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Hypsographic Data
How big is 1400 million cubic kilometers? What if we made a giant cube of the ocean? How big would it be?
The average ocean volume is
1.4 x 1021 liters, or 1.4 x 1018 m3, or 1.4 x 109 km3
The average depth for the oceans is approximately 4 km.
How big is the ocean?
How big is that compared to a 12″diameter globe?1000 km/6400 km = x cm/16 cm, x = 2.5cm or about 1 inch
The cube root of 1.4 x 109 km3 is approximately 1000 km.
So we have a 1000 km3 cube.
How big is the ocean?
How big is the atmosphere?
Earth is an oblate spheroid due to rotation, and best represented mathematically by an ellipsoid.
What is the size and shape of Earth?
Equatorial radius = 6,378,137 m
Polar radius = 6,356,752 m
Satellite Altimeter
Geoid Surface TopographyThe geoid is a surface of equal potential energy (PE); a.k.a. an equipotential surface; a.k.a. a “level” surface.
Departures of the geoid from the ellipsoid
PE=m·g·h
Seafloor TopographyWhere is Earth’s longest mountain range?
Bathymetry – the process of determining seafloor
topography
Deepsea Sediment TypesWhy are they different?
How deep is the Ocean?
• Mariana Trench Z = - 11,022 m• If pressure is hydrostatic, how many atmospheres did
the bathyscaphe Trieste have on its hull?
Hydrostatic Equation
p = - g z
where is seawater density
g is gravity
z is water depth
p is pressure (1 Nm-2 = 1 Pa)
Ocean Data Collection
Note that many areas of the ocean have no in situ observations.
Pilot Charts provide general information – US Navy Publication
RV Operations
Historical Instruments
What we measure
• Temperature
• Conductivity
• Pressure
• Velocity
• Sound speed
• Position
• Time
• Transparency
What we calculate
• Density
• Salinity
• Depth
• Heat Flux
• Volume Transport
• Dynamic Height
• Geostrophic Currents
OCN 5401
Questions?
Chapter 1
