I generate 2 maps with r.sun (1 Jan), the first one setting albedo=0, and the second one setting albedo=2.0 but I received the same values (look at statistics calculated by r.univar). Why?
n: 2399778
minimum: 0
maximum: 5007.23
range: 5007.23
mean: 1847.94
mean of absolute values: 1847.94
standard deviation: 678.436
variance: 460275
variation coefficient: 36.7131 %
sum: 4434638181.5777397156
1st quartile: 1567.93
median (even number of cells): 1825.47
3rd quartile: 2170.94
90th percentile: 2649.47
n: 2399778
minimum: 0
maximum: 5007.23
range: 5007.23
mean: 1847.94
mean of absolute values: 1847.94
standard deviation: 678.436
variance: 460275
variation coefficient: 36.7131 %
sum: 4434638181.5777397156
1st quartile: 1567.93
median (even number of cells): 1825.47
3rd quartile: 2170.94
90th percentile: 2649.47
My goal is to generate a map for the exergy (available energy) of solar radiation, so I need a map without diffuse and reflected radiation. Is it correct to use r.sun and as output beam_rad or global_rad? and if I set the albedo to 2.0, is this effect added to the irradiation or is it subtracted? I hope I was clear…
I generate 2 maps with r.sun (1 Jan), the first one setting
albedo=0, and the second one setting albedo=2.0 but I
received the same values (look at statistics calculated by
r.univar). Why?
beam_rad only gives you the available incident radiation, not the
absorption. As I understand it, albedo is used in the reflection
maps in hilly terrain.
My goal is to generate a map for the exergy (available
energy) of solar radiation, so I need a map without diffuse
and reflected radiation. Is it correct to use r.sun and as
output beam_rad or global_rad? and if I set the albedo to
2.0, is this effect added to the irradiation or is it
subtracted? I hope I was clear…
if you want to know all incoming radiation, use the global sum.
if you have a very reflective steep hillside positioned to
reflect light back on your study site, the reflected radiation
map should go up. I'm not sure if that 20% is removed from the
steep hillside's value, or if that just stays as available
incident light.
further experimentation &/or reading the code would be needed
to say for sure...
I want to know if albedo effect is added or subtracted to global radiation calculation…or it is not computed…
What do you think about the following expression?
if you want to know all incoming radiation, use the global sum.
I want to know the available radiation that should be global radiation minus the radiation that was reflected by atmosphere and ground. Only the radiation that which is not reflected drives terrestrial, oceanic and atmospheric processes.
Il giorno 09/set/2011, alle ore 02:18, Hamish ha scritto:
Salvatore wrote:
I generate 2 maps with r.sun (1 Jan), the first one setting
albedo=0, and the second one setting albedo=2.0 but I
received the same values (look at statistics calculated by
r.univar). Why?
beam_rad only gives you the available incident radiation, not the
absorption. As I understand it, albedo is used in the reflection
maps in hilly terrain.
My goal is to generate a map for the exergy (available
energy) of solar radiation, so I need a map without diffuse
and reflected radiation. Is it correct to use r.sun and as
output beam_rad or global_rad? and if I set the albedo to
2.0, is this effect added to the irradiation or is it
subtracted? I hope I was clear…
if you want to know all incoming radiation, use the global sum.
if you have a very reflective steep hillside positioned to
reflect light back on your study site, the reflected radiation
map should go up. I'm not sure if that 20% is removed from the
steep hillside's value, or if that just stays as available
incident light.
further experimentation &/or reading the code would be needed
to say for sure...