I just checked over 12 months of my NOAA reports, and they were all correct, but I do my summary reports in the same way as the rest of the site - in metric - C, mm and knots - so probably not that helpful a comment!! Even without conversions though the standard weewx generates float values with huge numbers of decimals when the input data did not contain such precision - hence my amendment to the field definitions in the database.
On Sunday, 18 December 2016 08:31:24 UTC+2, Josh Smith wrote: > Yeah I realize that. The only reason I mention this was that in the > Monthly NOAA Climate Summary the total rainfall doesn't match the sum of > the daily rainfall. It just looks a little weird but likely no one would > really notice. It doesn't happen that often either. > > > > On Saturday, December 17, 2016 at 11:25:59 PM UTC-7, Andrew Milner wrote: >> >> ..... and I thought I was a pedant !!!!!!!!!!!!! >> >> most stations with a tipping cup measuring device provide the rain >> measurements in metric and/or imperial as being measured in units of .3 or >> .2 mm or .01" per tip - which means there is probably already a >> rounding error before the floats even begin to have an effect depending on >> whether the measuring cup was actually manufactured to imperial standards, >> metric standards or is just somewhere in-between!!!! Davis uses .2, >> Fineoffset use .3 .......... The implication is that an error of .01" over >> a month is probably (possibly) insignificant given the likely error in the >> initial reading anyway!!!! >> >> I limit the digits in my MySQL database by setting the datatype to >> double(5,2) for rain and rainrate and double(5 or 6,1) for other fields so >> that I at least do not have to look at masses of decimal digits when >> viewing the tables with phpmyadmin. I've never checked to see if this >> beneficial change (to me) affects any calculations though!!! >> >> >> >> >> On Sunday, 18 December 2016 07:50:05 UTC+2, Josh Smith wrote: >> >>> Sorry if this as been discussed before but after searching through the >>> discussions I couldn't find one that matches my issue exactly. I noticed >>> the month rainfall total for my station was off by 0.01". After some >>> testing, I figured out this was due to the conversion of rainfall data from >>> mm to inches. The data is stored as a float with 16 significant digits >>> (i.e. 0.04 is stored as 0.0405511811023656) in the database. Thus, when >>> using the sum tag like $month.rain.sum, it returns a float with two decimal >>> place rounded up. So a raw monthly rainfall sum produces 0.3251968503937174 >>> which becomes 0.33 inch using the $month.rain.sum. I noticed this was an >>> issue when sending data to Wunderground in 2013 which requires data in US >>> units.This has been fixed >>> <https://groups.google.com/forum/#!searchin/weewx-user/US$20conversion$20rain%7Csort:relevance/weewx-user/h7entGBwgRk/WAdYgZldR8QJ>. >>> >>> I checked my data on Wunderground and it is reporting the correct amount of >>> 0.32 inches so I am thinking a similar change needs to be made to the >>> StdReport. I am running the latest version of WeeWx 3.6.2. Let me know if >>> you need more info or I missed a fix for this. Thanks. >>> >>> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
