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 [email protected]. For more options, visit https://groups.google.com/d/optout.
