[GRASS-user] Creating turbidity raster file

[Dylan Beaudette]

On Monday 09 February 2009, Hamish wrote:
> buraq wrote:
> > I have formatted csv files for every month which is like
> > latitude;longitude;turbidityValue. So I want to create
> > raster files from these csvs for using in r.sun.
>
> v.in.ascii -> convert .csv to a vector points file
> g.region  # set up raster grid
> v.surf.rast -> interpolate vector points to raster surface
>

Minor correction:

v.surf.rast ---> v.surf.rst


>
>
> I have worried about r.sun's Linke Turbidity factor values in areas with
> big changes in elevation. Is turbidity value heavily dependent on altitude?
>

It should, as it is based on a measure of optical thickness (air mass):

-------- Extracted from a document ------
m = \frac{1}{sin(\alpha) + 0.15(\alpha + 3.885)^{-1.253}} e^{-0.0001184 \times 
A}

\noindent
where $\alpha$ is the solar elevation angle at (12:00 pm local time) on each 
day of the year, and $A$ is the weather station elevation in meters above 
mean sea level (MSL). 
-------- Extracted from a document ------

This stuff is also on pages 40-41 of this document:
http://169.237.35.250/~dylan/d_e_beaudette-ms_thesis.pdf

Cheers,

Dylan

>
> Hamish
>






-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341