The Solar Semidiurnal Pressure Wave over North America

A geographical representation of the amplitude and phase distribution of the solar sernicliurilal pressure oscillation over North America shows clearly the amphidromic point expected here because of the superposition of the traveling and standing semidiurnal waves. It indicates also certain peculiarities in the phase :~nd amplitude distribution which may bc due t o orogritphic and coastal influences. The seasonal variations of the solar semidiurnal pressure nitve for the westcrn stations are quite different from those for the stations in the centml plaius and in the east of the continent. Especially the total phase change throughout the pear is much smaller in the west.