1 August 2016

FM13 weather reports messages in CW


Oceanographic and Hydrographic observations are sent daily by the Hydrographic ships of the Russian Navy at fixed times 00, 06, 12 and 18 UTC.  Such messages are not sent directly to GSVMF ground stations but forwarded via Naval HQs:

RJP99 547 18 4 2214 547 = FOR RJH74 RJH45 = ... (via RIT, NSF HQ Severomorsk)
RMCW 6T2 18 23 16TT 6T2 = SML FOR RJE73 RJH45 =... (via RCV, BSF HQ Sevastopol))

In fact, looking for example at the FM-13 reports (at least here in Southern Europe) you may see that most of these messages almost always report two recipients, mostly RJE73 RJH45 or RJH74 RJH45, usually using the "sml" priority indicator: I do not know if the recipients are local GSVMF offices at each HQ naval bases (RIT, RCV,...) or just GSVMF central offices:

RJH45 = MOSCOW NAVAL METEO
RJE73 = BLACK SEA FLOT METEO
RJH74 = NORTHERN FLEET METEO
RJD38 = BALTIC FLOT METEO
RJE65 = BLACK SEA FLOT HQ, NOVOROSSIYSK
 
 They use the standard observation method as described by NOAA in their observation handbook, and within this message format there is a Lat/Long position report for where the observation took place: so you are able to localize the positions of the ships by decoding the Code FM-13-X-SHIP (or shortly FM-13). This ships synoptic code is comprised of 23 groups of symbolic letters representing meteorological and oceanographic elements, report identification and ship location data (see resources later at the end of this post).

1) Ship current position is coded in the Ships Synoptic Code Section 0:
... 99LaLaLa QcLoLoLoLo ...
... 99662 10345 ...

99 Data on Position Follow

LaLaLa (662) Latitude in degrees and tenths of a degree. Always coded with three digits, the first two digits are actual degrees, the last digit for tenths of a degree (66.2)

Qc
(10) Quadrant of the globe (specify whether the latitude is north or south and the longitude east or west). 
If north of the equator (north latitude):
- 1 when east of the Greenwich Meridian (east longitude)
- 7 when west of the Greenwich meridian (west longitude)
If south of the equator (south latitude):
- 3 when east of the Greenwich meridian (east longitude)
- 5 when west of the Greenwich meridian (west longitude)



LoLoLoLo (345) Longitude in degrees and tenths of a degree. Always coded with four digits, with the leading (hundreds) figure coded as 0 or 1. The first three digits are actual degrees, the last digit for tenths of a degree (34.5)

2) the ship movement data is coded in Section 2:
... 222DsVs ...
... 22232 ...

222 indicator
Ds (3)
true ship’s course made good during the three hours preceeding the time of observation:
0
Ship hove to
1
NE
2 E
3 SE
4 S
5 SW
6 W
7 NW
8 N
9 Unknown
/ Not reported

Vs (2) Ship’s average speed, in knots, made good during the three hours preceeding the time of observation:
0
0 knot
1 1 to 5 knots
2 6 to 10 knots
3 11 to 15 knots
4 16 to 20 knots
5 21 to 25 knots
6 26 to 30 knots
7 31 to 35 knots
8 36 to 40 knots
9 Over 40 knots
/ Not reported

Examples:

VVV RJD99 DE RBC89 QSA? QTC RBC89 572 9 5 0955 572 = FOR RJD90 RJH74 =
050?? 99662 10345 41/96 9230? 00050 40000 52020 70222 89/// 22232 00030 20202 232// 40302 88000 05016 = + RBC89


in plain text:
"ship  RBC89 (calling RJD99) at (Moscow) time 0955 was at 66.2N 34.5E , heading SouthEast @ 6-10kts"
the position of RBC89 is decoded from 99|662 10|345, with the heading/speed obtained from 222|32.

CW "771 19 9 1551 771 ...99548 10198...22242...AR RMWT K"
in plain text:
"ship RMWT position at 1551 Moscow time: 54.8N 19.8E  heading South @ 6-10kts"


Since the time of reception differs from the one indicated in the preamble (does not matter if UTC or Moscow Time), it is presumed that the preamble time is the time when the message was prepared and not the time of the transmission: i.e. the data relate to the observation at 1603 Moscow Time (1203z) but sent (and then received) at 1220z.

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