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14270_85
Figure  4-3.SUROB  worksheet.

Aerographers Mate, Module 02-Miscellaneous Observations and Codes
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Q1. Q2. Q3. Q4. Q5. Q6. Q7. Q8. Q9. Q10. REVIEW  QUESTIONS What  publication  outlines  procedures  for conducting surf observations? What are two factors that can create surf? What are the boundaries of the surf zone? When   a   wave   enters   shallow   water,   what happens  to  the  wave  speed,  wavelength,  and wave height? How is wave steepness defined? The hydrography in a surf zone includes what elements? How does the presence of a sandbar effect waves moving into a surf zone? What descriptive term is used to classify a beach with a slope of 1:25? What affect might a sandbar have on small craft operations? What is meant by the term "wave refraction"? THE  SURF  OBSERVATION LEARNING  OBJECTIVES:  Describe  the procedures  used  to  observe  surf  conditions. Describe  how  to  record  and  transmit  surf observations. Surf  observers  report  surf  conditions  by  using  a special code. Individual surf elements are reported by using standard designators, such as ALFA (to indicate significant   breaker   height),   BRAVO   (to   indicate maximum  breaker  height),  and  so  on.  Surf  forecasts (SURFCSTS) are issued in the same format and are just one  part  of  the  Amphibious  Objective  Area  Forecast (AOAFCST)   produced   by   forecaster   personnel. SUROBs  are  recorded  on  a  locally  reproduced  SUROB worksheet (fig. 4-3). BEACH  FAMILIARIZATION During   amphibious   operations,   beaches   are identified  by  color  codes.  A  3-mile-long  section  of beach, for example, may be broken down into shorter sections  identified  as  Red  Beach,  Purple  Beach,  or Green Beach. Normally, even on an irregular coastline, planners try to divide the larger beaches into sections with   similar   characteristics.   The   orientation   of   the beach and the beach slope should be fairly uniform for a beach  called  Green  Beach,  even  though  an  adjacent beach  area,  perhaps  called  Red  Beach,  may  have  a dramatically  different  orientation  and  slope.  In  addition to color designations, beaches may also be identified by letter  abbreviations  alone.  When  tasked  to  provide SUROBs,   you,   the   observer,   must   first   familiarize yourself  with  the  beach  designations  and  boundaries involved, since separate observations may be required for each beach area. SURF  OBSERVATION  ELEMENTS The  SUROB  worksheet  is  completed  (and  saved) for each individual SUROB. The observation number, the date and time of the observation (in UTC), and the beach identification are entered on each form as the first part of each SUROB report. Breaker  Height  (ALFA/BRAVO) When  observing  the  surf,  you  must  observe  the breaker heights of 100 individual breakers. Normally, breaker height is evaluated in an area where the waves are   breaking   nearest   the   beach.   Breaker   height   is estimated to the nearest half-foot and is entered in the Wave  Height  Observation  blocks  on  the  SUROB worksheet.  After  observing  100  individual  breakers, enter   the   significant   breaker   height,   which   is   the average  height  of  the  highest  one-third  of  all  the observed  breakers.  Enter  to  the  nearest  1/2  foot,  as element  ALFA  on  the  SUROB  report.  Enter  the maximum  breaker  height  (the  height  of  the  single highest  breaker  observed)  to  the  nearest  1/2  foot  as element BRAVO. Breaker heights are usually best estimated from a position close to the waterline on the beach. One fairly accurate method for estimating breaker height calls for the observer to line up the top of the breaker crest with the  horizon.  The  height  of  the  breaker  is  the  vertical distance from this line to the seaward edge of the uprush zone. The uprush zone is the area on the beach where the waves cause the water to temporarily rush up on the sand, and then recede on the wave backwash to expose the  sand.  This  method  becomes  less  accurate  as  the distance  from  the  observer  to  the  breakers  increases. See figure 4-4. In cases where a longshore sandbar is present, the highest  breakers  may  occur  over  the  sandbar,  with  only smaller breakers occurring near the beach. This is the case at low tide. If you observe higher, more significant breakers  offshore  (over  a  submerged  sandbar),  enter 4-4







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