calculation and mapping Albedo

[BaffourAwuah]

Can anybody here gives me some suggestions as to the best way to calculate and map Albedo effect.  Those of you don't know what it is, Albedo specifies the percentage of incoming solar radiation on a surface that reflects back. I need help. Thanks, folks.

[DanPatterson_Retired · Accepted solution]

Albedo is determined from measurement...as per you definition... and it can be used with respect to particular wavelengths or wave bands..  Generic values can be obtained from climatology texts etc.

• Is your desire to ascribe albedo values to land surfaces?
• are you referring to shortwave (within visible range) or longwave/infrared albedo?
• are you interested in albedo at particular wavelengths?
• what type of surfaces are you interested in?
• do you just want average albedo or are you interested in values that may vary by time of day or surface roughness?

Just some thoughts.

[BaffourAwuah]

Thanks Dan.  Yes my desire is to ascribe albedo values to mountain surface where there are snow stability in most part of the year making sunlight reflection possibly high. I was thinking in generic terms to find out the part of the mountain that faces the sun most. I hope you get my point.

[DanPatterson_Retired]

Then you need the Aspect tool in the Spatial Analyst or 3D analyst extension or aspect function

http://desktop.arcgis.com/en/desktop/latest/tools/spatial-analyst-toolbox/aspect.htm

http://desktop.arcgis.com/en/desktop/latest/manage-data/raster-and-images/aspect-function.htm

You should also have a look at...

http://desktop.arcgis.com/en/desktop/latest/tools/spatial-analyst-toolbox/an-overview-of-the-solar-r...

[BaffourAwuah]

I really apreciate your suggestions. Both aproaches seem so interesting. For now I don't have the extention tool for Spatial Analysyst or 3 D analyst and the Radiation tool analyst but I have requested for one. Please do you think only the historical mountainous snow raster data and their associate  statistics are enough?

[DanPatterson_Retired]

If that is what you have, it is definitely a starting part, particularly if you can show that the historical data is consistent.

[BaffourAwuah]

Hi again, Dan,

Sorry for the nagging. Still on my Albedo stuff. I now have my Solar Radiation calculated, Aspect
image, and Snow dataset. Please any suggestion as to the way forward?

[DanPatterson_Retired]

You will have to come up with your classification scheme since aspect are floating point numbers.  You can use the reclassify tool amongst others and class the slopes and aspects to appropriate classes along with your snow dataset (ie deep, shallow etc) and use the combine tool to delineat areas that meet certain criteria (ie N facing shallow slopes have the deepest snow...or whatever you are interested in)

[BaffourAwuah]

Hi again, Dan.

The Reclassification and the Combine tool is working well and giving me some
interesting tables. The only problem is that I'm trying to make sense of the
values from different combination and tables to get some Albedo values. I am
attaching a sample of the combination of Snowdata and Radiation for some
suggestions.

[DanPatterson_Retired]

the first class (value 1) ... there are 543 cells that are the combination of snowdtptrec and mradiationrec (whatever those) represent.  etc etc

some times it is better to make a table out of them  like a pivot table

                 snow typ class

rad cla        1      2      3      4      5

             1

             2                                    8       (your last class)

              3

             4    543                                       (your first)

fill in the matrix