the sam way thankyou

[steve]

Cumulus only allows rollover of everything at the same time, either midnight (used by most Cumulus users) or 0900 (with the option of 1000 in summer) as used 'officially' in the UK.

If you wanted different start/end times for different items, then I think you would have to load the data logs into a spreadsheet or a database and do your own analysis.

[Matt.j5b]

The bom measures rainfall in the 24 hours to 9am, minimum air temperature is measured in the 24 hours to 9am while maximum temperature is measured in the 24 hours from 9am.

See the following links for the bom recording standards:

http://www.bom.gov.au/climate/how/obser ... sure.shtml
http://www.bom.gov.au/climate/how/obser ... sure.shtml

[Sammytom1234]

Thanks guys that clears it up for me, would you recommend using the 9am rollover similar to the bom Matt or use the regular midnight time used by most cumulus users?

[Matt.j5b]

Using a 9am rollover would make the data more comparable with local bom data but there is nothing wrong with a midnight rollover. Way before electronic recording the recordings were reset at 9am rather than in the middle of the night and so to keep stations consistent with older records they have kept it at 9am. So it your decision whether you want to keep with the historic standard or just stick with midnight.

But using a midnight rollover for most of the time will get you a correct minimum temperature compared to a 9am rollover unless it doesn't happen overnight (which sometimes happens if the morning is cloudy and min will happen at sunset to midnight). A 9 am rollover will make the maximum temperature be recorded a day later as the bom records the maximum in the 24 hours from 9am as Cumulus can only do the same rollover time for all data. Rainfall will be very different between the rollover times particularity with a major rain event. 9am should give good results except the maximum temperature will be recorded one day later than the bom.