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Ocean and Coastal Currents GD3208-Coastal Environmental Survey
Geodesy and Geomatic Engineering Study Program Faculty of Earth Sciences and Engineering Bandung Institute of Technology
Dr.rer.nat. Wiwin Windupranata COZSES - Coastal and Oceanic Zone Sciences and Engineering System

Dr.rer.nat. Wiwin Windupranata @2013 - Geodesy and Geomatic Engineering Study Program - Faculty of Earth Sciences and Engineering - Bandung Institute of Technology
Objectives Students should be able to explain global and local (Indonesian) ocean circulation pattern as well as its forcing factor

Ocean Circulation Why It is Important
Impact all human activities on the ocean or in the coastal area
(transportation, fishing, mariculture, tourism and sport,
erosion and sedimentation, water pollution, etc)
Redistribute heat in global climatic pattern
How is the Movement of Ocean Waters
Currents, Tides and Waves Hydrodynamics
Ocean Circulation Ocean Currents

Driving Factors
In shallow water (coastal area)
tides the most important
bottom friction
bathymetry
fresh water discharges from rivers
In deep water (offshore area)
winds surface layer
density gradients deeper layer

Ocean Circulation Magnitudes of Ocean
Currents
the magnitude of currents in units of sverdrups (Sv)
1 sv = 1,000,000 m3/s
the magnitude of the major ocean currents range
from a few sverdrup to over 100 sverdrup
by comparison, the largest river in the world, the
Amazon, has a flow of approximately 0.2
sverdrup

Ocean Circulation

Atmospheric Processes
Winds flow from higher to lower atmospheric pressure
air pressure is the weight of the air from Earths surface to the top of the atmosphere and equals 1.04kg/cm2 (standard air pressure, one atmosphere) at sea level
change in pressure across a horizontal distance is a pressure gradient
greater the difference in pressure and the shorter the distance between them, the steeper the pressure gradient and the stronger the wind

Global wind pattern is controlled by the density of
atmosphere
Density is a function of temperature, pressure and
moisture content
Warm air is less dense than cold air and moist air is less
dense than dry air
Warm air has less pressure and cold air has more
pressure
Wind pattern is affected by solar heating

Atmospheric Processes Maximum Solar Heating at the equator (over 400 Watts per square meter) and minimum at the poles (less than 200 Watts per square meter)
At the equator, sunlight strikes the earth at a nearly perpendicular angle.
The atmosphere absorbs a certain fraction of the sunlight striking the earth. Sunlight travels a longer path through the atmosphere at high latitudes than it does at low latitudes.

Uneven solar heat distribution
Because air at the equator is warmer than air at the poles, it is less
dense
Because air at the equator is less dense, it rises while cold, dense
air at the poles sinks

Uneven solar heat distribution
three circulation cells form between the equator and each pole
air sinks at both 30 latitude and the poles; rises at about 60 latitude, moves north and south
due to the Coriolis effect, flow on a sphere curves: to the right in the northern hemisphere and to the left in the southern hemisphere.
the trade winds at tropical latitudes, and westerlies at mid latitudes are formed

Resulted Ocean Currents Gyre

Gyre
Western boundary currents -These are narrow, deep, fast
currents found at the western boundaries of
ocean basins
the Gulf Stream
the Japan Current
the Brazil Current
the Agulhas Current
the Eastern Australian Current

Gyre
Eastern boundary currents These currents are cold, shallow and broad, and their boundaries are not well defined
the Canary Current
the Benguela Current
the California Current
the West Australian Current
the Peru Current

Monsoon Monsoons are patterns
of wind circulation that change with the
season
Areas with monsoons generally have dry
winters and wet summers
In Indonesia (particularly western
part), monsoon creates dry and wet (rainy)
season

Dr. rer. nat. Wiwin Windupranata
Hydrographic Science and Engineering Research Division Faculty of Earth Science and Technology
Bandung Institute of Technology
21 Dec
20 Mar
20 Jun
22 Sep

Mar-Sep

Sep - Mar

Indonesian Surface Currents

Upwelling and Downwelling
Wind induced vertical circulation is vertical movement
induced by wind-driven horizontal movement of water
Upwelling is the upward motion of water. This motion brings cold,
nutrient rich water towards the surface
Downwelling is downward motion of water. It supplies the
deeper ocean with dissolved gases

Downwelling

Upwelling

Indonesian Throughflow Very importa

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