tw.txt  water temperature                         °C
tl.txt  air temperature                           °C
o2.txt  oxygen content                            mg/l
ot.txt  oxygen saturation                         %
lf.txt  conductivity                              micro S
ph.txt  pH-value
st.txt  global radiation                          W/m
uv.txt  uv absorption  254nm                      %
tr.txt  turbidity                                 %
ce.txt  chlorophyll-a total                       micro g/l