WORLD DATA CENTER A for Solar-Terrestrial Physics THE ALASKA IMS MERIDIAN CHAIN: MAGNETIC VARIATIONS FOR 9 MARCH-27 APRIL 1978 June 1980 WORLD DATA CENTER A National Academy of Sciences 2101 Constitution Avenue, N.W. Washington, D.C., U.S.A., 20418 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 [Snow and Ice]: World Data Center A: Glaciology [Snow and Ice] Inst. of Arctic & Alpine Research University of Colorado Boulder, Colorado, U.S.A. 80309 [Telephone: (303) 492-5171] 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] Oceanography: World Data Center A: Oceanography National Oceanic and Atmospheric Administration Washington, D.C., U.S.A. 20235 [Telephone: (202) 634-7249] Rockets and Satellites: World Data Center A: Rockets and Satellites Goddard Space Flight Center Code 601 Greenbelt, Maryland, U.S.A. 20771 [Telephone: (301) 344-6695] 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] 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 and Information Service, NOAA Boulder, Colorado, U.S.A. 80303 [Telephone: (303) 499-1000, Ext. 6467] 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 and Information Service, NOAA Boulder, Colorado, U.S.A. 80303 [Telephone: (303) 499-1000, Ext. 6521] 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. WORLD DATA CENTER A for Solar-Terrestrial Physics REPORT UAG-75 THE ALASKA IMS MERIDIAN CHAIN: MAGNETIC VARIATIONS FOR 9 MARCH-27 APRIL 1978 H.W. Kroehl and G.P. Kosinski National Geophysical and Solar-Terrestrial Data Center S.-I. Akasofu, G.J. Romick, C.E. Campbell and G.K. Corrick Geophysical Institute, University of Alaska C.E. Hornback and A.M. Gray Space Environment Laboratory June 1980 Published by World Data Center A for Solar-Terrestrial Physics, NOAA, Boulder, Colorado and printed by U.S. DEPARTMENT OF COMMERCE NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION ENVIRONMENTAL DATA AND INFORMATION SERVICE Boulder, Colorado, USA 80303 SUBSCRIPTION PRICE: $25.20 a year; $17.30 additional for foreign mailing; single copy price varies.* Checks and money orders should be made payable to the Department of Commerce, NOAA/NGSDC. Remittance and correspondence regarding subscriptions should be sent to the National Geophysical and Solar-Terrestrial Data Center, NOAA, Boulder, CO 80303. CONTENTS Page The International Magnetospheric Study, IMS ............. 1 U.S. IMS Participation .................................. 1 The Alaskan Chain ....................................... 2 Data Availability ....................................... 3 Daily Magnetic Variations Along Alaska Chain .......... 3 Average Magnetic Variations Along Alaska Chain ....... 3 References ............................................. 4 Acknowledgments ......................................... 4 Appendix: Daily Stack and Polar Plots of Alaska Chain Magnetic Variations (9 Mar - 27 Apr 1978) ............ 6 THE ALASKA IMS MERIDIAN CHAIN: MAGNETIC VARIATIONS FOR 9 MARCH - 27 APRIL 1978 by H.W. Kroehl¹, S.-I. Akasofu², G.J. Romick², G.P. Kosinski¹, C.E. Campbell¹, G.K. Corrick¹, C.E. Hornback¹ and A.M. Gray¹ ¹Data Studies Division, NOAA/EDIS/NGSDC, Boulder, CO 80303 ²Geophysical Institute, University of Alaska, Fairbanks, AK Space Environment Services Center, NOAA/ERL/SEL, Boulder, CO 80303 The International Magnetospheric Study, IMS (Text is adapted from a National Academy of Sciences report on the IMS [1974]). Recognizing the need for a more completely detailed understanding of the magnetosphere, the International Council of Scientific Unions through its Special (now Scientific) Committee on Solar-Terrestrial Physics launched the IMS, a carefully designed and highly coordinated program of spacecraft recordings together with ground-based, balloon, and rocket observing campaigns. The task of coordinating this multiplatform observing program fell upon the Satellite Situation Center and the IMS Central Information Exchange Office. The general scientific goals of IMS attempt to define and understand the key physical processes associated with the energy, mass, and momentum transfer from the solar wind to the magnetosphere and atmosphere. These energy-transfer mechanisms involve diverse phenomena such as direct particle injection, magnetic energy storage, local particle acceleration, electromagnetic waves, traveling ionospheric disturbances, and Joule heating of the ionosphere. Ionospheric manifestations of magnetospheric energy release, called magnetospheric substorms, characteristically have large-scale spatial, temporal, and amplitude variability. Geomagnetic observations provide the global basis for ground-based research during the IMS. They generate a unique and basic measure of the state of the magnetosphere for a number of reasons. Ground-based magnetometers record information about a variety of phenomena, ranging from the interaction of the solar wind with the magnetosphere to currents flowing in the upper atmosphere. The magnetometers operate as well in sunlight as in darkness and the recordings are unaffected by cloud cover, rain, or snow. Moreover, ground-based magnetometers require low telemetry rates, and their relative simplicity makes them well suited for unmanned operation. Differing spatial and temporal patterns of magnetic variations at different latitudes indicate that the distribution of magnetometer stations can be nonuniform. Near the geomagnetic equator, several stations are required to determine the global diurnal variations that dominate this region and result from the equatorial electrojet. At midlatitude in the Northern Hemisphere, a longitudinal chain of magnetometers is vital to the definition of substorm effects in the ionosphere and magnetosphere. Through the auroral zone and polar cap, latitudinal chains of stations spaced 1° apart are necessary to define and discriminate spatial from temporal variations of the ionospheric currents and supplying field-aligned currents. U.S. IMS Participation In support of the coordination aspects of the IMS, the United States established the Satellite Situation Center (SSC) and the IMS Central Information Exchange (IMSCIE) offices. The IMSCIE office, operated by NOAA/NGSDC and headed by J.H. Allen, publishes the monthly IMS Newsletter containing program plans, successful experiments and items of general interest. In addition to providing data and information for the IMS Newsletter, the SSC, operated by NASA/NSSDC and headed by Dr. James I. Vette, compiles and updates the Directory of Spacecraft and Experiment Scientific Contacts and computes and distributes the times of satellite conjunctions. The SSC has also conducted the Coordinated Data Analysis Workshops, a unique approach to the analysis of multidisciplinary data sets. Of central interest to this report is the U.S.-supported geomagnetic observations program of installing magnetometers, radio transmitters (for communications with SMS/GOES satellites) and/or magnetic tape recorders at 28 sites to complement/upgrade existing networks and facilities. The three meridional chains of stations crossing the north polar region of the Western Hemisphere are identified in IMS Newsletter 77-1 [1977] as the Alaska Chain, 12 stations between N61 and N89 near E265 (corrected geomagnetic coordinates); the Alberta Chain, nine stations between N62 and N71 near E304; and the Fort Churchill Chain, nine stations between N62 and N80 near B327. The U.S. IMS effort supports 10 Alaska Chain stations, one Alberta Chain station and six Fort Churchill Chain stations. One zonal chain located in the auroral zone and identified as the East-West Chain consists of seven stations near N68 and lies between E354 and E261; the other, called the Midlatitude Chain, consists of eight stations near N19 and lies between E32 and E214 (from east to west). Here the U.S. IMS effort supports six East-West stations and all eight Midlatitude stations. Funding for the U.S. IMS effort was provided by the National Science Foundation and NOAA. The Alaskan Chain The stations that at one time or another have been part of the Alaska Chain are identified in Figure 1. It should be noted that the quality of Isachsen data comes under question on 18 March 1978 and Talkeetna began operating in May 1978. The Geophysical Institute of the University of Alaska operates the IMS equipment at Eureka, Isachsen, Johnson Point, Sachs Harbor, Cape Parry, Inuvik, Arctic Village, Fort Yukon, and Talkeetna. The College magnetometer is operated by the U.S. Geological Survey as standard magnetic observatory. The Mould Bay magnetometer is operated by the Canadian Department of Energy, Mines and Resources as a standard magnetic observatory. The Anchorage magnetometer is part of the High-Latitude Monitoring Station operated by NOAA/Space Environment Laboratory (SEL). All instruments except the Anchorage one are triaxial fluxgate magnetometers.
Station Invariant Latitude
1 EUREKA 89.0°
2 ISACHSEN 85.2°
3 MOULD BAY 80.7°
4 JOHNSON POINT 77.6°
5 SACHS HARBOR 76.0°
6 CAPE PARRY 74.4°
7 INUVIK 71.0°
8 ARCTIC VILLAGE 68.6°
9 FORT YUKON 67.1°
10 COLLEGE 64.9°
11 TALKEETNA 62.9°
12 ANCHORAGE 60.8°
Fig. 1. The IMS Alaska Meridian Chain of geophysical observatories. Because of the expeditious manner in which these data were obtained, the standard IMS routine for data handling was not followed. Each station's location, component data received and data transfer mechanism are identified in Table 1. Analog records of X, Y and Z variations recorded at Eureka, Isachsen (9-17 March 1978) and Mould Bay (9-23 March 1978) were digitized at 1-min intervals. One-min Mould Bay X, Y and Z variations for 24 March - 27 April 1978 were received on magnetic tape. Ten-second D, H and Z variations data from Johnson Point through Arctic Village were telemetered via SMS/GOES satellites to SEL in Boulder. After processing, 5-min averages were recorded on magnetic tape and forwarded by SEL. The 1-min values of D, H and Z variations from Fort Yukon, College, and Anchorage also were received from SEL but were transmitted to Boulder via the High-Latitude Monitoring Station. Due to the different formats of the data (1-min point values, 1-min average values and 5-min average values of X, Y and Z or D, H and Z), initial efforts involved the development of a consistent data base. We chose to use 5-min average values of \( \Delta X_m \), \( \Delta Y_m \) and \( \Delta Z_m \), defined as variations in the invariant northward, eastward, and nadir directions, respectively, from a "quiet-day reference level." Average values were calculated, the 12 March 1978 average value was subtracted, and the resulting values were "rotated" appropriately for each station. These data comprise the plots shown on succeeding pages for the seven northernmost stations, namely Eureka through Inuvik. Table 1. Alaska Chain Data for 9 March - 27 April 1978
GEOGRAPHIC LAT. E. LONG. GEO MAGNETIC LAT. E. LONG. CORRECTED GEOMAGNETIC INVAR. SAMPLE MEDIUM COMMENTS
LAT. E. LONG. LAT.
Eureka 80.0 274.3 86.7 236.5 89.1 258.4 89.0 X, Y, Z Paper1
Isachsen 78.8 256.0 83.4 251.3 85.2 262.0 85.2 X, Y, Z Paper1
Mould Bay 76.2 240.6 79.1 256.4 80.6 263.5 80.7 X, Y, Z Paper1
X, Y, Z 1 min Tape 24 Mar - 27 Apr.
Johnson Pt. 72.5 241.7 76.9 271.7 78.0 276.4 77.6 D, H, Z 5 min Tape SELDADS2
Sachs Harbor 72.0 234.7 75.2 266.2 76.1 270.3 76.0 D, H, Z 5 min Tape SELDADS2
Cape Parry 70.2 235.3 73.9 270.9 74.7 274.2 74.4 D, H, Z 5 min Tape SELDADS2
Inuvik 68.3 226.7 70.6 266.2 71.1 269.0 71.0 D, H, Z 5 min Tape SELDADS2
Arctic Village 68.1 214.4 68.1 253.3 68.5 258.9 68.6 D, H, Z 5 min Tape SELDADS2
Ft. Yukon 66.6 214.7 66.8 257.6 67.0 260.7 67.1 D, H, Z 1 min Tape HIMS3
College 64.7 211.9 64.8 257.1 64.9 260.3 64.9 D, H, Z 1 min Tape HIMS3
Anchorage 61.2 210.1 61.0 258.1 60.9 260.7 60.8 D, H, Z 1 min Tape HIMS3
1Hand digitized 1-min point values 2Space Environment Laboratory Data Acquisition and Display System 3High-Latitude Monitoring Station Additional adjustments were required to the data from the four lowest latitude stations, because the "quiet-time reference level" was defined as the 6-h average value centered about 0000 UT (1244 magnetic local time). This value was then subtracted from each \( \Delta X_m, \Delta Y_m \) and \( \Delta Z_m \), for that day. Supplemental adjustments were made to the data recorded on 27 March 1978 and on 4, 5, 11, 15, 20, 23 and 24 April 1978 due to large daytime variations. The resulting data are shown on succeeding pages for Arctic Village through Anchorage. Data Availability The World Data Center A for Solar-Terrestrial Physics archives the IMS data from the Alaska, Alberta, Fort Churchill, East-West, and Midlatitude Chains. The variations data on magnetic tape are 1-min average values in the recording coordinate system, either geographic X, Y and Z or local D, H and Z, with respect to an arbitrary reference level. Inquiries should be directed to Mr. William Paulishak, World Data Center A for Solar-Terrestrial Physics, NOAA, D63, Boulder, CO 80303 USA. We would like to encourage the scientific community to use these unique data sets resulting from the IMS. It has been a major effort by many individuals and organizations to install and maintain the equipment and to process the data. Since the observing period is scheduled to the end of last year, it is now up to the scientific community to justify the outlay by using the data to better understand magnetospheric substorms and polar cap variations. Daily Magnetic Variations Along Alaska Chain The appendix contains stack plots of \( \Delta X_m, \Delta Y_m \) and \( \Delta Z_m \), generated from 5-min average values and a daily polar plot of half-hourly vectors of horizontal variations recorded along the Alaska Meridian Chain for 9 March - 25 April 1978. The stations organized by decreasing invariant latitude (see Table 1) are Eureka (EUR), Isachsen (ISA), Mould Bay (MOB), Johnson Point (JOP), Sachs Harbor (SAH), Cape Parry (CAP), Inuvik (INU), Arctic Village (AVV), Fort Yukon (FYU), College (COL), and Anchorage (ANC). The "quiet-time reference level" is noted by a tick mark and a zero; the tick marks along the y axis are spaced 250 nT apart. Coordinates of the polar plot are invariant latitude and time. The solid triangle outside the plot notes the average invariant time of the chain at 2330 UT. The position of the chain in these coordinates for each UT hour is shown in Figure 4. Average Magnetic Variations Along Alaska Chain In Figures 2 and 3, we show polar plots of the average day magnetic variations and "equivalent" currents. The magnetic variations are a simple average of the half-hourly values from each day. These vectors were then rotated 90° clockwise to approximate an equivalent ionospheric current system. Due to the large spatial and temporal variability of magnetospheric substorms, these plots should not be interpreted as a typical substorm equivalent current system (Kroehl and Richmond 1979 and Kamide 1979) but as the average magnetic variations recorded along the Alaska Chain for these days. From the equivalent current plot certain polar features are evident: namely, the eastward and westward auroral electrojet, the Harang discontinuity (northward equivalent current), the polar cap diurnal variation, and a dayside current most probably associated with the polar cleft. The least disturbed day is 12 March 1978 and the most disturbed day is 27 March 1978. Other days of interest are 14 and 30 March 1978 and 18, 20 and 22 April 1978. A computer-generated cine film has been made from the half-hourly polar plots and shows the temporal variations of the horizontal variation vectors for 9 March - 25 April 1978. The movie is on 16-mm film and runs for 7 min. Copies may be obtained for the cost of reproduction from H.W. Kroehl, NOAA/NGSDC, D64, Boulder, CO 80303 USA. References
Author(s) Year Title
KROEHL, H.W. and RICHMOND, A.D. 1979 "Magnetic Substorm Characteristics Described by Magnetic Potential Maps for 26-28 March 1976," in Dynamics of the Magnetosphere, S.-I. Akasofu (ed.), D. Reidel Pub. Co., New York, N.Y., pp. 269-286.
KAMIDE, Y. and MATSUSHITA, S. 1979 "Simulation Studies of Ionospheric Electric Fields and Currents in Relation to Field-Aligned Currents 2. Substorms," J. Geophys. Res., v. 84, no. A8, pp. 4099-4115.
NAS 1974 International Magnetospheric Study, Detailed Plan for a U.S. Ground-Based Research Program National Academy of Sciences, Washington, DC.
IMS Newsletter 1977 "North American Magnetometer Network," in IMS Newsletter 77-1, J.H. Allen, Ed. (National Geophysical and Solar-Terrestrial Data Center, Boulder, Colorado, USA 80303), pp. 5-7.
Acknowledgments The scientific community is indebted to many individuals and organizations in these closing days of the IMS observing period. The geomagnetic program is a truly multiorganizational effort involving the University of Alaska; the University of California at Los Angeles; the State University of New York at Albany; the University of Alberta; the Department of Energy, Mines and Resources (Canada); the Geological Survey; the National Oceanographic and Atmospheric Administration and the National Science Foundation. The principal investigators for the 5 chains are Dr. S.-I. Akasofu, Dr. G.J. Komack, Dr. R.L. McPherron, Dr. Kim, Dr. G. Rostoker and Dr. J. Walker. Individuals responsible for the Alaska Chain include A.H. Shapley and J.H. Allen of NGSDC; B.S. Delana of the University of Alaska; D.J. Williams, R.N. Grubb, P.L. Orswell, J.D. Schroeder and J.C. Joselyn of SEL; and J.A. Bradley and R. Kuberry of USGS. The Average Day Magnetic Variations ![Polar plot of the average day magnetic variations for 9 March to 27 April 1978. The variations shown represent simple averages of the half-hourly values from each day.](page_153_120_1042_627.png) Fig. 2. Polar plot of the average day magnetic variations for 9 March to 27 April 1978. The variations shown represent simple averages of the half-hourly values from each day. The Average Day Equivalent Currents ![Polar plot of the average day "equivalent" currents for 9 March to 27 April 1978. Diagram was generated by rotating the vectors of Figure 2 clockwise 90°.](page_153_820_1042_627.png) Fig. 3. Polar plot of the average day "equivalent" currents for 9 March to 27 April 1978. Diagram was generated by rotating the vectors of Figure 2 clockwise 90°. Fig. 4. Hourly location of Alaska Meridian Chain. Following Pages: APPENDIX Daily Stack and Polar Plots of Alaska Chain Magnetic Variations (9 Mar - 27 Apr 1978) EUR 0 ISR 0 MOB 0 JOF 0 SSH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GANMBS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 9, 1978 ALASKA MERIDIAN CHAIN 00-24 UT, MARCH 9, 1978 ALASKA MERIDIAN CHAIN START MARCH 9, 1978 0000 END MARCH 9, 1978 2330 00-24 UT, MARCH 9, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JAP 0 SRH 0 CAR 0 INU 0 ARV 0 FYU 0 CUL 0 ANC 0 1,000. GMNHS UT 00-24 UT, MARCH 10, 1978 ALASKA MERIDIAN CHAIN 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 00-24 UT, MARCH 10, 1978 ALASKA MERIDIAN CHAIN START MARCH 10, 1978 0000 END MARCH 10, 1978 2330 00-24 UT, MARCH 10, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARY 0 FYU 0 COL 0 ANC 0 EUR 0 ISR 0 MOB 0 JGP 0 SRH 0 CRP 0 INU 0 ARV 0 FYU 0 CEL 0 ANC 0 1000. GRAMMES 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 00-24 UT, MARCH 11, 1978 ALASKA MERIDIAN CHAIN START MARCH 11, 1978 0000 END MARCH 11, 1978 2330 00-24 UT. MARCH 11 . 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARY 0 FYU 0 COL 0 ANC 0 1000. GNNMS 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 00-24 UT, MARCH 12, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 START MARCH 12, 1978 0000 END MARCH 12, 1978 2330 00-24 UT, MARCH 12, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAR 0 INU 0 RAV 0 FYU 0 COL 0 ANC 0 1000. GRAMS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 13, 1978 ALASKA MERIDIAN CHAIN START MARCH 13, 1978 0000 END MARCH 13, 1978 2330 00-24 UT, MARCH 13 . 1978 ALASKA MERIDIAN CHAIN EUR 0 ISR 0 MOB 0 JDP 0 SAH 0 CAP 0 INU 0 ARV 0 FTU 0 CBL 0 ANC 0 1000. GRNMS UT GRNMS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 14, 1978 ALASKA MERIDIAN CHAIN START MARCH 14, 1978 0000 END MARCH 14, 1978 2330 00-24 UT, MARCH 14, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAR 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 EUR 0 ISA 0 MBB 0 JDP 0 SAH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 00-24 UT, MARCH 15 • 1978 ALASKA MERIDIAN CHAIN 00-24 UT, MARCH 15 • 1978 ALASKA MERIDIAN CHAIN START MARCH 15, 1978 0000 END MARCH 15, 1978 2330 00-24 UT, MARCH 15, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SRH 0 CHP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 EUR 0 ISR 0 MBB 0 JDF 0 SRH 0 CRP 0 INU 0 ARY 0 FTU 0 COL 0 ANC 0 1000. GRNMS X UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 16, 1978 ALASKA MERIDIAN CHAIN ![Seismograph traces for various stations along the Alaska Meridian Chain, labeled EUR, ISR, MBB, JDF, SRH, CRP, INU, ARY, FTU, COL, ANC, with time in UT from 00 to 24 hours.](page_0_0_1583_2048.png) START MARCH 16, 1978 0000 END MARCH 16, 1978 2330 00-24 UT, MARCH 16, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series plots for various stations](page_0_0_1583_2048.png) EUR 0 ISR 0 MGB 0 JGP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1,000. GAMMAS 0 2 4 6 8 10 12 14 15 18 20 22 24 UT 00-24 UT, MARCH 17 . 1978 ALASKA MERIDIAN CHAIN 0 2 4 6 8 10 12 14 15 18 20 22 24 UT 00-24 UT, MARCH 17 . 1978 ALASKA MERIDIAN CHAIN START MARCH 17, 1978 0000 END MARCH 17, 1978 2330 00-24 UT, MARCH 17, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 ANC 0 1,000. GRAMMAS X UT 00-24 UT, MARCH 18, 1978 ALASKA MERIDIAN CHAIN 00-24 UT, MARCH 18, 1978 ALASKA MERIDIAN CHAIN START MARCH 18, 1978 0000 END MARCH 18, 1978 2330 00-24 UT, MARCH 18, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MEB 0 JDF 0 SHH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1,000. GAMMAS X UT 00-24 UT, MARCH 19 • 1978 ALASKA MERIDIAN CHAIN ![Seismograph traces labeled with station codes and time axis](page_0_0_1583_2048.png) START MARCH 19, 1978 0000 END MARCH 19, 1978 2330 00-24 UT, MARCH 19, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 EUR 0 ISA 0 MCB 0 JDP 0 SRH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 00-24 UT, MARCH 20 • 1978 ALASKA MERIDIAN CHAIN 00-24 UT, MARCH 20 • 1978 ALASKA MERIDIAN CHAIN START MARCH 20, 1978 0000 END MARCH 20, 1978 2330 00-24 UT, MARCH 20, 1978 ALASKA MERIDIAN CHAIN ![Circular plot showing magnetic field vectors and time series plots for various stations](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JJP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GAMMAS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 21 • 1978 ALASKA MERIDIAN CHAIN ![Seismograph traces for various stations along the Alaska Meridian Chain, labeled EUR, ISA, MOB, JJP, SAH, CAP, INU, ARV, FYU, COL, ANC, with time in UT from 00 to 24 hours.](page_0_0_1583_2048.png) START MARCH 21, 1978 0000 END MARCH 21, 1978 2330 00-24 UT, MARCH 21, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series plots for various stations](page_0_0_1583_2048.png) EUR 0 ISR 0 MOB 0 JOP 0 SRH 0 CRP 0 INU 0 ARV 0 FTU 0 COL 0 ANC 0 LOOD, GRNMBs 00-24 UT, MARCH 22 • 1978 ALASKA MERIDIAN CHAIN 00-24 UT, MARCH 22 • 1978 ALASKA MERIDIAN CHAIN START MARCH 22, 1978 0000 END MARCH 22, 1978 2330 00-24 UT, MARCH 22, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISH 0 MOB 0 JOP 0 SRH 0 CRP 0 INU 0 ARY 0 FYU 0 COL 0 ANC 0 1000. GAMMAS UT X Y 00-24 UT, MARCH 23 . 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARRV 0 FYU 0 COL 0 ANC 0 START MARCH 23, 1978 0000 END MARCH 23, 1978 2330 00-24 UT, MARCH 23, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISH 0 MBB 0 JOP 0 SHT 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 00-24 UT, MARCH 24, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JAP 0 SRH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 START MARCH 24, 1978 0000 END MARCH 24, 1978 2330 00-24 UT, MARCH 24, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JGP 0 SAR 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 LOCO. 4 GAMMAS UT Y X UT 00-24 UT, MARCH 25 . 1978 ALASKA MERIDIAN CHAIN 00-24 UT, MARCH 25 . 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 KOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARRV 0 FYU 0 COL 0 ANC 0 START MARCH 25, 1978 0000 END MARCH 25, 1978 2330 00-24 UT, MARCH 25, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series plots for various stations](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAR 0 INU 0 ARV 0 FYU 0 COL 0 ANC D 1000. GAMMAS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 26 . 1978 ALASKA MERIDIAN CHAIN EUR D ISA D MOB D JOP D SAH D CAP D INU D ARV D FYU D COL D ANC D START MARCH 26, 1978 0000 END MARCH 26, 1978 2330 00-24 UT, MARCH 26, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1,000. GAMMAS UT. 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 27, 1978 ALASKA MERIDIAN CHAIN EUR D ISA D KGB D JDP D SAH D CAP D INU D ARV D FYU D COL D ANC D START MARCH 27, 1978 0000 END MARCH 27, 1978 2330 00-24 UT, MARCH 27, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series plots for various stations](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JDP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GAMMA5 UT X Y 0 2 4 6 8 10 12 14 16 18 20 22 24 0-24 UT, MARCH 28, 1978 ALASKA MERIDIAN CHAIN START MARCH 28, 1978 0000 END MARCH 28, 1978 2330 00-24 UT, MARCH 28, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAR 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GAMMAS. UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 29, 1978 ALASKA MERIDIAN CHAIN ![Seismograph traces labeled with station codes and time axis](page_0_0_1583_2048.png) START MARCH 29, 1978 0000 END MARCH 29, 1978 2330 00-24 UT, MARCH 29, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series traces for various stations](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARY 0 FYU 0 COL 0 ANC 0 1000. GAMMAS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 30, 1978 ALASKA MERIDIAN CHAIN ![Seismograph traces for EUR, ISA, MOB, JOP, SAH, CAP, INU, ARY, FYU, COL, ANC](page_0_0_1583_2048.png) START MARCH 30, 1978 0000 END MARCH 30, 1978 2330 00-24 UT, MARCH 30, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JUP 0 SRH 0 CRP 0 INU 0 ARV 0 FTU 0 COL 0 ANC 0 1000 GRAMAS Y UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 31, 1978 ALASKA MERIDIAN CHAIN 1000 GRAMAS X UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, MARCH 31, 1978 ALASKA MERIDIAN CHAIN START MARCH 31, 1978 0000 END MARCH 31, 1978 2350 00-24 UT, MARCH 31, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series traces for various stations](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JDP 0 SHH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GRMMAS UT. 0 2 4 6 8 10 12 14 16 18 20 22 24 UT. 0 2 4 6 8 10 12 14 16 18 20 22 24 UT. 0 2 4 6 8 10 12 14 16 18 20 22 24 UT. 00-24 UT, APRIL 1, 1978 ALASKA MERIDIAN CHAIN START APRIL 1, 1978 0000 END APRIL 1, 1978 2330 00-24 UT, APRIL 1, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOF 0 SAR 0 CRP 0 INU 0 ARY 0 FTU 0 COL 0 ANC 0 1000. GRMS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 2, 1978 ALASKA MERIDIAN CHAIN ![Seismograph traces labeled with station codes and time axis](page_0_0_1583_2048.png) START APRIL 2, 1978 0000 END APRIL 2, 1978 2330 00-24 UT, APRIL 2, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOF 0 SAH 0 CAP 0 INU 0 ARY 0 FYU 0 COL 0 ANC 0 1000. GAMMAS UT Y X 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 3, 1978 ALASKA MERIDIAN CHAIN ![Seismograph traces for various stations along the Alaska Meridian Chain, labeled EUR, ISA, MOB, JOF, SAH, CAP, INU, ARY, FYU, COL, ANC. The y-axis is labeled 'GAMMAS', and the x-axis is labeled 'UT'.](page_0_0_1583_2048.png) START APRIL 3, 1978 0000 END APRIL 3, 1978 2330 00-24 UT, APRIL 3, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MEB 0 JOP 0 SEH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GAMMAS UT Y 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 4, 1978 ALASKA MERIDIAN CHAIN 1000. GAMMAS UT X 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 4, 1978 ALASKA MERIDIAN CHAIN START APRIL 4, 1978 0000 END APRIL 4, 1978 2330 00-24 UT, APRIL 4, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JJP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GRAMMAS X UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 5, 1978 ALASKA MERIDIAN CHAIN 1000. GRAMMAS Y UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 5, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SPH 0 CAP 0 INU 0 ARV 0 FYU 0 CBL 0 ANC 0 START APRIL 5, 1978 0000 END APRIL 5, 1978 2330 00-24 UT, APRIL 5, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 LODO. GRAMMAS GANKAS UT Y X UT Y X 00-24 UT, APRIL 6, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JDP 0 SAH 0 CAP 0 INU 0 ARRV 0 FYU 0 COL 0 ANC 0 START APRIL 6, 1978 0000 END APRIL 6, 1978 2330 00-24 UT, APRIL 6, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 CBL 0 ANC 0 1000. GRAMAS X UT 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 7, 1978 ALASKA MERIDIAN CHAIN START APRIL 7, 1978 0000 END APRIL 7, 1978 2330 00-24 UT, APRIL 7, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISR 0 MOB 0 JJP 0 SHH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1,000. GRAMS. UT 0 2 4 6 8 10 12 14 16 18 20 22 24 Y 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 8, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JGP 0 SAH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 START APRIL 8, 1978 0000 END APRIL 8, 1978 2330 DD-24 UT, APRIL 8, 1978 ALASKA MERIDIAN CHAIN ![Circular plot showing magnetic field vectors and time series traces for various stations](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1,000. GAMMAS X UT Y 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 9, 1978 ALASKA MERIDIAN CHAIN START APRIL 9, 1978 0000 END APRIL 9, 1978 2330 00-24 UT, APRIL 9, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JJP 0 SRH 0 CARP 0 INU 0 ARV 0 FYU 0 CBL 0 ANC 0 1,000. GRNMS UT X Y 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 10 , 1978 ALASKA MERIDIAN CHAIN START APRIL 10, 1978 0000 END APRIL 10, 1978 2330 00-24 UT, APRIL 10, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JJP 0 SPH 0 CAP 0 INU 0 ARV 0 FTU 0 COL 0 ANC 0 1,000. GAMMAS 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 00-24 UT, APRIL 11, 1978 ALASKA MERIDIAN CHAIN START APRIL 11, 1978 0000 END APRIL 11, 1978 2350 00-24 UT, APRIL 11, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series plots labeled with station codes](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JDP 0 SAH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1,000 GRAMS UT X Y 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 12, 1978 ALASKA MERIDIAN CHAIN START APRIL 12, 1978 0000 END APRIL 12, 1978 2330 00-24 UT, APRIL 12, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FTU 0 COL 0 ANC 0 1000. GRMKAS UT Y X 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 13, 1978 ALASKA MERIDIAN CHAIN START APRIL 13, 1978 0000 END APRIL 13, 1978 2330 00-24 UT, APRIL 13, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARY 0 FYU 0 COL 0 ANC 0 1,000 GRAMMAS 00-24 UT, APRIL 14, 1978 ALASKA MERIDIAN CHAIN 00-24 UT, APRIL 14, 1978 ALASKA MERIDIAN CHAIN START APRIL 14, 1978 0000 END APRIL 14, 1978 2330 00-24 UT, APRIL 14, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series plots for various stations](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GAMMAS. X UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 15, 1978 ALASKA MERIDIAN CHAIN Y UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 15, 1978 ALASKA MERIDIAN CHAIN START APRIL 15, 1978 0000 END APRIL 15, 1978 2330 00-24 UT, APRIL 15, 1978 ALASKA MERIDIAN CHAIN EUR D ISA D MOB D JOP D SAH D CRP D INU D ARV D FYU D COL D ANC D 00-24 UT, APRIL 16 , 1978 ALASKA MERIDIAN CHAIN START APRIL 16, 1978 0000 END APRIL 16, 1978 2330 00-24 UT, APRIL 16, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SHH 0 CRP 0 INU 0 ARR 0 FYU 0 COL 0 ANC 0 EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1,000. GRNMS X Y UT 00-24 UT, APRIL 17, 1978 ALASKA MERIDIAN CHAIN START APRIL 17, 1978 0000 END APRIL 17, 1978 2330 00-24 UT, APRIL 17, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MAB 0 JDP 0 SRH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 00-24 UT, APRIL 18, 1978 ALASKA MERIDIAN CHAIN 00-24 UT, APRIL 18, 1978 ALASKA MERIDIAN CHAIN START APRIL 18, 1978 0000 END APRIL 18, 1978 2330 00-24 UT, APRIL 18, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CAP 0 INU 0 ARY 0 FYU 0 COL 0 ANC 0 1000- GAMMAS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 19 , 1978 ALASKA MERIDIAN CHAIN START APRIL 19, 1978 0000 END APRIL 19, 1978 2330 00-24 UT, APRIL 19, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series plots of magnetic data](page_0_0_1583_2048.png) EUR 0 ISA 0 MOB 0 JDP 0 SAH 0 CARP 0 INU 0 ARRV 0 FYU 0 COL 0 ANC 0 1000. GAMMAS. X Y UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 20 , 1978 ALASKA MERIDIAN CHAIN START APRIL 20, 1978 0000 END APRIL 20, 1978 2330 00-24 UT, APRIL 20, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series plots for various stations](page_0_0_1583_2048.png) EUR D ISH D KOB D JUP D SRI D CAP D INU D ARV D FYU D COL D ANC D 00-24 UT, APRIL 21, 1978 ALASKA MERIDIAN CHAIN START APRIL 21, 1978 0000 END APRIL 21, 1978 2330 00-24 UT, APRIL 21, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISR 0 MOB 0 JJP 0 SAR 0 CAR 0 INU 0 ARY 0 FYU 0 COL 0 ANC 0 00-24 UT, APRIL 22, 1978 ALASKA MERIDIAN CHAIN START APRIL 22, 1978 0000 END APRIL 22, 1978 2330 00-24 UT, APRIL 22, 1978 ALASKA MERIDIAN CHAIN EUR D ISA D MRB D JJP D SRH D CRP D INU D ARRV D FYU D COL D ANC D 1000: GMMAS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 23, 1978 ALASKA MERIDIAN CHAIN 00-24 UT, APRIL 23, 1978 ALASKA MERIDIAN CHAIN START APRIL 23, 1978 0000 END APRIL 23, 1978 2330 00-24 UT, APRIL 23, 1978 ALASKA MERIDIAN CHAIN EUR 0 ISA 0 MOB 0 JOP 0 SAH 0 CRP 0 INU 0 ARV 0 FYU 0 COL 0 ANC 0 1000. GRAMS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 24, 1978 ALASKA MERIDIAN CHAIN START APRIL 24, 1978 0000 END APRIL 24, 1978 2330 00-24 UT, APRIL 24, 1978 ALASKA MERIDIAN CHAIN EUR D ISA D MOB D JDP D SAH D CAP D INU D ARV D FYU D COL D ANC D 1,000. GRAMMAS 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 00-24 UT, APRIL 25, 1978 ALASKA MERIDIAN CHAIN 00-24 UT, APRIL 25, 1978 ALASKA MERIDIAN CHAIN START APRIL 25, 1978 0000 END APRIL 25, 1978 2330 00-24 UT, APRIL 25, 1978 ALASKA MERIDIAN CHAIN EUR D ISA D MOB D JDP D SAH D CAP D INU D ARV D FYU D CBL D ANC D EUR D ISA D MBB D JJP D SRH D CRP D INU D ARV D FYU D CEL D ANC D 1000. GRN/MAS 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 00-24 UT, APRIL 26 , 1978 ALASKA MERIDIAN CHAIN 1000. GAMMAS 0 2 4 6 8 10 12 14 16 18 20 22 24 UT 00-24 UT, APRIL 26 , 1978 ALASKA MERIDIAN CHAIN START APRIL 26, 1978 0000 END APRIL 26, 1978 2330 00-24 UT, APRIL 26, 1978 ALASKA MERIDIAN CHAIN EUR D ISA D KOB D JOP D SAH D CAP D INU D ARV D FYU D CBL D ANC D 1000. GRAMMAS UT 0 2 4 6 8 10 12 14 16 18 20 22 24 EUR 0 ISA 0 MOB 0 JDP 0 SHH 0 CAR 0 INU 0 ARV 0 FTU 0 COL 0 ANC 0 1000. GAMMAS Y UT 0 2 4 6 8 10 12 14 16 18 20 22 24 00-24 UT, APRIL 27, 1978 ALASKA MERIDIAN CHAIN START APRIL 27, 1978 0000 END APRIL 27, 1978 2330 00-24 UT, APRIL 27, 1978 ALASKA MERIDIAN CHAIN ![Polar plot showing magnetic field vectors and time series traces for various stations](page_0_0_1583_2048.png) Between 6 and 12 UAG Reports are published at irregular intervals each year. Subscriptions may be ordered through the National Geophysical and Solar-Terrestrial Data Center, Environmental Data and Information Service, NOAA, Boulder, CO 80303, USA. The annual subscription price is $25.20 ($17.30 additional for foreign mailing). Each year the single copy prices total less than $25.20, the expiration date for all subscriptions will be extended. Back issues may be purchased at the prices shown below plus a $2.00 handling charge per order; some reports, though, are available only on microfiche. Orders must include check or money order payable in U.S. currency to the Department of Commerce, NOAA/NGSDC. UAG-1 "ISOY Night Airglow Data," by L.L. Smith, F.E. Roach, and J.M. McKennan, ESSA Aeronomy Laboratory, July 1968, 305 pp, $1.75. UAG-2 "A Reevaluation of Solar Flares, 1964-1966," by Helen W. Dodson and E. Ruth Hedeman, McMath-Hulbert Observatory, Pontiac, MI, University of Michigan, August 1968, 28 pp, $0.30. UAG-3 "Observations of Jupiter's Sporadic Radio Emission in the Range 7.6-41 MHz, 6 July 1966 through 8 September 1968," by James W. Warwick and George A. Dulk, University of Colorado, Boulder, CO, October 1968, 35 pp, $0.55 (microfiche only). UAG-4 "Abbreviated Calendar Record 1966-1967," by J. Virginia Lincoln, Hope I. Leighton and Dorothy K. Kropp, ESSA Aeronomy and Space Data Center, Boulder, CO, January 1969, 170 pp, $1.25. UAG-5 "Data on Solar Event of May 23, 1967 and its Geophysical Effects," compiled by J. Virginia Lincoln, World Data Center A, Upper Atmosphere Geophysics, Boulder, CO, February 1969, 120 pp, $0.65. UAG-6 "International Geophysical Calendars 1957-1969," by A.H. Shapley and J. Virginia Lincoln, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, March 1969, 25 pp, $0.30. UAG-7 "Observations of the Solar Electron Corona: February 1964-January 1968," by Richard T. Hansen, High Altitude Observatory, NCAR, Boulder, CO, Kamuela, HI, October 1969, 12 pp, $0.15. UAG-8 "Data on Solar-Geophysical Activity October 24 - November 6, 1968," Parts 1 and 2, compiled by J. Virginia Lincoln, March 1970, 312 pp, $1.75 (includes Parts 1 and 2). UAG-9 "Data on Cosmic Ray Event of November 18, 1968 and Associated Phenomena," compiled by J. Virginia Lincoln, World Data Center A, Upper Atmosphere Geophysics, Boulder, CO, April 1970, 109 pp, $0.55. UAG-10 "Atlas of Ionograms," edited by A.H. Shapley, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, May 1970, 243 pp, $1.50. UAG-12 "Solar-Geophysical Activity Associated with the Major Geomagnetic Storm of March 8, 1970," Parts 1, 2 and 3, compiled by J. Virginia Lincoln and Dale B. Bucknam, World Data Center A, Upper Atmosphere Geophysics, Boulder, CO, April 1971, 466 pp, $3.00 (includes Parts 1-3). UAG-13 "Data on the Solar Proton Event of November 2, 1969 through the Geomagnetic Storm of November 8-10, 1969," compiled by Dale B. Bucknam and J. Virginia Lincoln, World Data Center A, Upper Atmosphere Geophysics, Boulder, CO, May 1971, 76 pp, $0.90. UAG-14 "An Experimental, Comprehensive Flare Index and Its Derivation for 'Major' Flares, 1955-1969," by Helen W. Dodson and E. Ruth Hedeman, McMath-Hulbert Observatory, Pontiac, MI, University of Michigan, July 1971, 25 pp, $0.30. UAG-16 "Temporal Development of the Geophysical Distribution of Auroral Absorption for 30 Substorm Events in each of ISOY (1964-65) and IASY (1960)," by P.M. Barkey, University of Alaska, Fairbanks, AK; V.M. Driatskii, Arctic and Antarctic Research Institute, Leningrad, USSR; K. Henriksen, Auroral Observatory, Tromso, Norway; D.H. Jelly, Communications Research Center, Ottawa, Canada; T.I. Shchuka, Arctic and Antarctic Research Institute, Leningrad, USSR; A. Theander, Kiruna Geophysical Observatory, Kiruna, Sweden; and J. Yliniemi, University of Oulu, Oulu, Finland, September 1971, 131 pp, $0.70. UAG-17 "Ionospheric Drift Velocity Measurements at Jicamarca, Peru (July 1967 - March 1970)," by Ben R. Balsley, NOAA Aeronomy Laboratory, Boulder, CO, and Ronald F. Woodman, Jicamarca Radar Observatory, Instituto Geofisico del Peru, Lima, Peru, October 1971, 45 pp, $0.55 (microfiche only). UAG-18 "A Study of Polar Cap and Auroral Zone Magnetic Variations," by K. Kawasaki and S.-I. Akasofu, University of Alaska, Fairbanks, AK, June 1972, 21 pp, $0.20. UAG-19 "Reevaluation of Solar Flares 1967," by Helen W. Dodson and E. Ruth Hedeman, McMath-Hulbert Observatory, University of Michigan, Pontiac, MI, and Marta Rovira de Miceli, San Miguel Observatory, Argentina, June 1972, 15 pp, $0.15. UAG-21 "Preliminary Compilation of Data for Retrospective World Interval July 26 - August 14, 1972," by J. Virginia Lincoln and Hope I. Leighton, World Data Center A for Solar-Terrestrial Physics, Boulder, CO, November 1972, 128 pp, $0.70. UAG-22 "Auroral Electrojet Magnetic Activity Indices (AE) for 1970," by Joe Haskell Allen, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, November 1972, 146 pp, $0.75. UAG-23 "U.R.S.I. Handbook of Ionogram Interpretation and Reduction," Second Edition, November 1972, edited by W.R. Piggott, Radio and Space Research Station, Slough, UK and K. Rauer, Arbeitsgruppe fur Physikalische Weltraumforschung, Freiburg, GFR, November 1972, 324 pp, $1.75. UAG-23A "U.R.S.I. Handbook of Ionogram Interpretation and Reduction," Second Edition, Revision of Chapters 1 - 4, edited by W.R. Piggott, Radio and Space Research Station, Slough, UK, and K. Rauer, Arbeitgruppe fur Physikalische Weltraumforschung, Freiburg, GFR, November 1972, 135 pp, $2.14. UAG-24 "Data on Solar-Geophysical Activity Associated with the Major Ground Level Cosmic Ray Events of 24 January and 1 September 1971," Parts 1 and 2, compiled by Helen E. Coffey and J. Virginia Lincoln, World Data Center A for Solar-Terrestrial Physics, Boulder, CO, December 1972, 482 pp, $2.00 (includes Parts 1 and 2). UAG-25 "Observations of Jupiter's Sporadic Radio Emission in the Range 7.6-41 MHz, 9 September 1968 through 9 December 1971," by James W. Warwick, George A. Dulk and David G. Swann, University of Colorado, Boulder, CO, February 1973, 35 pp, $0.35. UAG-26 "Data Compilation for the Magnetospherically Quiet Periods February 19-23 and November 29 - December 3, 1970," compiled by Helen E. Coffey and J. Virginia Lincoln, World Data Center A for Solar-Terrestrial Physics, Boulder, CO, May 1973, 129 pp, $0.70. UAG-27 "High Speed Streams in the Solar Wind," by D.S. Intriligator, University of Southern California, Los Angeles, CA, June 1973, 16 pp, $0.15. UAG-28 "Collected Data Reports on August 1972 Solar-Terrestrial Events," Parts 1, 2 and 3, edited by Helen E. Coffey, World Data Center A for Solar-Terrestrial Physics, Boulder, CO, August 1977, 313 pp, $2.95. UAG-29 "Auroral Electrojet Magnetic Activity Indices AE(11) for 1968," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, October 1973, 148 pp, $0.75. UAG-30 "Catalogue of Data on Solar-Terrestrial Physics," prepared by NOAA Environmental Data Service, Boulder, CO, October 1973, $1.50. Supersedes UAG-11, 15, and 20 catalogs. UAG-31 "Auroral Electrojet Magnetic Activity Indices AE(11) for 1969," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, February 1974, 142 pp, $0.75. UAG-32 "Synoptic Radio Maps of the Sun at 3.3 mm for the Years 1967-1969," by Earle B. Mayfield, Kenneth P. White III, and Fred I. Shimabukuro, Aerospace Corp., El Segundo, CA, April 1974, 26 pp, $0.35. UAG-33 "Auroral Electrojet Magnetic Activity Indices AE(10) for 1967," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, May 1974, 142 pp, $0.75. UAG-34 "Absorption Data for the IGY/IGC and IQSY," compiled and edited by A.H. Shapley, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO; W.R. Piggott, Appleton Laboratory, Slough, UK; and K. Rauer Arbeitsgruppe fur Physikalische Weltraumforschung, Freiburg, GFR, June 1974, 381 pp, $2.00. UAG-35 "Catalogue of Digital Geomagnetic Variation Data at World Data Center A for Solar-Terrestrial Physics," prepared by NOAA Environmental Data Service, Boulder, CO, July 1974, 20 pp, $0.20. UAG-36 "An Atlas of Extreme Ultraviolet Flashes of Solar Flares Observed Via Sudden Frequency Deviations During the ATM-SKYLAB Missions," by R.F. Donnelly and E.L. Berger, NOAA Space Environment Laboratory; Lt. J.D. Busman, NOAA Commissioned Corps; B. Henson, NASA Marshall Space Flight Center; T.B. Jones, University of Leicester, UK; G.M. Lerfeld, NOAA Wave Propagation Laboratory; K. Najita, University of Hawaii; W.M. Retallack, NOAA Space Environment Laboratory and W.J. Wagner, Sacramento Peak Observatory, October 1974, 95 pp, $0.35. UAG-37 "Auroral Electrojet Magnetic Activity Indices AE(10) for 1966," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, December 1974, 142 pp, $0.75. UAG-38 "Master Station List for Solar-Terrestrial Physics Data at WDC-A for Solar-Terrestrial Physics," by R.W. Buhmann, World Data Center A for Solar-Terrestrial Physics, Boulder, CO; Juan D. Federer, University of Denver, Denver, CO; and M.N. Shea and D.F. Smart, Air Force Geophysics Laboratory, Hanscom AFB, MA, December 1974, 110 pp, $1.00. UAG-39 "Auroral Electrojet Magnetic Activity Indices AE(11) for 1971," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, February 1975, 144 pp, $2.05. UAG-40 "H-Alpha Synoptic Charts of Solar Activity for the Period of Skylab Observations, May 1973 March 1974," by Patrick S. McIntosh, NOAA Space Environment Laboratory, February 1975, 32 pp, $0.48. UAG-41 "H-Alpha Synoptic Charts of Solar Activity During the First Year of Solar Cycle 20 October 1964 - August 1965," by Patrick S. McIntosh, NOAA Space Environment Laboratory; and Jerome T. Nolte, American Science and Engineering, Inc, Cambridge, MA, March 1975, 25 pp, $0.48. UAG-42 "Observations of Jupiter's Sporadic Radio Emission in the Range 7.6-80 MHz 10 December 1971 through 21 March 1975," by James W. Warwick, George A. Dulk and Anthony C. Riddle, University of Colorado, Boulder, CO, April 1975, 49 pp, $1.15. UAG-43 "Catalog of Observation Times of Ground-Based Skylab-Coordinated Solar Observing Programs," compiled by Helen E. Coffey, World Data Center A for Solar-Terrestrial Physics, Boulder, CO, May 1975, 159 pp, $3.00. UAG-44 "Synoptic Maps of Solar 9.1 cm Microwave Emission from June 1962 to August 1973," by Werner Graf and Ronald N. Bracewell, Stanford University, Stanford, CA, May 1975, 183 pp, $2.55. UAG-45 "Auroral Electrojet Magnetic Activity Indices AE(11) for 1972," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, May 1975, 144 pp, $2.10. UAG-46 "Interplanetary Magnetic Field Data 1963-1974," by Joseph H. King, National Space Science Data Center, NASA Goddard Space Flight Center, Greenbelt, MD, June 1975, 382 pp, $1.95. UAG-47 "Auroral Electrojet Magnetic Activity Indices AE(11) for 1973," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, June 1975, 144 pp, $2.10. UAG-48A "Synoptic Observations of the Solar Corona during Carrington Rotations 1580-1596 (11 October 1971 - 15 January 1973)," [Reissue of UAG-48 with quality images], by R.A. Howard, M.J. Koomen, D.J. Michels, R. Toussy, C.L. Betwiser, P.E. Roberts, R.T. Seal, and J.D. Whitney, U.S. Naval Research Laboratory, Washington, DC, and R.T. and S.F. Hansen, C.J. Garcia and E. Yasukawa, High Altitude Observatory, NCAR, Boulder, CO, February Observatory 1976, 200 pp, $4.27. UAG-49 "Catalog of Standard Geomagnetic Variation Data," prepared by NOAA Environmental Data Service, Boulder, CO, August 1975, 125 pp, $1.85. UAG-50 "High-Latitude Supplement to the USASI Handbook on Ionogram Interpretation and Reduction," edited by W.R. Pigott, British Antarctic Survey, c/o Appleton Laboratory, Slough, UK, October 1975, 294 pp, $4.00. UAG-51 "Synoptic Maps of Solar Coronal Hole Boundaries Derived from He II 304A Spectroheliograms from the Manned Skylab Missions," by J.D. Bohlin and D.M. Rubenstein, E.O. Hulbert Center for Space Research, U.S. Naval Research Laboratory, Washington, DC, November 1975, 30 pp, $0.54. UAG-52 "Experimental Comprehensive Solar Flare Indices for Certain Flares, 1970-1974," by Helen W. Dodson and E. Ruth Hedeman, McMath-Hulbert Observatory, University of Michigan, Pontiac, MI, November 1975, 27 pp, $0.60. UAG-53 "Description and Catalog of Ionospheric F-Region Data, Jicamarca Radio Observatory (November 1966 - April 1969)," by W.L. Clark and T.B. Van Zandt, NOAA Aeronomy Laboratory, Boulder, CO, and J.F. McClure, University of Texas at Dallas, Dallas, TX, April 1976, 10 pp, $0.33. UAG-54 "Catalog of Ionosphere Vertical Soundings Data," prepared by NOAA Environmental Data Service, Boulder, CO, April 1976, 130 pp, $2.10. UAG-55 "Equivalent Ionospheric Current Representations by a New Method, Illustrated for 8-9 November 1969 Magnetic Disturbances," by Y. Kamide, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO; H.W. Kroehl, Data Studies Division, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO; M. Kanamitsu, Advanced Study Program, National Center for Atmospheric Research, Boulder, CO; Joe Haskell Allen, Data Studies Division, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO; and S.-I. Akasofu, Geophysical Institute, University of Alaska, Fairbanks, AK, April 1976, 91 pp, $1.60. 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, CO, April 1976, 37 pp, $1.39. UAG-57 "Manual on Ionospheric Absorption Measurements," edited by K. Rauer, Institut fur Physikalische Weltraumforschung, Freiburg, GFR, June 1976, 202 pp, $4.27. UAG-58 "ATSG Radio Beacon Electron Content Measurements at Boulder, July 1974 - May 1975," by R.B. Fritz, NOAA Space Environment Laboratory, Boulder, CO, September 1976, 61 pp, $1.04. UAG-59 "Auroral Electrojet Magnetic Activity Indices AE(11) for 1974," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, December 1976, 144 pp, $2.16. UAG-60 "Geomagnetic Data for January 1976 (AE(7) Indices and Stacked Magnetograms)," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, July 1977, 57 pp, $1.07. UAG-61 "Collected Data Reports for STIP Interval II 20 March - 5 May 1976," edited by Helen E. Coffey and John A. McKinnon, World Data Center A for Solar-Terrestrial Physics, Boulder, CO, August 1977, 313 pp, $2.95. UAG-62 "Geomagnetic Data for February 1976 (AE(7) Indices and Stacked Magnetograms)," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, September 1977, 55 pp, $1.11. UAG-63 "Geomagnetic Data for March 1976 (AE(7) Indices and Stacked Magnetograms)," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, September 1977, 57 pp, $1.11. UAG-64 "Geomagnetic Data for April 1976 (AE(8) Indices and Stacked Magnetograms)," by Joe Haskell Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, February 1978, 55 pp, $4.00. UAG-65 "The Information Explosion and Its Consequences for Data Acquisition, Documentation, and Processing," by G.K. Hartmann, Max-Planck-Institut fur Aeronomie, Lindau, GFR, May 1978, 36 pp, $0.75. UAG-66 "Synoptic Radio Maps of the Sun at 3.3 mm 1970-1973," by Earle B. Mayfield and Fred I. Shimabukuro, Aerospace Corp., El Segundo, CA, May 1978, 30 pp, $0.75. UAG-67 "Ionospheric D-Region Profile Data Base, A Collection of Computer-Accessible Experimental Profiles of the D and Lower E Regions," by L.F. McNamara, Ionospheric Prediction Service, Sydney, Australia, August 1978, 30 pp, $0.88. UAG-68 "A Comparative Study of Methods of Electron Density Profile Analysis," by L.F. McNamara, Ionospheric Prediction Service, Sydney, Australia, September 1978, 56 pp, $1.41. UAG-69 "Selected Disturbed D-region Electron Density Profiles. Their relation to the undisturbed D region," by L.F. McNamara, Ionospheric Prediction Service, Sydney, Australia, October 1978, 50 pp, $1.29. UAG-70 "Annotated Atlas of the H Synoptic Charts for Solar Cycle 20 (1964-1974) Carrington Solar Rotations 1487-1616," by Patrick S. McIntosh, NOAA Space Environment Laboratory, Boulder, CO, February 1979, 330 pp, $3.50. UAG-71 "Magnetic Potential Plots over the Northern Hemisphere for 26-28 March 1976," A.D. Richmond, NOAA Space Environment Laboratory, Boulder, CO; H.W. Kroehl, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO; M.A. Henning, Lockheed Missiles and Space Co., Aurora, CO; and Y. Kamide, Kyoto Sangyo University, Kyoto, Japan, April 1979, 118 pp, $1.75. UAG-72 "Energy Release in Solar Flares, Proceedings of the Workshop on Energy Release in Flares, 26 February - 1 March 1979, Cambridge, Massachusetts, U.S.A.," edited by David M. Rust, American Science and Engineering, Inc. Cambridge, MA and A. Gordon Emslie, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, July 1979, 68 pp, $1.50. UAG-73 "Auroral Electrojet Magnetic Activity Indices AE(11-12) for January - June," by J.H. Allen, C.C. Abston, J.E. Salazar and J.A. McKinnon, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO, August 1979, 111 pp, $1.75. UAG-74 "ATS-6 Radio Beacon Electron Content Measurements at Ootacamund, India, October 1975 - July 1976," by S.D. Bouwer, K. Davies, R.F. Donnelly, R.N. Grubb, J.E. Jones and J.H. Taylor, NOAA Space Environment Laboratory, Boulder, CO, and R.G. Rastogi, M.R. Deshpande, H. Chandra and G. Sethia, Physical Research Laboratory, Ahmedabad, India, March 1980, 60 pp, $2.50.