AIS Message Definitions

AIS Message: imo_met_hydro (001:11:)

Description:

IMO meteorological and hydroglogical data. Specified in SN/Circ.236 Annex 2. Also defined in IALA Guidelines on AIS, Vol 1, Part 1, Ed. 1.3. Guildeline No 1028.

Note:All unavailable values are defined to be the highest possible number in the next following

Name NumberOfBits ArrayLength Type Units Description
MessageID 6 uint AIS message number. Must be 8
RepeatIndicator 2 uint Indicated how many times a message has been repeated
0: default
3: do not repeat any more
UserID 30 uint Unique ship identification number (MMSI)
Spare 2 uint Reserved for definition by a regional authority.
dac 10 uint Designated Area Code
fid 4 uint Functional Identifier
Position_longitude 25 decimal degrees Location of the vessel East West location
Position_latitude 24 decimal degrees Location of the vessel North South location
datetime 16 uint FIX: break hhmmss into subfields. Think it is 5 bits day, 5 bits hour, 6 bits min that match SLS.
avewind 7 uint knots Average wind speed values for the last 10 minutes. FIX: why is 121-126 not valid???
windgust 7 uint knots Wind gust is the max wind speed value reading during the last 10 minutes. FIX: why is 121-126 not valid???
winddir 9 uint degrees Wind direction. No idea if this is the latest, ave, median, etc. FIX: find out!
windgustdir 9 uint degrees Wind direction for the gust.
airtemp 11 decimal degrees Celsius Bry bulb temperature
relhumid 7 uint percent Relative humidity
dewpoint 10 decimal degrees Celsius Bry bulb temperature - FIX: should this be a udecimal??
airpressure 9 udecimal hPa Air pressure. FIX: 9 bits only goes 0..511
airpressuretrend 2 uint Air pressure trend
0: steady
1: decreasing
2: increasing
3: unavailable
horizvis 8 udecimal nm Horizontal visibility
waterlevel 9 decimal m Water level (incl. tide)
waterleveltrend 2 uint Water level trend
0: steady
1: decreasing
2: increasing
3: unavailable
surfcurspeed 8 udecimal knots Surace current speed
surfcurdir 9 uint degrees Surface current direction
curspeed2 8 udecimal knots Level 2 current speed
curdir2 9 uint degrees Level 2 current direction
curlevel2 5 uint m Measuring level below sea surface for level 2
curspeed3 8 udecimal knots Level 3 current speed
curdir3 9 uint degrees Level 3 current direction
curlevel3 5 uint m Measuring level below sea surface for level 3
sigwaveheight 8 udecimal m Significan wave height
waveperiod 8 uint sec Wave period - FIX: How does to fit to the power spectrum?
wavedir 9 uint degrees Wave direction - FIX: please define this better
swellheight 8 udecimal m Swell height
swellperiod 8 uint sec Swell period - FIX: How does to fit to the power spectrum?
swelldir 9 uint degrees Swell direction - FIX: please define this better
seastate 4 uint Beaufort scale Sea state according to the Beaufort scale
0: Calm
1: Light air
2: Light breeze
3: Gentle breeze
4: Moderate breeze
5: Fresh breeze
6: Strong breeze
7: Near gale
8: Gale
9: Strong gale
10: Storm
11: Violent storm
12: Hurricane
15: unavailable
watertemp 10 decimal degrees Celsius Water temp (FIX: at surface? Any requirements on how measured?)
preciptype 3 uint WMO scale index According to WMO
0: FIX: find the WMO list of types
7: unavailable
salinity 9 decimal 0/00 Salinity - FIX: by what standard? Measured how?
ice 1 bool Yes or no for the presence of ice. FIX: what types of ice constitute a yes??
Spare 6 uint Must be zero. FIX: this does not seem slot aligned.