[GRASS-SVN] r51180 - grass/trunk/raster/r.sunmask

[svn_grass at osgeo.org]

Author: neteler
Date: 2012-03-29 01:34:35 -0700 (Thu, 29 Mar 2012)
New Revision: 51180

Modified:
   grass/trunk/raster/r.sunmask/r.sunmask.html
Log:
+examples

Modified: grass/trunk/raster/r.sunmask/r.sunmask.html
===================================================================
--- grass/trunk/raster/r.sunmask/r.sunmask.html	2012-03-29 08:33:07 UTC (rev 51179)
+++ grass/trunk/raster/r.sunmask/r.sunmask.html	2012-03-29 08:34:35 UTC (rev 51180)
@@ -15,21 +15,24 @@
 latitude/longitude for the SOLPOS algorithm. The elevation is not considered
 in the sunset/sunrise calculations.
 
-<h2>Notes</h2>
+<h2>NOTES</h2>
 
 r.sunmask and daylight savings: Rather than convert time to GMT, the solpos
 algorithm uses what is called Local Standard Time, which is generally
 defined politically as an offset from GMT.  So the key is the offset from
 GMT, which the solpos Time Zone parameter.  If the user specifies clock time
 (different for winter and summer), he/she would have to change the Time Zone
-parameter seasonally in r.sunmask (timezone parameter).
+parameter seasonally in r.sunmask (timezone parameter). See also 
+<a href="http://en.wikipedia.org/wiki/Daylight_saving_time_by_country">Daylight saving time by region and country</a>.
+
 <p>
 Note: In latitude/longitude locations the position coordinates pair
 (east/west) has to be specified in decimal degree (not D:M:S). If
 not specified, the map center's coordinates will be used.
 Also <em>g.region -l</em> displays the map center's coordinates.
 
-<p>Note for module usage with <em>-g</em> flag and calculations
+<p>
+Note for module usage with <em>-g</em> flag and calculations
 close to sunset/sunrise:
 
 <pre>
@@ -51,7 +54,45 @@
 correction for atmosphere refraction. The output without 
 <em>-g</em> flag contains related indications.
 
+<h2>EXAMPLE</H2>
 
+Example for North Carolina sample data set for the calculation
+of sun position angles and more:
+
+<div class="code"><pre>
+# set the region to a place near Raleigh (NC)
+g.region rast=elev_lid792_1m -p
+
+# compute the sun position
+r.sunmask -s --v elev_lid792_1m out=dummy year=2012 month=2 \
+          day=22 hour=10 minute=30 sec=0 timezone=-5
+Using map center coordinates: 638650.000000 220375.000000
+Calculating sun position... (using solpos (V. 11 April 2001) from NREL)
+2012/02/22, daynum: 53, time: 10:30:00 (decimal time: 10.500000)
+long: -78.678856, lat: 35.736160, timezone: -5.000000
+Solar position: sun azimuth: 143.006424, sun angle above horz. (refraction corrected): 36.233883
+Sunrise time (without refraction): 06:58:11
+Sunset time  (without refraction): 17:58:47
+
+# with -g flag
+r.sunmask -s -g --v elev_lid792_1m out=dummy year=2012 month=2 \
+          day=22 hour=10 minute=30 sec=0 timezone=-5
+Using map center coordinates: 638650.000000 220375.000000
+Calculating sun position... (using solpos (V. 11 April 2001) from NREL)
+date=2012/02/22
+daynum=53
+time=10:30:00
+decimaltime=10.500000
+longitudine=-78.678856
+latitude=35.736160
+timezone=-5.000000
+sunazimuth=143.006424
+sunangleabovehorizon=36.233883
+sunrise=06:58:11
+sunset=17:58:47
+</pre></div>
+
+
 <h2>Acknowledgements</h2>
 Acknowledgements: National Renewable Energy Laboratory for their
 <a href="http://rredc.nrel.gov/solar/codes_algs/solpos/">SOLPOS 2.0</a> sun position