This post is intended to get information and feedback from John Klein, the author of the weewx-purple extension.
I recently set up two pupleair outdoor sensors and installed the weewx-purple extension. All is working well, but I have some questions about the calculation of AQI and the US EPA correction for PM2.5 used in the extension. I reviewed the reference document (https://cfpub.epa.gov/si/si_public_file_download.cfm?p_download_id=539905&Lab=CEMM) and it proposes the following averaging operations: 1. Average each column to 1-hr average (e.g. 8:00-8:59= 8am average) 2. Exclude hour if less than 90% of the measurements are available in the hour average 3. Exclude hour if 1-hr A&B averages are different by BOTH: 5 µg m-3 & 70%† My question is if the extension applies these averaging and data exclusion operations? From the graphs produced it appears that the 1 hour average is not used, because the graphs show peaks that are not present when compared with the 1 hour average graphs obtained directly from the purpleair website. My suspicion is that the correction applied is limited to the following formula PM2.5=0.541*PA_cf1(avgAB)-0.0618*RH +0.00534*T +3.634 Thanks in advance for any feedback. -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/7611aae6-cd34-4554-8282-261b1cac370fn%40googlegroups.com.
