introduction to oceanography dr. marianne e. mcnamara

Introduction to Oceanography

Dr. Marianne E. McNamara

First, An icebreaker…

• Your major• Your year/Part time or full time• Your plans• Your objectives• Your interests

What is oceanography?

• Oceanography is the study of the ocean– An interdisciplinary science:

• Geology• Geography• Chemistry• Physics• Biology• Astronomy

What is oceanography?

• Oceanography consists of several specialized disciplines– Marine Biology (Biological oceanography)– Chemical Oceanography– Geological Oceanography– Physical Oceanography

– Marine Engineering– Marine Ecology– Marine Management

Chemical Oceanograph

y

Oceanography ≠ Dolphins!

Physical Oceanograph

y

Geological Oceanography

Biological Oceanograph

y

…but it is one way to unleash your inner dolphin hugger…

Got Ocean?• The ocean covers 71% of the Earth’s surface• Accounts for >97% of the Earth’s water!• The average depth of the ocean is 3,800

meters (12,500 feet) and at its deepest depth is 7,000 ft greater than the highest elevation on land (Mt. Everest 29,000 ft; Mariana Trench 36,163 ft)

• The average temperature of the ocean is only 3.9 C (39 F) ̊� ̊�

Oceanography

• For our convenience, the oceans are separated into 5 named ocean basins (and many smaller seas), but they all constitute one world ocean; one great intermixing mass of saline (salty) water

• All oceans are, in fact, interconnected with one another

One World Ocean

• Pacific Ocean (the largest)

• Atlantic Ocean• Indian Ocean• Arctic Ocean• Southern Ocean

One World Ocean

http://www.gebco.net/data_and_products/gebco_world_map/images/gda_world_map_large.jpg

Pacific OceanAtlantic Ocean

Indian Ocean

Arctic Ocean

Southern Ocean

The Ocean’s Origins• The Earth is believed to be 4.6 billion years old• During the Earth’s formation, heavy (dense)

metals such as iron and nickel gravitated towards the hot center in a molten state

• At the same time, lighter elements such as aluminum and silicon rose towards the surface, forming the Earth’s crust

The Ocean’s Origins

• Crust is made up of different rock types, and so is thinner and thicker in places

• Thick = land; thin = ocean!

The Ocean’s Origins• Eventually, the young Earth cooled enough

such that water vapor condensed and collected in the ocean basins

• As water collected, it dissolved minerals within the rocks

• After 20 million years of rain, the oceans were born!

Why study oceanography?

• ~80% of all Americans live within 1 hour of an ocean or Great Lake

• 100% of all Long Islanders live within 1 hour of the Atlantic Ocean

• 50% of the world’s population live on a coastline

Why study oceanography?

We live on Long ISLAND; The ocean is our backyard!!!

Why study oceanography?

• Our Earth is a BLUE planet

• Why blue?

http://www.nasa.gov/centers/goddard/images/content/95573main_plankton_satellite.jpg

Why study oceanography?

• More than half of the oxygen we breath is produced in the ocean!

Why study oceanography?

• Oceans moderate the Earth’s climate

Why study oceanography?

"Old Inlet" breach in Fire Island caused by Sandy. Photo by National Park Service

Why study oceanography?• Because it’s the stuff of legends

(and nightmares…)

Why study oceanography?• Because it’s the stuff of legends

(and inspirations)

Why study oceanography?

• So you can understand this on a deeper level

http://www.youtube.com/watch?v=hwlZUKv57B4

Why study oceanography?

Why study oceanography?

Why study oceanography?

Oceanography

• Oceanography deals with understanding the complex relationships between physics, geology, chemistry and biology

• Oceanography must consider the relationships between land and sea, and within the ocean itself

The History of Oceanography• Explorers and scientists have been studying

the oceans for millennia and centuries, respectively

1769 chart of the Gulf Stream by Benjamin Franklin

History of Oceanography

• In fact, the units of latitude and longitude were developed by Alexandrian (Greek) scholars ~200 years BCE

• Latitude and longitude are systems of imaginary lines dividing the surface of the Earth

• Essential for navigation

Latitude and Longitude

• Latitude lines run parallel to the equator• Longitude lines run from pole to pole

The History of Oceanography

• The most famous and extensive study of the ocean was conducted by the British in the 19th century– The HMS Challenger sailed the seas between

1872-1876– Motivated by economic and military interests– Explored nearly every all parts of the world’s

ocean• Seawater samples, biological samples, depths,

sediment composition

The Challenger expedition

• Voyage track from 1872-1876; remains the longest continuous oceanographic survey

History of Oceanography• The Challenger expedition successfully

disproved the Azoic hypothesis – the belief that no life existed below 550 meters

• Collection of life in the depths launched the science of marine biology!

Oceanography: The Final Frontier?