SENTINEL-3 Altimetry Unit definitions


The units used in the SRAL/MWR Level-2 products are SI units, except for angles which use degrees as opposed to radians.

Table 1: SRAL/MWR Level-2 products units
Quantity Unit Symbol
Length metre m
Mass kilogram kg
Time second s
Angle degree °
Frequency Hertz Hz


The SRAL/MWR Level-2 product variables may have an offset and/or a scale factor applied in the netCDF output files to maintain maximum precision using an integer data type variable. They shall be considered when reading the values of these variables. An example is shown below for the altitude variable at 1 Hz:

int alt(time);

alt:long_name = "1 Hz altitude of satellite";
alt:_FillValue = 2147483647;
alt:units = "m";
alt:add_offset = 1.30e+06;
alt:scale_factor = 1.00e-04;
alt:coordinates = "lon lat";

The data are stored in 32-bit integers (long). The value of the altitude expressed in metres (SI) of the satellite can be recovered using:

alt_si =(alt *scale_factor) + add_offset

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