During a Pibal observation, how are true wind
direction and speed computed?
Which publication contains detailed information
on conducting Pibal observations?
What software package contains a program fur
automatic computation of Pibal observation
What color Pibal balloon is normally used when
the sky is clear?
UPPER-AIR REPORTING CODES
LEARNING OBJECTIVES: Recognize the
applications for upper-air observation
Identify the observation
location and time in an upper-air report.
Identify the standard upper-air observation
Upper-air codes are designed to allow transmission
of a large amount of data using only a small number of
characters. The numerically coded data allows the
report to be decoded by a weather person in any country,
regardless of the language spoken. More importantly,
this numerically coded format can be readily
transmitted by computer. These codes may be easily
loaded into computer programs that analyze the upper-
air data, plot graphical displays, and then calculate
probable changes in the reported conditions. The
resulting information serves as an invaluable forecast
Fleet Numerical Meteorology and Oceanography
Center, and to the National Weather Service's
environmental prediction system at the National
Meteorological Center. Navy and Marine Corps
observers must be able to decode all upper air
observation codes. And, as stated earlier, they must be
able to encode, or verify, the MRS computer encoding
of the various forms of the TEMP code.
IDENTIFYING MESSAGE CODE FORM
Nearly all coded upper-air-report messages contain
a four-letter code identifier as the first group of the first
line of data. All upper-air codes except the AMDAR
code have a common format for the data identification
line. As encoded for transmission, identification data
appears in the first line of the message. The symbolic
format for the identification data groups is as follows:
MiMiMjMj YYGGId IIiii (land stations)
MiMiMjMj D. . . .D 99LaLaLa QcLoLoLoLo
(ship/aircraft/mobile land stations)
The first group, MiMiMjMj, is found in nearly
every international coded report, and is the code
identifier. The MiMi identifies the code type. See the
second column of table 1-7. The MjMj identifies which
part of the multi-part upper-air reports is contained in
the section of the report: AA for Part A, BB for Part B,
and so forth. If all of the observed data is routinely
distributed as a single message, such as the CODAR
report, the MjMj is encoded XX. The first group of the
coded report also contains the observation time and the
location of the sounding.
IDENTIFYING OBSERVATION TIME AND
The WMO has established standard times for
conducting upper-air observations: they are the
synoptic hours of 0000Z, 0600Z, 1200Z, and 1800Z.
Most balloon releases actually take place 30 to 45
minutes before these times so that the scheduled
observation time actually occurs near the middle of the
Because of time, personnel, and budget
considerations, most stations do not conduct
observations at each of the synoptic hours. If only two
upper-air soundings are taken per day, they are taken at
0000Z and 1200Z. If only one upper-air sounding is
conducted, it is taken at 0000Z or 1200Z, whichever
time is closest to local sunrise.
Reports of conditions measured during any of the
various upper-air observations are normally encoded in
WMO international codes for dissemination.
International upper-air observation reporting codes
were established by the WMO to allow all countries of
the world to exchange data. Because there are many
different types of upper-air observations conducted
each day, several similar codes are in use to efficiently
report the data collected. Table 1-7 shows the different
types of upper-air observations conducted, the types of
data observed and reported, and the WMO International
code form used to format the report.
Reports received in these codes are routinely used
by weather personnel for routine aviation support,
weather-forecasting support, and as input for TESS.
Additionally, these observations provide primary input
to the Navys environmental prediction system at the