ATMOSPHERIC PRESSURE 7 
Table 8. Results of Fourier analysis (harmonic coefficients) of diurnal waves of atmospheric 
pressure for latitude ranges, Carnegie, 1928-29 





Latitude range and number of days of record 

15°N-5°N, 
44 days 
25°N-15°N, 
32 days 

Coefficients in mm 
aj -0.094 -0.022 -0.104 +0.079 +0.142 + 0.022 
ag +0.138 +0.068 +0.140 +0.224 +0.262 +0.253 
ag —0.009 +0.014 +0.027 +0.007 +0.009 +0.024 
a4 +0.034 +0.014 -0.032 -0.023 +0.006 +0.009 
by - 0.059 +0.098 - 0.032 +0.256 +0.295 +0.191 
bg - 0.184 - 0.109 - 0.158 - 0.355 - 0.567 - 0.718 
b3 - 0.014 - 0.044 - 0.035 +0.001 - 0.019 - 0.002 
bg +0.005 - 0.011 0.000 - 0.006 - 0.030 - 0.031 
Amplitudes in mm 
cy 0.111 0.100 0.109 0.267 0.328 0.192 
C9 0,230 0.129 0.212 0.420 0.625 0.761 
c3 0.017 0.046 0.045 0.007 0.021 0.024 
C4 0.034 0.018 0.032 0.024 0.030 0.032 
Phase angles in ° 
4 238.0 347.5 252.8 17.1 25.7 6.6 
42 143.3 147.9 138.5 147.8 155.2 160.6 
$3 213.0 162.6 142.6 83.8 153.4 94.6 
o4 81.6 128.0 270.0 256.8 168.0 164.2 


Latitude range and number of days of record 
5°N-5°S, SeS—1onse 15°S-25°S, 
29 days 45 days 33 days 




25°S-35°S, 
22 days 
15°N-15°S, 
118 days 
35°S-45°S, 
9 days 

Coefficients in mm 
ay - 0.022 - 0.038 +0.002 - 0.085 — - 0.098 - 0.0134 
a +0.277 +0.358 +0.252 +0.239 +0.185 +0.2964 
ag +0.015 + 0.042 +0.050 - 0.010 +0.023 +0.0272 
a4 - 0.005 +0.002 - 0.009 +0.062 - 0.010 +0.0024 
by +0.452 +0.366 +0.146 +0.110 - 0.008 + 0.3362 
bo - 0.882 - 0.725 - 0.716 - 0.415 - 0.207 - 0.7752 
bg +0.011 - 0.041 - 0.031 - 0.113 - 0.090 - 0.0112 
by - 0.013 - 0.014 - 0.006 +0.033 +0.003 - 0.0192 
Amplitudes in mm 
cy 0.453 0.368 0.146 0.138 0.099 0.336 
C5 0.924 0.809 0.759 0.479 0.278 0.829 
cy 0.019 0.059 0.059 0.114 0.093 0.029 
cy 0.014 0.014 0.011 0.071 0.010 0.019 
; Phase angles in ° 
o1 357.2 354.1 0.9 322.3 265.1 357.8 
$2 162.6 15327 160.6 150.0 138.2 159.1 
$3 54.3 134.6 122.3 185.2 165.7 112.2 
o4 201.0 171.3 233.6 62.0 285.6 174.0 

4 Means of values for ranges 15° N-5° N, 5° N-5° S, and 5° S-15° S, from which c and ¢ 
were determined. 
The harmonic dial, which has been described by 
Bartels [8], illustrated in figures 6-10, 21, is a conven- 
ient device for diagrammatically representing these har- 
monic coefficients. One hour is represented on the cir- 
cumference of the circle by 15°, 30°, 45°, and 60° for 
the 24-hour, 12-hour, 8-hour, and 6-hour waves respec- 
tively. It is thus possible to show the phase angles and 
amplitudes of the several waves on a single diagram. A 
circle whose radius represents the probable error of the 
computations has been drawn around each point so plot- 
ted; the value of the radius has been determined by inter- 
polation between values of standard deviation for a sin- 
gle day. This method has been developed by Bartels [9] 
for pressure data for Potsdam and Batavia. 
The primary values were (0.16 mm/YN) for latitudes 
15° north to 15° south, (0.20 mm/VN) for +20°, (0.24 
mm/VN) for +30°, and (0.28 mm/VN) for +40°. The nu- 
merator represents the interpolated standard deviation 
for a single day, and the denominator the square root of 
the number of days (N) of observation. The probable er- 
ror, pg, implies that there are as many deviations great- 
er as there are smaller. 
For comparison, the data of the Carnegie and Gauss 
[2] are plotted together on a single harmonic dial which 
is in figure 6. The phase angles in this figure appear 
very regular; the mean for latitudes 35° north to 35° 
south falls within a range of 12° 08’ (25.6 minutes of 
time). Except within the ranges of latitude 15° north to 
15° south and 15° to 25° south, the values of the Gauss 
for the amplitudes of these pressure oscillations are 
greater than similar values computed from the data of 
the Carnegie. This result is not of great significance, 
