Download (UAVs) as an Element of the Integrated Ocean Observing System

Employing Unmanned Aerial Vehicles (UAVs) as an Element of the
Integrated Ocean Observing System
A. S. Lomax
Itri Corporation, Director NOAA Projects
W. Corso
Lockheed Martin Space Operations
J. F. Etro
Itri Corporation, President
well known – relatively inexpensive broad-scale and
repeatable observations – as are some of the limitations and
challenges – low spatial resolution as well as modeling the
target and transfer medium. UAVs used in the coastal
zone as a new platform for remote sensing have a role to
play as a coastal component of the IOOS.
Abstract - The Integrated Ocean Observing System (IOOS)
provides a framework to integrate environmental data with
existing and new technologies resulting in information that
will improve our use and management of oceanic and coastal
areas. The coastal zone is a dynamic biological, chemical,
physical, and geological environment that is rich with
opportunities for commerce and in need of well thought out
resource management and conservation.
In order to
maintain responsible stewardship of this delicate environment
while sharing coastal resources for economic benefit, we must
have a means to measure, monitor, and characterize processes,
parameters, and habitats accurately, in a timely fashion, and
cost-effectively.
While in situ observations and
measurements provide the most precise and accurate means
of data collection, this method is limited by its coarse spatial
and/or temporal resolution and the potentially high cost of
increasing fidelity. Satellite remote sensing provides a means
of collecting large geographic views of data, but the
information available from satellites can be constrained by (1)
the spatial and spectral resolution of the sensor, (2)
atmospheric absorption and other effects, (3) data refresh
time of sensor platforms, and (4) cost.
Airborne remote sensing provides a mechanism for
overcoming shortcomings of space-borne sensors but typically
at a high cost and with restrictions on flight regulations and
endurance. In some types of operations, Unmanned Aerial
Vehicles (UAVs) are less expensive and more flexible to
operate than manned aircraft and continuing developments in
the field are increasing the operational capabilities of these
platforms and the variety of available sensors for data
collection. Employment of UAV platforms and associated
sensors, coordinated with in situ and other remote sensors,
provides a powerful tool in characterizing the coastal ocean
for habitat monitoring, hazard response and mitigation,
resource management, and commercial use. UAVs can be a
critically important element of the national coastal
component of IOOS.
II. WHY UAVS FOR COASTAL OCEAN SCIENCE?
UAVs come in all shapes and sizes – from long-range,
high endurance models like the U.S. Air Force Global
Hawk with ranges on the order of thousands of miles to
small, man-portable UAVs with ranges of a few miles.
Each UAV, much like the spectrum of remote sensing
sensors, has advantages and limitations. In designing for
a particular mission, there are trade-offs between cost to
build, cost to operate, size, range, payload, and required
support infrastructure. A large UAV like the Global
Hawk (44 ft body, 116 ft wingspan, 2000 lb payload)
offers outstanding performance (42 hour endurance, 13,000
mile range) and capability (electro-optical, infrared, and
synthetic aperture radar sensors) but at a high cost ($20-30
million per unit) while requiring significant support
infrastructure [1]. While these capabilities would be
invaluable for coastal ocean observations, the cost to
acquire and operate this type of platform is prohibitively
high.
A more reasonable option for the coastal ocean
community is a family of small, lightweight UAVs
currently in development and production. These UAVs
provide the right balance between capability and
performance (Table I) and cost.
These UAVs are
propelled by gasoline-powered engines, are capable of
programmed or manually-controlled flight, and require
minimal ground space for launch and recovery. These
aircraft could be operated from a ship with existing
catapult-launch technology and emerging technology for
soft water landings.
The UAV system includes a
ground station which is used to program missions, make
in-flight adjustments, and receive, process, display and
potentially disseminate real-time imagery and imagery
products. These UAVs can be packaged with their
ground station to fit into a mid-sized sport utility vehicle
and they typically involve relatively simple assembly and
user-friendly operation. Currently, operational sensor
I. INTRODUCTION
Remote sensing, in its broadest definition, is the
observation or measurement of something from afar. It is
commonly thought of in terms of satellite-borne sensors
but it also includes airborne sensors and underwater
acoustic sensors. The advantages of remote sensing are
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TABLE I
in the practical sense, marine resource managers and public
health officials may not require an absolute quantitative
value of algae concentration in order to decide whether or
not to suspend fishing in coastal areas or close beach
access to the public. Instead, these decision-makers may
only need high-resolution, near-realtime imagery that
shows a clearly-defined, in space and time, plume of color
in the ocean. This plume could be imaged using a
panchromatic camera and enhanced through the use of
filters or image processing techniques. It is this type of
operational product that can be made readily available
through the use of a UAV.
Another application of UAVs is based in the flexibility
of changing sensor characteristics. It is possible to quickly
change out filters on an optical sensor so that very specific
bands may be quickly understood and observed. For
example it has been noted that the limited spectral
resolution of widely available sensors represented a
challenge to mapping sea grasses in coastal areas of the
State of Washington because the spectral band sets do not
provide the resolution to discriminate between
co-occurring plant species [2]. It may be possible with
UAVs to tune the band observed very specifically to the
phenomena or species of interest by a quick and
inexpensive trial and error process.
The National Ocean Research Leadership Council
(NORLC) has identified that an IOOS must be designed to
provide data and information that serves seven societal
goals:
(1) Improve predictions of climate change and weather
and their effect on coastal communities and the
nation (Weather & Climate);
(2) Improve the safety and efficiency of maritime
operations (Maritime Operations);
(3) More effectively mitigate the effects of natural
hazards (Natural Hazards);
(4) Improve national and homeland security (Homeland
Security);
(5) Reduce public health risks (Public Health);
(6) More effectively protect and restore healthy coastal
ecosystems (Ecosystem Health); and
(7) Enable the sustained use of ocean and coastal
resources (Living Resources). [3]
In order to achieve these goals, the NORLC identified 20
core variables that must be measured and monitored.
Many of these core variables, listed in Table II, can be
measured using existing technologies that can be mounted
on or deployed by UAVs. Each of these capabilities or
potential capabilities is discussed briefly below.
• Salinity Current remote sensing techniques for
measuring salinity employ microwave wavelengths.
Small enough microwave sensors do not currently
exist to permit such measurements from small
UAVs but as technology progresses, this could be
possible in the future. While a new technique for
estimating salinity has been proposed using
outgoing longwave radiation (OLR - a parameter
that could be measured using infrared sensors) [4],
this technique requires the use of large-scale
NOMINAL SPECIFICATIONS OF UAVS FOR COASTAL OCEAN
SCIENCE AND OPERATIONS MISSIONS
Parameter
Wing span
Fuselage length
Payload
Endurance
Cruising speed
Nominal mission altitude
Value
2-4m
1-3 m
Up to 10 kg
Up to 8-10 hrs
75-100 kph
150-350 m AGL
packages small enough to meet payload restrictions for
small UAVs are panchromatic (visible) and infrared
imagers.
Small UAVs like these have some significant
advantages over other air- and space-borne remote sensing
platforms. They can fly lower than aircraft and will
generate imagery of high spatial resolution (on the order of
< 0.2 m and less).
UAVs can fly below low clouds removing that potential
obstruction from the field of view. The cost of some
operations is significantly lower for UAVs. In some
instances, a UAV could be operated for collecting imagery
at about 1/3 of the cost to the customer below the cost for
comparable spatial coverage from a manned aircraft.
Overhead costs and full system labor expenses, including
crew staffing, are less expensive than those associated with
manned flight operations. The minimal launch and
recovery requirements also may ensure that UAVs can get
to places that aircraft can’t reach very easily and also
provide a platform that can be deployed more rapidly than
manned aircraft. Also, in general, UAVs make less noise
than aircraft and are smaller and less intrusive, so it is less
likely to disturb the natural environment it is observing.
Small UAVs do have some limitations to their
operational capabilities. First, their payload capacity
limits the sensors that are currently available for operations
to collecting visible and infrared imagery. In some cases,
a UAV must stay in constant contact with its ground
station which limits it to operations within line-of-sight.
Furthermore, slow speeds of advance and short duration
flights may limit the extent of the mission. Despite these
limitations, UAVs can be a valuable data collection
platform when employed in the context of their
capabilities.
III. UAVS AS A COMPONENT OF IOOS
A. IOOS Core Variables and Societal Goals
UAVs have current capabilities and future potential to
measure several IOOS core variables in order to support
several of the seven societal goals of the IOOS. An
example of this may be illustrated by a case of a Harmful
Algal Bloom (HAB). Extensive research efforts have
been dedicated to modeling the spectral characteristics of
various species of harmful algae in hopes of ultimately
developing algorithms for measuring concentrations of
these algae in optically-complex coastal waters. However,
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TABLE II
IOOS CORE VARIABLES THAT UAVS COULD MEASURE
Core Variable
Salinity
Temperature
Bathymetry
Sea Level
Surface Waves
Surface Currents
Ice Distribution
Contaminants
Dissolved Nutrients
Fish Species
Fish Abundance
Zooplankton Species
Optical Properties
Heat Flux
Ocean Color
Bottom Character
Pathogens
Dissolved O2
Phytoplankton Species
Zooplankton Abundance
•
•
•
Current
Capability
Future
Capability
X
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X
X
X
X
X
X
x
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x
X
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X
?
?
gridded climatic data that would not match well
with fine-scale UAV-measured OLR.
Temperature Miniature thermal infrared cameras
currently exist that can be mounted on a UAV for
measuring sea surface temperature. The technical
specifications for one such camera include a
7.5-13.5 µm spectral range, a nominal thermal
range of 0-40 C, and a normalized thermal
resolution of < 0.04 C [5].
Bathymetry Studies have shown the ability to
measure nearshore bathymetry using hyperspectral
imagers and LIDAR systems (e.g. [6], [7]).
While these systems do not yet exist in an
off-the-shelf operational package that can fit on a
small UAV, technological advances will, in the
near future, miniaturize these types of sensors to
allow them to be flown on such a platform.
Visible imagery collected from an UAV can also
be processed in a way such that video
frame-to-frame pixel matching will allow terrain
and shallow water bathymetry mapping by using
photogrammetric techniques.
Surface waves
Miniature, air-launched wave
buoys have been developed for use in military
operations [8]. These buoys are designed to
measure non-directional wave spectra so as to yield
significant wave height and significant wave period
data.
These buoys are also equipped with
thermistors to measure sea surface temperature.
While the buoys were designed for deployment
from larger aircraft, through some re-engineering
of the buoy and the UAV, these small buoys (~ 2
kg) could be deployed from UAVs to a location
where wave data may be required for a specified
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amount of time. An example where this may be
useful is in monitoring and predicting the
dispersion of oil following a spill.
Surface currents UAVs will likely not be able to
directly measure surface currents directly because
this typically involves the use of HF radar which
require large antennae.
However, techniques
could be developed that would infer surface
currents by other means. First, miniature drifting
buoys deployed from a UAV as discussed above, if
equipped with a GPS transponder, could be tracked
in a Geographic Information System (GIS) to yield
surface current speed and direction.
A
less-precise technique would be to use change
detection algorithms in a GIS to monitor the
movement of ocean features revealed through
infrared or ocean color imagery collected from a
UAV.
Ice distribution Sea ice distribution and extent
can be measured using infrared and panchromatic
cameras on UAVs. Change detection techniques
applied to time-series imagery can be used to
measure ice motion. Trained ice analysts can
infer rough magnitudes of ice thickness and type
using panchromatic (visible) imagery.
While
UAVs would not be useful in providing a piece of
the long-term climatic sea ice record, they could
provide an extremely valuable data source for
tactically ensuring safety of navigation through the
Great Lakes.
Contaminants Because IOOS focuses more on
collecting data on surface runoff of contaminants
over a long-term continuous record rather than
from specific, unrelated events, the IOOS
Development Plan does not include oil spill
monitoring as an aspect of the contaminant core
variable [9].
UAVs can provide a flexible,
inexpensive, and timely solution for collecting
visible and infrared imagery of oil spills to be used
in response and restoration activities that
encompass several of the seven goals.
Furthermore, data and imagery collected from oil
spill events should become part of the IOOS data
archive as it could prove valuable in case studies of
lessons learned and for impact assessments of
ecosystem health.
Optical properties and ocean color
UAVs
possess both a near-term capability and future
capability with respect to ocean optics and color.
In the near-term, panchromatic cameras on UAVs
can provide high-resolution, true-color images of
near-shore features. Through the use of filters or
image processing techniques, it is possible to
retrieve specific spectral information on a
particular feature. With investment in research
and development, multi- and hyperspectral sensors
will be miniaturized so as to fit within the payload
constraints of these UAVs. Prime applications for
UAVs in this arena are to use them to provide
high-resolution monitoring and tracking of HABs
in addition to benthic mapping (shallow, clear
waters), coral reef monitoring, and assessment of
coastal habitats for threatened or endangered
species.
• Heat flux Heat flux measurements from satellites
typically uses infrared imagery in the same bands
available in UAV-capable sensors. However,
most applications for heat flux data involve
broad-scale and long-term studies and UAVs
would not be a practical solution for contributing to
this aspect of IOOS in the microscale.
• Phytoplankton species and zooplankton abundance
As multi- and hyperspectral sensors become
available, measurements of phytoplankton and
zooplankton may be possible as algorithms are
developed in the scientific community.
The NORLC matched the seven societal goals to any
necessary core parameters that would be needed to support
the goal. The results of this analysis are in Table III. By
taking the union of Table II, the core parameters that could
be measured from UAVs, and Table III, the core
parameters mapped to societal goals, it is clear that UAVs
can serve as a data collection platform in support of each of
the societal goals.
and sensor resolution), and relatively inexpensive platform
for responding to short-duration, localized data
requirements. But as in military operations, tactical-scale
operations are always driven by some prior knowledge of
the environment and the need, from a strategic level, to
conduct the mission. It is in this scheme that UAVs
would provide value to the IOOS: collecting high-fidelity
data that can not be collected efficiently by other means in
response to a requirement driven by end-user requirements
and the end-to-end systems view of the ‘big picture’. Three
potential example operational employments of UAVs in
the context of IOOS are given below.
Example 1 Derived products from MODIS imagery
reveal the potential presence of a HAB along the
Mississippi and Alabama Gulf Coast that could potentially
threaten the oyster fisheries and tourist activities along the
coast and associated barrier islands. A UAV is used to
collect imagery of the Sound in order to determine the
exact extent and motion of the bloom. The UAV team
sets up operations near Biloxi and on the first day conducts
8 hours of continuous flight operations collecting visible
imagery over the Sound with a spatial resolution of 1 m.
During initial flight operations, the team, receiving a
real-time video link, discovers the presence and precise
location of a red plume in the water.
The team
immediately re-programs the flight plan in order to capture
higher resolution imagery of the plume. Local marine
resource managers are present with the UAV team and are
able to make immediate, informed decisions regarding the
closure of oyster beds and canceling of tourist boats
traveling to the Gulf Islands National Seashore. At the
end of the day’s flight operations, the imagery and its
associated metadata are uploaded to an appropriate IOOS
Primary Data Assembly and Quality Control (PDAQC)
point to become part of the IOOS data holdings. The next
day, the team continues flight operations monitoring the
changing shape, size, and motion of the HAB permitting
further decisions that impact public health and marine
resource management.
B. UAV Concept of Operations (CONOPS) in IOOS
UAVs are employed by the military in both strategic
and tactical applications, both of which have parallels in
utilization for coastal ocean science. In tactical military
applications, UAVs are vectored to specific, localized
missions whether it be to conduct surveillance or to carry
out offensive operations. Scientifically speaking, tactical
employment of UAVs would involve missions near shore
dedicated to a very specific event (e.g. incident response
vice general surveillance). The range and time-on-station
requirements for tactical scientific employment are not
nearly as robust and fall in line with the capabilities of
UAVs discussed above. These UAVs provide a mobile,
flexible (in terms of sensor packages, data collection plans,
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TABLE III.
available to researchers who have an interest in studying
the refuge’s ecosystem.
Because of the wireless
infrastructure available in the area, the team is able to
immediately upload imagery and metadata to an IOOS
PDAQC as soon as it has been processed and
geo-referenced thus allowing the pictures to be captured in
the daily news cycle for inclusion in the local and national
evening news reports.
Example 3
The process is finally complete
designating the Northwestern Hawaiian Islands Coral Reef
Ecosystem Reserve (NWHI) the 14th National Marine
Sanctuary. In order to survey and characterize this
sparsely-studied ecosystem and because of the lack of
adequate facilities to deploy manned aircraft, a UAV team
is sent aboard a research vessel collecting various in-situ
data and samples. The UAV team conducts surveillance
flights over each reef/atoll/island by launching the UAV
from the ship and recovering it after it lands softly in the
water nearby.
Equipped with a miniaturized
hyperspectral sensor, the imagery that is collected will
serve two purposes. First, once the vessel returns to
Honolulu and the imagery is uploaded to an IOOS PDAQC,
the scientific community will be able to analyze the ~0.2 m
resolution data to catalogue and assess the ecosystem.
The second purpose of this data set is that it will serve as a
high resolution baseline reference for change detection
studies as observations, both remotely-sensed and in-situ,
are made in the future.
Each of the above scenarios describes potentially real
events and real applications of a UAV as it may contribute
to the IOOS.
IOOS CORE PARAMETERS THAT SHOULD BE MEASURED IN
ORDER TO IMPACT SOCIETAL GOALS (ADAPTED FROM [9]).
CURRENT PARAMETERS MEASURABLE FROM UAVS ARE IN
BLUE WHILE FUTURE CAPABILITIES ARE INDICATED IN
Core
Parameter
Salinity
Temperature
Bathymetry
Sea Level
Surface Waves
Surface
Currents
Ice
Distribution
Contaminants
Dissolved
Nutrients
Fish Species
Fish
Abundance
Zooplankton
Species
Optical
Properties
Heat Flux
Ocean Color
Bottom
Character
Pathogens
Dissolved O2
Phytoplankton
Species
Zooplankton
Abundance
Weather &
Climate
Marine
Operations
Natural
Hazards
Homeland
Security
Public
Health
Ecosystem
Health
Living
Resources
GREEN.
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IV. OPEN TECHNICAL AND OPERATIONAL ISSUES
While UAVs do have the potential to play an important
role as a component of the Observation Subsystem of
IOOS, there are operational and technical issues that would
need to be resolved before UAVs could be “plugged in” to
the system. Some of these issues include:
• Use of very high fidelity spatial data In nearly all
instances the pixel sizes of the data generated by a
small UAV will be less than 0.3 meters. In some
cases it can be as small as 3 centimeters. Is the
IOOS community ready to use very high fidelity
data in science and operations?
• Development of advanced sensors for small UAVs
Current technology limits the suite of sensors
available for small UAVs to panchromatic and
infrared. Further technological development is
required to miniaturize multi- and hyperspectral
sensors and LIDAR systems that would fit within
the weight and size limitations of small UAVs.
Development of these advanced sensors will
greatly expand the potential applications for UAVs
in the IOOS.
• Sufficiency of reconnaissance tools Until the
CONOPs for employing UAVs is fully developed
and tested, it is uncertain if the broad-scale satellite
sensors will prove to be an adequate
Example 2 In the midst of a storm, an oil tanker runs
aground in the vicinity of Philadelphia Naval Shipyard
releasing tens of thousands of gallons of crude oil into the
Delaware River threatening marine life in the river and the
protected ecosystem of the nearby John Heinz National
Wildlife Refuge. A UAV team arrives on scene to map
and track the oil spill. After setting up operations in a
small parking lot adjacent to the river, the UAV team
initially conducts an orientation flight to determine the
extent of the spill. This visible imagery is used to direct
teams in real-time who are deploying booms to contain the
spill. After these teams’ actions are set in motion and the
buoy is deployed, the UAV team re-programs the flight
plan to collect imagery over the Wildlife Refuge. This
imagery will serve as baseline data for subsequent
change-detection analyses that will aid in monitoring any
necessary clean-up activities in the refuge. This data,
once archived in the IOOS infrastructure, will be freely
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•
•
•
reconnaissance tool for directing the localized
employment of UAVs. The question to be
answered is whether or not the spatial and temporal
resolution of satellite sensors are sufficient to direct
the flight of a UAV to an area of interest within the
nominal range of the UAV and do so in a timely
manner.
Employment of a variable-resolution sensor
Satellite-borne sensors orbit the earth at fixed
altitudes which leads to fixed spatial resolutions in
data products.
However, UAVs may fly at
variable altitudes which will lead to a variable
resolution capability for the sensors it carries.
This will require, for each application of UAV data
collection (e.g. oil spill, HABs, etc.), that the user
determine the required spatial resolution for the
imagery and, therefore, the UAV flight altitude.
Staging of UAVs and response time The practical
employment of UAVs will be limited by their
range, time on station, and the number of UAVs in
the operational fleet. There are two options for
the strategic employment of UAVs: distributed and
centralized. In a distributed deployment, UAVs
would be staged around the country’s coastline to
respond quickly to local data collection
requirements. The advantage of a distributed plan
is that it shortens the response time to an incident
or event. In a centralized employment, a few
UAVs would be staged at a single location with an
associated infrastructure to transport the UAV and
associated equipment and personnel to the required
location in the required timeframe. By centrally
locating a group of transportable UAVs,
efficiencies are gained in minimizing the support
infrastructure. Such a CONOPS would emulate
the U.S. Coast Guard’s National Strike Force who
is charged with providing experts to oil and
hazardous material spill events.
Accepting UAV data of opportunity in IOOS
When weighing the role that UAVs can play in the
IOOS and the type of data that they can provide,
the IOOS community should consider the potential
differences in requirements between research
quality and operational quality data and products.
When considering those variables that can be
measured from UAVs, consideration must be given
to redefining the standards for what is considered
useful IOOS data. Typical data and derived
products in the context of IOOS as we see it today
are considered research quality adhering to very
high standards of precision, accuracy, and
confidence. Derived products often require the
use of complex algorithms that must be
peer-reviewed and extensively tested and validated.
However, in many practical operational situations
where IOOS will have its greatest impact, such
high standards may be unnecessary or
cost-prohibitive.
Data quality standards for
operational decision-making may be lower than
•
those standards required for scientific research.
Those persons who used early TIROS information
will certainly attest to the value of using the data
and information available. The value that may be
derived from all types of data will be recovered in
the metadata associated with the data.
Assigning quality tags to UAV-collected data The
IOOS development plan calls for developing
standards of quality control (QC) so that QC flags
can be assigned to IOOS data sets prior to entering
the DMAC subsystem [9]. As the marine science,
user, and data management communities
collaborate on defining these standards, attention
must be given to defining the metadata standards
specifically for imagery from UAV platforms.
Because of the differences in data quality
requirements between the operational and research
communities, it will be imperative to engage both
communities so that standards are defined for and
in terminology understood by both groups.
V. CONCLUSION
“To make the most effective decisions for protecting and
preserving ocean resources, accurate information from an
ocean observing system is required to allow for detection
and prediction of the causes and consequences of changes
in marine and coastal ecosystems, watersheds and nonliving resources” [10]. UAVs and associated sensors
enhance the remote sensing backbone of the IOOS
architecture and provide timely, accurate, and
cost-effective information on coastal oceans.
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