Mini   Rawin   System   Operating   Procedure,   and   the MARWIN  MW  12,  User’s  Guide.  The  display  panel prompts the operator for input. The equipment should be left in the standby mode except when no soundings are to be taken for several days or when the system is to be  moved.  The  system  will  automatically  run  self- diagnostic checks (after a brief warm-up period) when initially   powered   up. After  self-diagnostics,  the equipment will display the date and time (UTC). Initial setup  parameters,   such   as   station   elevation, latitude/longitude,  etc.,  must be entered by using the "SYSGEN" function. Operation control keys “CMND” and "C1" through "C5" are used to initiate or terminate data  sequences.  The  LCD  window  directly  above  the operation control keys identifies the function of each key  during  each  particular  sequence.  The  data  entry keypad is used to manually enter data. To  conduct  an  upper-air  sounding,  the  operator normally runs through the following sequence, which is detailed in the operator’s manual: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Preparation of the balloon Preparation of the rawinsonde instrument and battery Entry of rawinsonde calibration data Rawinsonde telemetry and receiver check GPS/NAVAID system signal reception check Connection   of   rawinsonde   instrument   to balloon Obtain release authorization Balloon release (system automatically starts) Surface weather observation and entry of data Entry of termination data Print out coded upper-air messages or data as desired (or download to diskette) BALLOON  PREPARATION Preparation  of  the  balloon  is  not  covered  in  the MRS  operator’s  manual. Certain  aspects  of  balloon storage, handling, and release procedures are covered in the Federal Meteorological Handbook Number 3. Meteorological   balloons   are   spherical   films   of synthetic rubber (neoprene) that, when inflated with a lighter-than-air gas (helium or hydrogen), rise into the upper   atmosphere. Sizes  of  balloons  vary  by application, but all are measured by the weight of the neoprene  used  to  make  the  balloon.  Meteorological balloons are extremely thin. The rubber is from 0.002- to   0.004-inch   thick   when   inflated   for   release,   but decreases to less than 0.00001 inch at bursting altitude. To  state  it  more  graphically,  the  balloon  at  release  is thinner  than  an  ordinary  piece  of  writing  paper,  and decreases to 1/200th to 1/400th of its original thickness at altitude- a mere film of rubber. It is not hard to see that the smallest cut, bruise, or scratch sustained during preflight preparation is almost sure to cause the balloon to burst at a lower altitude. Careful preflight handling of these balloons is mandatory. Although meteorological balloons  come  in  100-,  300-,  600-,  and  1200-gram sizes, we will consider only the 100-gram and 300-gram balloons. The  100-gram  neoprene  balloons  are  recommended for normal MRS soundings and should be used during high-wind  conditions. The   300-gram   neoprene balloons are better suited for higher flights. Shipboard and MET users report average MRS soundings to the 130-hPa  pressure  level  (about  48,000  feet)  using unconditioned 300-gram balloons, and average flights to  the  300-  to  250-hPa  level  (32,000  feet)  using unconditioned  100-gram  balloons.  However,  the  RS-80 series rawinsondes are designed for soundings in excess of  30  kilometers  (well  above  the  25-hPa  level)  and routinely  ascend  above  that  altitude  at  most  synoptic locations. Balloons should be stored in their original sealed containers in a room isolated from large electric motors or  generators.  Motors  and  generators  emit  ozone, which is detrimental to neoprene. Ideal temperature for storage  would  be  in  the  range  of  10°C/50°F  to 30°C/85°F.  Temperatures  below  freezing  and  above 50°C/120°F   should   be   avoided   during   storage. Balloons deteriorate with age; they should be used in the order of their production dates to avoid excessive aging. If  by  necessity  balloons  are  stored  at  temperatures below  freezing,  they  should  be  removed  to  a  room having temperatures of 18°C/65°F or higher for at least 12 hours before use, to avoid any damage that would result  if  they  were  removed  from  the  container  and unfolded  when  cold.  The  balloons  are  extremely delicate, especially when softened by conditioning. No part of the balloon except the neck should be touched with bare hands. Use soft rubber gloves or soft cotton gloves, or use the plastic bag in which the balloon was received as a glove to handle any portion other than the neck of the balloon. 1-6