quadrant 7 (north of equator, west of prime meridian) as
12.238° North, 095.139° West, whereas 71224/09514/
is the same position reported only to the nearest
hundredth of a degree.
The last part of the identification section is the
optional group 6Q1QtQA/. This group is based on
WMO Code Table 3334 and is used as a quality control
indicator, with Q1 and QA used for position and Qt for
time. This group must be encoded manually. See table
2-4.
METEOROLOGICAL DATA
Within the meteorological data section, winds, air
temperature, dewpoint temperature, and relative
humidity may be reported. In addition, pressure data,
such as station pressure, sea level pressure, and 3 hour
pressure tendency, may also be reported. Each group in
section 1 is only reported if the buoy actually measures
the information. All groups are identical to the ship
Synoptic code (WMO 13-X SHIP), except for the use of
the group indicator 0 for the wind data group and the
relative humidity group (29UUU).
The meteorological section is identified by the
group 111QdQx. The code figure Qd is the quality
control indicator, and Qx indicates the position of any
one group in this section that is not good, if applicable.
Otherwise, Qx is encoded as a 9. In our example, the
groups 00308 10255 29075 30132 40133 52003 report
winds from 030° true at 08 knots, air temperature
25.5°C, relative humidity of 75%, station pressure of
1013.2 hPa, and sea-level pressure at 1013.3 hPa. The
last group is the pressure tendency and amount of
change (hPa) during the past 3 hours. Only three codes
are used for tendency (2 = pressure increasing, 4 =
pressure steady, 7 = pressure decreasing). In our ex-
ample, the pressure is indicated as rising and up 0.3 hPa.
SURFACE MARITIME DATA
As with the meteorological data, each section 2
surface maritime data group is only included if the
information is measured by the buoy. The indicator
222QdQx will always precede any surface maritime
data, but is itself omitted if no groups from section 2 are
reported. The group 0snTwTwTw is used to report the
sea-surface temperature. The code figure sn is the sign
of the temperature (0 = positive, 1 = negative). For
example, the group 00262 reports sea-surface
temperature at 26.2°C.
Qd = Quality control indicator
Qd1 = Quality control indicator for temperature/
salinity.
Qd2 = Quality control indicator for current
(set/drift) profile.
Q1QA = Quality control indicator for position.
Qt = Quality control indicator for time.
Code
Figure
0 = Data not checked
1 = Data good
2 = Data inconsistent
3 = Data doubtful
4 = Data wrong
5 = Data value has been changed
Some buoys contain a sensor that measures wave
action.
If the sensor measures wave period to the
nearest second and wave height to the nearest half-
meter, code group 1PwaPwaHwaHwa is used. In our
example, 10302 reports a wave period of 3 seconds, and
a wave height as 2 half-meters (3 feet). Other buoys
contain more accurate instruments that measure wave
period to the nearest tenth of a second and wave height
to the nearest tenth meter. These buoys report wave
period to the nearest tenth of a second in the group
20PwaPwaPwa, and wave height to the nearest tenth
meter in the group 21HwaHwaHwa.
OCEANOGRAPHIC DATA
Section 3 is used to report readings obtained from
sensors on a drifting buoy’s tail. Sensors are normally
fixed to the tail at set intervals. Most drifting buoys only
measure temperature, but more sophisticated buoys
may include salinity measuring devices and water
current measurement devices at various levels.
The data groups in the first portion of section 3
following the 333Qd1Qd2 8887k2 indicator groups are
used to report seawater temperature and salinity
readings. The Qd1 and Qd2 are used to indicate the
quality of the temperature/salinity profile and the
quality of the current (set and drift) profile,
respectively. The indicator k2 is the method used for the
salinity measurement as per WMO Code 2263 (0 = no
measurement, 1 = electronic sensor with better than
0.02% accuracy, 2 = electronic sensor with less than
0.02% accuracy, and 3 = sample analysis). As of the
late 1990s few buoys carry salinity sensors.
Table 2-4.—WMO Code Table 3334
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