@gjr80 Thank you for the in-depth explanation, now I understand the issue better. Although it did not bring me any closer to solving the problem. I left most of the settings in weewx.conf at default. The unit in my weewx.conf is metricwx. In weewx.sdb, in the ‘archive’ table, in the usUnits column, I have a value of 1.
In the other thread (https://groups.google.com/g/weewx-user/c/EN_elfqKhlI) I wrote back to @michael.k that rebuilding the daily summaries did nothing, although the rain data looks reasonable in my opinion. *Translated with DeepL.com <https://www.deepl.com/?utm_campaign=product&utm_source=web_translator&utm_medium=web&utm_content=copy_free_translation> (free version)* poniedziałek, 5 maja 2025 o 09:47:28 UTC+2 gjr80 napisał(a): > Short answer re rain units is it depends. Rain is recorded in the database > using the rain units of the unit system used by the database. The unit > system of the database used by a WeeWX instance is specified by the > [StdConvert] > target_unit setting in weewx.conf. Possible unit systems are US (the > default), Metric or MetricWx. The US unit system records rain in inches, > Metric records rain in cm and MetricWx records rain in mm. If you have a > WeeWX database but don't have the corresponding weewx.conf used with the > database you can look at the usUnits column in the archive table in the > database. If each row contains the value 1 the database uses the US unit > system, a value of 16 means the database uses the Metric unit system and a > value of 17 means the database uses the MetricWx unit system. > > The wsum column in the archive_day_rain table contains the weighted sum > of all archive record rainfall values for the day concerned (probably > better described as the sum of all weighted archive record rainfall values > for the day concerned). The weighted rainfall for an archive interval is > obtained by multiplying the rainfall recorded in the archive interval by > the archive interval. The wsum column is used when calculating aggregates > for observations when the archive interval is not constant (some history; > initially WeeWX required all archive records to have the same archive > interval, later this restriction was relaxed and the wsum column was > implemented to ensure meaningful aggregates could still be calculated). The > wsum column is typically used for observations where you are interested > in the daily average, eg daily average temperature, humidity etc where your > archive table consists of records with differing archive intervals (if you > did not use a weighted sum short period high or low values could skew the > aggregate). For rainfall the typical aggregate of interest is the sum which > is independent of the archive interval and hence the wsum column in > itself is largely meaningless and can be ignored. By the sounds of your > investigation the sum values are correct. > > Gary > On Sunday, 4 May 2025 at 19:49:15 UTC+12 Tomasz Lewicki wrote: > >> Further to my earlier thread about deleting or modifying values in the >> database (https://groups.google.com/g/weewx-user/c/EN_elfqKhlI), I would >> like to understand in what units precipitation is expressed. I am comparing >> the current and previous records of precipitation values in the station >> software and in Weewx, and I cannot reconcile them in any way. For 24 >> hours, my station recorded 15 mm of precipitation, while the wsum field in >> the archive_day_rain table shows 1588.2. What does this mean? >> >> I found a thread titled "Weewx WD Import - Rain data units, values" ( >> https://groups.google.com/g/weewx-user/c/Umc6L8NqXvc), but did not find >> an answer to my question there. >> >> I summed the rainfall data for the whole day from the database using the >> query (1746223200 = 2025-05-03 00:00:00 localtime, 1746309600 = 2025-05-04 >> 00:00:00 localtime) and exported it to a CSV file: >> >> select datetime(dateTime,'unixepoch','localtime'),dateTime,rain from >> archive where dateTime < 1746309600 and dateTime >= 1746223200; >> >> Another query: >> >> select sum(rain) from archive where dateTime < 1746309600 and dateTime >= >> 1746223200; >> >> Summing the rainfall both ways from the 'rain' column in the 'archive' >> array gave me the same value as 'sum' in the 'archive_day_rain' array. >> Where then did the value of 1588.2 in the wsum column come from? > > -- 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]. To view this discussion visit https://groups.google.com/d/msgid/weewx-user/94b6a66f-fa34-40a7-a179-6ca9dd1fc282n%40googlegroups.com.
