EM 1110-2-1100 (Part II)
30 Apr 02
Atlantic tropical storm tracks during the period 1886-1980
where n is the number of nodes along the axis of the basin, h is the water depth, and lB is the length of the
basin. The fundamental and maximum period corresponds to Tn for n = 1. As shown in Figure II-5-30b,
nodes (locations of no vertical deflection) are located at interior points and antinodes (locations of maximum
deflection) are located on the boundaries of the basin. Longitudinal seiches oscillate from end to end, while
transverse seiches oscillate from side to side in the basin.
For an open rectangular basin (Figure II-5-30c), the free oscillation period is written as follows:
(1 % 2 n) g h
e. The fundamental mode corresponds to n=0. As shown in Figure II-5-30c, the node is located on the
opening with an antinode on the opposite end.
Water Levels and Long Waves