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What were the changes in the recent revision of the TMY3 weather files?

asked 2015-02-24 20:01:35 -0500

Joe Huang gravatar image

updated 2017-05-04 06:17:14 -0500

The TMY3s for 1,020 US locations were released in 2005 to become the defacto standard set of typical year weather for the US and dependencies. However, there've been a couple of problems that have plagued the TMY3s, including inconsistent units in the illuminance values, and faulty reporting of liquid precipitation. The latter problem has not been helped by the rumors that the TMY3s do not contain liquid precipitation or that they are completely useless.

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@Joe, can you split this into a question and an answer?

__AmirRoth__ gravatar image __AmirRoth__  ( 2015-02-24 20:21:47 -0500 )edit

Sure. I can retain the first paragraph of my Question as further explanation of the Question, and move the rest as an Answer to the Question. Like watching Jeopardy, I'm still learning the proper format for posing and then answering questions. I'll try to see if I can edit my question right now.

Joe Huang gravatar image Joe Huang  ( 2015-02-24 20:58:22 -0500 )edit

This has just been done! (had to increase the number of characters to the minimum allowed)

Joe Huang gravatar image Joe Huang  ( 2015-02-24 21:03:23 -0500 )edit

You can also "accept" your answer as the "definitive" or "helpful" answer, by clicking the checkmark. I believe you have enough karma points to do that.

__AmirRoth__ gravatar image __AmirRoth__  ( 2015-02-24 21:17:44 -0500 )edit

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answered 2015-02-24 21:01:28 -0500

Joe Huang gravatar image

White Box Technologies (yours truly), in collaboration with NREL, has now revised the TMY3 weather files to correct these two problems, as well as adding some QC touches, among them the replacement of all missing records with interpolated or filled values for visibility, ceiling height, aerosol optical depth, and albedo, and the addition of a new variable for Present Weather.

The only impact from these changes are for daylighting simulations, e.g., Radiance, that use the illuminance values, and for building simulations, e.g., EnergyPlus, that use the liquid precipitation to model green roofs or moisture transport through the building envelope. The addition of Present Weather may be of use to simulation programs that keep track of rain or snow fall, and is also helpful in assessing the reported liquid precipitation. Filling in missing data for Visibility, Ceiling Height, etc., should have no impact on the use of the TMY3s, but improves their overall record-keeping. For details of the revision, please see this report.

The revised TMY3 files are available either on the NREL Web site in their original *TMY3.CSV format or the WBT web site in the *.epw, *.BINM, and *.FIN4 formats.

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Asked: 2015-02-24 20:01:35 -0500

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Last updated: Feb 24 '15