[GRASS-user] Possible to model exatmospheric radiation with r.sun?

[Dylan Beaudette]

On Monday, May 16, 2011, Jonathan Greenberg wrote:
> Folks:
> 
> I was wondering if there is a way to turn the atmosphere "off" in
> r.sun, and model a top of atmosphere radiation?
> 
> --j

Hi Jonathan,

If you check out the metadata associated with the output from r.sun, you will 
find the following: (note the "Extraterrestrial irradiance" entry)

r.info rad_beam.187
 +----------------------------------------------------------------------------+
 | Layer:    rad_beam.187                   Date: Thu Mar 24 17:17:43 2011    
|
 | Mapset:   PERMANENT                      Login of Creator: dylan           
|
 | Location: ca630                                                            
|
 | DataBase: /home/dylan/grass                                                
|
 | Title:     ( rad_beam.187 )                                                
|
 | Timestamp: none                                                            
|
 |----------------------------------------------------------------------------|
 |                                                                            
|
 |   Type of Map:  raster               Number of Categories: 255             
|
 |   Data Type:    FCELL                                                      
|
 |   Rows:         1396                                                       
|
 |   Columns:      553                                                        
|
 |   Total Cells:  771988                                                     
|
 |        Projection: UTM (zone 10)                                           
|
 |            N:    4235950    S:    4221990   Res:    10                     
|
 |            E:     697230    W:     691700   Res:    10                     
|
 |   Range of data:    min = 4492.042  max = 7758.583                         
|
 |                                                                            
|
 |   Data Description:                                                        
|
 |    generated by r.sun                                                      
|
 |                                                                            
|
 |   Comments:                                                                
|
 |     ----------------------------------------------------------------       
|
 |     Day [1-365]:                              187                          
|
 |     Solar constant (W/m^2):                   1367                         
|
 |     Extraterrestrial irradiance (W/m^2):      1321.303439                  
|
 |     Declination (rad):                        0.396193                     
|
 |     Latitude min-max(deg):                    38.1250 - 38.2500            
|
 |     Sunrise time min-max (hr.):               4.72 - 4.72                  
|
 |     Sunset time min-max (hr.):                19.28 - 19.28                
|
 |     Time step (hr.):                          0.5000                       
|
 |     Linke turbidity factor:                   3.0                          
|
 |     Ground albedo:                            0.200                        
|
 |     -----------------------------------------------------------------      
|
 |                                                                            
|
 |    r.sun -s elevin="ned10m" aspin="aspect10m" aspect=270 slopein="slope\   
|
 |    10m" slope=0.0 lin=3.0 alb=0.2 beam_rad="rad_beam.187" day=187 step=\   
|
 |    0.5 dist=1.0 numpartitions=1                                            
|



> -- 
> Jonathan A. Greenberg, PhD
> Assistant Project Scientist
> Center for Spatial Technologies and Remote Sensing (CSTARS)
> Department of Land, Air and Water Resources
> University of California, Davis
> One Shields Avenue
> Davis, CA 95616
> Phone: 415-763-5476
> AIM: jgrn307, MSN: jgrn307 at hotmail.com, Gchat: jgrn307
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
> 


-- 
Dylan E. Beaudette
USDA-NRCS Soil Scientist
California Soil Resource Lab
http://casoilresource.lawr.ucdavis.edu/