Early Transmission Message, and Parts A, B, C, and D.
Each part of a code may be sent as a separate message as
soon as the data is evaluated and encoded. The Early
Transmission Message is manually composed while the
first data levels are being received. Part A is available
from the computer first, even while the observation of
the higher levels is still being measured. Part B is
available a short time later. Parts C and D are not
available until after the upper-air sounding has been
terminated. Many stations send each part as a separate
message.
Because of this, upper-air reports may be
received in parts at different times after the synoptic
hour.
With rapid electronic equipment, the number of
messages, rather than message length, is often the key
factor in speed of transmission. The MRS processor,
when connected to a desktop computer or the TESS,
rather than a printer, allows for formatted and
completely composed messages to be delivered
transmission-ready to the communications center.
Whether all parts are included in a single message will
depend upon a number of factors that change from day
to day. When broken into separate sections, the Early
Transmission Message has first transmission priority;
Parts A and C have second priority; and Parts B and D
have third priority.
Identification Data Section
Each part of TEMP code contains data for up to 10
code sections. These sections are not readily apparent
in the coded message, and except for Section 1,
Identification Data, the type of data that each section
contains varies from part to part.
The identification data for each part of the code is
nearly identical, and it is contained in the first line of
each message part.
We have already discussed the
format of the identification data used with upper-air
codes, and the “data type” identifiers for the different
TEMP codes. Data type TTAA indicates a TEMP code
report from a fixed land station (message Part A), while
UUDD indicates a TEMP SHIP coded report from a
ship (message Part D), and so forth.
The only difference in the identification data for the
TEMP and the other upper-air codes is the indicator in
the YYGGId group, and the method used to encode the
UTC date for YY. The TEMP code uses indicator Id in
message Parts A and C, but contains indicator a4 in Part
B. In Part D, the indicator is replaced by a "/." The Id is
the indicator for the highest mandatory pressure level
for which winds are reported (WMO code table 1734).
If, for example, winds are reported to the 50-hPa level,
the indicator as used in Part A would be "1," because
Part A would include winds to the 100-hPa level; and
the indicator in Part C would be "5," because the winds
in Part C would be reported to the 50-hPa level. The a4
in Part B is a code figure for the type of measuring
equipment used (WMO code table 0265), which should
be reported as a 0 for the MRS system. The coding of
the date, YY, identifies the wind-speed reporting units.
If the wind speeds are reported in knots, as are all U.S.
Military observations, 50 is added to the UTC day of the
month. The 22d day of the month would be encoded 72.
When the winds are reported in the standard meters per
second, YY is simply the day of the month.
With the exception of the identification data, the
data contained in each message part is the same for the
different "TEMP" code forms. A TEMP report, a
TEMP MOBIL report; a TEMP SHIP report, and a
TEMP DROP report will all encode the same data using
identical data formats.
Q38.
Q39.
Q40.
Q41.
Q42.
Q43.
Q44.
Q45.
Q46.
Q47.
REVIEW QUESTIONS
What is the purpose of the upper-air observation
code?
What activity would use the FM 38-X TEMP
MOBIL code?
What are the standard times for conducting
routine upper-air observations?
If only one daily upper-air observation is
required, what standard time should be
selected?
How are ship locations identified?
Parts "A" and "C" of a TEMP coded message
contain what type of information?
What is the purpose of an early transmission
message?
What type of information would be contained in
an upper-air message with the header
“UUAA"?
In an upper-air message, when is 50 added to the
date?
What does the information “TTAA 59121”
indicate?
PART A - LOWER MANDATORY LEVELS
Part A of the coded message contains identification
data, pressure, temperature, dew-point depression,
1-23
