# Radiation output times offset

**URL:** <https://cms-helpdesk.ncas.ac.uk/t/radiation-output-times-offset/1266>\
**Category:** Uncategorized\
**Tags:** Monsoon2\
**Created:** [23 November 2023 14:54 UTC](https://cms-helpdesk.ncas.ac.uk/t/radiation-output-times-offset/1266 "2023-11-23T14:54:20Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![rglazer](https://avatars.discourse-cdn.com/v4/letter/r/65b543/32.png) [@rglazer](https://cms-helpdesk.ncas.ac.uk/u/rglazer)\
**Post date:** [23 November 2023 14:54 UTC](https://cms-helpdesk.ncas.ac.uk/t/radiation-output-times-offset/1266/1 "2023-11-23T14:54:20Z")

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Hello,

I’ve noticed that for any radiation variables I output there’s an offset in time from any other output I get. I am running a RNS setup on monsoon and have requested 15 min (instantaneous) radiation output. However when I look at my radiation output the timestamps do not say 0,15,30,45 minutes as I would expect but says 15:04,30:04,45:04,00:04 all offset by 15 minutes plus whatever the model timestep is (4 seconds in this case). For most applications this offset effectively by 4 seconds is not important but in the future I would like to understand what is going on and try to get the radiation out at the time I expect. The suite I’m working on is u-cv482.

Thanks a lot for your help,  
Russell

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**Author:** ![grenville](https://dub1.discourse-cdn.com/flex013/user_avatar/cms-helpdesk.ncas.ac.uk/grenville/32/29_2.png) [@grenville](https://cms-helpdesk.ncas.ac.uk/u/grenville)\
**Post date:** [1 December 2023 11:57 UTC](https://cms-helpdesk.ncas.ac.uk/t/radiation-output-times-offset/1266/2 "2023-12-01T11:57:56Z")

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Hi Russell

This is how the UM works - radiation diagnostics are labelled by the end of the time step.

u-cv482 has `lts0 = .true.` for T15MIN which probably accounts for starting at 15.

Grenville

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<div class="post-metadata">

**Author:** ![rglazer](https://avatars.discourse-cdn.com/v4/letter/r/65b543/32.png) [@rglazer](https://cms-helpdesk.ncas.ac.uk/u/rglazer)\
**Post date:** [4 December 2023 17:57 UTC](https://cms-helpdesk.ncas.ac.uk/t/radiation-output-times-offset/1266/3 "2023-12-04T17:57:31Z")

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I see so this is standard behavior for radiation output, all timestamps are from the end of the time step whereas other UM output is from the beginning?

I have other stash output on the same time domain but only radiation has this 15 min offset. But if I understand, radiation stash is affected by this lts0 setting but others are not?

Thank you