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I'm looking at a historical weather data report and the TMAX and TMIN are like this: 44 and -21, the following day 72 and 17. First I thought it was Fahrenheit, but the conversion didn't make any sense because it would be +6°C one day and +22°C the following day in January in NY, NY.

Then the note said - * Values denoted with “*” (i.e. temperature values) are in Celsius degrees to tenths on csv.

Does it mean 44 is actually 4.4 and 72 is 7.2? That would make much more sense.

More examples TMAX/TMIN:

44/-21, 72/17, 83/-10, 128/61, 106/-49, -49/-71

PS. I know there is a possible duplicate that MAY have an answer to my question, unfortunately it doesn't. Some comments (not the answer itself or the question) explain WHY it is the case in vague and guessing terms, but it doesn't give an answer to WHAT it is, which is my question. Nobody can say for sure if 44 is 4.4 and -21 is -2.1 and I can't rely on guesses.

arkaia
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Vegan Sv
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  • My accepted answer to the previous question quotes the official NCDC description of the data format. That's not vague guessing, that is an explicit, official definition of the units by the organization responsible for producing the data files. If you feel that my answer to that question is too vague, please feel free to post a comment on the answer itself explaining how you feel I could improve it. – Pont Jul 05 '16 at 04:46

2 Answers2

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Your question is similar to this one: Deciphering NCDC data

In the comments for that question I posted the following two comments which will most likely answer your questions:

regarding the usage of tenths of a degree, it may be a continuation of an ancient data format from the early era of computers. Removing decimal points changes numbers to integers. In old computers memory capacity & calculating speed was an issue. In binary digits, integers are half the size of floating point numbers & a quarter the size of double precision numbers. Hence the use of integers speeds up calculations & requires less memory (disk drives, tape & RAM) than floating point numbers. In the old days, tape was used heavily as an external storage medium

There is logic in maintaining the old data format for consistency. If the data format was changed then all the old data would need to be changed & checked to ensure there were no errors. If the format was changed as of a certain date but the old data remained in the old format, people would need to be mindful of the change & when it occurred. Analysis apps would need to first check if the data was from before or after the date of change, condition the data accordingly before doing the calculations. It's easier to keep the old format

Community
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Fred
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    Thanks, I saw that question and the comments and I wasn't sure if that answers my question, it didn't sound like a definite answer, but more like a guess; that's why I posted my question. So I'm still not sure if 44/-21 means 4.4/-2.1. Do you know that for sure? I'm working on something and I can't rely on guesses.. – Vegan Sv Jun 21 '15 at 02:28
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    A direct and unequivocal answer to the question would make this an awesome answer. – Matt Hall Jun 21 '15 at 19:39
  • @kwinkunks Totally agree with you! – Vegan Sv Jun 21 '15 at 19:51
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I looked up the actual data in Celsius and compared to what I have and yes 44 is 4.4 and -21 is -2.1.

When it says Celsius degrees to tenths you have to divide it by 10 and you will get the actual temperature.

Vegan Sv
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  • Vegan Sv answer is straight forward. However, please cross check it in correlation to other variables too, whether it is make sense or not. This extra effort will make you more confident with your conclusion. – Santosa Sandy Jul 05 '20 at 16:50