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Steve Markstrom: OK welcome to the PRMS training
video on the Solar Table process.

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In this case there is only one module for
this process.

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The module is called Soltab.

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And that's what I'm going to talk about here.

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Basically, for each HRU, for each day of the
solar year, which is 365 days, a value of

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potential or clear sky short wave solar radiation
is computed.

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And then when the model runs, depending on
which day it is simulating it goes and gets

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that value and knows that's the clear sky
solar radiation value for that HRU on that

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day.

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This module also computes day length.

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There's a couple of references there if you're
so inclined.

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Alright, so if you look at the PRMS users'
manual there's a couple of equations.

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Basically, what we're trying to do is get
the solar declination of each HRU on each

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day.

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And you can see that equation there 1-2, which
is, yeah, a lot of trig.

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Actually, no user input other than the location
and elevation and slope of the HRUs.

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From the declination, you can see the declination
term here and the HRU latitude, we can compute

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the sunrise and the sunset on each HRU on
each day.

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Because in this case, it's symmetrical, sunrise
is the negative of sunset.

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So those two are computed this way here.

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Then from both of those, you can determine
the length of the day.

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Then this equation here, 6-1 is used to compute
the solar table.

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And you can see again, a lot of trig.

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But there's the declination, the latitude
and then the day length right there.

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Those plug in and we get out the solar table
for all of the HRUs.

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And that's it.