Hi all,<br>running r.sun on a mountain area with time=8 and day=1, I got negative values for the diffuse radiation fraction. <br>I even get negative global radiation!<br>Where am I wrong?<br><br> +----------------------------------------------------------------------------+
<br> | Layer: 1_8_d Date: Fri Oct 12 07:53:50 2007 |<br> | Mapset: zodoardo Login of Creator: zodoardo |<br> | Location: Valledaosta |
<br> | DataBase: //media/sda7/zodoardo/cartografia/grassdb |<br> | Title: ( r.sun solar model output ) |<br> | timestamp: none |
<br> |----------------------------------------------------------------------------|<br> | |<br> | Type of Map: raster Number of Categories: 255 |
<br> | Data Type: FCELL |<br> | Rows: 864 |<br> | Columns: 1290 |
<br> | Total Cells: 1114560 |<br> | Projection: UTM (zone 32) |<br> | N: 5096987.5 S: 5032187.5 Res: 75 |
<br> | E: 422587.5 W: 325837.5 Res: 75 |<br> | Range of data: min = -18.926418 max = 53.797997 |<br> | |
<br> | Data Source: |<br> | |<br> | |
<br> | |<br> | Data Description: |<br> | generated by r.sun |
<br> | |<br> | Comments: |<br> | ---------------------------------------------------------------- |
<br> | Day [1-365]: 1 |<br> | Local (solar) time (decimal hr.): 8.0000 |<br> | Solar constant (W/m^2): 1367 |
<br> | Extraterrestrial irradiance (W/m^2): 1412.689562 |<br> | Declination (rad): -0.401581 |<br> | Latitude min-max(deg): 45.4214
- 46.0199 |<br> | Sunrise time (hr.): 7.74 |<br> | Sunset time (hr.): 16.26 |<br> | Daylight time (hr.):
8.52 |<br> | Solar altitude (deg): 2.1959 |<br> | Solar azimuth (deg): 127.0877 |<br> | Linke turbidity factor:
3.1 |<br> | Ground albedo: 0.200 |<br> | ----------------------------------------------------------------- |<br> | |
<br> | r.sun -s elevin="DEM" aspin="DEM_asp" slopein="DEM_sl" lin=3.1 alb=0\ |<br> | .2 beam_rad="1_8_b" diff_rad="1_8_d" refl_rad="1_8_r" day=1 step=0.5\
|<br> | time=8 |<br> | |<br> +----------------------------------------------------------------------------+
<br><br> +----------------------------------------------------------------------------+<br> | Layer: 1_8_g Date: Fri Oct 12 08:20:06 2007 |<br> | Mapset: zodoardo Login of Creator: zodoardo |
<br> | Location: Valledaosta |<br> | DataBase: //media/sda7/zodoardo/cartografia/grassdb |<br> | Title: ( 1_8_g ) |
<br> | timestamp: none |<br> |----------------------------------------------------------------------------|<br> | |
<br> | Type of Map: raster Number of Categories: 255 |<br> | Data Type: FCELL |<br> | Rows: 864 |
<br> | Columns: 1290 |<br> | Total Cells: 1114560 |<br> | Projection: UTM (zone 32) |
<br> | N: 5096987.5 S: 5032187.5 Res: 75 |<br> | E: 422587.5 W: 325837.5 Res: 75 |<br> | Range of data: min = -10.351157 max = 327.495667
|<br> | |<br> | Data Source: |<br> | |
<br> | |<br> | |<br> | Data Description: |
<br> | generated by r.mapcalc |<br> | |<br> | Comments: |
<br> | 1_8_b + 1_8_d + 1_8_r |<br> | |<br> +----------------------------------------------------------------------------+
<br><br>Thanks in advance for your help.<br>