World Data Center A consists of the Coordination Office and seven Subcenters:

World Data Center A
Coordination Office
National Academy of Sciences
2101 Constitution Avenue, N.W.
Washington, D.C., U.S.A. 20418
[Telephone: (202) 389-6478]

Glaciology:
World Data Center A:
Glaciology
U.S. Geological Survey
1305 Tacoma, Washington, U.S.A. 98402
[Telephone: (206) 593-6506]

Rotation of the Earth:
World Data Center A:
Rotation of the Earth
U.S. Naval Observatory
Washington, D.C., U.S.A. 20390
[Telephone: (202) 254-4023]

Meteorology (and Nuclear Radiation):
World Data Center A:
Meteorology
National Climatic Center
Federal Building
Asheville, North Carolina, U.S.A. 28801
[Telephone: (704) 258-2850]

Solar-Terrestrial Physics (Solar and Interplanetary Phenomena, Ionospheric Phenomena, Flare-Associated Events, Geomagnetic Variations, Magnetospheric and Interplanetary Magnetic Phenomena, Aurora, Cosmic Rays, Airglow):
World Data Center A
for Solar-Terrestrial Physics
Environmental Data Service, NOAA
Boulder, Colorado, U.S.A. 80302
[Telephone: (303) 499-1000, Ext. 6467]

Oceanography:
World Data Center A:
Oceanography
National Oceanic and Atmospheric Administration
Washington, D.C., U.S.A. 20235
[Telephone: (202) 634-7249]

Solid-Earth Geophysics (Seismology, Tsunamis, Gravimetry, Earth Tides, Recent Movements of the Earth's Crust, Magnetic Measurements, Paleomagnetism and Archeomagnetism, Volcanology, Geothermics):
World Data Center A
for Solid-Earth Geophysics
Environmental Data Service, NOAA
Boulder, Colorado, U.S.A. 80302
[Telephone: (303) 499-1000, Ext. 6521]

Rockets and Satellites:
World Data Center A:
Rockets and Satellites
Goddard Space Flight Center
Code 601
Greenbelt, Maryland, U.S.A. 20771
[Telephone: (301) 982-6695]

Notes:
1. World Data Centers conduct international exchange of geophysical observations in accordance with the principles set forth by the International Council of Scientific Unions. WDC-A is established in the United States under the auspices of the National Academy of Sciences.
2. Communications regarding data interchange matters in general and World Data Center A as a whole should be addressed to: World Data Center A, Coordination Office (see address above).
3. Inquiries and communications concerning data in specific disciplines should be addressed to the appropriate subcenter listed above.
# TABLE OF CONTENTS

| SECTION I: GENERAL DISCUSSION | Page |
|-------------------------------|------|
| 1. Introduction               | 1    |
| 2. Data Selection and Processing | 1   |
| 3. Auroral Electrojet Magnetic Activity Indices | 2   |
| 4. Acknowledgments            | 3    |
| 5. References                 | 3    |

| SECTION II: COMMON SCALE MAGNETOGRAMS | Page |
|---------------------------------------|------|
| 1. Stacked Common Scale Magnetograms for Whole Month (H, Z, and D Variations) | 4    |
| 2. Stacked Common Scale Magnetograms by Station Day (H Variations) | 8    |

| SECTION III: PRELIMINARY AE(7) INDICES, MARCH 1976 | Page |
|---------------------------------------------------|------|
| 1. Discussion of Graphs, Tables, and Statistical Information | 40   |
| 2. Graphs of AU, AL, AE, and AO for Each Day of the Month | 40   |
| 3. Tables of AE, AO, AU, and AL Indices             | 47   |
| 4. Tables of Observatories Supplying Hourly AU and AL | 51   |
| 5. Statistical Information                         | 53   |
Geomagnetic Data for March 1976
(AE(7) Indices and Stacked Magnetograms)

by

J. H. Allen, C. C. Abston and L. D. Morris
NGSDC/EDS/NOAA
Boulder, Colorado 80302 USA

SECTION I. GENERAL DISCUSSION

1. Introduction

This is the third of a series of data reports in support of the International Magnetospheric Study (IMS) and includes selected geomagnetic variation data for March 1976; the first (UAG-60) gave similar data for January 1976. Included herein are analog records from seven auroral zone stations; preliminary AE indices based on these data; and various related tables, graphs, and statistics. It is expected that this series will continue on an increasingly timely schedule and with data from additional stations which may be processed in time for publication.

2. Data Selection and Processing

The seven observatories supplying data for this report are shown in Figure 1. These are Leirvogur (LR), Narssarssuaq (NAS), Fort Churchill (FC), Barrow (BW), Tixie Bay (TI), Dixon Island (DI), and Abisko (AI). They were chosen from among the list of 12 observatories whose records are now routinely

Fig. 1. Provisional AE(7) network.
used by WDC-A for Solar-Terrestrial Physics in the derivation of Auroral Electrojet (AE) magnetic activity indices. Reasons for their selection were (1) records from these sites are most promptly available, (2) the sites are about evenly spaced in longitude, and (3) each location has demonstrated its importance in the prior derivation of AE indices [Allen and Kroehl, 1975]. We hope that as digital data processing from other observatories becomes more routine the network can be expanded, and we can include data from College, Great Whale River, and Yellowknife to improve the station distribution for these prompt indices.

Among the stations supplying data for this publication, only Fort Churchill and Barrow are presently recording digital variations on-site. Both observatories use flux-gate instruments supplemented by proton precession magnetometers and generate more or less routine absolute observations. Each component's amplitude is recorded every 10 s (20 s for BW) on magnetic tape, and analog chart records are prepared as backup data. These high-time-resolution digital data are processed at central facilities responsible for each observatory. Obvious errors (usually spikes) are corrected and 1-min average values are computed. These preliminary data are sent on tape to WDC-A for Solar-Terrestrial Physics where they are plotted and checked for stability of quiet-time levels (baseline drift), presence of noise, and day-to-day continuity. As necessary, remaining spikes are removed, and "temporary" baselines are adopted to compensate for data problems that would affect derivation of AE indices.

All the other observatories record magnetic variations photographically. Their magnetograms are copied on 35 mm microfilm for transfer to WDC-A for Solar-Terrestrial Physics together with calibration information. Here they are reproduced as almost original size magnetograms and digitized at 1-min intervals using semiautomatic scaling equipment. Resulting digital tapes of component amplitudes relative to baselines are passed through the same plotting and other quality control processes as the original digital data described above.

After completion of quality control checks, all digital records are merged and replotted to common time and amplitude scales. These are the monthly D, H, and Z component and daily H (or X) component stacked plots included in this report. For most observatories intervals of missing data are apparent in one or more components. These may arise from (1) loss of on-site digital data, (2) noise in original digital data, (3) movement of traces off magnetograms during large excursions with no secondary trace for that component, (4) lack of low-sensitivity storm magnetograms for disturbed periods, and (5) loss of intermixing of analog traces during large, rapid field fluctuations. Every reasonable effort is made at WDC-A for Solar-Terrestrial Physics to curve-follow disturbed traces. Effects of data gaps are seen in AE indices only when they occur at a critically located station and in the H component. Often they are only apparent in the graphs of AU or AL.

3. Auroral Electrojet Magnetic Activity Indices

The AE index gives a global, quantitative measure of auroral zone magnetic activity resulting from enhanced ionospheric currents associated with magnetospheric substorms. As defined by Davis and Sugiura [1966], AE is the total range of H component deviations from quiet-time levels of the field at a selected group of high-latitude magnetic observatories. Typically, a constant quiet-time H value is determined for each observatory and subtracted from recorded H values. The resultant deviations for all stations may be plotted to common time and amplitude scales and graphically superposed on a common reference or zero level. Then the amplitudes of the enclosing upper and lower envelopes from moment-to-moment give the values of AU and AL, respectively. The range between them is AE, i.e., AU-AL=AE. Their average is (AU+AL)/2=Ao (often indicated AO because many computers lack the ability to produce lower case characters).

Complete discussions of AE and associated indices can be found in the two papers referenced above and in the series of WDC-A for Solar-Terrestrial Physics Reports UAG-22, 29, 31, 33, 37, 39, 45, 47, and 59 which cover the years 1966-1974. Each of these contains precautionary notes about the inherent limitations of AE indices, even when derived from a relatively complete station network. Additional notes on AE are given before the daily index graphs (page 40) and the figures based upon minute-to-minute "frequency of index provision" by each station. Also given in this report are figures showing the cumulative amplitude of H deviation for times when each station was providing AU and AL indices (pages 55 and 57).
4. **Acknowledgments**

The authors of this IMS data report are on the staff of the National Geophysical and Solar-Terrestrial Data Center (NGSDC) of the Environmental Data Service, National Oceanic and Atmospheric Administration. WDC-A for Solar-Terrestrial Physics is collocated with NGSDC and shares the same staff. We wish to recognize the efforts of those persons who operate the high-latitude magnetic observatories and process the data from them. Recognition is also due the operators who patiently curve-follow, check, and correct the data from which this report is compiled. Mr. W. I. Paddock has carefully adopted the temporary baseline values and checked each stage of the digitization. We hope that IMS participants who find this report useful or who can suggest improvements will correspond with the authors.

5. **REFERENCES**

| Author(s) | Year | Title |
|-----------|------|-------|
| ALLEN, J. H. | 1972 | Auroral Electrojet Magnetic Activity Indices (AE) for 1970, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-22. |
| ALLEN, J. H., C. C. ABSTON, and L. D. MORRIS | 1973 | Auroral Electrojet Magnetic Activity Indices AE(11) for 1968, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-29. |
| ALLEN, J. H., C. C. ABSTON, and L. D. MORRIS | 1974a | Auroral Electrojet Magnetic Activity Indices AE(11) for 1969, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-31. |
| ALLEN, J. H., C. C. ABSTON, and L. D. MORRIS | 1974b | Auroral Electrojet Magnetic Activity Indices AE(10) for 1967, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-33. |
| ALLEN, J. H., C. C. ABSTON, and L. D. MORRIS | 1974c | Auroral Electrojet Magnetic Activity Indices AE(10) for 1966, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-37. |
| ALLEN, J. H., C. C. ABSTON, and L. D. MORRIS | 1975a | Auroral Electrojet Magnetic Activity Indices AE(11) for 1971, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-39. |
| ALLEN, J. H., C. C. ABSTON, and L. D. MORRIS | 1975b | Auroral Electrojet Magnetic Activity Indices AE(11) for 1972, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-45. |
| ALLEN, J. H., C. C. ABSTON, and L. D. MORRIS | 1975c | Auroral Electrojet Magnetic Activity Indices AE(11) for 1973, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-47. |
| ALLEN, J. H., C. C. ABSTON, and L. D. MORRIS | 1976 | Auroral Electrojet Magnetic Activity Indices AE(11) for 1974, *World Data Center A for Solar-Terrestrial Physics*, Report UAG-59. |
| ALLEN, J. H. and H. W. KROEHL | 1975 | Spatial and Temporal Distributions of Magnetic Effects as Derived from AE Indices, *J. Geophys. Res.* 80, 3667-3677. |
| DAVIS, T. N. and M. SUGIURA | 1966 | Auroral Electrojet Activity Index AE and Its Universal Time Variations, *J. Geophys. Res.* 71, 785-801. |
SECTION II. COMMON SCALE MAGNETOGRAMS

1. Stacked Common Scale Magnetograms for Whole Month (H, Z, and D Variations)

The three following graphs display condensed stacked plots of the H, Z, and D variations, respectively, for seven stations minute-by-minute over the entire month. Component intensities are to the nearest 1 gamma, and declination changes are to the nearest 0.1 minute of arc. Positive H, Z, and D changes are north, down, and east, respectively. Amplitude scales given at the bottom of each figure correspond to the original centimeter scale reproduced at lower right. For each station the North Polar Distance (N.P.D.) and East Longitude (E. Long.) are given.
2. Stacked Common Scale Magnetograms by Station Day (H Variations)

The following stacked plots of H (or X) common scale magnetograms are reproduced from the digital magnetic variations data obtained as described on page 2. Each station is identified by the abbreviation from Figure 1 and two coordinates: North Polar Distance (N.P.D.) and East Longitude (E. Long.). The amplitude scale is given at lower left of each figure and corresponds to the centimeter scale at lower right. The amplitude scale is the same for each day except when the range of deviation would cause a trace to exceed the space reserved for it. For such days (see, for example, 2-3 March 1976) the scale is increased in uniform steps to assure nonoverlapping traces. To call attention to the scale change (similar to switching to storm magnetograms), the new value is enclosed in a box.

The label "NGSDC (BOULDER) yy/mm/dd", at the bottom of first day plot, identifies the source of the published data and the day on which the plots were prepared. The difference between data recording date and its preparation date provides an indication of the time required to collect the records, to initiate program development, and to process the data.
1. Discussion of Graphs, Tables, and Statistical Information

The following figures display the familiar AU, AL, AE, and AO graphs for each day of the month and are based upon 1-min data samples. As indicated at the top of each frame, these indices are derived from data from only seven auroral zone observatories and, as such, are considered "provisional." WDC-A for Solar-Terrestrial Physics intends to update these indices during and after the IMS and to publish "final" graphs and summary tables in the usual UAG Report format for each year.

Following the pages of AE graphs are Tables 1-4 (pages 47-50) containing the index (AE, AO, AU, AL) amplitudes for each hour of each UT day of the month, the monthly averages for each hour and for the hours of the designated 5Q and 5D days, and the average amplitudes for each day and for the whole month. Tables 5-6 (pages 51-52) give the station having the largest hourly average positive and negative deviations (hourly AU and AL) for each hour of each day in the month. These provide a key to the graphs of AU and AL by usually indicating which station's magnetogram provided the extreme deviations giving AU or AL for that hour. Sometimes the most extreme deviation during an hour will have occurred at another station. The general patterns, however, of UT time of AU and AL provision by each station are the same whether based on hourly averages or on minute-by-minute extremes.

Table 7 (page 53) gives the number of times (1-min intervals) during the month when the indicated station provided the AU and AL index in each hour of the UT day. For the relatively sparse station distribution used in this AE(7) derivation, it is not surprising that each station could produce at least one extreme positive and negative deviation in almost every hour of the day. However, the overall pattern is for the most frequent observation of the maximum positive H deviation to occur around 6 hours before Local Geomagnetic Midnight (LGM) and the most negative H deviation to occur around 3 hours after LGM [Allen and Kroehl, 1975]. Individual station deviations from this pattern may be due to the dominant influence of a few isolated large substorms during a relatively quiet month. This should become apparent as more months of data are similarly analyzed.

Table 8 (page 53) gives the monthly average of quiet-time H for each observatory. This is computed from the 1-min H scalings on the 5 quiet days of the month, using known or assumed H baselines.

Figures 2-5 (pages 54-57) graphically display the details suggested by the tabulation of hourly station frequency of AU and AL contribution. The "frequency of 1-min AU provision by station" (Figure 2) for the month is a smoothed curve showing the number of times that each station contributed the extreme positive deviation from minute-to-minute, N(AU). An 11-point running mean was used on the raw numbers of contributions for the 1440 1-min intervals of the UT day. Data for the UT day are duplicated (0000-2400 UT shown twice) so that the end of the day will not interrupt the regular pattern of progressive index contribution as each station rotates into the critical region (around 1800 LGT). Arrows mark UT times of LGM for each station. Figure 3, on the opposite page, shows the "total amplitude of most positive H variations." This is a smoothed graph for each station's cumulative amplitude of deviation for each minute when it was providing the AU index. Each scale division on the right side represents +500 gammas. Comparison of these curves with the N(AU) graphs of Figure 2 shows that the largest magnitude positive excursions generally occur at the same time when the stations most often provide AU indices. Occasional postmidnight minor peaks result from disturbances for which the H component at one site is first a negative extreme (giving AL) for several minutes and then swings briefly to

2. Graphs of AU, AL, AE, and AO for Each Day of the Month

(Text continued on page 46)
a positive extreme before recovery. Such events are infrequently observed in AE indices derived from 10 to 12 stations because usually another station is in position to monitor the true eastward electrojet effect rather than having oscillatory variations near LGM providing AU.

The graph "frequency of 1-min AL provision by station" (Figure 4) shows the smoothed curve for the number of times in the month that each station provided AL during each minute of the UT day, N(AL). Evidently the pattern is for a station to rotate into the most probable region for encountering extreme negative H deviations some hours after LGM. Unusual, asymmetric peaks in frequency of AL provision by any station may be attributed to disturbances on only a few days of the month. Such unevenness due to a few isolated events should average out over the course of a year. Figure 5 shows the corresponding "total amplitude of most negative H variations." This is the cumulative amplitude of negative H observed by each station during those minutes when they were providing AL. Each scale division on the right side is -1000 gammas. Again, the comparison of cumulative amplitudes and N(AL) curves can indicate the most probable time of occurrence of larger amplitude events.

For Figures 2-5 slightly elevated levels of the curve for any station during normally quiet hours indicate possible difficulty with the quiet-time level for some days of the month. This information will be used as a quality control check for the final derivations of AE(12) indices at a later date.
3. Tables of AE, AO, AU, and AL Indices

Table 1. AE Indices

| MARCH | 1976 | UT  |值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 | 值 |
|-------|------|-----|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|       |      | 01  | 348 | 314 | 337 | 330 | 408 | 156 | 142 | 124 | 102 | 062 | 100 | 416 | 304 | 159 | 226 | 331 | 201 | 164 | 104 | 070 | 141 | 247 | 194 | 174 | 215 |
|       |      | 02  | 110 | 098 | 198 | 570 | 375 | 356 | 385 | 191 | 102 | 085 | 156 | 137 | 137 | 292 | 399 | 637 | 766 | 594 | 236 | 209 | 539 | 688 | 333 | 618 | 349 |
|       |      | 03  | 513 | 599 | 391 | 517 | 493 | 390 | 442 | 412 | 225 | 143 | 291 | 245 | 568 | 136 | 109 | 086 | 116 | 815 | 478 | 162 | 364 | 568 | 435 | 618 | 380 |
|       |      | 04  | 501 | 501 | 449 | 096 | 042 | 053 | 106 | 167 | 100 | 074 | 421 | 228 | 135 | 066 | 131 | 166 | 122 | 097 | 133 | 236 | 117 | 028 | 033 | 046 | 169 |
|       |      | 05  | 032 | 053 | 177 | 216 | 263 | 239 | 259 | 138 | 133 | 327 | 370 | 216 | 184 | 139 | 169 | 147 | 328 | 142 | 209 | 149 | 290 | 358 | 674 | 161 | 222 |
|       |      | 06  | 118 | 258 | 481 | 289 | 299 | 217 | 132 | 203 | 104 | 295 | 249 | 033 | 026 | 041 | 318 | 894 | 877 | 963 | 637 | 586 | 325 | 678 | 588 | 195 | 367 |
|       |      | 07  | 468 | 727 | 414 | 208 | 214 | 155 | 260 | 108 | 230 | 175 | 603 | 391 | 357 | 154 | 165 | 935 | 851 | 722 | 256 | 186 | 307 | 670 | 373 | 241 | 382 |
|       |      | 08  | 651 | 839 | 644 | 410 | 481 | 301 | 247 | 496 | 568 | 239 | 361 | 252 | 324 | 559 | 469 | 319 | 228 | 410 | 662 | 527 | 328 | 447 | 501 | 352 | 442 |
|       |      | 09  | 122 | 074 | 346 | 775 | 277 | 421 | 349 | 437 | 151 | 104 | 210 | 358 | 672 | 624 | 647 | 716 | 424 | 587 | 817 | 489 | 337 | 412 | 740 | 580 | 445 |
|       |      | 10  | 493 | 204 | 319 | 563 | 629 | 264 | 138 | 139 | 151 | 471 | 401 | 227 | 168 | 490 | 440 | 629 | 347 | 609 | 346 | 351 | 158 | 177 | 424 | 500 | 360 |

VALUES ARE EXPRESSED IN GAMMAS
MEAN
Table 2. AO Indices

| UT | 1976  |
|----|-------|
| 01 | -062 -101 -104 -003 -066 -014  |
| 02 | -026 -006 -02 -003 -066 -011  |
| 03 | -140 -243 -045 -012 -012 -012  |
| 04 | -165 -094 -101 -008 -013 -013  |
| 05 | 010 -003 -037 -006 -052 -001  |
| 06 | 015 -028 -106 -001 -001 -001  |
| 07 | -114 -321 -008 -025 -025 -025  |
| 08 | -279 -239 -009 -029 -029 -029  |
| 09 | -157 -005 -031 -031 -031 -031  |
| 10 | 011 -016 -022 -008 -015 -015  |
| 11 | -263 -250 -084 -084 -084 -084  |
| 12 | -154 -153 -013 -013 -013 -013  |
| 13 | 039 -233 -013 -013 -013 -013  |
| 14 | -030 -117 -087 -087 -087 -087  |
| 15 | -027 -015 -008 -008 -008 -008  |
| 16 | -054 -021 -022 -005 -005 -005  |
| 17 | -156 -146 -057 -057 -057 -057  |
| 18 | 081 -065 -013 -013 -013 -013  |
| 19 | 018 -023 -023 -023 -023 -023  |
| 20 | -046 -016 -009 -009 -009 -009  |
| 21 | 014 -008 -008 -008 -008 -008  |
| 22 | 002 -002 -002 -002 -002 -002  |
| 23 | 005 -006 -006 -006 -006 -006  |
| 24 | 003 -007 -007 -007 -007 -007  |
| 25 | 007 -007 -007 -007 -007 -007  |
| 26 | -041 -049 -089 -136 -136 -136  |
| 27 | -135 -285 -123 -123 -123 -123  |
| 28 | -262 -116 -004 -004 -004 -004  |
| 29 | -032 -200 -162 -089 -142 -142  |
| 30 | -001 -005 -002 -012 -004 -004  |
| 31 | -092 -071 -002 -009 -036 -036  |

Values are expressed in gammas.
Table 3. AU Indices

VALUES ARE EXPRESSED IN GAMMAS

| MARCH 1976 UT | 1   | 2   | 3   | 4   | 5   | 6   | 7   | 8   | 9   | 10| 11| 12| 13| 14| 15| 16| 17| 18| 19| 20| 21| 22| 23| 24| MEAN |
|----------------|-----|-----|-----|-----|-----|-----|-----|-----|-----|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 01             | 111 | 055 | 064 | 161 | 137 | 064 | 084 | 063 | 085 | 035 | 046 | 155 | 062 | 057 | 083 | 065 | 071 | 045 | 062 | 043 | 065 | 054 | 060 | 055 | 074 |
| 02             | 021 | 13 - | 078 | 068 | 070 | 088 | 078 | 023 | 084 | 045 | 065 | 051 | 049 | 051 | 040 | 055 | 048 | 060 | 041 | 058 | 044 | 050 | 059 | 073 |
| 03             | 061 | 078 | 036 | 084 | 045 | 051 | 049 | 051 | 040 | 055 | 048 | 060 | 041 | 058 | 044 | 050 | 059 | 073 | 071 | 078 | 075 | 073 | 077 | 069 |
| 04             | 024 | 028 | 023 | 019 | 019 | 030 | 048 | 042 | 016 | 028 | 013 | 035 | 086 | 042 | 055 | 020 | 024 | 021 | 018 | 014 | 016 | 018 | 029 |

MEAN

Q 21 Q 22 Q 23 Q 24 Q 25

D 26 D 27 D 28 D 29 D 30 D 31
Mean 051 057 068 055 059

5Q MEAN Layering
Mean 024 029 028 021 025 029 039 033 029 024 020 018 031 022 020 023 028
Table 4. AL Indices

| MARCH | UT | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 MEAN |
|-------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1976  |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 01    | -237 -258 -272 -270 -268 -266 -264 -262 -260 -258 -256 -254 -252 -250 -248 -246 -244 -242 -240 -238 -236 -234 -232 |
| 02    | -281 -292 -303 -314 -325 -336 -347 -358 -369 -380 -391 -402 -413 -424 -435 -446 -457 -468 -479 -490 -501 -512 -523 |
| 03    | -397 -418 -439 -460 -481 -502 -523 -544 -565 -586 -607 -628 -649 -670 -691 -712 -733 -754 -775 -796 -817 -838 -859 |
| 04    | -416 -437 -458 -479 -499 -520 -541 -562 -583 -604 -625 -646 -667 -688 -709 -730 -751 -772 -793 -814 -835 -856 -877 |
| 05    | -405 -426 -447 -468 -489 -510 -531 -552 -573 -594 -615 -636 -657 -678 -699 -720 -741 -762 -783 -804 -825 -846 -867 |
| 06    | -444 -465 -486 -507 -528 -549 -570 -591 -612 -633 -654 -675 -696 -717 -738 -759 -780 -801 -822 -843 -864 -885 -906 |
| 07    | -348 -369 -390 -411 -432 -453 -474 -495 -516 -537 -558 -579 -599 -620 -641 -662 -683 -704 -725 -746 -767 -788 -809 |
| 08    | -605 -626 -647 -668 -689 -710 -731 -752 -773 -794 -815 -836 -857 -878 -899 -920 -941 -962 -983 -1004 -1025 -1046 -1067 |
| 09    | -041 -062 -083 -104 -125 -146 -167 -188 -209 -230 -251 -272 -293 -314 -335 -356 -377 -398 -419 -440 -461 -482 -503 |
| 10    | -404 -425 -446 -467 -488 -509 -530 -551 -572 -593 -614 -635 -656 -677 -698 -719 -740 -761 -782 -803 -824 -845 -866 |
| 11    | -523 -442 -361 -280 -200 -119 -40 -59 -78 -97 -116 -135 -154 -173 -192 -211 -230 -249 -268 -287 -306 -325 -344 -363 |
| 12    | -373 -292 -211 -130 -49 -68 -87 -106 -125 -144 -163 -182 -201 -220 -239 -258 -277 -296 -315 -334 -353 -372 -391 -410 |
| 13    | -157 -568 -361 -154 -63 -72 -81 -90 -99 -108 -117 -126 -135 -144 -153 -162 -171 -180 -189 -198 -207 -216 -225 -234 |
| 14    | -167 -300 -368 -143 -52 -61 -70 -79 -88 -97 -106 -115 -124 -133 -142 -151 -160 -169 -178 -187 -196 -205 -214 -223 |
| 15    | -108 -374 -661 -134 -43 -52 -61 -70 -79 -88 -97 -106 -115 -124 -133 -142 -151 -160 -169 -178 -187 -196 -205 -214 |
| 16    | -176 -97 -104 -256 -122 -051 -061 -071 -081 -091 -101 -111 -121 -131 -141 -151 -161 -171 -181 -191 -201 -211 -221 |
| 17    | -388 -357 -194 -133 -219 -154 -259 -199 -244 -194 -239 -189 -234 -184 -229 -179 -224 -174 -219 -169 -214 -164 -209 |
| 18    | -277 -236 -111 -024 -062 -055 -096 -150 -095 -149 -094 -148 -093 -147 -092 -146 -091 -145 -090 -144 -089 -143 -088 |
| 19    | -011 -104 -067 -032 -107 -153 -197 -225 -199 -234 -193 -229 -188 -225 -183 -222 -178 -218 -173 -212 -168 -207 -163 |
| 20    | -005 -019 -051 -064 -032 -087 -061 -236 -192 -227 -191 -222 -186 -217 -181 -212 -172 -203 -164 -194 -160 -185 -155 |
| 21    | -004 -006 -011 -014 -036 -021 -026 -101 -049 -065 -020 -044 -017 -058 -031 -071 -040 -061 -029 -050 -039 -049 -028 |
| 22    | -006 -012 -011 -009 -006 -006 -032 -008 -010 -007 -010 -008 -010 -009 -010 -009 -010 -009 -010 -009 -010 -009 -010 |
| 23    | -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 -001 |
| 24    | -038 -136 -083 -033 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 -003 |
| 25    | -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 -000 |
| 26    | -133 -165 -239 -340 -222 -547 -756 -672 -545 -458 -361 -274 -187 -100 -11 -112 -123 -134 -145 -156 -167 -178 -189 -190 |
| 27    | -340 -578 -340 -222 -547 -756 -672 -545 -458 -361 -274 -187 -100 -11 -112 -123 -134 -145 -156 -167 -178 -189 -190 |
| 28    | -568 -303 -303 -089 -239 -428 -229 -115 -064 -046 -026 -016 -006 -006 -006 -006 -006 -006 -006 -006 -006 -006 -006 |
| 29    | -121 -454 -454 -339 -373 -408 -267 -228 -054 -093 -080 -026 -026 -026 -026 -026 -026 -026 -026 -026 -026 -026 -026 |
| 30    | -026 -027 -022 -050 -030 -027 -116 -140 -232 -131 -127 -120 -252 -221 -225 -225 -225 -225 -225 -225 -225 -225 -225 |
| 31    | -268 -245 -081 -045 -082 -045 -065 -072 -050 -068 -093 -093 -093 -093 -093 -093 -093 -093 -093 -093 -093 -093 -093 |
| MEAN  | -202 -243 -200 -193 -191 -148 -127 -115 -115 -115 -115 -115 -115 -115 -115 -115 -115 -115 -115 -115 -115 -115 -115 |
| 5Q MEAN| -010 -031 -024 -013 -010 -024 -071 -033 -027 -038 -034 -034 -034 -034 -034 -034 -034 -034 -034 -034 -034 -034 -034 |
| 50 MEAN| -305 -323 -429 -450 -312 -198 -221 -158 -216 -234 -178 -224 -224 -224 -224 -224 -224 -224 -224 -224 -224 -224 -224 |

VALUES ARE EXPRESSED IN GAMMAS
### Table 5. Observatories Supplying Hourly AU Based on Mean Values

**MARCH 1976**

| UT | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|
|    | BW | BW | BW | BW | BW | BW | TI | BW | TI | DI | DI | DI | AI | LR | LR | AI | BW | NAS | LR | FC | BW | FC |
|    | BW | BW | BW | BW | BW | BW | BW | BW | LR | DI | DI | DI | AI | LR | AI | LR | LR | LR | NAS | FC | FC | FC |
|    | BW | BW | BW | BW | BW | BW | TI | TI | TI | LR | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | BW | BW | BW | BW | BW | BW | BW | BW | TI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | BW | BW | BW | BW | BW | BW | BW | BW | TI | DI | TI | TI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | NAS | FC | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | TI | DI | NAS | BW | DI | AI | AI | LR | LR | LR | NAS | LR | FC | FC |
|    | FC | BW | BW | BW | BW | BW | BW | BW | BW | TI | NAS | DI | DI | DI | TI | AI | AI | AI | LR | LR | LR | NAS | NAS | FC | FC |
|    | BW | BW | BW | BW | BW | BW | TI | BW | DI | DI | DI | TI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | BW | BW | BW | BW | BW | BW | TI | TI | TI | BW | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | FC | BW | BW | BW | BW | BW | BW | BW | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI |
|    | FC | FC | TI | TI | DI | TI | LR | TI | LR | LR | DI | DI | DI | DI | AI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | DI | DI | DI | TI | AI | LR | DI | LR | LR | NAS | LR | BW | FC | FC |
|    | FC | BW | BW | FC | BW | BW | BW | BW | BW | BW | BW | BW | TI | TI | TI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | FC | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | TI | TI | TI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | FC | FC | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI |
|    | FC | FC | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI |
|    | Q21 | NAS | FC | FC | FC | FC | BW | BW | BW | BW | BW | BW | TI | TI | BW | BW | DI | DI | DI | DI | DI | DI | DI | DI |
|    | Q22 | DI | FC | FC | FC | BW | BW | BW | BW | BW | BW | BW | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | Q23 | FC | FC | FC | FC | BW | BW | BW | BW | BW | BW | BW | TI | TI | TI | FC | FC | TI | LR | LR | AI | NAS | NAS | FC | FC |
|    | Q24 | FC | FC | FC | FC | FC | BW | BW | BW | BW | BW | BW | DI | DI | DI | AI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | Q25 | FC | BW | BW | FC | BW | BW | BW | BW | BW | BW | BW | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI | TI |
|    | D26 | FC | FC | BW | BW | TI | TI | DI | AI | FC | AI | AI | AI | AI | LR | LR | LR | LR | LR | LR | LR | LR | LR | LR |
|    | D27 | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | BW | TI | LR | NAS | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | 28 | BW | BW | FC | BW | BW | BW | BW | BW | LR | NAS | DI | DI | DI | AI | LR | LR | LR | LR | LR | LR | LR | LR | LR |
|    | 29 | FC | BW | BW | BW | BW | DI | BW | TI | TI | TI | TI | TI | TI | TI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | 30 | FC | FC | FC | FC | BW | BW | BW | BW | BW | TI | TI | TI | TI | TI | TI | DI | DI | DI | DI | DI | DI | DI | DI | DI |
|    | 31 | FC | BW | FC | BW | BW | BW | BW | BW | TI | TI | TI | TI | TI | TI | DI | DI | DI | DI | DI | DI | DI | DI | DI | DI |

**IDENTIFICATION**

- **GEOGRAPHIC**
  - LAT
  - LONG

- **GEOMAGNETIC**
  - LAT
  - LONG

**IDENTIFICATION**

- **GEOGRAPHIC**
  - LAT
  - LONG

- **GEOMAGNETIC**
  - LAT
  - LONG

* The seven observatories providing data for this report. Remaining stations will be added as their records become available in time for processing.

*AI = ABISKO*
*BW = BARROW*
*CC = C. CHELYUSKIN*
*CO = COLLEGE*
*GWR = GREAT WHALE R.*
*DI = DIXON ISLAND*
*FC = FT. CHURCHILL*
*LR = LEIRVOGUR*
*NAS = NARSSARSSUAQ*
*TI = TIXIE BAY*
*UE = CAPE WELLEN*
Table 6. Observatories Supplying Hourly AL Based on Mean Values

| MARCH | UT   | IDENTIFICATION | GEOGRAPHIC | GEOMAGNETIC | IDENTIFICATION | GEOGRAPHIC | GEOMAGNETIC |
|-------|------|----------------|------------|-------------|----------------|------------|-------------|
|       |      |                |            |             |                |            |             |
| 1     | AI   | LR             | FC         | FC          | FC             | FC         | FC          |
| 2     | AI   | LR             | NAS        | NAS         | NAS            | NAS        | NAS         |
| 3     | AI   | LR             | NAS        | NAS         | NAS            | NAS        | NAS         |
| 4     | AI   | LR             | NAS        | NAS         | NAS            | NAS        | NAS         |
| 5     | AI   | NAS            | FC         | FC          | FC             | FC         | FC          |
| 6     | AI   | LR             | LR          | FC          | FC             | BW         | BW          |
| 7     | AI   | LR             | LR          | NAS         | NAS            | NAS        | NAS         |
| 8     | AI   | LR             | LR          | NAS         | NAS            | NAS        | NAS         |
| 9     | D10  | AI             | AI          | AI          | AI             | AI         | AI          |
| 10    | AI   | LR             | LR          | FC          | FC             | FC         | FC          |
| 11    | AI   | LR             | LR          | NAS         | NAS            | NAS        | NAS         |
| 12    | AI   | LR             | LR          | NAS         | NAS            | NAS        | NAS         |
| 13    | AI   | LR             | LR          | NAS         | NAS            | NAS        | NAS         |
| 14    | AI   | LR             | LR          | NAS         | NAS            | NAS        | NAS         |
| 15    | AI   | LR             | LR          | NAS         | NAS            | NAS        | NAS         |
| 16    | AI   | LR             | LR          | NAS         | NAS            | NAS        | NAS         |
| 17    | AI   | LR             | LR          | FC          | FC             | BW         | BW          |
| 18    | Q21  | TI             | TI          | NAS         | NAS            | NAS        | NAS         |
| 19    | Q22  | TI             | TI          | NAS         | NAS            | NAS        | NAS         |
| 20    | Q23  | TI             | TI          | NAS         | NAS            | NAS        | NAS         |
| 21    | Q24  | TI             | TI          | NAS         | NAS            | NAS        | NAS         |
| 22    | Q25  | NAS            | TI          | TI          | TI             | TI         | TI          |
| 23    | D26  | LR             | LR          | LR          | LR             | LR         | LR          |
| 24    | D27  | AI             | LR          | LR          | LR             | LR         | LR          |
| 25    | D28  | LR             | LR          | LR          | LR             | LR         | LR          |
| 26    | D29  | LR             | LR          | LR          | LR             | LR         | LR          |
| 27    | D30  | TI             | TI          | TI          | TI             | TI         | TI          |
| 28    | D31  | LR             | LR          | NAS         | NAS            | NAS        | NAS         |

* The seven observatories providing data for this report. Remaining stations will be added as their records become available in time for processing.

AL = MINIMUM DELTA H
5. Statistical Information

Table 7. Station Frequency of AU and AL Contribution.

| STA | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
|-----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|
| AU- LR | 24 | 0  | 0  | 33 | 21 | 38 | 111| 99 | 246| 190| 36 | 45 | 56 | 137| 192| 353| 713| [556]| 732| 393| 333| 210| 73 | 136|
| AL- LR | 523| 830| 1059| 718| 636| 241| 109| 10 | 31 | 55 | 119| 139| 96 | 36 | 101| 29 | 13 | 8  | 4  | 0  | 9  | 71 | 194| 443|
| AU- NAS | 174| 7  | 1  | 3  | 4  | 0  | 0  | 3  | 61 | 144| 76 | 36 | 48 | 10 | 7  | 45 | 186| 309| 565| [953]| 655| 372| 399| 343|
| AL- NAS | 85 | 207| 337| 677| 763| 1274| 1042| 722| 420| 80 | 53 | 4  | 63 | 98 | 99 | 142| 37 | 5  | 6  | 2  | 9  | 12 | 6  | 8  |
| AU- FC  | 969| 921| 607| 505| 200| 69 | 13 | 12 | 28 | 25 | 19 | 15 | 76 | 75 | 151| 143| 87 | 38 | 32 | 105| 407| 881| [1084]| 1014|
| AL- FC  | 1  | 38 | 58 | 109| 181| 167| 464| 877| 915| 1005| 933| 962| 760| 562| 274| 167| 121| 144| 192| 213| 132| 60 | 6  | 3  |
| AU- BW  | 630| 838| 1093| 1127| 1353| [1439]| 1424| 1035| 833| 551| 312| 210| 75 | 40 | 61 | 168| 192| 246| 285| 214| 300| 279| 202| 313|
| AL- BW  | 17 | 8  | 3  | 23 | 27 | 0  | 63 | 117| 272| 401| 583| 645| 775| 905| 1035| [1044]| 754| 451| 236| 168| 87 | 77 | 85 | 65 |
| AU- TI  | 1  | 18 | 50 | 98 | 68 | 131| 167| 431| 383| 509| [594]| 566| 387| 180| 157| 40 | 23 | 22 | 3  | 0  | 0  | 0  | 4  | 0  |
| AL- TI  | 326| 266| 222| 239| 182| 29 | 10 | 0  | 2  | 5  | 14 | 7  | 28 | 102| 236| 324| 592| [627]| 509| 409| 482| 437| 419| 345|
| AU- DI  | 62 | 76 | 109| 89 | 174| 151| 119| 241| 268| 389| 725| 918| [1039]| 1012| 743| 674| 308| 81 | 28 | 35 | 101| 92 | 50 |
| AL- DI  | 58 | 28 | 12 | 13 | 58 | 144| 164| 111| 141| 61 | 14 | 20 | 64 | 47 | 73 | 128| 319| 621| 908| [953]| 886| 605| 441| 266|
| AU- AI  | 0  | 0  | 0  | 5  | 40 | 32 | 26 | 39 | 41 | 52 | 98 | 70 | 179| 406| [549]| 437| 351| 308| 215| 163| 130| 17 | 6  | 4  |
| AL- AI  | 850| 483| 169| 81 | 13 | 5  | 8  | 23 | 79 | 253| 144| 83 | 74 | 10 | 42 | 26 | 24 | 4  | 5  | 118| 255| 598| 709| 730|

Table 8. Monthly Quiet-Time H Reference Values.

| Station | March 1976 |
|---------|-------------|
| LR      | 12334 gammas |
| NAS     | 11950       |
| FC      | 7330        |
| BW      | 9841        |
| TI      | 7949        |
| DI      | 6493        |
| AI      | 11822       |
UAG Series of Reports

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UAG-51 "Synoptic Maps of Solar Coronal Hole Boundaries Derived from He II 304Å Spectroheliograms from the Manned Skylab Missions", by J. D. Bohlin and D. M. Rubenstein, E. O. Hulbert Center for Space Research, Naval Research Laboratory, Washington, D. C. 20375 U.S.A., November 1975, 30 pages, price 54 cents.

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UAG-56 "Iso-intensity Contours of Ground Magnetic H Perturbations for the December 16-18, 1971 Geomagnetic Storm", by Y. Kamide, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80302 and Geophysical Institute, University of Alaska, Fairbanks, Alaska 99701 (currently Guest worker at Data Studies Division, NOAA/EDS/NGSDC, Boulder, Colorado 80302), April 1976, 37 pages, price $1.39.

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