ION.  ANT. —11 IONOSPHERIC DATA AT SYOWA BASE (ANTARCTICA) February 1968 — July 1968 Issued in May 1970 Prepared by THE RADIO RESEARCH LABORATORIES MINISTRY OF POSTS AND TELECOMMUNICATIONS NUKUI-KITAMACHI, KOGANEI-SHI, TOKYO, JAPAN. ION.  ANT. — 11
February 1968—July 1968 RADIO RESEARCH LABORATORIES NUKUI-KITAMACHI, KOGANEI-SHI, TOKYO, JAPAN
CONTENTS

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SYMBOLS  AND  TERMINOLOGY
All symbols and terminology in the table of ionospheric data are used in accor ­ dance with the First Report of the Special Committee on World - Wide Ionospheric Report of the Soundings (URSI/AGI), Brussels, September 2, 1956, and the Secnd Committee, May, 1957, supplementary to the First Report.

a. Descriptive Symbols
Used following the numerical value on monthly tabulation sheets. Measurement influenced by, or impossible because of, A the presence of a lower thin layer, for example Es. B Measurement influenced by, or impossible because of, absorption in the vicinity of f-min. C Measurement influenced by, or impossible because of, any non- ionospheric reason. Measurement influenced by, or impossible because of, D the upper limit of the normal frequency range. Used in a  qualifying sense, see below. E Measurement influenced by, or impossible because of, the lower limit of the normal frequency range. Used in a qualifying sense, see below. Measurement influenced by, or impossible because of, the presence of spread echoes. Measurement  influenced  or  impossible because the ionization density is too small compared with that of a lower thick layer. Measurement influenced by, or impossible because of, the presence of a stratification. Measurement influenced by or impossible because the trace has no sufficiently definite cusp between layers. Measurement questionable because the ordinary and extraordinary components are not distinguishable. Conditions are such that the measurement cannot readily be interpreted, for example, in the presence of oblique echoes. Measurement refers to the ordinary component. Measurement influenced by, or impossible because of, absorption in the vicinity of a critical frequency. Measurement influenced by, or impossible because of, interference or atmospherics. Forked trace which may influence the measurement. Measurement influenced or impossible because the echo lies out- side the height range recorded. Measurement refers to the extraordinary component. Intermittent trace. Third magneto-ionic component present. Used as a preceeding symbol on monthly tabulation sheets. D greater than and t E I less than..... Missing value has been replaced by an interpolated value. Ordinary component characteristic deduced from the extraordinary component. Value determined by a sequence of observations, the actual observation being inconsistent or doubtful. Uncertain or doubtful numerical value. Measurement deduced from the third magnetoionic component. 3 F G H L M N O R S v W X Y Z b. Qualifying Symbols J T U Z 7 OBSERVED AT: IONOSPHERIC ・DATA LIST OF MEDIAN VALUES
FER, 1968 r > L IONOSPHERIC   DATA LIST OF MEDIAN VALUES
.4 8 IONOSPHERIC DATA LIST  OF  MEDIAN  VALUES OBSERVED AT: ATR , 1968 4
d OBSERVED AT:  SYNA ENSE IONOSPHERIC  'DATA' LIST OF MEDIAN VALUES
IONOSPHERIC DATA LIST  OF  MEDIAN  VALUES 5 10 1 T L
- h
14
+ IONOSPHERIC DATA
A 4 +
ls - 16 P
d.
IONOSPHERIC DATA
にr
6 → Y
IONOSPHERIC DATA 24 -1 ti YしY Y
26
K , IONOSPHERIC DATA
54
4 30
32
IONOSPHERIC DATA 33 pho
1 34
F
38 IONOSPHERIC  DATA
+ L
IONOSPHERIC DATA 42 h s 1 2
44
d
48 t
IONOSPHERIC DATA
なっr 52
56 f -4 T 4 > = iス
58
IONOSPHERIC DATA 60 Y - Y 4 sタ4 r F
62