In Hemisfer, sites are defined by parameters that are saved in a file named
SITES.CSV. The location of the SITES.CSV file depends on the
permissions that users have on the installation folder of the software. In a standard
installation, users do not have write permisssions there and the SITES.CSV file is
thus put in the AppData\Roaming\Hemisfer folder within the user folder. In this
case, installing a new version of Hemisfer will not affect the current SITES.CSV
file. However, if the programme folder of Hemisfer is writeable (typically on an
external drive for a portable use) then the SITES.CSV file will be located directly
there. If there is a SITES.CSV file in the current folder from which photographs
and parameter files are being loaded, then the sites defined therein will be used. It is
finally also possible to load a specific sites file
by clicking on the load sites 
button.
Delta-T's HemiView SITES.CSV files
have a similar structure and can thus also be read by Hemisfer. Users who
work with many different sites may prefer to enter sites' parameters directly into
a SITES.CSV file with a text editor or a spreadsheet software. Beware,
however, of possible format changes that may be introduced if you edit a
SITES.CSV file with a spreadsheet software: in some cases, it may become
unreadable for Hemisfer.
For each site, the following parameters are defined in the sites file:
Th site name is used to group photographs when calculating a synthesis of results per site.
This piece of text is used only as a comment, not affecting the calculations.
Latitude and longitude are given in degrees. The gographic location of the site affects the relative position of the sun in the sky and is thus used in the calculation of the light regime. It does not require a precision better than 3 decimals and does not affect the calculation of LAI.
The elevation of the site is used to calculate the light transmission through the atmosphere. It does not affect the calculation of LAI.
Declinations for any location and time can for example be found at https://ngdc.noaa.gov/geomag/calculators/magcalc.shtml.
The magnetic declination can be set as a property of the site. It is defined as a positive angle if the magnetic north is right of the geographic north (east declination), negative if it is left (west declination). However, it is also possible to define the declination as a property of single pictures, that is in their parameter files. This is because the declination is not constant but varies with time. It may thus be different on pictures from the same site taken at different moments. Further, the declination as set in Hemisfer can be used to correct the magnetic effect of the photography material itself (camera, lens, gimbals, tripod).If a declination is defined in a parameter file, then it will override the site declination. Choose to save or not the declination along with the parameter file by checking or not the corresponding box on the site tab within the options dialogue.
The time zone of the site is used in conjunction with the longitude to calculate the position of the sun at any time of the day. If the user choses to have calculations in solar time, then neither the longitude nor the time zone play any role.