Can you use solar radiation to show surface heat?

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10-25-2016 06:54 AM
KathrynAngleton
New Contributor III

I know there's a difference between solar and thermal radiation, however, I can't find any thermal data. I have LiDAR and processed it to show solar radiation. Obviously, where the sun hits down, it's going to be hot. So, would you say this is a good enough substitute? Or is there a specific dataset I should be using instead?

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3 Replies
DanPatterson_Retired
MVP Esteemed Contributor

solar insolation (visible, infrared etc) and its manifestation to surface temperature is affected by surface type, moisture content, the radiative properties of the surface itself and myriad of other things like surface albedo both (in visible and thermal bands).  Basically all you can say for a uniform is how much is coming in at any point. The adsorption of the energy and the thermal properties of the material will determine how it is manifested as surface temperature... ie flat calm water beside a flat sand beach on a sunny day... water surface is going to be cooler since it has a higher heat capacity than dry sand.

KathrynAngleton
New Contributor III

Hi Dan, thanks for the information. What I'm trying to do is show how hot our streets are to get more trees planted on our sidewalks. Some of our streets have great tree canopy, so I wanted to show how those streets are cooler for pedestrians than the streets without or with little tree coverage. With that in mind, is solar radiation good enough to display and back up my claims that more tree canopy will help? I hope this makes sense.

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DanPatterson_Retired
MVP Esteemed Contributor

Why not show the shading provided by the trees.  Pick a couple of times of a day for several days, say the equinoxes and soltices, then +/- minus solar noon for your area (ie usually not 12:00), but when the sun is at its highest... then 2 hours on either side.  You can calculate those simply using standard textbook equations (maybe even in the Solar Analyst).  If you have the data that enables you to 'cover' and area with trees, you can separate those that are not directly in the sun vs those that acquire their heat throught ambient temperature.  It is not how much the differences are but the potential for temperature differences that is important.