[GRASS-dev] [GRASS GIS] #2081: r.sun (mode 2): sawtooth bug in diffuse irradiation map

[GRASS GIS]

#2081: r.sun (mode 2): sawtooth bug in diffuse irradiation map
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 Reporter:  hamish  |       Owner:  grass-dev@…              
     Type:  defect  |      Status:  new                      
 Priority:  major   |   Milestone:  6.4.4                    
Component:  Raster  |     Version:  svn-develbranch6         
 Keywords:  r.sun   |    Platform:  Linux                    
      Cpu:  x86-64  |  
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 Hi,

 in investigating #2014 I noticed there's a bug in the calculation for
 diffuse sunlight when the sun is at low angles to the horizon. the overall
 trend seems ok, but there's a sawtooth pattern which follows the curvature
 of the lines of latitude.

 The attached screenshots are for Ross Island in Antarctica, epsg:3286
 bounds:
 {{{
 north:      1437000
 south:      1341000
 west:       17000
 east:       119000
 res:        100
 }}}

 ?

 made with:
 {{{
 DAY=060
 r.sun -s elevin=etopo1.ross_island step=0.05 \
        beam_rad=erebus.direct.$DAY diff=erebus.diffuse.$DAY day=$DAY
 }}}


 thanks,
 Hamish

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2081>
GRASS GIS <http://grass.osgeo.org>