Remote Sensing Techniques for Oceanography Satelitte and In Situ Observations

Remote Sensing Techniques
for Hydrosphere

Arife Tuğsan ISIACIK COLAK
Istanbul Technical University Faculty of Maritime, Tuzla 34940, Turkey
isiacik@itu.edu.tr

AGENDA
1. Definition of Earth Science-Hydrology-Oceanography
2. Why do WE study the oceans?
3. Remote Sensing Study Area Hydrology - Oceans & Coastal
Monitoring
4. Critical Marine Issues
5. Ocean and Water Parameters -Ocean Monitoring and
Forecasting- Technical Information for Instruments and
In-Situ Observations Systems
6. RS Application Examples for the Critical Marine Issues
7. Conclusion

1.What is Earth Science?
Earth science is a broad term for any branch of science
that deals with the study of any part of the Earth,
including its environments, climates, and composition.
There are several general types of earthscience that are
roughly grouped according to the broader fields into
which they fall and which correspond to four area that
divide the Earth and its immediate environment:

1. the atmosphere,
2. the lithosphere or geosphere,
3. the biosphere, and
4. the hydrosphere
are the domains into which all types of Earth science fall

What is Hydrosphere and
Hyrdology?
The hydrosphere in physical geography describes the
combined mass of water found on, under, and over the
surface of a planet.
Hydrology is the study of the movement, distribution,
and quality of water on Earth and other planets,
including the hydrologic cycle, water resources and
environmental watershed sustainability.
Domains of hydrology
include hydrometeorology, surface
hydrology, hydrogeology, drainage basin management
and water quality, where water plays the central role.
Oceanography and meteorology are not included
because water is only one of many important aspects
within those fields.

Earth Hydrosphere
 The Earth's hydrosphere consists chiefly of the oceans,
but technically includes all water surfaces in the world,
including inland seas, lakes, rivers, and underground
waters down to a depth of 2,000 m.

 Approximately 71% of the planet's surface
(~3.6x108 km2) is covered by saline water that is
customarily divided into several principal oceans and
smaller seas.

Branches
 Chemical hydrology is the study of the chemical characteristics of water.
Ecohydrology is the study of interactions between organisms and the
hydrologic cycle.
Hydrogeology is the study of the presence and movement of ground water.
Hydroinformatics is the adaptation of information technology to hydrology
and water resources applications.
Hydrometeorology is the study of the transfer of water and energy between
land and water body surfaces and the lower atmosphere.
Isotope hydrology is the study of the isotopic signatures of water.
Surface hydrology is the study of hydrologic processes that operate at or
near Earth's surface.
Drainage basin management covers water-storage, in the form of reservoirs,
and flood-protection.
Water quality includes the chemistry of water in rivers and lakes, both of
pollutants and natural solutes.

Applications of Hydrology
 Determining the water balance of a region.
 Determining the agricultural water balance.
 Designing riparian restoration projects.
 Mitigating and predicting flood, landslide and drought risk.
 Real-time flood forecasting and flood warning.
 Designing irrigation schemes and managing agricultural productivity.
 Part of the hazard module in catastrophe modeling.
 Providing drinking water.
 Designing dams for water supply or hydroelectric power generation.
 Designing bridges.
 Designing sewers and urban drainage system.
 Analyzing the impacts of antecedent moisture on sanitary sewer systems.
 Predicting geomorphological changes, such as erosion or sedimentation.
 Assessing the impacts of natural and anthropogenic environmental change on water resources.
 Assessing contaminant transport risk and establishing environmental policy guidelines.

HYDROSPHERE

The hydrosphere encompasses water in all
three phases (i.e., ice, liquid, and vapor) that continually
cycles from one reservoir to another witin the Earth
system. Water is unique among the chemical
components of the Earth system in that it is the only
naturally occurring substance that co-exists in all three
phases at normal temperatures and pressures near Earth’s
surface.

The ocean, by far the largest reservoir of water
in the hydrosphere, covers about 70.8% of the planet’s
About 97.2% of the hydrosphere is ocean salt water; other
After the oceans next largest reservoir in the hydrosphere
is glacial ice, most of which covers much of Antarctica and
Greenland. Ice and snow make up 2.1% of water in the
hydrosphere Planet Earth,

Oceanography
 Oceanography also called oceanology or marine
science, is the branch of Earth science that studies the
ocean. It covers a wide range of topics,
including marineorganisms and ecosystem dynamics;
ocean currents, waves, and geophysical fluid
dynamics; plate and the geology of the sea floor;
and fluxes of various chemical substances and physical
properties within the ocean and across its boundaries.

The study of oceanography is divided into branches:

 Biological oceanography, or marine biology, is the study
of the plants, animals and microbes of the oceans and
their ecological interaction with the ocean;

 Chemical oceanography, or marine chemistry, is the
study of the chemistry of the ocean and its chemical
interaction with the atmosphere;

 Geological oceanography, or marine geology, is the study
of the geology of the ocean floor including plate
tectonics and paleoceanography;

 Physical oceanography, or marine physics, studies the
ocean's physical attributes including temperature-salinity
structure, mixing, waves, internal waves,
surface tides,internal tides, and currents.

2. WHY DO WE STUDY THE OCEANS?

We have to study oceans ;
to develop an understanding of the total Earth system
and the effects of natural and human-induced changes
on the global environment.
Our oceans play a major role in influencing changes in
the world's climate and weather. Collecting and
analyzing long-term ocean data is very important
source. The analysis of remotely-sensed ocean data
makes it possible to understand the ocean in new and
exciting ways.

…
 Using remote sensing data and computer models,
it is possible investigate how the oceans affect the
evolution of weather, hurricanes, and climate.

 Oceans control the Earth's weather as they heat
and cool, humidify and dry the air and control
wind speed and direction.

…
 Long-term weather patterns influence water supply,
food supply, trade shipments, and property values. We
can't escape the weather, or even change it--but being
able to predict its impact. And only by understanding
the dynamics of the oceans can we begin to do this.

3. Remote Sensing Study Area
Hydrology - Oceans & Coastal
Monitoring

RS Hydrological Applications
include :
1. wetlands mapping and monitoring,
2. soil moisture estimation,
3. snow pack monitoring / delineation of extent,
4. measuring snow thickness,
5. determining snow-water equivalent,
6. river and lake ice monitoring,
7. flood mapping and monitoring,
8. glacier dynamics monitoring (surges, ablation)
9. river /delta change detection
10. drainage basin mapping and watershed modelling

RS;Oceans & Coastal Monitoring Applications

Ocean pattern identification:
 currents,

 regional circulation patterns,

 shears,

 frontal zones,

 internal waves, gravity waves,

 eddies, upwelling zones,

 shallow, water bathymetry

 Storm forecasting
 wind and wave retrieval
 Fish stock and marine mammal assessment
 water temperature monitoring
 water quality
 ocean productivity, phytoplankton concentration and drift
 aquaculture inventory and monitoring
 oil spill mapping and predicting oil spill extent and drift
 strategic support for oil spill emergency response decisions
 Shipping, navigation routing, traffic density studies
 operational fisheries surveillance
 near-shore bathymetry mapping
 Intertidal zone, tidal and storm effects
 delineation of the land /water interface
 mapping shoreline features / beach dynamics
 coastal vegetation mapping

4. Critical Marine Issues

 Maritme Safety And Security
 Marine Resources
 Coastal & Marıne Envıronment
 Weather, Clımate & Seasonal Forecastıng
 Overfishing
 Sea Temoerature Rise
 Marine Pollution
 Sea Level Rise
 Marine Invasive Species

5. OCEAN MONITORING
and FORECASTING

 For OCEAN MONITORING
and FORECASTING we have to know ocean
parameters for the critical marine issues first of
all.

OCEAN PARAMETERS

Temperature
Currents
Salinity
Sea ice
Sea level
Wind
Biogeochemistry
Water Quality Parameters

Why measure sea surface
temperature?
 Sea surface temperature (SST) is the temperature of the ocean near the
surface. Knowing the temperature of this part of the ocean is
absolutely essential for many reasons. For oceanographers,
meteorologists and climatologists, it is one of the signs/results of the
exchange of energy between the ocean and the atmosphere. For
marine biologists, it is the parameter that determines the development
of different biological organisms. For fishermen, important
temperature variations as seen on a map (thermal fronts) indicate
prolific fishing zones.
 Meteorological phenomena such as El Niño or tropical
hurricanes/cyclones are the direct consequences of specific
temperature variations at the sea-surface.
 Sea surface temperature varies between -1,8°C, temperature at which
sea water freezes, and +30°C near/below the Equator.

How SST is measured

 By satellite
•Infrared radiometers
•Microwave radiometers

In-situ techniques
•Ships of opportunity
•Drifting buoys
•Argo profiling floats
•Moored buoys
 Numerical models
Numerical atmospheric or oceanic models are also capable of
calculating sea surface temperature. Models are calibrated by
comparing the sea surface temperature produced by the model with
that measured by different sensors.

Satellite Instruments
Instrument Type Ocean Parameter Instrument Name Satellite
Used
Spectroradiometer Sea Surface MODIS Aqua (NASA, USA)
Temperature MERIS Envisat (ESA,
Europe)
Infrared Sea Surface AVHRR (NOAA, USA) +
radiometer Temperature AATSR METOP (Eumetsat,
MODIS Europe)
Envisat (ESA, Europe)
SEVIRI
Aqua, Terra (NASA,
GOES USA)
MeteoSat ( Eumetsat,
Europe)
(NOAA, USA)
DMSP (NASA, USA)
Microwave Sea Surface SSM/ITMI DMSP (NASA, USA)
radiometer Temperature AMSR-E TRMM (NASA, USA)
MWR Aqua (NASA, USA) +
JMR, AMR (developed by JAXA,

Which Satellite Instruments are
used for monitoring SST ?
 MODIS (or Moderate Resolution Imaging Spectroradiometer) is
a key instrument aboard the Terra (EOS AM) andAqua (EOS
PM) satellites.
 Terra's orbit around the Earth is timed so that it passes from
north to south across the equator in the morning, while Aqua
passes south to north over the equator in the afternoon.
 Terra MODIS and Aqua MODIS are viewing the entire Earth's
surface every 1 to 2 days, acquiring data in 36 spectral bands, or
groups of wavelengths. These data improve our understanding
of global dynamics and processes occurring in the oceans, and in
the lower atmosphere. MODIS is playing a vital role to predict
global change accurately.

Technical Information
 Orbit:705 km, 10:30 a.m. descending node (Terra) or 1:30 p.m.
ascending node (Aqua), sun-synchronous, near-polar,
circularScan Rate:20.3 rpm, cross trackSwath
Dimensions:2330 km (cross track) by 10 km (along track at
nadir)Telescope:17.78 cm diam. off-axis, afocal (collimated),
with intermediate field stopSize:1.0 x 1.6 x 1.0 mWeight:228.7
kgPower:162.5 W (single orbit average)Data Rate:10.6 Mbps
(peak daytime); 6.1 Mbps (orbital average)Quantization:12
bitsSpatial Resolution:250 m (bands 1-2)
500 m (bands 3-7)
1000 m (bands 8-36)Design Life:6 years

Cont….
 MERIS is a programmable, medium-spectral resolution, imaging
spectrometer operating in the solar reflective spectral range.
Fifteen spectral bands can be selected by ground command.
 The instrument scans the Earth's surface by the so called "push-
broom" method. Linear CCD arrays provide spatial sampling in the
across-track direction, while the satellite's motion provides
scanning in the along-track direction.
 MERIS is designed so that it can acquire data over the Earth
whenever illumination conditions are suitable. The instrument's
68.5° field of view around nadir covers a swath width of 1150 km.
This wide field of view is shared between five identical optical
modules arranged in a fan shape configuration.

 Status
Operational
 Type
Imaging multi-spectral radiometers (vis/IR)
 Technical Characteristics
Accuracy:
Ocean colour bands typical S:N = 1700
Spatial Resolution:
Ocean: 1040m x 1200 m, Land & coast: 260m x 300m
Swath Width:
1150km, global coverage every 3 days
Waveband:
VIS-NIR: 15 bands selectable across range: 390 nm to 1040 nm(bandwidth programmable
between 2.5 and 30 nm)
 Earth Topics
Land ( Vegetation ), Ocean and Coast ( Ocean Colour/Biology ), Atmosphere (
Clouds/Precipitation )

Advanced Very High Resolution Radiometer - AVHRR
 The AVHRR is a radiation-detection imager that can be
used for remotely determining cloud cover and the
surface temperature. Note that the term surface can
mean the surface of the Earth, the upper surfaces of
clouds, or the surface of a body of water. This scanning
radiometer uses 6 detectors that collect different bands
of radiation wavelengths as shown below. The latest
instrument version is AVHRR/3, with 6 channels, first
carried on NOAA-15 launched in May 1998.

Cha
Resolutio
nnel Waveleng Typical
n at
Num th (um) Use
Nadir
ber
Daytime
cloud and
1 1.09 km 0.58 - 0.68
surface
mapping
Land-water
2 1.09 km 0.725 - 1.00
boundaries
Snow and
3A 1.09 km 1.58 - 1.64 ice
detection
Night cloud
mapping,
3B 1.09 km 3.55 - 3.93 sea surface
AVHRR/3 temperatur
e
Channel Night cloud
mapping,
Characteristics 4 1.09 km 10.30 - 11.30 sea surface
temperatur
e
Sea surface

AATSR
 Advanced Along-Track Scanning Radiometer (AATSR) is one of
the Announcement of Opportunity (AO) instruments on board the
European Space Agency (ESA) satellite ENVISAT. It is the most
recent in a series of instruments designed primarily to measure Sea
Surface Temperature (SST), following on from ATSR-1 and ATSR-2
on board ERS-1 and ERS-2. AATSR data have a resolution of 1 km at
nadir, and are derived from measurements of reflected and
emitted radiation taken at the following wavelengths: 0.55 µm,
0.66 µm, 0.87 µm, 1.6 µm, 3.7 µm, 11 µm and 12 µm.
 Special features of the AATSR instrument include its use of a
conical scan to give a dual-view of the Earth's surface, on-board
calibration targets and use of mechanical coolers to maintain the
thermal environment necessary for optimal operation of the
infrared detectors.

Status
Operational
Type
Imaging multi-spectral radiometers (vis/IR) &
Multipledirection/polarisation radiometers
Technical Characteristics
Accuracy:
Sea surface temperature: <0.5K over 0.5 deg x 0.5 deg (lat/long)area with
80% cloud cover Land surface temperature: 0.1K (relative)
Spatial Resolution:
IR ocean channels: 1km x 1km, Visible land channels: 1km x 1km
Swath Width:
500 km
Waveband:
VIS - NIR: 0.555, 0.659, 0.865 micrometers, SWIR: 1.6
micrometers,MWIR: 3.7 micrometers, TIR: 10.85, 12 micrometers
Earth Topics
Land ( Vegetation ), Ocean and Coast ( Sea Surface Temperature ),
Atmosphere ( Clouds/Precipitation )

Poseidon 2-Poseidon 3- RA 2
 The Poseidon-2 altimeter is the main instrument
on the Jason-1 mission. Derived from the
Poseidon-1 altimeter on Topex/Poseidon, it
measures sea level, wave heights and wind speed.
It operates at two frequencies and is also able to
estimate atmospheric electron content.
Function
 Poseidon-2 measures range (the distance from the
satellite to the Earth's surface), wave height and
wind speed.

 Principle

 The altimeter emits a radar beam that is reflected back to the antenna
from the Earth's surface.Poseidon-2 operates at two frequencies (13.6 GHz
in the Ku band and 5.3 GHz in the C band) to determine atmospheric
electron content, which affects the radar signal path delay. These two
frequencies also serve to measure the amount of rain in the atmosphere.

 Technical data
 Poseidon-2, or SSALT (for Solid State ALTimeter), uses solid-state
amplification techniques.
 Emitted Frequency (GHz)Dual-frequency (Ku, C) - 13.575 and 5.3Pulse
Repetition Frequency (Hz)2060 interlaced {3Ku-1C-3Ku}Pulse duration
(microseconds)105Bandwidth (MHz)320 (Ku and C)Antenna diameter
(m)1.2Antenna beamwidth (degrees)1.28 (Ku), 3.4 (C)Power
(W)7RedundancyYesSpecific featuresSolid-State Power Amplifier.
Dual-frequency for ionospheric correction,
High resolution in C band (320 MHz)

RA-2
Radar Altimeter 2 (RA-2) is an instrument for determining the
two-way delay of the radar echo from the Earth's surface to a very
high precision: less than a nanosecond. It also measures the power
and the shape of the reflected radar pulses.

It is a nadir-looking pulse-limited radar altimeter based on the
heritage of ERS-1 RA functioning at the main nominal frequency of
13.575 GHz (Ku Band), which has been selected as a good
compromise between the affordable antenna dimension that
provides the necessary gain and the relatively low attenuation
which experience the signals propagating through the
troposphere. ,

Status:Operational
Type Radar altimeter
Technical Characteristics AccuracyAltitude: better than
4.5cm, Wave height: better than 5% or 0.25mSpatial
ResolutionSwath WidthWavebandMicrowave: 13.575Ghz
(Ku-Band) & 3.2GHz (S-Band)
ApplicationsSnow and Ice (Sea Ice) Atmosphere (Winds)
Land (Topography/Mapping) Ocean and Coast (Ocean
Waves,Ocean Currents and Topography)

Poseidon 3
 The Poseidon-3 altimeter is the main instrument on the Jason-2
mission. Derived from the Poseidon-1 altimeter on Topex/Poseidon
and Poseidon-2 on Jason-1, it measures sea level, wave heights and
wind speed. It operates at two frequencies and is also able to estimate
atmospheric electron content.
Poseidon-2 being integrated on Jason-1. Poseidon-3 on Jason-2 is
similar
(Credits CNES/Alcatel)
 Function
 Poseidon-3 measures range (the distance from the satellite to the
Earth's surface), wave height and wind speed.
 (m)1.2Antenna beamwidth (degrees)1.28 (Ku), 3.4 (C)Power
(W)7RedundancyYesSpecific featuresSolid-State Power Amplifier.
Dual-frequency for ionospheric correction,
High resolution in C band (320 MHz)

Principle
The altimeter emits a radar beam that is reflected back to the antenna from the
Earth's surface (see how altimetry works for details). Poseidon-3 operates at
two frequencies (13.6 GHz in the Ku band and 5.3 GHz in the C band) to
determine atmospheric electron content, which affects the radar signal path
delay. These two frequencies also serve to measure the amount of rain in the
atmosphere.
Technical data
Poseidon-3, or SSALT (for Solid State ALTimeter), uses solid-state amplification
techniques. Emitted Frequency (GHz)Dual-frequency (Ku, C) - 13.575 and
5.3Pulse Repetition Frequency (Hz)2060 interlaced {3Ku-1C-3Ku}Pulse
duration (microseconds)105Bandwidth (MHz)320 (Ku and C)Antenna
diameter

THE MAIN FAMILIES OF IN-SITU OBSERVING SYSTEMS

 Argo profiling floats
Argo profiling floats measure
mainly Temperature and
Salinity from sea surface to
2000 m depth with good,
consistent spatial resolution.

 Argo is an international collaboration that collects
high-quality temperature and salinity profiles from
the upper 2000m of the ice-free global ocean and
currents from intermediate depths. At present
there are three models of profiling float used
extensively in Argo. All work in a similar fashion
but differ somewhat in their design characteristics.
At typically 10-day intervals, the floats pump fluid
into an external bladder and rise to the surface over
about 6 hours while measuring temperature and
salinity.

 Satellites determine the position of the floats when
they surface, and receive the data transmitted by the
floats. The bladder then deflates and the float returns
to its original density and sinks to drift until the cycle
is repeated. Floats are designed to make about 150 such
cycles.

Research vessels
 Research vessels deliver
several high-accurate parameters
(including Chlorophyll-a and
Temperature)
from sea surface to the ocean
floor, but with intermittent spatial
coverage.

Gliders
Gliders provide physical data (Temperature, Salinity
and Currents) as well as biogeochemical data
(Chlorophyll-a, oxygen, nutrients,…) from surface to
1000 m below the surface, depending on the
equipment. These instruments can be steered from
shore via satellite.

 An underwater glider is a type of autonomous
underwater vehicle (AUV) that uses small changes in
its buoyancy in conjunction with wings to convert vertical
motion to horizontal, and there by propel itself forward
with very low power consumption.Gliders typically make
measurements such as temperature, conductivity (to
calculate salinity), currents, chlorophyll fluorescence,
optical backscatter, bottom depth, and (occasionally)
acoustic backscatter.

 They navigate with the help of periodic surface GPS fixes,
pressure sensors, tilt sensors, and magnetic compasses.
Vehicle pitch is controllable by movable internal ballast (usually
battery packs), and steering is accomplished either with a rudder
(as in Slocum) or by moving internal ballast to control roll .
Buoyancy is adjusted either by using a piston to flood/evacuate a
compartment with seawater (Slocum) or by moving oil in/out of
an external bladder Commands and data are relayed between
gliders and shore by satellite.
 Gliders vary in the pressure they are able to withstand.
The Slocum model is rated for 200 meter or 1000 meter depths.

Bathythermographs (XBT)
 Bathythermographs are launched
from either research or
commercial vessels and measure
Temperature from the surface
down to 450-750 m below sea
surface

Surface Moorings
Surface moorings measure
a wide variety of sub-surface
variables including
Temperature, Salinity,
Currents over
long periods of time.
These data are essential
for model validation.

 Moorings include:
an anchor — usually iron weights
 cables — typically made of steel, nylon, or Kevlar
 bottom floats — often air-filled glass balls, shrouded in
plastic, which keep the mooring string upright, taut, and off
the sea bottom
 release mechanisms — mechanical devices which break the
morning chain and allow the instruments to float to the
surface upon command by a science technician
 subsurface floats and/or surface buoys — commonly made of
foam or other buoyant, non-compressible materials; also
used to keep the mooring upright and support instruments

 Above the water, moored buoys may be mounted
with meteorological sensors, communications
systems (such as satellite or radio transmitters and
receivers), and solar panels. Below the water line,
buoys hold various instruments, including: current
meters, temperature and pressure sensors,
sediment traps, chemical sensors, power supplies,
data recorders, and acoustic modems

Coastal Surface Electro-Optical-Mechanical (EOM) Mooring

Ferry Boxes
 Ferry boxes are found on
board ferries or regional
ships. They
measure Temperature,
Salinity, Turbidity,
 Chlorophyll, nutrient,
Oxygen, pH and algal
types.

Ferrybox derives its name from fitting ferries on regular
crossings with a suite or “box” of autonomous sensors for
measuring key ocean properties. Core measurements are
temperature, salinity, chlorophyll-fluorescence and
turbidity but can include other variables such as pCO2
(the partial pressure of carbon dioxide), dissolved oxygen,
macro-nutrients, pH and currents. These data, which
mostly come from the upper few metres of the water
column, are collected at high frequency (seconds to
minutes) and subsets are sent in near real time via satellite
communications to shore for remote system checks and to
marine data centres for further dissemination. Other

Ferrybox systems have automated water sampling
capabilities for additional measurements such as
algal pigments. One key advantage of Ferryboxes is
that they are reliant on plentiful power supplies
from the ship, unlike other in-situ sampling
platforms which rely on the limited life-spans of
batteries

Major Advantage of FerryBoxes are:

-For automated ocean observing it soon became clear that
monitoring of surface waters using buoys, piles and
platforms with ins situ sensors is very expensive
- enough energy on the ships --> more complicated
analyser system can be used
- sheltered conditions inside the ship --> sophisticated
equipment can be installed
- easy maintenance in the harbour --> no additional ship
time is needed
- the information from a transect is often better than from
a single location

Why salinity is measured?
 Sea Surface Salinity is a key parameter to estimate the influence of
oceans on climate. Along with temperature, salinity is a key factor that
determines the density of ocean water and thus determines the
convection and re emergence of watermasses.
The thermohaline circulation crosses all the oceans in surface and at
depth, driven by temperature and salinity.
 A global "conveyor belt" is a simple model of the large-scale
thermohaline circulation. Deep-water forms in the North Atlantic,
sinks, moves south, circulates around Antarctica, and finally enters the
Indian, Pacific, and Atlantic basins. Currents bring cold water masses
from North to South and vice versa.
 This thermohaline circulation greatly influences the formation of sea
ice at the world’s poles, and carries ocean food sources and sea life
around the planet, as well as affects rainfall patterns, wind patterns,
hurricanes and monsoons.

How is it measured ?
 By satellite
•Microwave radiometer (starting in 2009 with the launch
of SMOS)
 In situ techniques
•Profiling floats
•Moored buoys
Models are crucial to estimate this parameter. With an ocean
mixed-layer model (between 50 and 1000 m depth), Sea
Surface Salinity can be estimated by modeling external
(winds, evaporation/precipitation, river runoffs...) and
internal (horizontal transport, vertical mixing,...) influences.

SALINITY
Instrument Ocean Instrument Satellite
Type Parameter Used Name
Microwave •Atmospheric SSM/ITMI DMSP (NASA,
radiometer water vapor AMSR-E USA)
content MWR TRMM (NASA,
•Atmoshperic JMR, AMR USA)
water liquid Aqua (NASA,
content (cloud) USA) +
•Rain rates (developed by
•Sea-ice JAXA, Japan)
concentration, Envisat (ESA,
type, extent Europe)
•SST Jason-1, Jason-2
•Salinity (Cnes, France +
NASA, USA)

Which Satellite Instruments
are used for monitoring
Salinity ?

TRMM Instruments
TRMM Microwave Imager The Tropical Rainfall
Measuring Mission's (TRMM) Microwave Imager
(TMI) is a passive microwave sensor designed to
provide quantitative rainfall information over a wide
swath under the TRMM satellite. By carefully
measuring the minute amounts of microwave energy
emitted by the Earth and its atmosphere, TMI is able
to quantify the water vapor, the cloud water, and the
rainfall intensity in the atmosphere.

Advanced Microwave Scanning Radiometer AMSR-E

 The Advanced Microwave Scanning Radiometer for
EOS (AMSR-E) is a twelve-channel, six-frequency,
total power passive-microwave radiometer system. It
measures brightness temperatures at 6.925, 10.65, 18.7,
23.8, 36.5, and 89.0 GHz. Vertically and horizontally
polarized measurements are taken at all channels.

AMSR-E
It will provide instantaneous measurements for the following data
products:
Rainfall over ocean
Rainfall
Sea surface temperature,
Total integrated water vapor over the ocean
Total integrated cloud water over the ocean
Ocean surface wind speed
Surface soil wetness
Sea ice concentration
Snow depth over sea ice
Sea ice drift .
Snow water equivalent over land.

Which In- Situ Instruments are
used for monitoring Salinity?

THE MAIN FAMILIES OF IN-SITU OBSERVING SYSTEMS

 Argo profiling floats
Argo profiling floats measure mainly Temperature and
Salinity from sea surface to
2000 m depth with good,
consistent spatial resolution.

Gliders
Gliders provide physical data (Temperature, Salinity
and Currents) as well as biogeochemical data
(Chlorophyll-a, oxygen, nutrients,…) from surface
to 1000 m below the surface, depending on the
equipment. These instruments can be steered from
shore via satellite.

Surface Moorings
a wide variety of sub-surface variables
including Temperature,
Salinity, Currents over

Ferry boxes
 Ferry boxes are found on
board ferries or regional
ships. They
measure Temperature,
Salinity,
Turbidity,and Chlorophy
ll, nutrient, Oxygen,
pH and algal types.

CURRENTS
Why measure currents?

 By transporting heat and energy, ocean currents play a major role in
shaping the climate of Earth’s many regions.
 Surface currents (restricted to the upper 400 m of the ocean) are
generally wind-driven and develop their typical clockwise spirals in the
northern hemisphere and counter-clockwise rotation in the southern
hemisphere (for warm currents).
 Deep ocean circulation is the result of a number of factors including
temperature and salinity variations in water masses, shorelines,
subsurface topography, tides, etc.
 Currents are extremely important for maintaining the earth's heat
balance.
 Currents known as upwelling also bring bring cold, nutrient-rich water
from the depths up to the surface.

How current is measured ?
 By satellite
 Altimeters (for geostrophic currents)
 Altimeters +scatterometers (to see surface currents +
winds)
In situ techniques
 Argo (deep ocean currents)
 Drifting buoys
 One of the important outputs of ocean models are the
currents, at any depth. Forecasting currents is one of the
main applications of numerical models.

Ocean parameter
Instrument type Instrument name Satellite
measured
Altimeter •Sea-surface height Poseidon-2 Jason-1 (CNES,
•Ocean surface wind RA-2 France + NASA,
speed Poseidon-3 USA)
•Wave height Envisat (ESA,
•Sea ice Europe)
Jason-2 (CNES,
France + NASA,
NOAA, USA +
Eumetsat, Europe)
Scatterometer •Wind speed and ASCAT Metop (Eumetsat,
heading (10 m above Europe)
ocean surface)
•Rain
•Sea ice
concentration

Surface moorings
a wide variety of sub-surface variables
including Temperature,
Salinity, Currents over

Sea Ice
Why We measure Sea Ice?

 Ice covers a substantial part of the Earth's surface and
is one of the major factor in commercial shipping and
fishing industries, Coast Guard and construction
operations, and global climate change studies.

How Sea Ice is measured?
 By satellite
 Microwave radiometers (concentration, drift)
 Microwave scatterometers (extent, edge, type)
 Infrared sensors (extent)
 SAR sensors
 Altimeters (extent, iceberg detection, thickness, edge)
 In-situ techniques
 Ice buoys (temperature, mass, drift)
 Ocean models are capable of taking sea ice into account. Ice models are
coupled with ocean models. The ocean model provides a model of ice, sea
state (temperature, salinity, currents) and other observations necessary to
calculate the evolution of parameters such as thickness, velocity,
concentration, drift…

Ocean parameter
measured
Spectroradiometer Aqua (NASA, USA)
MODIS Envisat (ESA, Europe)
•Sea Ice Cover
MERIS
Microwave SSM/ITMI DMSP (NASA,
TRMM (NASA,
radiometer •Sea-ice AMSR-E Aqua (NASA,+
concentration, MWR (developed by JAXA,
type, extent JMR, AMR Japan)
Envisat EU
Jason-1, Jason-2 (Cnes,
France + NASA,
Altimeter •Sea-surface height Poseidon-2
Jason-1 (CNES, France +
•Ocean surface RA-2 NASA, USA)
wind speed Poseidon-3 Envisat (ESA, Europe)
•Wave height Jason-2 (CNES, France +
NASA, NOAA, USA +
•Sea ice Eumetsat, Europe)

Scatterometer •Sea ice ASCAT Metop (Eumetsat,
Europe)
concentration

Synthetic Aperture Radarsat-1, Radarsat-2,
•Sea ice monitoring Canada
Radar (SAR) Envisat, Europe

ASCAT
 ASCAT stands for Advanced SCATterometer. It is a microwave
radar instrument onboard the EUMETSAT polar
orbit METOP satellites, and it estimates wind (speed and
direction) over the ocean, retrieves soil moisture and identifies
snow and ice.
 Scatterometers are active radar instruments and therefore both
emit and receive microwave radiation. This radiation has the
advantage of not being affected by clouds and this is why
scatterometers are known to be able to scan the surface in almost
all weather conditions. With regard to wavelength, there are in
fact two types of scatterometers: C band (ASCAT) and Ku band
(OSCAT, the scatterometer onboard the polar orbit Indian Space
Research Organization OceanSat2 satellite, not used in this case
study.

 ASCAT emits microwave radiation with a wavelength of 5.7 cm.
This radiation is resonant with centimeter-scale ocean waves of
comparable wavelength due to the so-called Bragg scattering
mechanism, and is sent back to the sensor. This backscatter
radiation coming from the water surface can then be processed
in order to compute near-surface ocean wind speed and
direction.
 This capability relies on the assumption that the small-scale
ocean waves responsible for the backscatter are in equilibrium
with the wind. As wind speed increases, surface roughness also
increases and more microwave radiation is scattered towards the
direction of the radar source

 ASCAT is composed of two sets of three antennas that
cover two distinct areas located to the left (one set) and to
the right (the other set) of the satellite track, therefore
being considered a double swath scatterometer
unlikeQuikscat or OSCAT, which are single swath
scatterometers.

In- Situ Observations -Ice
buoys (temperature, mass, drift)

Ice buoys have been used extensively in Arctic and
Antarctic regions to track ice movement and are available
commercially for deployment by ships or aircraft. Such
buoys are equipped with low temperature electronics and
lithium batteries that can operate at temperatures down to
-50°C. In addition to the regularly-computed Argos
locations the ice buoys can be equipped with satellite
navigation receivers (e.g. GPS) which can compute even
more accurate positions.


SEA LEVEL
Why measure sea level?
 The sea surface is anything but flat. There are bumps and
troughs , all due to different physical characteristics such as
gravity, currents, temperature and salinity… Since we do
not know much about the ocean’s bottom, it is easier to
refer to “sea height” instead of sea depth. Sea level is
measured with reference to a fixed surface height. By
analyzing variations from this reference point, scientists
determine ocean circulation (currents and eddies at the
edges of holes and bumps), seasonal or inter-annual
variations, or even longer periods (long-term rise in sea
level).

 How is it measured?

By satellite
 Altimeters
Numerical models
All numerical models simulate sea level.

Ocean parameter
measured
Altimeter •Sea-surface height Poseidon-2 Jason-1 (CNES,
•Ocean surface RA-2 France + NASA,
wind speed Poseidon-3 USA)
•Sea ice Europe)
Jason-2 (CNES,
France + NASA,
NOAA, USA +
Eumetsat, Europe)

SEA LEVEL MEASUREMENTS

TIDE GAUGES

NEW GEODETIC TECHNIQUES

Developments in new geodetic techniques (CGPS,
DORIS, Absolute Gravity) are progressing for monitoring
vertical land movements. This will eventually provide
estimates of ‘absolute’ sea level change.

99

WIND
Why measure wind
 Surface winds, combined with other atmospheric
forces (solar energy, precipitation rate, evaporation
rate) are all responsible for the movement of water
masses in the ocean, and are thus responsible for
ocean currents.
 Marine winds shape the ocean, and can cause waves as
high as a mountain to swell during a storm. They are
the source of many legends and color the moods of
seafarers around the world.

How is it measured?
By satellite
 Microwave radiometers
 Microwave scatterometers
 SAR
 Altimeters
Numerical models
Numerical weather forecasting models make it
possible to understand sea surface winds. They are
many of these models in operation today.

measured
Microwave SSM/ITMI DMSP (NASA, Microwave
•Atmospheric water
radiometer AMSR-E USA) radiometer
vapor content
MWR TRMM (NASA,
•Atmoshperic water
JMR, AMR USA)
liquid content
Aqua (NASA, USA)
(cloud)
+ (developed by
•Rain rates
JAXA, Japan)
•Sea-ice
Envisat (ESA,
concentration,
Europe)
type, extent
Jason-1, Jason-2
•SST
(Cnes, France +
•Salinity
NASA, USA)

Altimeter •Sea-surface height Poseidon-2 Jason-1 (CNES, Altimeter
•Ocean surface RA-2 France + NASA,
wind speed Poseidon-3 USA)
•Sea ice Europe)
Jason-2 (CNES,
France + NASA,
NOAA, USA +
Eumetsat, Europe)

Scatterometer •Wind speed and ASCAT Metop (Eumetsat, Scatterometer
heading (10 m Europe)
above ocean
surface)
•Rain
•Sea ice
concentration

BIOGEOCHEMISTRY
Why measure biogeochemistry/ocean colour?

 Phytoplankton (vegetable plankton) is the first link
in the ocean’s food chain, and is the main source of
food for most fish. Phytoplankton contains
chlorophyll, which instigates photosynthesis in the
ocean, absorbs atmospheric CO2 and releases oxygen
in sunlight. More than any land-based plant,
phytoplankton is the biggest producer of oxygen on
Earth. Knowing the chlorophyll content of the
ocean’s surface levels is an important way to measure
primary production, as well as of global ocean health.

How is it measured?

By satellite
 Spectroradiometers

Ocean
Instrument type parameter Instrument name Satellite
measured
Spectroradiomet •Chlorophyll Aqua (NASA,
er content USA)
•Organic and MODIS Envisat (ESA,
mineral content MERIS Europe)
•Sea surface
temperature
•Sea Ice Cover

WATER PARAMETERS to DETERMINE
WATER QUALITY

 Remote sensing techniques can be use to assess several
water quality parameters (i.e., suspended, sediments
(turbidity), chlorophyll, temperature optical and thermal
sensors on boats, aircraft, and satellites provide both
spatial and temporal information needed to understand
changes in water quality parameters necessary for
developing better management practices to improve water
quality.

The color of the Earth’
surface, especially the
color of the ocean, results
primarily from biological
processes.

Measuring the absorption
and backscattering
characteristics of ocean
surface, we can estimate
the concentrations of
different kinds of matter
suspended in seawater,
including phytoplankton
cells.

Remote sensing of indicators of water quality offers
the potential of relatively inexpensive, frequent, and
synoptic measurements using sensors aboard aircraft
and/or spacecraft.

Suspended sediments, chlorophylls, DOM,
temperature, and oil are water quality indicators that
can change the spectral and thermal properties of
surface waters and are most readily measured by remote
sensing techniques.

Example of Level 2 data:

MODIS Total Suspended Solids , 2000 December 6, 17:05

SUSPENDED SEDIMENT

Suspended sediments are defined as solid particles transported in
a fluid media or found in deposit after transportation by flowing
water, wind, glacier and gravitational action. Their
concentration in a water body is affected by many factors. In
rivers, the concentration depends on the water’s flow rate,
turbidity, soil erosion, urban runoff, and wastewater and septic
system effluent, while in lakes, decaying plants and animals,
bottom-feeding fish, and wind/wave action play a larger role. In
general, the reflectance of water increases with increased
suspended sediment concentrations (positive correlation) and
decreases with increased salinity (negative correlation).

Dissolved Oxygen
 Measures of dissolved oxygen (DO) refer to the
amount of oxygen contained in water, and define
the living conditions for oxygen-requiring
(aerobic) aquatic organisms. Oxygen has limited
solubility in water, usually ranging from 6 to 14 mg
L -1 . DO concentrations reflect an equilibrium
between oxygen-producing processes
(e.g. photosynthesis) and oxygen-consuming
processes

 Oxygen solubility varies inversely with salinity,
water temperature and atmospheric and
hydrostatic pressure.
 Dissolved oxygen consumption and production are
influenced by plant and algal biomass, light
intensity and water temperature (because they
influence photosynthesis), and are subject to
diurnal and seasonal variation

CHLOROPHYLL
Nutrients and substances are required for a healthy aquatic
environment, an excess of these inputs leads to nutrient
enrichment and eutrophication of the lake.
Eutrophication of a water body is usually quantified in
terms of the concentration of the chlorophyll contained in
the algal/plankton.

Turbidity
Turbidity is another commonly used water quality variable.
It is a measure of optical scattering in the water and,
hence, closely related to the amount of suspended
particles. I.e. if the amount of chl a (phytoplankton)
and/or suspended sediments is high, the turbidity value
is also high. Typically, a single band in the visible or near-
IR region can be used to map turbidity with reasonable
accuracy (Lindell et al., 1999)

The first satellite based sensor devoted to water quality
measurements was the Coastal Zone Color Scanner
(CZCS) . Then,
SeaWiFS (Sea-viewing Wide Field Sensor,
Airborne instruments such as AISA (Airborne Imaging
Spectrometer for Application), CASI (Compact Airborne
Spectrographic Imager) and HyMap
MODIS and MERIS
AVHRR
ALOS satellite

Examples for the
Monitoring Critical
Marine Issuses

Ship Based Oil Pollution
Monitoring

Marine Pollution Sources
 Oil Pollution

 Heavy Metals and their products

 Bioaccumulation

 Disposal of Radioactive Materials

 Discharge of Sewage

 Harmful Algal Blooms 4

Major inputs of Oil to the Marine
Environment
 37% comes from industrial wastes, reach

the sea, via storm water drain, creeks,
sewage and rivers.

 12% from ship accidents involving

tankers.

 33% from vessels illegal operations

 9% absorbed from atmosphere.

 7% comes from natural sources like

fissures from sea bed.

 2% during explorations and 4

Ship Based Oil Pollution
 MARPOL defines oil as; petroleum in any form
including crude oil, fuel oil, sludge, oil refuse and
refined products (other than petrochemicals which are
subject to the provisions of Annex II of the present
Convention) 5

SHIP’S SURVEY

NIPPON KAIJI KYOKAI

3.1 Why Ships Discharge Illegal Oil Waste and
Oily Water to the Sea ?

 Three categories of oily waste generally accumulate
onboard especially on large and very old vessels
 Bilge water
 Sludge
 Oil cargo residue

Illegal Oil Discharge Source: Bilge Waste

 Machinery spaces especially on large commercial
vessels generate oily waste products and leakage
everyday.

Illegal Oil Discharge Source: Sludge Waste

 In order to prevent damage to engine systems and improve
combustion, the fuel should be purified. After purifying the
residues and oily water’re called as sludge.

Illegal Oil Discharge Source:
Oil Cargo Residue Waste

Tankers carry oil and oily product in bulk. After each
change of cargo type, cargo tanks should be cleaned.
Tank washing operations are carried out by steam water
for cleaning cargo tanks and these washing and cleaning
operations produce oily waste water.

 The best method for dealing with bilge water, sludge and slop
is storing and delivering ashore as disposal but storing these
oily water and oily products on board causes less cargo
transportation and too much cost for delivering the oily
products a shore as disposal. These are the great reason why
ships make illegal discharging.

Ship Accidents, Involving Tankers Cause Serious
Oil Pollution.

131

Any Accidents with Oil Pollution

FIRE

Exxon Valdez, March 1989, Alaska

Mega Borg, June 1990, Texas

Cibro Savannah, March 1990, New Jersey

Burmah Agate, November 1979, Gulf of Mexico

SINKING

Argo Merchant, December 1976, Nantucket Island

Different Tools to Detect and Monitor Oil Spills
There are different remote sensing applications for detection of oil pollution/spills
on sea surface. In the electromagnetic spectrum, Oil gives different responses and
signatures to radiation from different wavelengths. Different tools to detect and
monitor oil spills:

– Vessels
Remains necessary in case of oil sampling, but they can cover a very limited area.

-Airborne
 SLAR (Side looking airborne Radar)
 LFS (Laser Fluorosensor)
 MWR (Microwave radiometry)
 IR/UV (Infrared/ultraviolet line scanner)
 FLIR (Forward looking infrared)
 Camera/video

- Satellite
 SAR (Synthetic Aperture Radar)
 Optical Sensors

 ULTRAVIOLET

Detect oil spills at thin layers, not usable at night, and wind slicks, sun glints
and biogenic material.

 VISIBLE
In the visible region of EM spectrum oil has a higher surface reflectance than
water and absorbs energy showing black or brown signatures, limited and
cause mistakes due to atm. condition . 7

 THERMAL INFRARED
Emmisivity difference between oil (0.972 μm) and water (0.993 μm) leads to
different brightness temperatures, Therefore, oil layers appear colder than
water in thermal images. For thickness of oil slicks, as the thickness
increases they appear hotter in the infrared images Limited for very thin oil
slicks. 7

Microwave Sensors - RADAR
Microwave sensors are the most applicable tools for oil slick
monitoring since they are not affected by clouds, haze, weather
conditions and day/night differences.7

Radio Detection and Ranging (RADAR) operates in the
microwave portion of the electromagnetic spectrum.

Synthetic Aperture Radar (SAR)
Most common microwave sensor for oil slick detection is SAR.
The main mechanism in detection of oil slicks is the dampening
effect of oil on water. Dampening of sea waves results in reduced
radar return from the affected area, so that oil slicks appear as
relatively dark features on the SAR scenes.9

G. Franceschetti,2002 SAR Raw Signal Simulation of Oil Slicks in Ocean Environments 2002
Pic Ref: Yonggang. J, First Institute of Oceanography SOA.2009

SAR can be used on both airborne and space borne observational
platforms
Advantage
 Day & night observation.
 All-weather capability.
 High spatial resolution.
 Wide area coverage.
Pic Ref: Yonggang. J, First Institute of Oceanography SOA.2009

Disadvantage
 No wind.
 Strong winds (above 13m/sec).
 Look – alikes.

Remote Sensing of Marine
Resources
 Fish Stock Managment
 protection and the sustainable management of
living marine resources in particular for
aquaculture, fishery research or regional fishery
 Fisheries Research
 Assess and monitorthe level of contaminants in
fish
 Favorable area for fish farms

Need Parameters
 Temperature
 Sea level
 Currents
 Chlorophyll-a
 Dissolved oxygen
 Nutrients


COASTAL & MARINE ENVIRONMENT

Physical and marine biogeochemical components are
useful for water quality monitoring and pollution
control
Sea level rise helps to predictcoastal erosion.
Sea surface temperature is one of the primary physical
impacts of climate change and many marine ecosystems
in seas are affected by rising sea temperature.
Currents are useful for selecting locations for offshore
windmill parks or thermal energy conversion field

Requested Parameters
 Temperature
 Salinity
 Currents
 Sea Level
 Chlorophyll-a
 Dissolved oxygen
 Nutrients

WEATHER, CLIMATE & SEASONAL FORECASTING

 Physical parameters of the ocean's surface are used as
boundary conditions for atmospheric models.
 Changes in sea ice extent, concentration and volume
are signals used to detect global warming for instance.

http://www.myocean.eu/web/18-product-showcase.php?item=23
 http://www.esrl.noaa.gov/psd/map/clim/sst_olr/el_nino_anim.shtml

Monthly Mean of Maps of Sea Level Anomalies, El Niño area, during November 1997.

 Short and Medium Weather forecasting
 Seasonal Forecast
 Climate Change
 Future Sea Levels and
 Snow – Ice melting and effects on Global Warming

Requested Parameters

 Temperature
 Salinity
 Currents
 Sea Level
 Sea Ice

Conclusion
 Studying Remote sensing techniques for monitoring
Earth Enviroment without ocean parameters and water
quality parameters are not enough.

M/T Independenta, Tanker Accident,Big explosion, fire, pollution and tanker
wreck for years at İstanbul Strait

Thank You, Any Question?

Remote Sensing Techniques for Oceanography Satelitte and In Situ Observations

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