Description of parameter abbreviations:
at = Air temperature (C)
dp = Dew point (C)
wd = Wind direction (degrees from, 0=north, 90=east)
ws = Wind speed (m/s)
wg = Maximum wind gust (m/s)
cc = Cloud cover (%)
sr = Solar Radiation (W/m^2)
ap = Barometric pressure (mb)
wt = Water temperature (C)
wvh = Significant Wave height (m)
wvp = Wave period (s)
wvd = Wave direction (deg)
trans = Water transparancy measured using beam transmissometers (1/m)
currents = Water currents, u- and v-compontents (cm/s)
cond = Specific conductance (uS/cm)
DO = Dissolved oxygen concentration (mg/L)
pH = pH
Turb = Turbidity (NTU)
chl = Chloryphyll concentration (ug/L)

See also http://www.glerl.noaa.gov/ifyle/data/data.lmd.fmt for lmd file units.

All other units are defined in the metadata files.