...
From the rserial output, I see Rsw.in change from about 926 W/m2 before cleaning to 912 W/m2 after. Thus, the effect of the dirt/pollen/smoke/oil/etc. was an enhancement of incoming solar radiation by about 1.4%. Obviously, the primary effect of the dirt was to enlarge the image of the solar disk. This effect will be difficult to model and thus correct the data. It would have been a good idea to measure the direct and diffuse radiation separately. When I measure the other NR01, I'll also take data using the shadowing paddle.
Round 2:
Continuing the ARTSE piggy-back, also tested NR12 at about 11:20 on 1 Aug 2017. This time the procedure was:
- make sure data were being recorded on USB stick
- nevertheless, also logged data through minicom, with rserial running
- ran in clear skies for a while
- shaded Rsw.in for 20s with a paddle. (forgot this time that I should crouch down to prevent my head from being visible to radiometers)
- shaded Rlw.in for 20s with paddle
- added water to wetness sensor to indicate cleaning
- wetted and wiped Rsw.in
- same to Rlw.in (was visibly dirty)
- same to Rlw.out
- same to Rsw.out
- dry-wiped Rsw.in
- same to Rlw.in
- same to Rlw.out
- same to Rsw.out
- wiped dry the wetness sensor (showed total time cleaning was 175s)
- shaded Rsw.in for 20s with paddle
- shaded Rlw.in for 20s with paddle
All of this is to try to get the effect of cleaning separately for direct and diffuse radiation (though we don't expect much change on Rlw), since previous data showed that a correction model might need to treat direct and diffuse separately.
In this case, the results were:
total before/after: