Class Information Introduction to Remote Sensing Our Earth

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Class InformationIntroduction to Remote
SensingOur Earth

• Guido Cervone EOS 121- Lecture I

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Topics

• Class Information
• Introduction to Remote Sensing
• Our Earth

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Introduction

• Guido Cervone
• Assistant ProfessorDepartment of Geography and
  Geoinformation Sciences (GGS)
• ContactsOffice Research 1, room 221Telephone
  703.993.1799email gcervone_at_gmu.educlass
  website http//cervone.gmu.edu/teaching/csi759MS
  N gcervone_at_gmu.edugtalk gcervoneYahoo
  gcerv1AIM gcerv1

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Our Home

• How well do you know it?
• How big is it?
• Whats its mass?
• How far away is from the Sun? and from the Moon?
• How fast does it spin on itself? Clockwise or
  Counter clockwise?
• How fast does it revolve around the sun?
• How much surface is covered by land? And by
  water?
• Is it a perfect sphere?
• What is it composed of?
• Does it have a magnetic field?

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Earth Characteristics

• Earth is the third planet in the solar system in
  terms of distance from the Sun
• The diameter of the Earth at the equator is
  12,756 km (7,926 miles), and its circumference at
  the equator is 40,075 km (24,901 miles)
• The Mass of Earth is approximately 6 1024 kg.
  Its density is 5,515.3 kg/m³
• 70 is covered by oceans, 30 by land
• The Earth's shape is that of an oblate spheroid
• Earths gravitational constant is equal to 6.67 x
  1011 newton m2/kg2

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Earth-Sun Distance

• Sun-Earth distance is on the average 150 million
  kilometers (Identified with AU)
• Scientists were able to measure the distance to
  Venus very precisely using radar.
• Then a simple trigonometry problem gave the exact
  Sun-Earth distance.
• Why cant we use radar directly to measure the
  Earth-Sun distance?

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Moon-Earth Distance

• The actual Earth-Moon distance ranges from about
  360,000 to 405, 000 kilometers, depending on the
  position in the Moon's orbit.
• A full lunar cycle is 29 days

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Earth Interior

• The Earth formed about 4.6 billion years ago,
  along with the other solar planets and the Sun
  itself.
• The planets built up by accretion of rocky and
  gaseous debris (asteroidal, planetesimal
  meteoritic materials and comets) through
  collision of orbiting bodies.
• The Earth's materials are diverse and variable.
  Most variation occurs in the outermost 200
  kilometers, in the lithosphere.

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Earth Interior
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Types of Rock

• Igneous rocks form directly by crystallizationof
  hot melts made up of silicates (SimOn) combined
  with Fe, Mg, Ca, Al, Na, K, Ti, H2O). Minerals
  formed from these make up nearly all the mantle
  and crust.
• Rocks at the surface decompose/disintegrate by
  reaction with the atmosphere/hydrosphere to
  produce solid debris and soluble chemicals that
  are transported/deposited to form sediments, that
  upon burial are converted to Sedimentary rocks.
• Previously formed rocks that are heated and
  pressurized when buried to shallow to moderate
  depths (5 to 70 km) of the crust recrystallize as
  solids to form Metamorphic rocks

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Rock Lifecycle
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Earth Composition

• The Earth consists of a solid and liquid portion
  and an atmosphere of gaseous portion.
• The percentage composition of the Earth's solid
  and liquid materials (by mass) is
• 34.6 Iron, 29.5 Oxygen, 15.2 Silicon, 12.7
  Magnesium, 2.4 Nickel, 1.9 Sulfur, 0.05
  Titanium
• Oxygen is chemically combined with many
  substances to produce liquid and solid compounds.
  Although water (H2O) is a dominant compound on
  Earth, Hydrogen is not listed above because of
  its small mass.
• Silicon Dioxide (SiO2) is sand, and that compound
  makes up a large portion of the Earth's mass.
  Much of the Iron is in the Earth's core and is
  responsible for the Earth's magnetic field.
• Although most people think air is mainly Oxygen,
  the atmosphere of the Earth actually consists of
  79 Nitrogen (N2), 20 Oxygen (O2) and 1 of
  other gases such as Carbon Dioxide (CO2).

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Earths Atmosphere

• Troposphere This layer is characterized by a
  decrease in temperature with respect to height,
  at a rate of about 6.5ºC per kilometer, up to a
  height of about 10 km. All the weather activities
  (water vapour, clouds, precipitation) are
  confined to this layer. A layer of aerosol
  particles normally exists near to the earth
  surface. The term upper atmosphere usually refers
  to the region of the atmosphere above the
  troposphere.

• Stratosphere The temperature at the lower 20 km
  of the stratosphere is approximately constant,
  after which the temperature increases with
  height, up to an altitude of about 50 km. Ozone
  exists mainly at the stratopause. The troposphere
  and the stratosphere together account for more
  than 99 of the total mass of the atmosphere.
• Mesosphere The temperature decreases in this
  layer from an altitude of about 50 km to 85 km.
• Thermosphere This layer extends from about 85 km
  upward to several hundred kilometers. The
  temperature may range from 500 K to 2000 K. The
  gases exist mainly in the form of thin plasma,
  i.e. they are ionized due to bombardment by solar
  ultraviolet radiation and energetic cosmic rays.
• Many remote sensing satellites follow the near
  polar sun-synchronous orbits at a height around
  800 km, which is well above the thermopause.

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Earth Rotation

• The Earth rotates on itself counter clockwise
  approximately 1500 km per hour.  The actual speed
  depends on the latitude of the observer. 
• The Earth orbits the Sun at a speed of 29.79 km
  (18.51 miles) per second, or 107,870 km (67,000
  miles) per hour.
• The entire solar system is orbiting through our
  Milky Way Galaxy at nearly half a million km per
  hour
• And as if that wasn't enough, the Virgo Cluster,
  of which our galaxy is a member, is moving at
  nearly a million km per hour towards a point in
  interclusteral space known as the Great
  Attractor.

Think about it the next time you feel tired to go
out!
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Earth Seasons
Why is the Northern Hemisphere warmer during the
summer than during the winter?
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Earth Magnetosphere

• The iron-nickel core of the Earth acts as a giant
  magnet, comparable to a dipole bar magnet.
• The Earth's magnetic field is like a dipole
  magnet only close to the surface.
• The Earth's magnetic field extends far out into
  space for thousands of miles

Compass readings
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Earth Magnetosphere

• The extremely hot atmosphere of the Sun is a
  plasma (a gas consisting of charged particles,
  mostly electrons and protons)
• Solar plasma streams radially into space at high
  speed and pulls the Sun's magnetic field with it

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Earth Magnetosphere

• The electrified particles and the solar magnetic
  fieldare called the solar wind.
• These bits of the Sun come streaming at us at
  velocities of 450 km/second or more.
• While light travels from Sun to Earth in about 8
  minutes, the solar wind usually reaches Earth in
  2 or 3 days.
• The solar wind particles flowing directly from
  the Sun toward the Earth encounter the
  magnetosphere much as water in a swift stream
  comes upon a large rock.

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Earth Magnetosphere

• Passage through the bow shock region reduces the
  speed and changes the motion of the particles
• Most of the shocked solar wind particles are
  deflected around the magnetosphere
• The magnetosphere effectively shields the Earth
  from most of the direct solar wind

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Earth Magnetosphere

• Some solar wind plasma can, however, travel along
  the Earth's magnetic field lines
• When the solar wind enters the polar cups, it
  follows the magnetic field lines toward Earth.
• Through the polar cusps, high-speed charged
  particles from the solar wind bombard our upper
  atmosphere
• This allows more particles to reach the the upper
  atmosphere which cause aurora borealis in the
  northern hemisphere and the aurora australis in
  the southern hemisphere

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Earth Magnetosphere

• Earth Magnetosphere was discovered by one of the
  earliest satellite missions!
• Explorer 1, on January 31, 1958, four months
  after the Soviet Union launched Sputnik I

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Van Allen Radiation Belts

• A Geiger counter mounted Explorer 1, provided
  surprising evidence that the Earth is surrounded
  by intense particle radiation
• Two huge zones of trapped electrons and protons
  encircle the Earth like donuts

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Van Allen Radiation Belts

• The Inner V.A. Belt reaches its maximum intensity
  at 5000 km (3000 miles) but extends inward to
  about 1000 km (600 miles). the inner belt is
  marked by protons brought in mainly as cosmic
  rays
• The Outer Belt starts at 1500 km (9300 miles) and
  peaks at 22000 km (15500 miles). The outer belt
  is dominated by trapped electrons from the solar
  wind
• Important about Van Allen Belts
• They provide protection from potentially
  devastating particle bombardments - a fact
  critical to the successful development of life on
  Earth
• Both spacecraft and humans would need to be
  shielded effectively when passing through the
  Belts.

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Aurora Borealis and Australis

• The Van Allen Belts become much weaker above 75N
  and 75S.
• This allows more particles to reach the upper
  atmosphere and collide with oxygen, nitrogen and
  argon atoms in the air to generate ions that in
  their excited states give off constantly moving,
  colorful, wavy displays
• This geophysical phenomenon occurs mainly at the
  higher latitudes but sometimes extends below 40

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View of the Auroras from Space

• A satellite named SOHO whose job is to monitor
  solar activity reported intense solar storms
• This was predicted to produce a spectacular
  aurora borealis
• A NASA satellite called Polar (launched in 1996)
  designed to monitor just such phenomena produced
  this view in the visible from space

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Geoid

• The geoid is an equipotential surface which
  (approximately) coincides with the mean ocean
  surface.
• It represents the departure from the ellipsoidal
  surface caused by differences in gravitational
  attraction caused by variations in density

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Geoid

• Over the years gravity measurements have led to
  both generalized and regional models of the
  geoid.

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How can we Compute Gravity?

• The prime use and successes of gravity satellites
  have been in surveying the topography of oceans
  and other large bodies of water.
• Because of their high rates of orbital velocity
  and other complications, satellites do not
  normally carry accelerometers to measure direct
  changes in gravitational attraction along their
  orbital tracks.
• Instead, gravity variations can be calculated
  from changes in the position (shifts in orbital
  height) of a satellite as it orbits

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Grace Mission

• GRACE (Gravity Recovery and Climate Experiment)
  launched on March 17, 2002
• GRACE is actually a pair of satellites in the
  same orbit at 500 km but 220 km apart (formation
  flying)
• Each GRACE satellite uses microwave signals to
  determine very precisely the vertical distance
  between spacecraft and points on the surface

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Grace Results
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Grace Results

• The Earth Geoid changes over time
• Such variations suggest what is known as
  isostatic adjustments
• Isostasy refers to the tendency for the Earth's
  outer sphere to experience forces that cause its
  surface to rise or fall as loads are added or
  removed
• The response is not instantaneoous but occurs
  over time

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Grace Results

• From March through about July the geoid in the
  Amazon is somewhat higher than average but this
  elevation transitions into lower heights from
  September through December
• The added load, leading to the blue stage, is the
  accumulation of water in the Amazon Basin during
  the rainy season

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What is the Atmosphere

• Envelope of gases, energy, particles, and liquids
  held to earth by gravity, which varies slightly
  by latitude and longitude and varies greatly by
  elevation and extends up to 10,000 km.
• Shields earth from the full range of solar and
  cosmic radiation, traps heat in natural
  greenhouse effect
• Has mass and exerts pressure
• A unit of pressure (14.72 lbs/sq in, c.105
  Pascals, 1013 mb) mean pressure at sea level at
  45 deg. lat ( 1 Newton .225 lbs, N m-2
  Pascal)
• 1/2 atmos. mass below 5,500 m. 99 below 30 km

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Nebular hypothesis that the solar system formed
by gravitational contraction of an enormous cloud
of largely helium and hydrogen (minor amounts of
other elements).

• Nebula, the large cloud of dust and gases.
• Rotation of the cloud causes it to flatten into a
  disk. Most material in the cloud was pulled
  toward the center of rotation.
• Gravitational attraction in the center of the
  cloud causes it to become denser and to heat up
  (forming the protosun).
• Small "eddies" in the cloud undergo similar
  rotation and contraction, concentrating material
  in the cloud. Results in the formation of the
  protoplanets.
• As the cloud clears the heat of the sun drives
  light gases off the inner protoplanets. 
• The process complete by about 4.5 billion years
  ago.
• Earth experienced a period of internal melting
  (due to initial
• high temperatures and heat from radioactive
  decay).

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Differentiation of the early Earth

• When melting of the Earth began dense elements
  sank towards the center of and light elements
  rose towards the surface (forming minerals that
  make up the crust).

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Earth Forms

• Lighter material rose to surface crust denser
  sank to the core bollide collisions
• As the Earth cooled and differentiated, the crust
  became thicker and continents began to "grow" by
  plate tectonics
• First crust likely basaltic (like modern oceanic
  crust) and lacked continents
• At zones of subduction, intrusion of magma into
  overlying crust would have caused thickening to
  form continental crust.

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Earth Age

• Oldest continental igneous rocks are 3.8 billion
  years old.
• Oldest sedimentary rocks (sandstones) are 4.2
  billion years old.
• Therefore, granitic continental crust must have
  been present by 4.2 billion years ago.
• By 2.5 billion years ago, large continental
  masses were present.

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First Atmosphere

• Composition - Probably H2, He, neon, Ar
• These gases are relatively rare on Earth compared
  to other places in the universe and were probably
  lost to space early in Earth's history because
• gravity is not strong enough to hold lighter
  gases
• Earth still did not have a differentiated core
  (solid inner/liquid outer core) which creates
  Earth's magnetic field (magnetosphere Van Allen
  Belt) which deflects solar winds.
• Once the core differentiated the heavier gases
  stayed anchored

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Second AtmosphereProduced by volcanic outgassing
and bollides.  

• Gases were similar to those of modern volcanoes
  (H2O, CO2, SO2, CO, S2, Cl2, N2, H2) and NH3
  (ammonia) and CH4 (methane)
• Comets bearing H2O
• No free O2 at this time (not found in volcanic
  gases).
• Ocean Formation - As the Earth cooled, H2O
  produced by outgassing could exist as liquid in
  the Early Archean, allowing oceans to form.
• CO2 is 12, where does it go?

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• Oxygen cycle
• Oxygen Production
• Photochemical dissociation - breakup of water
  molecules by ultraviolet
• Produced O2 levels approx. 1-2 current levels
• At these levels O3 (Ozone) can form to shield
  Earth surface from UV
• Photosynthesis - CO2 H2O sunlight organic
  compounds O2 - produced by cyanobacteria, and
  eventually higher plants - supplied the rest of
  O2 to atmosphere. Thus plant populations
• Oxygen Consumers
• Chemical Weathering - through oxidation of
  surface materials (early consumer)
• Animal Respiration (much later)
• Burning of Fossil Fuels (much, much later)

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Atmosphere by 4 billion years ago

• Virtually no O2
• Carbon dioxide CO2
• Water vapor H2O
• Nitrogen N2
• Hydrogen H2
• Hydrogen Chloride HCl
• Sulfur Dioxide SO2

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Origin of O2

• Some O2 came from
• 2H2O ultraviolet rays 2H2 O2
• Lost to space 2H2
• (Early sun with gt UV)
• More came from photosynthesis
• CO2 H2O light ( chlorophyll) (CH2O) O2

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Evidence for O2 and Cyanobacteria

• Photosynthesis requires chlorophyll, produced by
  some organisms (e.g., plants)
• The oldest that could produce chlorophyll are
  cyanobacteria single celled sea organisms that
  lacked an organized nucleus
• First cyanobacteria appeared about 3.5 bya and
  were anaerobic
• But very common in rocks lt about 2.5 bya
• There is strong correlation between O2 levels in
  the atmosphere and the development of life, on
  Earth. 

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http//www.ucmp.berkeley.edu/precambrian/precambri
an.html
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Cyanobacteria or"blue-green algae" go back to 3.5
by
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Oldest Fossil 3.5 bya

• Stromatolite Colony
• either blue-green algae or bacteria

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Oxygens Rise

• As Oxygen levels increased, aerobic organisms
  developed ? even more Oxygen
• Oxygen levels became high enough to support more
  complex life ? more oxygen
• By 600 million years ago Oxygen levels had almost
  reached modern levels, about 20 and O3 starts to
  form in stratosphere ?
• The evolution of land plants, resulted in a
  modest increase in O2
• Variation in O2 levels over the past 500 million
  years reflect changes in plant cover on Earth

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Variation in O2 over last 500 million years
reflects plant cover
Carboniferous warm, moist, tropical settings O2
levels almost doubled. Permian and Triassic arid
conditions on land O2 levels dropped to below
15.
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Rock Record O2 in the atmosphere has increased
with time

• Iron (Fe) is extremely reactive with oxygen. Fe
  in the rock record tells us much about
  atmospheric evolution.
• Archean - Find minerals that only form in
  non-oxidizing environments Pyrite (FeS2),
  Uraninite (UO2).
• Banded Iron Formation chert iron oxide, iron
  carbonate, iron silicate, iron sulfide. Major
  source of iron ore magnetite (Fe3O4), common in
  rocks 2.0 - 2.8 B.y.
• Red beds (continental siliciclastic deposits) are
  never found in rocks older than 2.3 B. y., but
  are common during Phanerozoic time. Red beds are
  red because of the highly oxidized mineral
  hematite (Fe2O3), that probably forms secondarily
  by oxidation of other Fe minerals that have
  accumulated in the sediment.

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American Museum of Natural History 2 billion
year old banded iron formation, Ontario
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Garden of the Gods, Colorado Springs, CO
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Biological Evidence of O2 buildup

• Chemical building blocks of life could not have
  formed in the presence of atmospheric oxygen.
  Chemical reactions that yield amino acids are
  inhibited by presence of very small amounts of
  oxygen.
• Oxygen prevents growth of the most primitive
  living bacteria such as photosynthetic bacteria,
  methane-producing bacteria and bacteria that
  derive energy from fermentation. Conclusion -
  Since today's most primitive life forms are
  anaerobic, the first forms of cellular life
  probably had similar metabolisms.
• Today these anaerobic life forms are restricted
  to anoxic (low oxygen) habitats such as swamps,
  ponds, and lagoons.

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Ozone

• An important atmospheric ingredient to make
  terrestrial life (land-based) possible was the
  formation of the Ozone layer, to protect life
  forms from ultraviolet radiation
• In the upper atmosphere, UV radiation breaks up
  O2 into singular oxygen atoms, these recombine
  with O2 into a strong structure of O3, Ozone
• Increase of plants on land increased
  photosynthesis increased O2 production CO2
  consumption

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Geologic Time Climate Questions

• 1. In Precambrian
• Weak sun paradox (standard model of solar
  physics 70-80 luminosity of early sun), which
  means a temp 10-15 K below today, but evidence of
  similar T
• increase retention of IR (CO2) change in
  spectral output model is wrong Iceball Earth
• 2. Long-Term controls on climate
• Solar Radiation variation in atmospheric gases
  Mountain Building Milankovich Cycles plate
  tectonics ocean-atmosphere interactions

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References

• http//willshare.com/willeyrk/creative/earthfax/ea
  rthfax.htm
• http//en.wikipedia.org/wiki/Earth
• http//www.crisp.nus.edu.sg/research/tutorial/atm
  os.htm
• http//ssdoo.gsfc.nasa.gov/education/lectures/magn
  etosphere/index.html
• http//rst.gsfc.nasa.gov/Front/tofc.html