and longitude of the observation, exactly as used in the ship synoptic reports.   The  MMMU_LaU_Lo  group  is  a second  location  reporting  group,  which  contains  the Marsden  Square  number  of  the  location,  MMM  (see Appendix  II)  and  Marsden  sub-grid  locations  U_La  (a repeat  of  the  units  digit  of  the  latitude)  and  U_Lo  (a repeat  of  the  units  digit  of  the  longitude).  Some computers  use  only  the  Marsden  group  to  enter  the position of the upper-air report in the analysis program. The latitude and longitude groups are used by people to determine  the  exact  location. Both  groups  must  be correct. In  place  of  the  latitude,  longitude,  and  Marsden Square  groups,  permanent  shore  stations  report  only one group: IIiii. This is the WMO block (11) and station number (iii) exactly as used, and described in module 1, for   the   Land   Synoptic   code.   Mobile   land   stations include an additional group  (h_Oh_Oh_Oh_Oi_m) that reports the station elevation in either meters or feet. The  breakdown  of  all  the  different  upper-air reporting  codes  and  code  formats  is  contained  in  the WMO Publication 306, Manual on Codes, Volume 1, International   Codes.   The   majority   of   these   coded messages  are  "read"  automatically  by  computers  and entered  into  analysis  programs  for  use.  In  selected situations   where   manual   decoding   is   required,   the observer should consult WMO Publication 306. Both the TEMP code and the PILOT code forms are routinely used  by  observers  to  encode  observed  data.  We  will discuss these codes in the following text. TEMP  CODE LEARNING  OBJECTIVES:  Identify  the differences  and  similarities  in  the  four  forms  of the   TEMP   code.   Describe   the   information contained  in  each  part  of  the  TEMP  coded report. Explain the format and the meaning of each coded part of the TEMP report. Describe the  modifications  added  to  the  International code form in WMO Region IV. Describe the format and contents of an Early Transmission Message. PART  A PART  C Mandatory   Levels   SFC   Mandatory  Levels  100  hPa to  100  hPa and   higher PART  B PART  D Significant  Levels  SFC Significant  Levels  100  hPa to  100  hPa and   higher Although  used  by  computers,  the  TEMP  coded upper-air information is also used extensively in many manual   applications.   For   detailed   analysis,   TEMP coded data is decoded and plotted on a Skew-T, Log P Diagram,  or  on  horizontal  or  time  section  diagrams. The  TEMP  code  is  the  primary  upper-air  reporting code. Every observer must be thoroughly familiar with this  code. The different forms of the TEMP codes are used to report data gathered in the rawinsonde, radiosonde, or rabal observations, depending on the site used to launch the  balloon.  However,  aircraft-launched  dropsondes use a slightly different code format. The four different forms of the TEMP code are listed in table 1-7. COMPOSITION  OF  THE  REPORTS (MESSAGE) All four forms of the TEMP code are broken down into four parts to speed distribution. Additionally, each code part is divided into data sections. The data sections contain   information   in   five-digit   groups,   although letters are used in one or two groups in the identification data section. Each figure in each group is significant to its  position  in  the  group  and  to  its  position  in  the message. Therefore, the established order of the groups in  the  messages  must  be  maintained.  When  observed data is not available for an element, a slant (/) is used instead.  This  is  done  to  preserve  continuity  of  the groups and sections as required. Message Parts Each  TEMP  code  part  may  be  transmitted  as  an independent message. This is done to speed distribution of  the  reports,  because  a  sounding  usually  takes  a considerable   amount   of   time.   A   radiosonde   may continue to report usable data 2 to 3 hours after release. The parts are identified as A, B. C, and D. Data at and below the 100-hPa level is reported in Parts A and B, and data above 100 hPa is reported in Parts C and D. Parts  A  and  C  contain  data  pertinent  to  the standard atmospheric pressure surfaces,  which are also called the mandatory reporting levels. Parts B and D contain data pertinent to the significant levels. These are the levels that have been determined significant due to temperature and/or humidity change. and changes in wind  speed  or  direction.  The  following  diagram  may help clarify what data IS included in each section: All   military   stations   designated   to   encode   and transmit  upper-air  observations  encode  and  transmit  the 1-22