Abstract. In this paper, a regional study of mode-2 internal
solitary waves (ISWs) at the Pacific coast of Central America is carried out using the seismic reflection method. The observed relationship between
the dimensionless propagation speed and the dimensionless amplitude (DA) of
the mode-2 ISW is analyzed. When DA < 1.18, the dimensionless
propagation speed seems to increase with increasing DA, divided into two parts with different growth rates. When
DA > 1.18, the dimensionless propagation speed increases with
increasing DA at a relatively small growth rate. We
suggest that the influences of seawater depth (submarine topography),
pycnocline depth, and pycnocline thickness on the propagation speed of the
mode-2 ISW in the study area cause the relationship between
dimensionless propagation speed and DA to
diversify. The observed relationship between the dimensionless wavelength
and the DA of the mode-2 ISW is also analyzed. When
DA < 1, the nondimensional wavelengths seem to change from 2.5 to 7
for a fixed nondimensional amplitude. When DA > 1.87, the
dimensionless wavelength increases with increasing DA. Additionally, the seawater depth has a great influence on the
wavelength of the mode-2 ISW in the study area. Overall, the wavelength
increases with increasing seawater depth. As for the vertical structure
of the amplitude of the mode-2 ISW in the study area, we find that it is
affected by the nonlinearity of the ISW and the pycnocline deviation
(especially the downward pycnocline deviation).