[GRASS-user] Creating turbidity raster file

[José Antonio Ruiz Arias]

>
> 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
>
>
>
> 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?

Linke turbidity is certainly height-dependent given the higher optical
path length at lower elevations. A simple approximated pressure correction
might be applied if the turbidity at a given altitude z' is known:

TL(z)=TL(z')exp(-(z-z')/8435.2)

with z and z' given in meters. This could be easily applied using r.mapcalc

Jose


>
> Hamish
>
>
>
>
>
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-- 
José A. Ruiz-Arias
Solar Radiation and Atmosphere Modelling Group
http://www.ujaen.es/investiga/tep220
Physics Department, University of Jaén
Campus Lagunillas, Building A3 066
23071 Jaén Spain
Tlf: +34 953 212 474
Fax: +34 953 212 838