If I calculate daily accumulated precipitation or daily maximum temperature from global climate data, will I be getting statistics over different local times, because the operation uses the climate model time which is UTC?

So for example, on day N I will get the maximum temperature from

  • midnight to 11:59pm in London, Dhaka, Portugal (UTC 0)
  • 10am on day N to 9:59am on day N+1 in eastern Australia (UTC+10)
  • 5pm on day N-1 to 4:59pm on day N in western US and Canada (UTC-7)
  • $\begingroup$ Welcome to EarthScience.SE. Commonly, ones uses UTC for calculating daily, monthly, annual, etc. means. Your example is correct. One has to be quite careful, when one compares measurements with model data. Depending on the database/source of the measurement data it is in UTC or local time. $\endgroup$ Jan 24 '19 at 13:20
  • $\begingroup$ thanks very much Daniel $\endgroup$
    – HamishC
    Jan 24 '19 at 23:42
  • $\begingroup$ I imagine it may depend upon what source you are looking at. For example, US daily climate reports which detail the max/min/precip are for midnight to midnight local time. Whereas indeed other climate data products you might get at NCDC or from reanalysis or such may be UTC based. Typically I've seen observation data from such sources to most often be delivered in UTC format indeed, so if calculating daily max/min you'd definitely have to account for that! $\endgroup$ Jan 25 '19 at 12:16

Yes, your understanding is correct.

(this is a really short answer because I can't think what else to say!)

I'm no expert on this type of simulation, but I suspect that any application where you care whether something happens in day 158 or day 159 is probably not an application that you want to be using a global climate model for...

  • 2
    $\begingroup$ Thanks very much Simon. It's a great point - although I want daily statistics, I'm interested in long term averages so I think it should be fine to stick with the UTC reference point. $\endgroup$
    – HamishC
    Jan 24 '19 at 23:49

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