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Weather Station Hardware => Davis Instruments Weather Stations => Topic started by: Bashy on January 22, 2022, 07:54:56 AM

Title: UV at this time of year?
Post by: Bashy on January 22, 2022, 07:54:56 AM
Hi folks, it looks like my UV stopped recording on the 9th of November last year, should there be at least something a this time of year in full sunlight?
Title: Re: UV at this time of year?
Post by: miraculon on January 22, 2022, 08:28:16 AM
Here is my UV for yesterday: Yest.    1.4 index at 1:26pm

Sometimes when I have snow on the sensors the readings are low as one would expect.

So yes, I do get both UV and Solar readings in Winter, here in northern Michigan USA.

Nothing is showing right now due to the fact that it is overcast and Sunrise was just 20 minutes ago. You can check this plot later and you should see both UV and Solar. It might not register a lot due to the forecast of overcast and snow for today. It was sunny yesterday when the UV amount of 1.4 was recorded.

(https://www.rogerscityweather.com/weatherdata/solaruv.png)

Greg H.
Title: Re: UV at this time of year?
Post by: davidmc36 on January 22, 2022, 08:31:00 AM
I certainly get UV of one-ish on sunny winter days at my latitude.
Title: Re: UV at this time of year?
Post by: Bashy on January 22, 2022, 08:57:24 AM
Dammit, looks like my uv sensor has given up then :(
5 years is all it lasted, same with my soil/leaf station board, that's a lot of money up the swanny, although, Davis support say they swap out as long as the leaf Station isn't over 5 years, but I don't think the UK supplier likes that idea :(
Title: Re: UV at this time of year?
Post by: Garth Bock on January 22, 2022, 05:44:19 PM
Getting UV here as well on my VPro 2 in the dead of winter. Have you checked the UV's plug in the ISS ? Pull it and clean it to make sure you are getting a good connection. Is it "dashed out" on the display ? Have you restarted your console/Envoy or whatever has the data logger ? All the years hanging here and other hardware forums and a failed UV sensor is kinda rare.
Title: Re: UV at this time of year?
Post by: Aardvark on January 22, 2022, 08:18:31 PM
I get about the same reading. the sun angle striking the sensor is not direct so the low readings.   I suspose if one wanted  to rotate the sensor toward the sun , perhaps a greater reading.    Oddly a person could get a sunburn in winter, before the froze to death.
Title: Re: UV at this time of year?
Post by: Mattk on January 22, 2022, 09:50:54 PM
Hearing of a failed Davis UV sensor is a rare one but they are rather a very expensive bit of kit compared to any of the Davis standard sensors
Title: Re: UV at this time of year?
Post by: Bashy on January 22, 2022, 10:58:49 PM
Hi guys, its not reading -- just 0.0, for similar full sunny days last January (2021) i was seeing 0.7 max UV, max solar for that day was 420, the other day it hit 470 with UV 0.0, i believe it doesn't register till 0.5, so at the very least i should see 0.5 at 470

Jan last year

 21 02:36hrs ,ET :1.0 mm  ,420.0 W/m  ,0.7 uv
 22 07:00hrs ,ET :0.5 mm  ,322.0 W/m  ,0.7 uv

Similar days this Jan

 19 01:54hrs ,ET :0.6 mm  ,436.0 W/m  ,0.0 uv
 20 00:24hrs ,ET :0.3 mm  ,473.0 W/m  ,0.0 uv
 21 02:36hrs ,ET :0.3 mm  ,429.0 W/m  ,0.0 uv

Granted, i cannot rule out bird doody, but that is very unlikely because they do not perch up on there, they stick to the older OS anemometer that's a little higher up, not once have a seen a bird on the Davis, many times a day i see doves or pigeons on the OS, i set it up that way so they will leave the Davis alone :)
Title: Re: UV at this time of year?
Post by: doubleohwhatever on January 23, 2022, 12:40:06 AM
Yep, your sensor is either covered in poop or dead (could be a connection issue - corrosion, etc). We've had some very dim and overcast days the last week and mine has been behaving as it should:
https://griffinparkweather.com/week.html
Title: Re: UV at this time of year?
Post by: Bashy on January 23, 2022, 03:31:26 AM
Yep, your sensor is either covered in poop or dead (could be a connection issue - corrosion, etc). We've had some very dim and overcast days the last week and mine has been behaving as it should:
https://griffinparkweather.com/week.html (https://griffinparkweather.com/week.html)

It could be poop but its unlikely, the bird would have to perch on the top of the pole, never seen them do that in all my time here, it looks like this was the last day of any UV reporting

Title: Re: UV at this time of year?
Post by: Bashy on January 23, 2022, 06:45:07 AM
I have checked the connection and it looks OK as far as I can tell, can the board be rebooted by removing the battery and solar? Or does it not work that way?

Looking back to this time last year, i only see 2 days that recorded any UV, 22nd and the 23rd of January, as i mention above..

 21 02:36hrs ,ET :1.0 mm  ,420.0 W/m  ,0.7 uv
 22 07:00hrs ,ET :0.5 mm  ,322.0 W/m  ,0.7 uv

I will keep an eye on it as it might be that i tightened the guy lines in such a way that the solar and UV are tilted off kilter a little, i have loosened the back guy (North side) and tightened the south side some, will see how that goes when the sun finally shows itself again, hopefully, tomorrow...
Title: Re: UV at this time of year?
Post by: Garth Bock on January 23, 2022, 08:34:26 AM
Sometimes unplugging and replugging the connector at the ISS end will do something. There is no reboot of the ISS board that has ever been mentioned. I was referring to reboot or restarting your console/Envoy or whatever receives your data. I had an old console that would freeze up about twice a year and pulling batteries would cure it (a later firmware update took care of it). If you have power cycled your data receiving end then the dirty bird scenario is the next thing.
Title: Re: UV at this time of year?
Post by: Bashy on January 23, 2022, 08:56:56 AM
Sometimes unplugging and replugging the connector at the ISS end will do something. There is no reboot of the ISS board that has ever been mentioned. I was referring to reboot or restarting your console/Envoy or whatever receives your data. I had an old console that would freeze up about twice a year and pulling batteries would cure it (a later firmware update took care of it). If you have power cycled your data receiving end then the dirty bird scenario is the next thing.

Thanks, I didn't think so re board, I am using WLL as the receiver, I will reboot it as well, thanks, will see how it goes...
Title: Re: UV at this time of year?
Post by: archae86 on January 23, 2022, 09:09:53 AM
Taking your reports in aggregate I think that your UV sensor has suffered a massive loss of sensitivity. Two additional contributing factors are that your location and the time of year mean that the real UV available is not so very much right now, and that Davis converts anything that would be reported as less than 0.5 to 0.0.

Probably it is not actually dead.

My first Davis UV sensor suffered a very considerable loss of sensitivity.  At age five years I activated a 1.40 calibration factor to attempt to compensate for the degradation to that point.  A year later when I called them to inquire about the options for getting it recalibrated they offered me a hot swap on refurbished replacement at a considerably lower price than I would have paid for new sensor. That replacement does not seem yet to have degraded at all in four years. So I don't think the sensitivity loss is a constant rate per year, nor do I think that all individual sensors suffer it exactly the same way. It seems to me that you got unlucky on that matter and that looking around your system for things to tinker with won't get you anywhere.

Of course, since I live in Albuquerque New Mexico, I did not see long months of 0.0, even with my degraded sensor, which was probably less degraded than yours now is.
Title: Re: UV at this time of year?
Post by: Bashy on January 23, 2022, 09:21:12 AM
Taking your reports in aggregate I think that your UV sensor has suffered a massive loss of sensitivity. Two additional contributing factors are that your location and the time of year mean that the real UV available is not so very much right now, and that Davis converts anything that would be reported as less than 0.5 to 0.0.

Probably it is not actually dead.

My first Davis UV sensor suffered a very considerable loss of sensitivity.  At age five years I activated a 1.40 calibration factor to attempt to compensate for the degradation to that point.  A year later when I called them to inquire about the options for getting it recalibrated they offered me a hot swap on refurbished replacement at a considerably lower price than I would have paid for new sensor. That replacement does not seem yet to have degraded at all in four years. So I don't think the sensitivity loss is a constant rate per year, nor do I think that all individual sensors suffer it exactly the same way. It seems to me that you got unlucky on that matter and that looking around your system for things to tinker with won't get you anywhere.

Of course, since I live in Albuquerque New Mexico, I did not see long months of 0.0, even with my degraded sensor, which was probably less degraded than yours now is.

I fear you might be right, sadly Davis do not offer the same deal(s) for customers outside the US.
Like we already know uv for the UK at the is time of year isn't much at all and I did have to add a offset fron the get go, those 0.7's you see above should actually be 0.5,cant remember how much I added, just checked, it was 30%,now that could be because the top of the mast may not have been level, hard to do with 6 guy lines and trying to eye it up front he bottom of the mast (10m), it is possible that the last time I touched the guy lines, I may have drgeed to more Northolt if that makes sense, I'm hoping that's what I did, but having said that, I do not think I have touched the mast in well over a year, I think it was 2020 the last time, I could be wrong mind but I don't remember touching it last year, I was going too to repka E the fan but I kept putting it off. Only time will tell, hoping for some sun tomorrow, I have rebooted the WLL now, I've also dragged the mast more southerly, so fingers crossed, only think I can do now is bring it down and hit it with some rubbing alcohol, that's Ok for the sensors isn't it?
Title: Re: UV at this time of year?
Post by: PaulMy on January 23, 2022, 11:35:55 AM

Quote
Two additional contributing factors are that your location and the time of year mean that the real UV available is not so very much right now, and that Davis converts anything that would be reported as less than 0.5 to 0.0.
I know very little about UV but my VP2 Plus (2018) seems to be ok and does report UV index from 0.1 and UV Dose MEDs from 0.01
http://www.komokaweather.com/cumulusmx/trends.htm#solar (http://www.komokaweather.com/cumulusmx/trends.htm#solar)

and http://www.komokaweather.com/cumulusmx/historic.htm#solar (http://www.komokaweather.com/cumulusmx/historic.htm#solar) and select All
VP2 Plus from May 2018 and before that Sunshine hours was from B-L Sunrecorder

Enjoy,
Paul
Title: Re: UV at this time of year?
Post by: Bashy on January 23, 2022, 11:45:19 AM

Quote
Two additional contributing factors are that your location and the time of year mean that the real UV available is not so very much right now, and that Davis converts anything that would be reported as less than 0.5 to 0.0.
I know very little about UV but my VP2 Plus (2018) seems to be ok and does report UV index from 0.1 and UV Dose MEDs from 0.01
http://www.komokaweather.com/cumulusmx/trends.htm#solar (http://www.komokaweather.com/cumulusmx/trends.htm#solar)

and http://www.komokaweather.com/cumulusmx/historic.htm#solar (http://www.komokaweather.com/cumulusmx/historic.htm#solar) and select All
VP2 Plus from May 2018 and before that Sunshine hours was from B-L Sunrecorder

Enjoy,
Paul

I think ya meant 0.5, youre in Canada I see, are you higher up the globe than the UK or lower?
Title: Re: UV at this time of year?
Post by: davidmc36 on January 23, 2022, 11:51:38 AM
London is about 51. In Ontario South we are mid 40's
Title: Re: UV at this time of year?
Post by: Bashy on January 23, 2022, 11:54:15 AM
London is about 51. In Ontario South we are mid 40's

Thanks so you're higher up, so in effect I should be recording higher uv than you if both are setup correctly, I can gaurrantee that mine is level at 10m it was at the bottom of the mast but the guy lines may have pulled it off kilter, bloody hard to know at that height...
Title: Re: UV at this time of year?
Post by: PaulMy on January 23, 2022, 12:18:24 PM

Quote
youre in Canada I see, are you higher up the globe than the UK or lower?
We are
Quote
komoka village weather Latitude N 42 57' 36"    Longitude W 81 26' 18"    Elevation 817 ft [/font][/color]



Quote
I think ya meant 0.5,

Using WLLive and in WL.com it shows UV Index from 0.1

Enjoy,
Paul

Title: Rubbing alcohol not OK
Post by: archae86 on January 23, 2022, 02:18:09 PM
hit it with some rubbing alcohol, that's Ok for the sensors isn't it?
Not according to Davis.
The manual I downloaded sometime for installation of the solar and UV sensors contains this direction:

"Hold the sensor body with the white diffuser pointed upward.  Do not touch the diffuser.  If you do, clean it after mounting using a cotton swab and ethyl alcohol.  Do no use rubbing alcohol."

Several of us have reported here using Everclear as a commercially available 95% ethanol preparation for this purpose.  However one person told us he was advised by Davis support that was not OK either, as it had an undesired contaminant.

Here in the US, the problem is that alcohol regulations get in the way of sale of simple ethanol to customers who are not laboratories, or places using it as an input ingredient.  I found someone selling on eBay from Bulgaria, so I affectionately call it my "Bulgarian booze".

Whether any of this actually matters I don't know.  As your sensor is already not working properly (apparently), I don't think you'd be risking much.  But the party line is not to use rubbing alcohol--specifically and by name.
Title: Re: UV at this time of year?
Post by: mcrossley on January 23, 2022, 05:13:42 PM
London is about 51. In Ontario South we are mid 40's

Thanks so you're higher up, so in effect I should be recording higher uv than you ...
eh? mid 40's puts them south of Paris. Quite a bit south of us.
Title: Re: UV at this time of year?
Post by: Bashy on January 27, 2022, 11:59:02 AM
Solar hit 450 today and no uv showed at all, 0.0
I took the DJI Mini 2 up earlier to see if I could see out and I saved these images from the video, to me, they both look clean?

(https://i.ibb.co/x8jnTNh/Screenshot-20220127-165301-Video-Player.png) (https://ibb.co/zHR3vzs)
(https://i.ibb.co/THjJgsg/Screenshot-20220127-165327-Video-Player.png) (https://ibb.co/LCjBZ3Z)
Title: Re: UV at this time of year?
Post by: doubleohwhatever on January 27, 2022, 12:19:09 PM
My guess would be either corrosion has formed on the connector or something inside the sensor died. Likely the latter but I'd check the connector before ordering a replacement just in case.
Title: Re: UV at this time of year?
Post by: Bashy on January 27, 2022, 03:23:31 PM
The connector is fine as far as I can see, no moisture on there either, it's quite clean all round in there.

I dont think I will get another one, over 700 worth of devices up the swanny. Having seen that someone a mile away from me has am ecowitt setup and their readings are pretty much identical to mine at a fraction if the cost, I would be foolish to stick with Davis, I will let this Davis die and I the mean time build up an ecowitt setup. I was foolish to think that Davis would last me longer than it has. I am also disappointed that the UK customers do not get the same treatment as our US friends, US get replacementd as long as its not over 5 years old, UK pays more and gets diddly squat in return. Plus, the Weatherlink is also a let down. So as it stands I am done with Davis.
Title: Re: UV at this time of year?
Post by: doubleohwhatever on January 27, 2022, 03:27:17 PM
Fair enough. Although if UV is important to you, I would look into the difference between the Davis UV sensor and the Ecowitt UV sensor. I haven't checked lately but the last time I did, the Ecowitt UV sensor was more of a light sensor and not a true UV sensor. This may or may not be important to you.
Title: Re: UV at this time of year?
Post by: Bashy on January 27, 2022, 03:30:18 PM
Fair enough. Although if UV is important to you, I would look into the difference between the Davis UV sensor and the Ecowitt UV sensor. I haven't checked lately but the last time I did, the Ecowitt UV sensor was more of a light sensor and not a true UV sensor. This may or may not be important to you.

As long as WD can read the uv from 1 to 8 for the UK, that's all in fussed about, uv is only really a guide, let's me know of its worth sunbathing lol
Title: Re: UV at this time of year?
Post by: Bashy on January 29, 2022, 07:24:33 AM
Wahoo, my UV just registered 1.0, solar hit just over 480, thank god for that, I did tension the southern guy line earlier today, so that may have helped. I'm a happy camper again
Title: Re: UV at this time of year?
Post by: petec2 on January 31, 2022, 12:28:57 PM
Hi All
My VP2 is at 53N. I'd had an iss issue (supercap) helpfully sorted by some people on this site. UV is v low here in Ireland at this latitude in winter but I thought my UV sensor was knackered as in December it read zero and I hadn't really looked at it at this time of year. However, on bright days in last two weeks it has occasionally registered 1 and I have attached a year's worth of a record.
On looking back dec/jan at 53N in Ireland has v low  UV -and i have only really used the readings in summer for sun cream alerts (and they concur with other local sites). so if i was you i wouldn't alter the uv sensor for a month and see what transpires?
pete
Title: Re: UV at this time of year?
Post by: Bashy on February 05, 2022, 08:00:48 AM
Thanks for the reply, it looks like we both have similar uv readings then, certainly for the winter time...
Title: Re: UV at this time of year?
Post by: petec2 on February 06, 2022, 12:19:23 PM
Hi again. i got interested in the low UV in winter and it is down to the high angle of incidence of the incoming radiation. where i have my VP2 the solar radiation comes in at an incredibly low angle (high incidence) in december (on the image only 13 degrees at peak). by march 17th (St Patrick's Day) the angle of the sun has already reached 35 degrees at peak and by the (approx) time of the summer solstice the angle of the sun at 53N is 60 degrees. hence large difference in UV readings. (I've thrown this together- not a sci paper!)
pete