The document discusses the physical properties of the ocean including temperature, salinity, density, and pressure. It describes how the ocean is stratified into three layers based on these properties: 1) the surface layer, 2) the thermocline/halocline/pycnocline, and 3) the deep ocean. The thermocline is the region where temperature changes rapidly with depth, usually between 50-500m, and separates the surface layer from the deep ocean. Similarly, the halocline is where salinity changes quickly and the pycnocline is the region of rapid density change.

1. 1
An Assignment
On
SRIJON PAUL (srijonpaul@gmail.com)
Institute of Marine Sciences and Fisheries, University of Chittagong
•TEMPERATURETHERMOCLINE
•SALINITYHALOCLINE
•DENSITYPYCNOCLINE

2. 2
Physical properties of the ocean are-
Temperature:Temperature is the amount of heat in a given area.
Water temperature is one of the most important physical properties of
the marine environment as it exerts an influence on many physical,
chemical, geochemical, and biological events. Temperature controls
the rates at which chemical reactions and biological processes take
place.
Salinity: The total amount of solid material in grams contained in
one kilogram of sea water when all the carbonate has been converted
to oxide, the bromine and iodine replaced by chlorine, and all organic
matter completely oxidized is salinity.
Density: The density of any substance is defined as the mass per
unit volume. Thus, in the c.g.s. system, density isstated in grams per
cubic centimeter.
Sea water density is a function of temperature,salinity and pressure.
Pressure:Pressure is an expression of force exerted on a surface
per unit area.It is the most common factor for ocean water.
These are the special four physical factors for ocean water or ocean
environment.

3. 3
Three layers exist in the ocean temperature-
1.The surface layer
2. Thermocline
3. The deep ocean
Thermocline: The layer of rapidly changing temperature called a
thermocline (thermo=heat, cline=slope). Temperature decreases
gradually below the permanent thermocline.
The thermocline usually a pycnocline.
Mainly between 50 m to 500 m.
Thermocline: Temperature

4. 4
Figure-01: Vertical distribution of Temperature in the ocean.( Rapid or
sudden change in temperature in vertical direction)
The vertical processes that affect the thermocline are :
1. Downward transfer of heat from the sea surface.
2. Upwelling or downwelling.
 Seasonal variation of thermocline
Figure-01(a)

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Latitudinal variation of thermocline
Figure-01(b
1. Permanent in the tropics.
2. Seasonal at temperate latitudes i.e. present in summer
and missing in winter.
3. Absent in the polar water.
Therefore,
thermocline (i.e.,
the inflection
point in
temperature-
depth graph) is
...
Depth
Temperature
Tropical
all year round,
in summer at

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According to salinity there are three layer exist in the ocean:
1.The surface layer
2. Halocline
3. The deep ocean
Halocline: Layer of rapidly changing salinity with depth is called a
halocline (halo=salt,cline=slope). An area where salinity changes
rapidly with depth is called a halocline.
Polar latitudes all
year round, in winter at temperate
latitudes
Halocline: Salinity

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Figure-02: Vertical distribution of salinity in the ocean.
Ocean density verticaly divided into three layers-
1.The surface layer
2. Pycnocline
3. The deep ocean
Pycnocline:The region of rapid density change is known as the
pycnocline (pycno=density, cline=slope). It acts as a barrier to vertical
water circulation.
Pycnocline: Density

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Figure-03: Density of ocean (Vertical view)
 Thermocline, Halocline,and Pycnocline Profile:

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Figure-04(a),(b):thermocline,haloclineandpycnocline.
 Vertical Temperature Salinity & Density Profile:

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The Ocean Is Stratified into Three Density Zones by Temperature
and Salinity
a. The surface zone or surface layer or mixed layer
b.The pycnocline, or thermocline or halocline
c. The deep ocean (~ 80% of the ocean is below the
surface zone.

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 References:
A. Essentials of Oceanography(10th Edition) by Alan P. Trujillo & Harold V. Thurman
Chapter-5: Water and Seawater (Page-128 to 159).
B. Introduction To Physical Oceanography by Robert H. Stewart
Chapter-6: Temperature,Salinity and Density (Page-73 to 101).
C. Invitation to Oceanography(6th Edition) by Paul R. Pinet
Chapter-5: The Properties of Seawater (page-134 to 186).
D. Oceanography An Invitation to Marine Science(7th Edition) by Tom Garrison
Chapter-6 : Water and Ocean Structure (page-154 to 181).
E. THE OCEANS THEIR PHYSICS, CHEMISTRY, AND GENERAL BIOLOGY by H. U.
SVERDRUP,MARTIN W. JOHNSON AND RICHARCD H. FLEMING
Chapter-3: Physical Properties of Sea Water (page-47 to 97)
F. BIOLOGICAL OCEANOGRAPHY AN INTRODUCTION (2nd Edition) by CAROL M. LALLI and
TIMOTHY R. PARSONS
Chapter-2: THE ABIOTIC ENVIRONMENT (page-16 to 38).
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