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dave allyn
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Looking at the NWAC site, several stations have data for solar radiation measured in watts per meter squared (w/mē). The numbers at Camp Muir go as high as mid 600's during the day. Mazama readings peak in low 20's. I have a hard time believing Muir recieves 30 times the solar radiation as Mazama. I found something that said readings could be 1000 w/mē at the earth's surface. 600 at Muir sounds feasible to me, like an overcast day. 20 w/mē at Mazama sounds dark. Anybody care to explain?
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philfort
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philfort
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 Wed Dec 07, 2022 8:51 pm |
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My theory is that the sensor is behind some trees to the south, so it's in the shade all day this time of year. If you look back at data earlier in the year for Mazama, the values were in the mid-100s until early November.
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Sculpin
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Sculpin
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Wed Dec 07, 2022 9:03 pm |
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| dave allyn wrote: | | I have a hard time believing Muir receives 30 times the solar radiation as Mazama. |
Your intuition is correct, something else is going on here. Ignoring the effects of clouds and trees, the average solar radiation might be 30% higher at Muir, but nothing like 3000%.
Between every two pines is a doorway to the new world. - John Muir
Between every two pines is a doorway to the new world. - John Muir
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gb
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gb
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Thu Dec 08, 2022 9:05 am |
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| dave allyn wrote: | | Looking at the NWAC site, several stations have data for solar radiation measured in watts per meter squared (w/mē). The numbers at Camp Muir go as high as mid 600's during the day. Mazama readings peak in low 20's. I have a hard time believing Muir recieves 30 times the solar radiation as Mazama. I found something that said readings could be 1000 w/mē at the earth's surface. 600 at Muir sounds feasible to me, like an overcast day. 20 w/mē at Mazama sounds dark. Anybody care to explain? |
If there were more NWAC stations that logged solar radiation, it would be easier to draw conclusions. But there are some glitches. Note that each day at 10:00 Muir sees a dramatic drop in solar radiation? And Mazama seems universally too low. But realize that in the past seven days Mazama has probably been foggy, so it would be pretty low anyways. You could verify that by watching the Sun Mountain webcam. https://www.sunmountainlodge.com/the-lodge/the-lodge-cam/ Still, I'd think Mazama under fog would have a similar reading to the lowest inputs you see in the past seven days at Muir for the given daylight hour - looks like 150-200 +-. Skies above the fog at Mazama may well have been sunny pretty often the last 7 days, so some radiation would get through the fog to sensors.
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hbb
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hbb
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Thu Dec 08, 2022 11:46 am |
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I don't really understand why you are comparing data from Paradise with Mazama, but if you want to cross-check the data from the Mazama station, the First Butte station logs solar radiation and is quite close to the Mazama station.
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philfort
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philfort
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Thu Dec 08, 2022 12:14 pm |
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| hbb wrote: | | I don't really understand why you are comparing data from Paradise with Mazama |
Because the fact that they are different by an order of magnitude suggests one of the sets of data is invalid.
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jaysway
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jaysway
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Thu Dec 08, 2022 12:50 pm |
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This isn't a very helpful comment so I'll keep this short, but I've done a bit of work with NWAC station data and there are lots of sensor errors and anomalies in the data. It's worth being very careful when analyzing their data. This is not an indictment on the NWAC stations, to the contrary the NWAC stations are a valuable resource (I donate to NWAC, both for their avalanche forecasting and their sensor network) but sensor data is often accompanied by data errors. I created a Python package for downloading NWAC data that I'm happy to share with anyone interested in analyzing their data.
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John_B
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John_B
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Thu Dec 08, 2022 1:20 pm |
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The Mazama site is located on the valley floor with trees around it. As gb said above the Methow Valley has been under an inversion for the past week or so and it's been cold and relatively dark during that time. With sun above the inversion level I have no doubt that Paradise is experiencing much sunnier weather than valley bottom sites under an inversion.
Here is the location of the Mazama NWAC station. It's not immediately under trees but with the current low sun angle the trees are undoubtably a factor in lower solar intensity at that site.
https://www.google.com/maps/@48.5977521,-120.4372876,174m/data=!3m1!1e3
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thunderhead
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| philfort wrote: | | Because the fact that they are different by an order of magnitude suggests one of the sets of data is invalid. |
Could be. Or that one is under clouds and the other is not. A glance at a weather satellite should tell the tale.
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philfort
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philfort
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Sun Dec 11, 2022 11:53 am |
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| thunderhead wrote: | | Could be. Or that one is under clouds and the other is not. A glance at a weather satellite should tell the tale. |
That's pretty much already been ruled out. The values have been abnormally low at the Mazama site for over a month.
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philfort
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philfort
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Sun Dec 11, 2022 12:04 pm |
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Here's the solar radiation at Mazama since Jan 1. Not sure what to make of this graph. It certainly seems like the sharp transition in early November is an issue with the data, or some change at the site. On the other hand, it roughly matches what it was like in January - except then there was a more smooth transition to spring/summer values.
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gb
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gb
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Mon Dec 12, 2022 4:50 am |
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| philfort wrote: | | Here's the solar radiation at Mazama since Jan 1. Not sure what to make of this graph. It certainly seems like the sharp transition in early November is an issue with the data, or some change at the site. On the other hand, it roughly matches what it was like in January - except then there was a more smooth transition to spring/summer values.
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Well, that does look like a glitch. Although we all know Eastern Washington gets foggy much of the time, absent storms, starting around Mid-November and running through mid-February from radiational cooling and the build-up of an inversion; it doesn't make sense that there would not have been at least a few periods of sunny skies. But the graph shows nada since early November - not any anomalous days.
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thunderhead
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| philfort wrote: | | That's pretty much already been ruled out. The values have been abnormally low at the Mazama site for over a month. |
Agree. East-side lowlands get foggy but generally not that foggy. Snow on the sensor?
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dave allyn
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Something changed. Up to 377 w/mē this afternoon.
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thunderhead
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If it goes back down after the next snow we will have our answer.
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