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CONS 127 > Oceans & Freshwater > Flashcards

Oceans & Freshwater Flashcards

1
Q

Oceans

A
  • The body of saltwater that
    covers 70% of the Earth’s
    surface
  • Contains 97% of Earth’s water
  • Atlantic, Pacific, Indian & Arctic
  • Southern is the newest ocean
    (Not recognized worldwide)
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2
Q

Freshwater

A
  • Naturally occurring liquid (or
    frozen) water containing low
    concentrations of dissolved salts
  • Glaciers, lakes, reservoirs, ponds,
    rivers, streams, wetlands and
    groundwater
  • Only 3% of Earth’s water
  • Less than 1% of Earth’s total
    surface area
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3
Q

Where is Earths water

A

total global water:
* 96.5 oceans
* 2.5 freshwater
* 0.9 other

fresh water
* 68.7 Glacier and ice cap
* 30.1 ground water
* 1.2 surface/other water

surface water
* 69 ground ice and permanfrost
* 20.9 lakes
* rest

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4
Q

Why Monitor the Oceans & Freshwater?

A

Very useful indicator of climate variability and change
* Community impacts
* Biodiversity impacts

Weather and climate prediction
* Ocean currents
* Regulation

Freshwater storage
* Water resource management
* Ecosystem
* Hydrology

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5
Q

Historical Monitoring of Oceans & Freshwater

A

People in boats:

  • Placing nets or instruments into the
    water
  • Collecting data on composition (of
    water and surfaces)
  • Building nautical charts
  • Understand tides, currents, etc

no standerlized data

still good to validate data

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6
Q

Monitoring the Oceans & Freshwater from
Space

A
  • Sea surface temperature
  • Sea levels
  • Freshwater storage
  • Habitat characteristics
  • Coral reefs
  • Salmon habitat in freshwater streams
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7
Q

Historical Sea Surface Temperature
Measurements

A
  • Before satellites, measurements
    from buoys were the main tool
  • Provides point measurements
  • At potentially very fine/high temporal
    scales
  • Every hour, minute, second, and
    millisecond if you’d like
  • All weather
  • still good to validate data
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8
Q

Sea Surface Temperature

A

* Provides fundamental information on global climate system
* Such as identifying El Niño and La Niña cycles
* Typically measured with passive sensors
* MODISoften preferable
* Better for coarse spatial scale(entire globe for example)
Better temporal resolution
* MODIS bands 31 & 32 used
* Thermal infrared
* Not all weather

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9
Q

Sea Surface Temperature

A
  • The ocean emits thermal infrared radiation
  • Measured from space by sensors like MODIS
  • And is proportional to sea surface temperature
  • Infrared radiation from the ocean comes from the top 10 microns of the surface
  • The ocean also emits radiation in the microwave part of the spectrum
  • Which is also proportional to sea surface temperature
  • Microwave radiation is from the top millimeter of the surface
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10
Q

Sea Surface Temperature

A

* Tropical Rainfall Measuring Mission (TRMM)

  • Has a Microwave Imager (TMI)
  • Still a passive sensor
  • Allows for sea surface temperature estimates in all weather conditions
  • Representative of the top 1mm of the
    surface
  • Orbit restricted to +/- 30° of the equator
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11
Q

What about below the surface?

A
  • Below surface measurements are
    primarily taken from mooring and
    drifter buoys
  • Mooring buoys are good for measuring time series through the depths of the water column
  • Most deeper ocean temperature data are measured from drifter buoys
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12
Q

What about Freshwater?

A
  • We use similar methods for
    monitoring lake surface
    temperature
  • MODIS frequently used(more spatial resolution)
  • Landsat used for smaller lakes(less spatial resolution)
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13
Q

An Example of Efficient Data Collection

A

By Satellite
* In the Mid Atlantic, a passing
satellite measuring sea surface
temperature may contain
around 600,000 pixels of data
* Covering an area of over 250,000 square miles

By Buoy
* Meanwhile, there are only
about a dozen buoys in the
same area
* Given the vast size and
variability of the ocean,** the
applications of these
measurements are limited**

But they are still needed to
validate satellite data

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14
Q

Sea Level: Why is it increasing?

A

Rising sea levels are from two
primary factors:

  • **Thermal expansion **of water from increased temperatures (water
    expands as it warms)

* Increased melting of land-based ice(glaciers and polar ice caps).

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15
Q

Satellites Used for Sea Level Measurements: RADAR

both below are RADAR’s

A
  • Topex/Poseidon Mission
  • 1992 – 2006
  • Joint mission between CNES (the
    French space agency) and NASA
  • The first time scientists were able to map ocean topography with accuracy

* Jason Series
* Jason 1, 2001 – 2013
* Jason 2, 2008 – 2019
* Jason 3: Launched 2016

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16
Q

Satellites Used for Sea Level Measurements: Gravitational sitelite

A
  • Gravity Recovery and Climate
    Experiment (GRACE)
  • Satellite mission that measures gravitational pull across the surface of the Earth
  • Which it relates to mass balance
  • Capable of:
  • Measuring sea level
  • Freshwater storage
  • Land mass storage
  • Main tool used to calculated geoid
17
Q

Earth Observation in Mesuring : Habitat Characteristics

A
  • Coral Reefs with Landsat
  • Salmon habitat with Lidar
18
Q

Coral Reefs

A
  • Coral reefs cover less than 0.01% of the total surface of the ocean
  • But are home to 5% of the global biota
  • And 25% of all marine species
  • Increase sea surface temperatures (among other causes) have led to increased coral bleaching
  • Bleaching makes reefs susceptible to:
  • Stress & disease
  • And increases the possibility of death
19
Q

Mapping Coral Reefs and LANDSAT

A
  • Landsat has emerged has a key tool formapping and monitoring coral reefs
  • Fine/moderate spatial resolution
  • Longest record through time since the 70s
  • Free dataset
  • Landsat 8 (and 9)** has ideal spectral bands**
  • Extra band in VIS blue
  • Extra sensitivity
  • Better signal to noise ratio
20
Q

Mapping Salmon Habitat

A
  • Salmon are a keystone species linked to:
  • Greater ecosystem diversity
  • Important ecosystem energy cycles
  • Economies & sustenance
  • They are vulnerable to many stressors and threats:
  • Climate change
  • Habitat degradation
  • Pollution
21
Q

Mapping Salmon Habitat with Lidar

A
  • Mapping habitat units is important for understanding salmon behaviour and abundance
  • Lidar allows for efficient data collection and mapping of:
  • Riffles
  • Pools
  • Cascades
  • Glides
  • Lidar can use terrain and structural data To map salmon habitat units
  • With very high accuracy
  • Up to 96% accuracy compering to doing it manually

having the salmon habitat mapped can help us understand habitat quality and salmon abudance

22
Q

Summary

A

Sea Surface Temperature
* MODIS - Thermal infrared bands
* TMI sensor onboard TRMM satellite- Microwave bands

Sea Level
* Topex/Poseidan
* Jason Series
* GRACE

** Habitat Characteristics**
* Coral reefs with Landsat
* Salmon habitat with airborne Lidar

23
Q

Advantages of Earth Observation Data for

Oceans & Freshwater

A
  • Standardized data
  • Efficient collection: cover all the global not only a small portion like the boyons
  • Coverage
  • Resolutions
  • Spatial
  • Temporal
  • Spectral

similar to biosphere

24
Q

What is one advantage of using satellite data to monitor sea surface
temperature when compared to historical methods?

A

satelites gives a much more covarage (the whole glob) while boyots only gives specifc points

CONS 127 (19 decks)

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