[GRASS-user] Creating turbidity raster file

[buraq]

Dylan Beaudette wrote:
> 
> 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
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> grass-user mailing list
> grass-user at lists.osgeo.org
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> 
> 


I took the turbidity values from soda-is.com. I entered no altitude value
for the latitude and longitude.

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