UNITED STATES DEPARTMENT OF THE INTERIOR

Transcription

1 UNTED STATES DEPARTMENT OF THE NTEROR GEOLOGCAL SURVEY t PRELMNARY GEOMAGNETC DATA COLLEGE OBSERVATORY FARBANKS, ALASKA * -i JUNE 1978 OPEN FLE REPORT F

2 ORDER OF CONTENTS Explanation of Data & Reports Magnetic Activity Report Outstanding Magnetic Effects Principal Magnetic Storms Preliminary Calibration Data & Monthly Mean Absolute Values Magnetogram Hourly Scalings Sample Format for Normal & Storm Magnetograms Normal Magnetograms Storm Magnetograms (When Normal is too disturbed to read)..

3 THS REPORT WAS PREPARED UNDER THE DRECTON OF JOHN B, TOWNSHENil, CHEF OF THE COLLEGE OBSERVATORY WTH THE ASSSTANCE OF OBSERVATORY STAFF /!EMBERS J, E, PAPP, ASST, CHEF, AND S, P, TLTON, AND N COOPERATON WTH THE GEOPHYSCAL NSTTUTE OF THE UNVERSTY OF ALASKA, THE COLLEGE OBSERVATORY S A PART OF THE BRANCH OF ELECTROFAGNETSM AND GEOMAGNETSM OF THE U,S, GEOLOGCAL SURVEY, COLLEGE OBSERVATORY PRELMNARY GEOMAGNETC DATA t NTRODUCTON The preliminary geomagnetic data included here is made available to scientific personnel and organizations, as part of a cooperative effort and on a data exchange basis because of the early need by some users. To avoid delay, all of the data is copied from original forms processed at the observatory; therefore it should be regarded as preliminary. nquiries about this report or about the College Observatory should be addressed to: Chief, College Observatory U.S. Geological Survey Yukon Drive on West Ridge Fairbanks, Alaska Requests for copies of the magnetograms except for the current month should be addressed to: World Data Center A-NOAA Environmental Data Service Boulder, Colorado Normal, Storm, and Rapid Run magnetograms and appropriate calibration data are processed daily at the observatory and are available for analysis or copying. Also available are mean hourly scalings, K-ndices, selected magnetic phenomena reports, and on a real-time basis are recordings from a 3-component flwgate magnetometer and F-component proton magnetometer. Magnetic Activity The K-ndex. The X-ndex is a logaritkxnic measurement of the ranee of the most disturbed comdonent (D or H) of the geomagnetic field for eight inter;als beginning , UT. t is a measure of the difference between the highest and lowest deviation from a smooth curve to be expected for a component on a magnetically quiet day, within a three hour interval. The Equivalent Daily Amplitude, AK. The K-ndex is converted into an equivalent range, ak, which is near the center of the limiting gamma ranges for a given K. The average of the eight Gaiues is called equivalent daily amplitude AK. The unit l0yhas been chosen so as notto give the illusion of an accuracy not justified. The schedule for converting gamma range to K, and K to ak is as follows: Gamma Range K - ndex - ak* 0 < The Magnetic Daily Character Figure, C. To each Universal day a character is assigned on the basis C=O, if it is quiet; C=l if it is moderately disturbed; C=2 if it is greatly disturbed. The method used to assign characters at the College Observatory is based on AK as follows: AK Range - C 0% s o+ 2 Routine assignment of C was discontinued at College on January 1, GEOMAGNETC DATA OBSERVATORY LOCATON The College Observatory, operated by the U. S. Geological Survey, is located at the University of Alaska, Fairbanks, Alaska. t is near the Auroral Zone and the northern limit of the.worldts greatest earthquake belt, the circum-pacific Seismic belt. Although the observatory's basic operation is in geomagnetism and seismology, it cooperates with other scientists and organizations in areas where the facility and personnel can be of service. The observatory is one of three operated by the USGS in Alaska. The others are located at Barrow and Sitka. The position of the observatory site is: Geographic latitude '51.6'n Geographic longitude o50.2'w Geomagnetic latitude ' Geomagnetic longitude ' Elevation meters Selected Phsr?slwna & Outstanding Magnetic Effects Prior to January 1, 1976, the Normal & Rapid Run records were reviewed at the observatory for selected magnetic phenomena and the events identified were forwarded to the UGG Commission on Magnetic Variations and Disturbances. This was discontinued on January 1, 1976, but a report on Outstanding Magnetic Effects is prepared monthly for this report. Principal Magnetic Storms Gradual and sudden commencement magnetic disturbances with at least one K-ndex of 5 or greater, which are believed to be part of a world-wide disturbance, are classified as principal magnetic storms. The time of the storm beginning and ending; direction and amplitude of sudden commencements; period of maximum activity; and storm range are reported. Monthly reports of these data are forwarded to the World Data Center A in Boulder, Colorado. Magnetogram Hourly Scalings Magnetogram hourly scalings are averages for successive periods of one hour for the D, H, and Z elements. The value in the column headed "01" is the average for the hour beginning 0000 and ending Note that the values on the scaling sheets are in tenths of mm with the decimal point omitted. The user of these scalings should keep in mind that the tabular values are hourly means and if he is interested in the detailed morphology of the magnetic field, he should refer directly to the magnetograms. Magnetograms The normal magnetograms in this report are reproduced at about one-thirl the size of the originals. Preliminary base-line values and scale values adopted for use with the original magnetogr~ms are included. For days when the magnetic field is tao disturbed for the Normal magnetogram to be real.ih7;.,storm magnetograms are reproduced. Absolutes, Base-lines, and Scale Values To determine the absolute value of the magnetic field from the hourly means or from point scalings the following equations should be used: D=BD+d.SD; H=B3+h.S A ; Z=BZ+z.SZ where D, H, and Z are absclute values; BD, BE and BZare base-line values; SD, SH and SZ are scale values: and d, h, and z are scalings in millimeters.

4 K SCALE USED: LOWER LMT FOR u = s. LOWER LMT FOR K * S... CURRENT SCALE VALUE D SCA L N G AND COMPUTATONS HAVE BEEN CHECKED. H APPROVED JOHN B. TOWNSHEND, CHD, COLWE OBSERVATORY OeSLRVER N CHAROL - NOAA CORM 70-1SS SUPERSEDES CbOS CORM 018 * U.S. GOVLRNMLNT PRlNTlNa OCClCL: b1-SO7 Z (mm) (Y/mm) (to nearest 107)

5 DATE OUTSTAND NG r!agnet C EFFECTS TME u. T. NATURE OF PHENOMENON l OBSERVATORY COLLEGE, ALASKA MONTH JUNE REMARKS YEAR , SSC* 09 llxx pi ssc 16 llxx pi2 - DENTFED BY: JEP VERFED BY: 1. NATURE OF PHENOMENON: sac, sac#, 81, si*, b, bp, bs, bps, pel, pc ~ 5, pg, pi 1, P 2, sfe. JBT

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