Sq and L variations



There has been a great increase in knowledge and understanding of solar quiet (Sq) and lunar (L) daily geomagnetic variations during the past four years. Large amounts of data for both geomagnetic fields and related upper atmospheric phenomena have been obtained by various techniques, and intensive efforts have been made in analyzing and interpreting the data with advanced computers. Matsushita [1967a, 1968a] summarized major studies of Sq and L variations and their equivalent current systems obtained up to 1967. Gupta [1967] discussed the relative importance of solar radiation and gravitational tides in causing geomagnetic variations, and Gupta and Chapman [1969] presented solar and lunar harmonics at 54 stations by spectral analyses. Malin and Chapman [1970] discussed the determination of lunar daily geophysical variations by the Chapman-Miller method and presented a useful computer program for the calculation. Campbell et al. [1971] found a galactic component of the geomagnetic field for quiet nighttime hours at Honolulu and San Juan after subtracting Sq and L fields.