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 YYGGI_d group, and the method used to encode the UTC date for YY. The TEMP code uses indicator I_d in message Parts A and C, but contains indicator a₄ in Part B. In Part D, the indicator is replaced by a "/." The I_d 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