AEROGRAPHER'S MATE 3 & 2 



green for every 10° of dewpoint, beginning with 

 any value divisible by 10. 



OTHER FEATURES. — There are numerous 

 other features analyzed on constant pressure 

 charts, but third and second class Aerographer's 

 Mates are not required to know the details and 

 the techniques of these features. The features 

 are the tropopause, the Jetstream, isotachs (lines 

 of equal wind speed), thickness lines, and the 

 like. However, since all Aerographer's Ms.tes 

 process constant pressure charts which have 

 these various features analyzed, they should 

 be familiar with the symbols used to rep- 

 resent the features on both the original chart 

 and the charts prepared for transmission by 

 facsimile. Table 11- 2 summarize sail the features 

 of upper air charts in general and shows the 

 standard markings to be used for the various 

 elements. 



Analysis Technique 



As with the surface chart, constant pres- 

 sure chart analysis should consist of the fol- 

 lowing four steps*. 



1. Before accomplishing anything else, re- 

 view the previous charts for the PAST HIS- 

 TORY of the constant pressure surface in ques- 

 tion. As with the surface analysis, first make 

 any corrections to the previous analysis that 

 may be necessary due to late or additional 

 reports. Trace the pertinent features of this 

 past history onto the chart being analyzed. In 

 many units the past history is traced to the 

 lastest chart before it is even plotted. 



2. Preliminary analysis. Before actually 

 drawing a constant pressure chart, it should 

 first be surveyed visually to get the general 

 overall idea of the windflow and the height 

 pattern that exists. 



3. Basic analysis. After the chart has been 

 visually checked and the general overall idea of 

 the windflow and height pattern noted, the actual 

 analysis may be started. 



First, sketch the contours lightly. Contours 

 nearly always parallel the wind direction. As 

 with isobars, contours are close together when 

 the wind speed is strong and far apart when 

 the wind speed is weak. 



Next, sketch the fronts and trough lines. 

 After sketching the fronts and trough lines, 

 sketch the isotherms and then any other re- 

 quired isopleths. 



4. Final analysis. When the basic analysis 

 is complete, the final analysis may be made. 



Smooth the contours and draw them heavily. 

 Label all contours with their correct values 

 Draw the fronts and trough lines. Fronts are 

 indicated in the same manner as on the sur- 

 face chart. Troughs are indicated as dashed 

 brown lines. Smooth the isotherms and label 

 each with the representative temperature value. 

 Smooth miscellaneous isopleths and label each 

 with the appropriate value. Label the high and 

 low height areas. 



NOTE: For ease in interpretation, the iso- 

 therms drawn on the 700-mb chart in figure 

 11-21 are dashed lines. 



A summary of the recommended procedures 

 for analyzing a constant pressure chart is as 

 follows: 



1. Study past history; trace it on th? cur- 

 rent chart. 



2. Sketch the contours lightly. 



3. Sketch the fronts or troughs. 



4. Smooth the contours and draw them heav- 

 ily. Label all contours with their correct 

 values, and in the correct manner. 



5. Draw the fronts or troughs heavily. 



6. Sketch the isotherms. 



7. Draw the isotherms heavily and label 

 them correctly. 



8. Sketch miscellaneous isopleths lightly. 



9. Dr.*w miscellaneous isopleths heavily and 

 label them correctly. 



10. Label the high and low height areas. 



OCEANOGRAPHIC CHARTS 



As with other meteorological charts, you must 

 first plot the oceanographic parameters before 

 an oceanographic chart can be analyzed. The 

 following paragraphs briefly discuys some of 

 the plotting procedures involved in oceanographic 

 charts. 



Plotting Sea Conditions 



The state of the sea is of utmost importance 

 in the preparation of ASWEPS charts, as it 

 denotes ship behavior and sonar-quenching char- 

 acteristics which are of considerable interest 

 when planning ASW and various other opera- 

 tions. 



Sea condition charts may be plotted daily, 

 utilizing data available over existing radio and 

 teletype networks. One important source of data 



216 



