AEROGRAPHER'S MATE 3 & 2 



Normally, the Aerographer's Mate does not 

 observe, record, or report surf. If these ob- 

 servations are required In special situations, 

 a comprehensive coverage of surf observation 

 techniques may be found in the Joint Surf Man- 

 ual, COMPHIBPACINST 3840. 3( ). 



Bathythermograph Observations 



We have confined our previous discussion to 

 observation of the surface of the sea* This 

 is only part of the larger picture involved 

 in describing the characteristics of ocean 

 structure. It is also important to be able to 

 observe the structure of the subsurface, or 

 underwater variables. These include, but are 

 not limited to, temperature, density, and 

 salinity. 



The sensing equipment used to determine 

 ocean temperature data was discussed in chap- 

 ter 4 of this manual. These instruments are 

 valuable aids for gathering information on the 

 structure of the sea. The other parameters 

 require more sophisticated equipment not nor- 

 mally utilized by the Aerographer's Mate. How- 

 ever, without an organized means of recording 

 and transmitting this temperature information, 

 it would be of limited value. The following 

 paragraphs provide information on the bathy- 

 thermograph (BT) log. 



THE BT LOG. — To aid the observer in 

 interpretation of the BT trace and to assure 

 the standardization of recording and reporting 

 bathythermograph observations, the Oceanogra- 

 pher of the Navy and the National Oceanic 

 and Atmospheric Administration have prepared 

 a bathythermograph log for use by fleet units. 



The BT Log, OCEANAV 3167/1 (6-72) is 

 one of the most completely self-contained ob- 

 servational forms in use. It provides all the 

 information required by the National Oceano- 

 graphic Data Center (NODC). 



UPPER AIR OBSERVATIONS 



There have been many advances in the tech- 

 nological fields of high-altitude aircraft, pro- 

 jectiles, missiles, and satellite development. 

 As a result of these advances, the scientific 

 study of the upper regions of the atmosphere 

 Is becoming increasingly more important. Since 

 meteorologists now have access to larger quan- 

 tities of data from the upper air, they are find- 

 ing new and more accurate methods of 

 forecasting the movement of storms. 



A knowledge of the weather conditions exist- 

 ing in the free air above the earth's surface 

 is extremely important in theoretical, statistical, 

 and climatological studies of the atmosphere 

 as well as their importance in the direct ap- 

 plication in daily forecasting and for their im- 

 mediate use by pilots. Coupled with the 

 information concerning surface conditions, this 

 knowledge affords the forecaster another di- 

 mension upon which to base his predictions. 



A basic understanding of the theory and 

 purpose of upper air observations enables an 

 Aerographer's Mate to understand better the 

 processes he performs in taking observations. 

 From the data thus obtained, maps, charts, 

 and graphs of the upper air conditions at var- 

 ious levels up to many thousands of feet are 

 constructed. 



The types of equipment used in obtaining 

 upper air observations were previously dis- 

 cussed in chapter 9 of this manual. The fol- 

 lowing information will discuss the types of 

 observations, their schedules, forms used, and 

 various upper air codes in use today. It is 

 not the intent of this section to describe the 

 many procedures to be followed in taking up- 

 per air observations. These are covered in 

 Federal Meteorological Handbooks 3, 4, 5, and 

 6, that are readily available at all upper air 

 observing stations. 



Types of Observations 



Upper air observations are measurements 

 of the atmospheric conditions above the earth's 

 surface. Upper air data may be determined by 

 one or more of the following methods: 



1. Pilot balloon (PIBAL), A pilot balloon 

 observation is a measurement of the direction 

 and speed of the wind above the earth's surface 

 obtained by visual means. The direction and 

 speed are computed from successive positions 

 of a free balloon which is assumed to have a 

 fixed ascensional rate. The positions are de- 

 termined from values of the balloon's elevation 

 and azimuth angle read each minute from a 

 theodolite. The ascensional rate tables for pilot 

 balloons are based on the averages derived 

 from a large number of flights triangulated 

 by two theodolites. The balloon may not be at 

 the exact height given by the table because of 

 the effect of local turbulence on the balloon. 

 This turbulence may cause the balloon to be 

 higher or lower than the height given in the 

 table, taut this discrepancy in height is not 



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