Physical Oceanography, Vol.
AUTOMATION OF RESEARCH IN SEAS AND OCEANS
TECHNOLOGIES OF MEASUREMENTS OF THE SEA LEVEL
V. A . G a i s k i i
and P. V. Gaiskii
We analyze the contemporary methods and means of measurements of the sea level and inland waters,
describe a CTD-meter designed at the Marine Hydrophysical Institute of the Ukrainian National of Sci-
ence for the determination of the sea level, formulate the requirements to the perfect meter of the water
level, and demonstrate that an electronic sounding stick based on the distributed Walsh thermoprofilo-
meters can play the role of a device of this kind.
According to [1–4], the sea level is a height of the free surface of the World Ocean measured relative to a
certain level conditionally regarded as zero. The variations of the level of natural waters are always of signifi-
cant interest for people as a factor of safety of the habitat and conditions of the economic activity. Initially,
these variations were visually recorded relative to the marks of high and low levels of water on rocks and then
relative to the marks of sounding sticks made on specially mounted panels, stakes, piles, bridge supports, etc.
Up to now, sounding sticks remain the most extensively used instruments for measuring the levels of water both
in the inland basins and in the seas due to their low cost and high reliability.
The visual readings of sounding sticks give the values of instantaneous water levels. By definition , the
observed (instantaneous) level includes the mean level, the tidal component, and the meteorological component.
According to the standard , the sea level is understood as a height of the sea surface free of the wind-
induced waves and swell and measured relative to the conditional level (sounding or gauge datum). Hence, the
information about the instantaneous level of waters should be filtered in a certain way for getting correct data
about the true level. However, the quantitative characteristics of this filtration are not commonly accepted or
established by standard specifications.
The time variations of the water level, e.g., of the Black Sea , can be simultaneously caused by various
natural phenomena, such as the river discharge, evaporation from the surface, atmospheric precipitation, water
exchange through the straits, anthropogenic wastes, sedimentation and densification of bottom depositions,
wind-induced redistribution of waters over the space, atmospheric pressure, space-and-time changes in the den-
sity of water, surge phenomena, wave processes (seiches and tidal oscillations), geodynamic forces (slow verti-
cal motions caused by the elevations and lowerings of Earth’s crust), and tsunamis. These phenomena have
various scales of space and time variations. Some of them are periodic and can be characterized by known spec-
tral-wave windows of existence. In this case, their contribution can be separated in processing the records of
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine.
Corresponding author; e-mail: email@example.com.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
58–73, July–August, 2010. Original article submitted February 25, 2009;
revision submitted April 6, 2009.
294 0928–5105/10/2004–0294 © 2010 Springer Science+Business Media, Inc.