PB 151399-1

ZDoulder laboratories

^o. 40 - I

I MEAN ELECTRON DENSITY VARIATIONS

OF THE QUIET IONOSPHERE

I - MARCH 1959

BY J. W. WRIGHT AND L. A. FINE

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

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NATIONAL BUREAU OF STANDARDS

technical ^Ttote

40-1

February i960

Mean Electron Density Variations

of the Quiet Ionosphere I - March 1959

by J. W. Wright and L. A. Fine

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MEAN ELECTRON DENSITY VARIATIONS OF THE QUIET IONOSPHERE

I - MARCH 1959

By J. W. Wright and L. A. Fine

Central Radio Propagation Laboratory

Abstract

The CRPL has initiated a program for large-scale compute*

tion of electron density profiles from ionospheric vertical

soundings. Scaling is performed at field stations permitting

computation of hourly profiles at the central laboratory.

These profiles are combined to form hourly mean quiet profiles

for each station and month. The results of this program for one month are illustrated graphically. This report is the

first of a series illustrating the electron density variations

o o in the mean quiet ionosphere between latitudes 15 N and 50 N

o along the 75 W meridian.

TABLE OF CONTENTS

Page

I Introduction ...................... 1 II Description of Basic Data ............... 3

III Description of Graphical Representation ........ 6

IV Discussion and Applications of the Data ........ 7

References .

• 10

o Hourly Vertical Crosssections along 75 W geographic

meridian . 12

Isoionic Maps (150,200,250,300,350,^00 km; Nmax, hmax,

Shmax, Shinf) ... 36

Electron Density vs. Time Curves (N(t)), (Newfoundland

Ft. Monmouth, White Sands, Grand Bahama, Puerto Rico) k6

MEAN ELECTRON DENSITY VARIATIONS OF THE QUIET IONOSPHERE

I - MARCH 1959

by

J. W. Wright and L. A. Fine

Central Radio Propagation Laboratory

I Introduction

Part of the basic responsibility of the Central Radio Propagation Laboratory is to gather ionospheric, solar, or other geophysical data necessary in the pursuit of research leading to

improvements in radio communication and knowledge of the earth's

upper atmosphere. The existing network of ionospheric vertical

sounding stations is an important source of such data. Typically,

the radio sounding data directly provide observations of peak

electron densities (corresponding to "critical" frequencies foE,

foFl, foF2), data on Sporadic E, and certain derived propagation

data such as maximum usable frequencies or MUF factors (Smith,

1939).

In fa-ct, the vertical sounding is potentially capable of

providing the complete electron density profile of the underside

of the ionosphere (i.e., below hmaxF2), and of providing a basis

for extrapolation to much greater altitudes. However, because

a lengthy and difficult calculation is required, little of this

work had been done until quite recently when techniques and

computers have become available, and the exigencies of the IGY

and satellite programs have made it imperative.
In the course of its development of facilities for electron

density profile calculations, the CRPL has succeeded in devising

means by which basic data for this purpose may be scaled by the

individual field stations, thereby decentralizing and simplifying

the most onerous part of the work. Through its own station network and in cooperation with the U. S. Army Signal Ionosphere

Stations of the Signal Radio Propagation Agency, the CRPL has

initiated an extensive systematic data reduction program, from

which hourly electron density profiles are being computed for

the following stations:

Puerto Rico (NBS, January 1959)

Grand Bahama Island (u. S. Army Signal Corps, February 1959)

Fort Monmouth, New Jersey (u. S. Army Signal Corps, Feb. 1959)

White Sands, New Mexico (u. S. Army Signal Corps, March 1959)

St. Johns, Newfoundland (u. S. Army Signal Corps, April 1959)

Adak, Alaska (u. S. Army Signal Corps, June 1959)

Okinawa, Ryukus (u. S. Army Signal Corps, June 1959)

Thule, Greenland (u. S. Army Signal Corps, July 1959)

Affiliation and approximate date of initial participation in this

program are given in parentheses.

The hourly electron density profiles are extensively used in

the research programs of CRPL, and are supplied directly to certain

other agencies as part of various research and practical activities,

However, in this comparatively early stage, broad dissemination of

the computed data is a somewhat difficult problem.

In an attempt to make at least a summary of the results of

the program widely and rapidly available, the CRPL has initiated

the present series of reports. These provide graphical representations of the monthly mean quiet hourly electron densities

from certain of the stations in the preceding list, from which

a fairly clear picture of the local ionosphere morphology may be

obtained.
This report contains these data for the stations at Newfoundland, Fort Monmouth, Grand Bahama Island, White Sands, and Puerto

Rico. Pertinent facts concerning these stations are given in the

following table;

Table 1

Geomag. Coordinates Geog. Coordinates

Station fH Lat. Dip

St. Johns, Newf. 1.38mc/s 58.5°n 72°N k7°33^ 52%) f w

Ft. Monmouth, N.J. l.k6 51.7°N 71.5°N ^0°15«N 7^°oi»w

White Sands, N.M. 1.30 ia.2°N 60 N 32°2^ 8 N I06°52 8 w

Grand Bahama Island 1.30 37.9°N 59-5°n 26%0 f N 78°22 , W

Puerto Rico 1.15 30°n 5l.5°N l8

o30'N 67°12'W

II Description of Basic Data

True heights of reflection of radio waves are calculated from

the observed or "virtual" heights by the method of Budden (195*0 > this method need not be described here except to point out that

full correction for geomagnetic field effects is made and that the

usual restrictions to monotonic profiles apply.

Tabulations of the mean electron density data at 10 km intervals and certain related quantities are the bases for the graphs

and charts. A sample for the Puerto Rico March data is given on page 11. The table on the following page identifies the quantities appearing on the tabulation.
Table 2 Quantity Units Remarks

Average Electron ~ ^ Density (n) xlO = electron/cm Body of table; given at

each 10 km of height

from the lowest hmin to

950 km.

NMAX

3 3 xlO = electron/cm The mean value of Nmax.

COUNT Count of the number of

profiles entering the

the mean.

HMIN Kilometers The average height of zero or very low electron density, obtained

by linear extrapolation

of the electron density

of the individual profiles.

HMAX Kilometers The average height of

maximum electron density, determined by

fitting a parabola to

the upper portion of

the individual profiles.

SHMAX xlO = electrons/

cm^ column

^10 on maps;

Obtained by averaging

the integration of the

individual profiles

between the limits

HMIN and HMAX.

SHINF -, ~ 10 , / xlO = electrons/

cm2 column

-13

(10 on maps)

The average total num- ber of electrons in a column to infinity

obtained by extrapolaof observed profiles

into the region above

HMAX. (See text)
The following particular features of the tabulated data should

be noted:

A. Averaging process . Eachhour of each day is identified with

its magnetic character figure, Kp. For each hour, those days for

which Kp is less than k+ are included in the "quiet" average. The

other days are similarly combined to form a "disturbed" average]

however, this rarely has physical significance because the number

of distrubed periods is usually small and the behavior of the ionosphere during disturbed hours is not consistent. Thus graphs for

these latter averages are not presented here.

B„ Determination of hmax . The nature of the "true height"

process is such that no direct measure of hmaxF2 is obtained, the

virtual height at Nmax being immeasurable. A useful procedure is

to fit the portion near hmaxF2 with a suitable curve and to determine hmax from this curve. A parabola is quite satisfactory for

this purpose; it is fitted to two of the highest true heights and

the measured value of Nmax(foF2).

C. Extrapolation of profiles above hmax . Before averaging,

the individual profiles are extrapolated above hmax by a Chapman

distribution of 100 km scale height. This assumed model seems to

agree well with the few published measurements dealing with the

profile of the F region above hmax (Wright, 1959) • Extrapolation

is necessary in order to calculate homogeneous averages near hmax

and the average profiles are, in fact, given to 950 km.

D. Integrated Electron Densities . The total number of electrons in a unit column of the ionosphere between the effective

bottom (hmin) and hmax is called Shmax; it is obtained by obtained by numerical integration of the observed profiles between these

limits. An estimate of the total electron content to infinity,

based upon the Chapman model, is called Shinf. It is obtained by

adding to Shmax the quantity N = 2.82 HNmax where H is an (assumed

constant) scale height for the region above hmax. Current evidence
(Wright, i960) indicates H = 100 km, is an acceptable choice.

Ill Description of Graphical Representation

The relative smoothness of mean quiet ionosphere data lends

itself to various kinds of graphical presentation which offer con- venient aids to the visualization of the height, geographic, and

temporal variability of the ionosphere. Three such graphical forms are included here, prepared from the tabulations described in Section II.

A, Vertical cross sections of the ionosphere along the 75 W

meridian . Pages 12 through 35 gi ve f°r each hour, a vertical cross section of the mean quiet ionosphere along a meridian section,

nominally the 75 W geographic meridian, for the month of March 1959*

Contours are parametric in "plasma" frequency (fM

) related to electron density N by

12,iK)0 f

N

(Mc/s) = N( electrons/cm^).

The height of maximum electron density is represented by a dashed

line. Note that the vertical scale is expanded about 5*5 times.

With the exception of White Sands, each of these stations is

reasonably close to the 75 W meridian (see Table l). There is the

possibility that some of the anomolies imposed by White Sands on these contours are the result of the well-known longitudinal

asymmetry of the ionosphere.

B. Local time vs Latitude Maps . Another form of presentation,

useful for indicating the two-dimensional geographic variations of

the ionosphere, is that illustrated by the maps of pages 36 through

45. Here, for fixed levels in the ionosphere (150,200,300,350,

400 Km), contours of electron density are drawn in the latitude

vs. local time plane. To the extent to which longitude variations

are negligible, these maps give also the longitude vs. latitude
I 7

distribution of electron densities at the indicated heights when it

is noon over the 75 W meridian. Similar maps for the peak density,

Nmax; its height, hmax; the total electron content to nmax, Shmax

and the estimated total electron content, Shinf, are also shown.

C. Electron density vs. time curves (N(t) curves) . The mean

quiet diurnal variation of electron density between 1^0 and h-00 km

heights above the sounding stations is illustrated by these curves. Dashed lines are used wherever the electron density at any height

falls below the peak density (i.e. when the height hmaxF2 falls

below the height for the curve in question. ) Such electron densities are the result of the extrapolations by the Chapman model

discussed in Section II C.

IV Disaussion and Applications of the Data

Mean quiet electron density data over wide geographic areas

are essential for application to numerous problems of both practical and scientific interest. For example, the assessment of the

radio refraction errors and Faraday rotation effects in satellite

tracking require a knowledge of the electron density profile in

the direction of the satellite or an estimate of the electron

density at the satellite itself. Alternatively these properties

of the ionosphere, or estimates of the total electron content in

a column, may be measured by observations from rockets and satellites, or from radar moon-echoes, and compared with ground-based

observations of the kind shown here.

Frequently it will be necessary to use instantaneous density

data because of the considerable variability of the ionosphere

about the quiet mean. In such cases, the mean data are of value

as a "reference level" in the design of the experiment; for example,

in the choice of radio frequencies, satellite heights, antennas,

etc.
8

Since electron density data represent virtually our only source

of continuous, widespread data on the earth's upper atmosphere, such

data also are essential to geophysical problems involving the electrical, neutral, and magnetic properties of the atmosphere.

For example, data on the vertical cross sections may be compared

with theoretical expectations for the meridional height dependence

of the quiet ionosphere. Several workers, (Hirono, 1955) > an(* Martyn (19!?6)j have investigated the equilibrium height (of hmax)

for an ionosphere controlled by diffusion, height-varying electron

loss rate, and uniform (or zero) vertical electron drift. The

results are qualitatively in agreement with these observations in

predicting a rise of hmax towards the equator in daytime and a reversal of this tendency at night.

The N(t) curves are perhaps the most physically significant

representation of electron density data. The strong solar control

at all levels and the important perturbations of this solar control

in the upper F region may be easily seen.
Acknowledgements

We are indebted to Mr. A. H. Shapley, Assistant Chief of the

Radio Propagation Physics Division for guidance in the course of

this program, and to Dr. H. H. Howe for the development of the

computer programs upon which the whole system heavily depends. The

cooperation of the U. S. Army Signal Radio Propagation Agency, in

particular, the enthusiastic assistance of Mr. F„ H. Dickson (chief)

and Mr. H. F. Busch (Chief, Field Operations), is essential to the success of the program and is gratefully acknowledged.
10

References

Budden, K. G., "A method for determining the variation of Electron

Density with height (n(z) curves) from curves of

equivalent height against frequency (h 8 (f) curves).

Proc, Cambridge Conf. on the Physics of the Ionosphere, pp 332-339, September 195**-, Pub. by the

Physical Society (1955)*

Martyn, D. F., "Processes controlling ionization distribution in the

ionosphere," Aust. J. Phys, ^, PP I6I-I65, March

1956.

Hirono, M.,

Smith, N.,

Wright, J. W.

"Effect of gravity and pressure gradient on vertical

drift in the F2 region," Rpt. on lono. Res. in

Japan, % No. 2, p 95-104, (1955).

"The relation of Radio Skywave Transmission to Ionosphere measurements," Proc. IRE, _2J, No, 5, pp 332-

3Vf> (1939).

"A model of the F region above hmaxF2," to appear

in Journal of Geophysical Research, January i960.
AVERAGE ELECTRON DENSITY KP BELOW 4.5 PUERTO RICO 60 W MAR 1959 TIME 0000 0100 0200 0300 0400 0500 0600 0700 0800 0900 1000 1100

AVERAGE ELECTRON DENSITY

PUERTO RICO 60 W

KP BELOW 4.5 MAR 1959

1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 COUNT 26 26 26 26 26 23 25 25 24 26 24 25 24 25 24 25 24 27 27 27 28 28 28 27 HMIN 251 244 235 224 223 239 265 137 110 109 109 108 108 108 109 109 109 111 200 233 231 247 262 260 NMAX 1260 1146 958 705 479 387 408 855 1511 2039 2406 2505 2529 2525 2429 2326 2231 2146 1968 1772 1464 1316 1312 1374 HMAX 350 335 328 325 357 388 392 304 295 310 318 329 340 352 362 366 368 367 368 367 378 387 388 367 SHMAX 771 667 561 457 411 351 317 638 1231 1830 2219 2505 2673 2770 2829 2742 2628 2457 1774 1469 1240 1074 980 907 SHINF

KM950

4326 3900 3262 2445 1762 1442 1468 3048 5494 7582 9007 9570 9807 9892 9682 9303 8921 8511 7327 6467 5370 4787 4681 4782

104 87.7 69.9 50.7 41.6 38.7 41.0 56.1 94.8 138 169 186 198 210 212 208 200 191 177 159 138 130 130 123 900 133 113 89.6 65.0 53.3 49.7 52.5 71.9 122 177 217 238 254 269 272 266 257 245 227 203 176 166 167 158 850 171 144 115 83.4 68,4 63.6 67.3 92.2 156 227 278 305 326 345 349 341 329 315 291 261 226 213 215 203

800 219 185 147 107 87.6 81.4 86.2 118 200 291 356 391 417 441 447 437 421 403 372 334 289 273 274 260

750 280 237 189 137 112 104 110 151 256 372 456 501 534 565 571 559 539 515 476 427 370 348 351 332

700 358 302 241 175 143 132 140 194 328 476 583 640 682 720 729 712 686 657 607 544 471 443 446 423

650 454 385 307 223 181 167 177 247 418 607 743 816 867 916 925 904 871 834 770 690 597 561 564 537 600 574 487 389 282 228 209 222 314 532 771 943 1033 1097 1156 1166 1139 1097 1050 969 869 749 703 70 7 676 550 717 610 488 354 283 257 273 397 673 972 1187 1298 1375 1445 1453 1416 1364 1305 1205 1080 928 867 872 841 500 879 753 604 438 344 308 327 495 842 1212 1475 1607 1696 1773 1774 1726 1660 1590 1466 1315 1122 1041 1049 1023 490 913 784 628 456 357 318 338 517 879 1264 1538 1673 1763 1841 1840 1789 1721 1648 1519 1363 1161 1076 1083 1060 480 947 814 653 475 369 327 348 538 917 1317 1601 1740 1832 1910 1906 1852 1781 1706 1572 1410 1199 1109 1117 1097 470 981 845 679 49 3 381 336 358 561 956 1371 1666 1808 1900 1978 1971 1914 1840 1763 1624 1457 1236 1141 1149 1133 460 1014 876 704 512 393 345 367 584 995 1426 1731 1876 1969 2046 2035 1974 1898 1819 1675 1502 1272 1172 1179 1169 450 1047 907 729 530 405 353 375 607 1036 148] 1796 1944 2037 2112 2097 2032 1954 1872 1724 1546 1306 1200 1208 1203 440 1079 937 754 549 415 359 383 630 1077 1536 1861 2011 2104 2177 2157 2088 2007 1923 1770 1588 1337 1226 1234 1235 430 1110 966 779 567 425 365 389 653 1118 1592 1926 2078 2169 2238 2213 2140 2056 1971 1813 1627 1366 1248 1256 1265 420 1138 995 803 584 434 369 394 676 1159 1647 1990 2142 2231 2297 2264 2187 2101 2014 1852 1662 1391 1266 1275 1292 410 1165 1022 826 601 442 372 398 699 1200 1701 2052 2204 2290 2350 2311 2229 2140 2052 1886 1693 1412 1279 1289 1316 400 1189 1047 848 617 448 373 399 721 1240 1753 2112 2263 2345 2398 2350 2264 2173 2085 1915 1719 1428 1286 1296 1336

390 1209 1070 868 632 453 371 396 743 1279 1804 2169 2317 2394 2440 2383 2291 2198 2109 1937 1738 1437 1286 1294 1350

380 1226 1090 886 645 456 367 390 764 1318 1851 2222 2366 2437 2473 2406 2309 2215 2126 1950 1750 1437 1274 1279 1359

370 1237 1107 902 657 456 359 379 783 1354 1895 2270 2409 2472 2498 2419 2317 2221 2132 1953 1752 1425 1250 1248 1357

360 1239 1119 916 666 453 349 364 800 1388 1935 2312 2445 2499 2511 2419 2310 2214 2126 1942 1741 1402 1211 1199 1340

350 1229 1125 926 673 448 335 342 816 1419 1969 2347 2472 2515 2510 2399 2281 2187 2104 1911 1714 1363 1153 1126 1303

340 1203 1122 933 677 439 316 316 829 1446 1998 2374 2488 2516 2486 2352 2227 2138 2061 1857 1665 1309 1078 1033 1241

330 1159 1105 932 677 427 294 283 840 1469 2019 2391 2490 2494 2432 2277 2146 2064 1996 1779 1591 1234 987 919 1154

320 1089 1071 921 673 412 270 247 847 1488 2031 2395 2468 2444 2341 2170 2040 1965 1908 1676 1493 1141 882 785 1033

310 989 1017 896 664 392 242 206 850 1500 2032 2376 2418 2359 2218 2043 1912 1843 1799 1553 1371 1028 763 634 881 300 858 934 855 646 368 212 164 846 1505 2011 2327 2333 2238 2067 1896 1765 1706 1673 1408 1229 900 635 476 700

290 698 819 7 90 616 339 180 122 831 1498 1959 2238 2213 2088 1896 1732 1609 1559 1533 1249 1064 757 504 335 500

280 506 675 701 574 304 148 84.6 801 1471 1872 2105 2059 1913 1707 1563 1448 1405 1386 1077 881 605 380 208 300

270 329 508 584 516 263 118 53.7 750 1418 1750 1933 1883 1725 1519 1391 1288 1248 1233 886 685 450 273 117 157 260 177 332 438 440 217 90.2 35.6 681 1335 1598 1733 1686 1530 1335 1226 1131 1095 1063 681 478 309 175 52.5 73.7

250 67.7 174 281 344 163 65.1 20.7 591 1223 1420 1518 1480 1340 1160 1074 989 954 936 464 282 188 98.2 15.9 32.4

240 20.1 61.6 143 227 109 43.5 10.5 488 1084 1235 1302 1273 1161 1009 939 865 830 799 259 139 103 44.0 2.4 10.9

230 2.8 12.2 66.3 119 68.4 27.4 1.8 377 925 1044 1092 1079 994 876 824 760 722 676 132 47.5 49.5 17.9 2.8 220 .4 24.4 52.6 38.5 13.2 272 755 858 901 905 857 768 729 671 631 568 83.2 8.5 23.7 5.4 .8 210 4.5 20.4 18.7 6.3 191 592 696 742 759 737 676 646 595 551 475 57.7 1.8 11.8 1.6 200 2.7 5.1 2.9 134 451 561 611 638 635 596 572 526 480 393 42.9 5.1

190 .4 2.0 97.6 340 453 509 540 546 525 503 463 415 324 32.4 1.7

180 1.7 73.8 259 365 425 460 472 461 439 405 356 266 26.2

170 .9 59.2 200 297 357 393 411 406 381 352 302 219 22.1

160 .1 51.5 161 245 304 338 357 356 331 304 257 183 19.5

150 45.9 136 205 259 293 311 310 288 263 220 156 17.8

140 41.9 121 177 223 254 270 270 251 227 192 138 16.9

130 35.7 112 159 197 224 238 239 223 202 173 127 15.9

120 26.1 103 148 180 204 218 219 205 188 160 115 14.7

110 5.4 25.6 63.4 90.7 110 120 83.2 77.9 73.1 61.3 25.2 4.2

12

800

700

600 —

500

111 t~UJ2

O

z

X

400 —

300

200

100

VERTICAL CRQSSECTION ALONG 75°W MERIDIAN

MARCH 1959

0000 75°W TIME

N- CONTOURS OF f N

h-MAX

NEWFOUNDLAND FORT MONMOUTH

I i

I 50°

HORfZONAL SCALE 5.5 X VERTCAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO R!CO

45" 40' 35° 30°

LATITUDE IN DEGREES

25" 20'

'>
13

800

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

0100 75°W TIME

1 1

700

600

500

Ui5

O

X

o

UJI

-

400

300

200

100

T T T

N- CONTOURS Of f N

h-MAX

HORSZONAL SCALE 5.5 XVERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I « I WHITE SANDS GRAND BAHAMA PUERTO RICO

I 1 50

«

45' 40 s 35° 30°

LATITUDE IN DEGREES N

25' 20'
Ik

VERTICAL CROSSECTION ALONG 75°W MERIDIAN

MARCH 1959

0200 75° W TIME

1 T T

~ 5-

•6 —

CONTOURS OF f N

h-MAX HORIZONAL SCALE 5.5 X VERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH

J 1

WHITE SANDS GRAND BAHAMA PUERTO RICO

1 I 50' 45 ( 40" 35° 30° 25°

LATITUDE IN DEGREES N

20" 15°'
15

800b

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

0300 75°W TIME

1

1 1 1 1

700

600

500

in

ccuj

»-uj

2O_)

I

UJ

400

300

200

100

N- CONTOURS OF fN

h-MAX

HORIZONAL SCALE 5.5 X VERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I i l WHITE SANDS GRAND BAHAMA

J I I

I

I

PUERTO RICO

50* 45' 40" 35° 30°

LATITUDE IN DEGREES N

25' 20'
16

800i

700

600

500

to

<rUi2

o

I

e>

hiI

400

300

200

VERTICAL CR0SSECTS0N ALONG

MARCH §959

0400 75°W

75°W MER5DSAN

too —

CONTOURS OF fn

h-MAX HORIZONAL SCALE 5.5 XVERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH

1 « I WHITE SANDS GRAND BAHAMA PUERTO RICO

50' 45' 40' 35° 30°

.ATITUDE IN DEGREES

25' 20'
IT

VERTICAL CROSSECTiON AlCNG 75°W MERIDIAN

MARCH 5959

0500 75°W TIME

600

500 —

in

crUJ

\~UJ2

O_1

X

o

I

400

300

200

100

N- CONTOURS OF fN

h-MAX

HORIZONAL SCALE 5.5 XVERTCAL SCALE

J

NEWFOUNDLAND FORT MONMOUTH

I i

i WHITE SANDS GRAND BAHAMA PUERTO RICO

i 50' 45' 40* 35°

LATITUDE

30°

DEGREES N

25' 20"
18

VERTICAL CROSSECTION ALONG 75°W MERID8AN

MARCH 1959

0600 75°W TIME

• 800

700

600

500

X

F

Uii

o

_J f* 400

z

X

X)r

• 300

• 200

.- 100 —

d

N CONTOURS OF fw

h-MAX

HORIZONAL SCALE 5.5 X VERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I i

l

WHITE SANDS GRAND BAHAMA PUERTO RICO

-i_J

50

45' 40' 35° 30°

.ATITUDE IN DEGREES N

25' 20" 15"
1?

800

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

0700 75°W TIME

1 T 1 T

700

600

500

en

ijj

6

x

X

400

300

200

100

rJ

-6 —

T

CONTOURS OF fN

h-MAX

HORIZONAL SCALE 5.5 X VERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH WHITEIII. SANDS GRAND BAHAMA PUERTO RICO

_1_J

50' 45' 40" 35° 30°

LATITUDE IN DEGREES N

25' 20'
20

800

700

600

500

400

h 300

- 200

100

<>

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

0800 75°W TIME

1 1 1

1 t

~2=3:

CONTOURS OF f N

h-MAX

NEWFOUNDLAND FORT MONMOUTH

I I I

HORIZONAL SCALE 5.5 X VERTCAL SCALE

WHITE SANDS GRAND BAHAMA

X _L

PUERTO RICO

50

45' 40' 35° 30°

LATITUDE IN DEGREES N

25' 20" 15*
21

800

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

0900 75°W TIME

700

600

500

in

'a: 'uj

'h- IUJ '2

O

IIo

'CZj

400

300 —

200

100

CONTOURS OF fN

h-MAX

HORIZONAL SCALE 5.5 XVERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH WHITE SANDS GRAND BAHAMA

I I I I PUERTO RICO

50" 45' 40* 35° 30°

LATITUDE IN DEGREES

25' 20"
22

VERTICAL CROSSECTION ALONG 75°W MERIDIAN

MARCH 1959

IOOO 75°W TIME

800

700

z

600

500

400

300

200

100

a

CONTOURS OF fN

h-MAX

NEWFOUNDLAND FORT MONMOUTH

±

HORIZONAL SCALE 5.5 X VERTCAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

I I I I L_J

50' 45" 40' 35° 30°

LATITUDE IN DEGREES N

25' 20'
500

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

MOO 7B°W TIME

1

700

600

500

to

trUJ

iij o

I

UJX

400

300

200

100

T T T

- 4

2—

CONTOURS OF fN

h-MAX

HORIZONAL SCALE 5.5 X VERTCAL SCALE

C>

NEWFOUNDLAND FORT MONMOUTH

I i

l

WHITE SANDS GRAND BAHAMA

I i 1i PUERTO RICO

_L_J

50' 45" 40' 35° 30°

LATITUDE IN DEGREES N

25' 20' 15
2k

800

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

1200 75°W TIME

1 1 1 I !~

700

600

500

400

" 300

' 200

100

CONTOURS OF fN

h-MAX

NEWFOUNDLAND FORT MONMOUTH

HORIZONAL SCALE 5.5 XVERTCAL SCALE

WHITE SANDS GRAND 8AHAMA PUERTO RICO

J. X L I 50* 45° 40' 35° 30°

LATITUDE IN DEGREES N

25' 20' I5«
25

VERTICAL CROSSECTIOfSS ALONG 75°W MERIDIAN

MARCH 1959

1300 75°W TIME

800 T

700

600

500

(A

orhi2

S

UJX

400

300

200

iOO

CONTOURS OF fw

h-MAX

HQR6Z0NAL SCALE 5.5 XVERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH

1 i

I WHITE SANDS GRAND BAHAMA

± JL J_

PUERTO RICO

50' 45* 40° 35 s 30*

LATITUDE IN DEGREES N

2520< 15
26

800

VERTICAL CROSSECTION ALONG 75°W MERI

MARCH 1959

1400 75°W TIME

T

. 700

600

500

400

300

200

100

CONTOURS OF fw

h-MAX

NEWFOUNDLAND FORT MONMOUTH

OL

HORIZONAL SCALE 5.5 XVERTCAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

L i__ L_j i_J

50« 45 s 35° 30°

LATITUDE IN DEGREES N

25' 20' I5<
800?

700

600

500

2O

X

S2I

400

300

200

100

27

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 6959

1500 75° TIME

CONTOURS OF fw

h-MAX

-

HORIZONAL SCALE 5.5 XVERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH WHITE SANDS GRAND BAHAMA PUERTO RICO

50

«

45" 40' 35° 30°

LATITUDE IN DEGREES N

25« 20*
28

eoor

VERTICAL CROSSECTION ALONG 75° MERIDIAN

MARCH S959

1600 75°W TIME

700

iOO

>00

400

1

300

200

100 — 2^3

CONTOURS OF fu

h-MAX

NEWFOUNDLAND FORT MONMOUTH

J I

HORIZONAL SCALE 5.5 X VERTCAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

50

45 s 40° 35* 30°

LATITUDE IN DEGREES N

25' 20' 15*
800

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

1700 75°W TIME

! f—

700

600

500

crUJH

UJO

X

UJX

400

300

200

100

T

~

CONTOURS OF fN

h-MAX

NEWFOUNDLAND FORT MONMOUTH

I i

l

HORIZONAL SCALE 5.5 XVERTCAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

J_ JL ± ±

50" 45° 40' 35° 30°

LATITUDE IN DEGREES N

25' 20*
30

VERTICAL CROSSECTION ALONG 75°W MERIDIAN

MARCH 8959

8800 75°W TIME

800

700

600

500

400

300

200

100

CONTOURS OF fu

h-MAX

NEWFOUNDLAND FORT MONMOUTH

HORIZONAL SCALE 5.5 X VERTCAL SCALE

WHITE SANDS GRAND BAHAMA

! i I i

PUERTO RICO

50* 45' 40" 35° 30°

LATITUDE IN DEGREES N

25' 20'
31

800

700 —

600 —

500 —

(/I

o

X

o

Ijj X

400 —

300

200

100

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

5900 75°W TIME

CONTOURS OF fN

h-MAX

HORIZONAL SCALE 5.5 X VERTCAL SCALE

J

NEWFOUNDLAND FORT MONMOUTH

I I I WHITE SANDS GRAND BAHAMA

_L

PUERTO RICO

1 1 50" 45' 40' 35° 30°

LATITUDE IN DEGREES N

25" 20' II
32

800

700 —

600

500

400

300

200

100

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

2000 75°W TIME

N- CONTOURS OF f'N h-MAX HORIZONAL SCALE 5.5 X VERTCAL SCALE

NEWFOUNDLAND FORT MONMOUTH WHITE SANDS GRAND BAHAMA

J 1 I 1 I 50' 45' 4Q ( 35° 30°

LATITUDE IN DEGREES N

25"

PUERTO RICO

i I 20° 15°
33

800

700

600 —

500

in

UJ

tUJ2

O

I

UJX

400 —

300 —

200 —

100 —

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

2100 75°W TIME

CONTOURS OF fw

h-MAX

HORIZONAL SCALE 5.5 X VERTCAL SCALE

&

NEWFOUNDLAND FORT MONMOUTH

I i l WHITE SANDS GRAND BAHAMA

JL

PUERTO RICO

50" 45' 40' 35° 30°

LATITUDE IN DEGREES N

25' 20' I'
3^

$00

VERTICAL CROSSECTION ALONG 75°W MERIDIAN

MARCH 1959

2200 75°W TIME

! T

700

600

500

E 400

300

200

100

T T

CONTOURS OF f

N

h-MAX

HORIZONAL SCALE 5.5 X VERTCAL SCALE

J

NEWFOUNDLAND FORT MONMOUTH

I i

I WHITE SANDS GRAND BAHAMA

I i I i

PUERTO RICO

_L_J

50" 45° 40" 35° 30°

LATITUDE IN DEGREES N

25' 20' 15'
35

800

VERTICAL CR0SSECTI0N ALONG 75°W MERIDIAN

MARCH 1959

2300 75°W TIME

700

600

500

a:

UJ

I-UJo

X

o

UJX

400

300 —

200

100

T

CONTOURS OF fN

h-MAX

HORIZONAL SCALE 5.5 XVERTCAL SCALE

J

NEWFOUNDLAND FORT MONMOUTH

I i I

WHITEl.i. SANDS GRAND BAHAMA PUERTO RICO

I I 50 * 45

'

40' 35° 30°

LATITUDE IN DEGREES N

25' 20* 15
36

ELECTRON DENSITY AT 150 KILOMETERS

MARCH 1959

GBI

75°W TIME IN HOURS

00

CONTOURS- ~, X I0~

5

r m3
37

50

NF45

FMTff35

WS30

GBI25

20

A?

1500

ELECTRON DENSITY AT 200 KILOMETERS

MARCH 1959

J L J L J L J L

/ \

JL__L I I I L J I I l 06 12 18 75°W TIME IN HOURS

00

CONTOURS^ ~% X I0" 5
38

50

NF45

FMtct35

WS30

GBh

25

ELECTRON DENSITY AT 250 KILOMETERS

MARCH 1959

20

PR

/

/

/

« 0.5

\

\

15! I l l j j j_ j

00 06

.J 1 I i L

12 J I I I L

18 75°W TIME IN HOURS00

CONTOURS = -^3 X 10

5
39

N°

ELECTRON DENSITY AT 300 KILOMETERS

MARCH 1959

50

NF45

FMTOV35

WS30-

GBb

85

X/

A

2

i

S 1

I

I

J L J L J L

I

J

(16

J L

12

J L

00 06 12 75°W T8ME IN HOURS

18 00

CONTOURS =j^5 X I0"

S
40

GBi

ELECTRON DENSITY AT 350 KILDMETERS

MARCH 1959

75°W TIME IN HOURS

CONTOURS •£%. X !0

-3
41

6BI

ELECTRON DENSITY AT 400 KILOMETERS

MARCH 1959

75°W TSME IN HOURS

CONTOURS *r*kL X 10 v .o-»
42

MAXIMUM ELECTRON DENSITY

MARCH S959

1 „ i

t I l I » l

I L_1—L—JL—

J

i J I I I 1 1

l I 75°W TIME IN HOURS

18 00

CONTOURS =^3 X I0"

S
43

HClGHT OF MAXIMUM ELECTRON DENSITY

MARCH 1959

GBI

75°W TIME IN HOURS

18 00

CONTOURS =hm
44

ELECTRON DENSITY INTEGRATED TO

HEIGHT OF MAXIMUM ELECTRON DENSITY

MARCH 1959

75°W TIME 6N HOURS

CONTOURS'

2 co! . x , -*2
45

50

ELECTRON DENSITY INTEGRATED TO INFINITY

MARCH 1959

NFFM

GBI

PR

15I 1 L 00

J I 1 I L J I I I L 06 12 75°W TIME IN HOURS

18 00

CONTOURS --^2 col. XIO"'3
46

N(t) ST JOHNS, NEWFOUNDLAND MARCH 1959

FIXED HEIGHTS IN Km
47

Nit) FORT MONMOUTH MARCH 1959

FIXED HEIGHTS IN Km
48

N(t) WHITE SANDS MARCH 1959

FIXED HEIGHTS IN Km

10E

45

wO

00zO

zo

o:

h-o

m

_l

UJ

00 02 04 06 08
49

N(t) GBI MARCH 1959

FIXED HEIGHTS IN Km

20 22 00
50

N(t) PUERTO RICO MARCH 1959

FIXED HEIGHTS IN Km

toz

UJO

zo

DC

I-o

UJ

_lUJ

U.S. DEPARTMENT OF COMMERCE

Frederick H. Mueller, Secretary NATIONAL RUREAU OF STANDARDS

A. V. Aslin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its major laboratories in Washington, D.C., and

Boulder, Colorado, is suggested in the following listing of the divisions and sections engaged in technical work.

In general, each section carries out specialized research, development, and engineering in the field indicated by

its title. A brief description of the activities, and of the resultant publications, appears on the inside of the front

cover. WASHINGTON, D.C.

Electricity and Electronics. Resistance and Reactance. Electron Devices. Electrical Instruments. Magnetic Measurements. Dielectrics. Engineering Electronics. Electronic Instrumentation. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Photographic Technology. Length. Engineering

Metrology.

Heat. Temperature Physics. Thermodynamics. Cryogenic Physics. Rheology. Molecular Kinetics. Free

Radicals Research. Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State Physics. Electron Physics. Atomic Physics. Neutron Physics. Radiation Theory. Radioactivity. X-rays. High

Energy Radiation. Nucleonic Instrumentation. Radiological Equipment.

Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistry. Analytical Chemistry. Inorganic

Chemistry. Electrodeposition. Molecular Structure and Properties of Gases. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Fluid Mechanics. Engineering Mechanics. Mass and Scale. Capacity, Density, and Fluid Meters. Combustion Controls.

Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Poly- mer Structure. Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion. Metal

Physics.

Mineral Products. Engineering Ceramics. Glass. Refractories. Enameled Metals. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Air Conditioning, Heating, and Refrigeration. Floor, Roof, and Wall Coverings. Codes and Safety Standards. Heat Transfer. Concreting Materials.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics. Data Processing Systems. SEAC Engineering Croup. Components and Techniques. Digital Circuitry.

Digital Systems. Analog Systems. Application Engineering.

• Office of Basic Instrumentation. • Office of Weights and Measures. BOULDER, COLORADO

Cryogenic Engineering. Cryogenic Equipment. Cryogenic Processes. Properties of Materials. Gas Liquefaction. Radio Propagation Physics. Upper Atmosphere Research. Ionospheric Research. Regular Propagation

Services. Sun-Earth Relationships. VHF Research. Radio Warning Services. Airglow and Aurora. Radio

Astronomy and Arctic Propagation.

Radio Propagation Engineering. Data Reduction Instrumentation. Modulation Research. Radio Noise. Tropospheric Measurements. Tropospheric Analysis. Propagation Obstacles Engineering. Radio-Meteorology. Lower Atmosphere Physics.

Radio Standards. High Frequency Electrical Standards. Radio Broadcast Service. High Frequency Impedance Standards. Electronic Calibration Center. Microwave Physics. Microwave Circuit Standards. Radio Communication and Systems. Low Frequency and Very Low Frequency Research. High Fre- quency and Very High Frequency Research. Ultra High Frequency and Super High Frequency Research. Modulation Research. Antenna Research. Navigation Systems. Systems Analysis. Field Operations.