58 



MANUAL OF MARINE METEOROLOGICAL OBSERVATIONS 



Code Table 16 



SYMBOLS "pp" and "ppp. "—Amount of barometric change 



in the last 3 hours 



> When the amount of the barometric pressure change equals or exceeds 9.0 milltbars, the group "99ppp" should be inserted In the message following 

 the "D,v,app" group. The "99" is the group Identifier, and "ppp" is the total amount of the pressure change (in tens, units, and tenths of millibars) 

 during the preceding 3 hours. When the group is inserted. "99" should be reported for "pp" in tne "D.v^pp" group. For example: If the total amount 

 of the pressure change is 13.4 millibars, the groups should be coded "D.vtf^ 99134." If the amount is9.9 millibars, tbegroupsare coded "D«v.a99 99090." 

 ("DaV.a" should be given appropriate values.) 



