Remote Sensing and Global Environmental Change E-Book

Sam J. Purkis

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 706

Veröffentlichungsjahr: 2011

Beschreibung

Remote Sensing plays a key role in monitoring the various manifestations of global climate change. It is used routinely in the assessment and mapping of biodiversity over large areas, in the monitoring of changes to the physical environment, in assessing threats to various components of natural systems, and in the identification of priority areas for conservation. This book presents the fundamentals of remote sensing technology, but rather than containing lengthy explanations of sensor specifications and operation, it concentrates instead on the application of the technology to key environmental systems. Each system forms the basis of a separate chapter, and each is illustrated by real world case studies and examples. Readership The book is intended for advanced undergraduate and graduate students in earth science, environmental science, or physical geography taking a course in environmental remote sensing. It will also be an invaluable reference for environmental scientists and managers who require an overview of the use of remote sensing in monitoring and mapping environmental change at regional and global scales. Additional resources for this book can be found at: href="http://www.wiley.com/go/purkis/remote">http://www.wiley.com/go/purkis/remote.

Leseprobe

Contents

Cover

Half Title Page

Title Page

Copyright

Preface

Acknowledgments

Chapter 1: Introduction

1.1 Key concepts

Chapter 2: Remote sensing basics

2.1 Electromagnetic waves

2.2 The electromagnetic spectrum

2.3 Reflectance and radiance

2.4 Atmospheric effects

2.5 Multispectral feature recognition

2.6 Resolution requirements

2.7 Key concepts

Chapter 3: Remote sensors and systems

3.1 Introduction

3.2 Remote sensors

3.3 Remote sensing platforms

3.4 The NASA Earth observing system

3.5 Global Earth observation systems

3.6 Existing image archives

3.7 Key concepts

Chapter 4: Digital image analysis

4.1 Image data format

4.2 Image pre-processing

4.3 Image enhancement and interpretation

4.4 Image classification

4.5 Image band selection

4.6 Error assessment

4.7 Time-series analysis and change detection

4.8 Field sampling using GPS

4.9 Use of Geographic Information Systems

4.10 Key concepts

Chapter 5: Monitoring Changes in Global Vegetation Cover

5.1 EM spectrum of vegetation

5.2 Vegetation indices

5.3 Biophysical properties and processes of vegetation

5.4 Classification systems

5.5 Global vegetation and land cover mapping programmes

5.6 Remote sensing of vegetation as a monitor for global change

5.7 Remote sensing of wetlands change

5.8 Fire detection

5.9 Key concepts

Chapter 6: Remote Sensing of Urban Environments

6.1 Urbanization

6.2 Urban remote sensing

6.3 Microwave sensing of subsidence

6.4 Textural metrics

6.5 Monitoring city growth

6.6 Assessing the ecology of cities

6.7 Urban climatology

6.8 Air quality and air pollution

6.9 Climate change as a threat to urbanization

6.10 Key concepts

Chapter 7: Surface and ground water resources

7.1 Remote sensing of inland water quality

7.2 Remote sensing sediment load and pollution of inland waters

7.3 Remote sensing non-coastal flooding

7.4 Bathymetry of inland waters

7.5 Mapping watersheds at the regional scale

7.6 Remote sensing of land surface moisture

7.7 Remote sensing of groundwater

7.8 Key concepts

Chapter 8: Coral reefs, carbon and climate

8.1 Introduction

8.2 The Status Of The World’s Reefs

8.3 Remote Sensing Of Coral Reefs

8.4 Light, Corals And Water

8.5 Passive optical sensing

8.6 Sensor-down versus reef-up sensing

8.7 Spectral unmixing

8.8 Image-derived bathymetry

8.9 LiDAR

8.10 Sonar

8.11 Sub-bottom acoustic profiling

8.12 Radar applications

8.13 Class assemblages and the minimum mapping unit

8.14 Change detection

8.15 Key concepts

Chapter 9: Coastal impact of storm surges and sea level rise

9.1 Predicting and monitoring coastal flooding

9.2 Coastal currents and waves

9.3 Mapping beach topography

9.4 LiDAR bathymetry

9.5 Key concepts

Chapter 10: Observing the oceans

10.1 Introduction

10.2 Ocean colour, chlorophyll and productivity

10.3 Hazardous algal blooms and other pollutants

10.4 Sea surface temperature

10.5 Ocean salinity

10.6 Physical ocean features

10.7 Ocean Observing Systems

10.8 Marine Gis

10.9 Key Concepts

Chapter 11: Monitoring Earth’s atmosphere

11.1 The status of Earth’s atmosphere

11.2 Atmospheric remote sensing

11.3 The ‘A-Train’ satellite constellation

11.4 Remote sensing atmospheric temperature

11.5 Atmospheric remote sensing of ozone

11.6 Atmospheric remote sensing of carbon dioxide

11.7 Remote sensing atmospheric dust

11.8 Clouds

11.9 Forecasting Earth’s atmosphere

11.10 Atmospheric models and reality

11.11 Hurricanes

11.12 Key concepts

Chapter 12: Observing the cryosphere

12.1 Introduction

12.2 The history and status of the polar ice sheets

12.3 Ice and sea level

12.4 Ice and climate

12.5 Present ice loss in context

12.6 Remote sensing of the Earth’s ice sheets

12.7 Ice sheet mass balance

12.8 Remote sensing permafrost

12.9 Key concepts

Chapter 13: Effective communication of global change information using remote sensing

13.1 Global environmental change as an interdisciplinary issue

13.2 Effective communication through accessibility of data

Chapter 14: Looking ahead: future developments

14.1 Emerging technologies

14.2 The near future

14.3 The more distant future

14.4 Advanced image analysis techniques

14.5 Looking ahead at a changing Earth

References

Index

REMOTE SENSING AND GLOBAL ENVIRONMENTAL CHANGE

This edition first published 2011, © 2011 by Samuel Purkis and Victor Klemas

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Library of Congress Cataloguing-in-Publication Data Purkis, Samuel J.

Remote sensing and global environmental change / Samuel Purkis and Victor Klemas. p. cm. Includes index. ISBN 978-1-4443-3935-2 (cloth) – ISBN 978-1-4051-8225-6 (pbk.) 1. Global environmental change–Remote sensing. 2. Environmental monitoring–Remote sensing. I. Klemas, V. II. Title. GE149.P87 2011 550.28’4–dc22

2010043279

A catalogue record for this book is available from the British Library.

This book is published in the following electronic formats: eBook 9781444340266; Wiley Online Library 9781444340280; ePub 9781444340273

Set in 10/12.5pt Minion by SPi Publisher Services, Pondicherry, India

Preface

This book is intended to provide the reader with a broad grounding in the science of Earth observation (EO) of our changing planet. It contains a comprehensive sequenced discussion covering the significant themes of global change, their causes and how they can be monitored through time. In doing so, it represents a good source of basic information while providing a general overview of the status of remote sensing technology. The text will serve as an invaluable reference for managers and researchers, regardless of their specialty, while also appealing to students of all ages.

The scope of the work yields a reference book that presents the science of EO through a series of pertinent real-world environmental case studies. It offers excellent background material for a course curriculum, being tuned in terms of its length and material covered to fit a variety of teaching scenarios.

The book has been written with students from both bachelors and masters degree programs in mind. For the former group, it contains sufficient material to support a full-semester course; for the latter, the work is intended to serve as a user-friendly introductory text for newcomers to a master’s program in environmental or climate change where the role of EO is considered. The book is thus aimed at a broad audience concerned with the application of remote sensing in Earth science, biological science, physical geography, oceanography and environmental science programs. It is designed for a reader who does not require an in-depth knowledge of the technology of EO, but who needs to understand how it is used as a key tool for mapping and monitoring global change. As such, the book is also intended to serve as an easily approachable text for professionals already working in fields such as ecology, environmental science and engineering, land use planning, environmental regulation, etc., who come across remote sensing in their work and would benefit from learning more about its practical uses, but who are disinclined to take another master’s course or delve into the mathematical tomes on the subject.

The first four chapters of the book introduce the fundamentals of EO, available platforms and the basic concepts of image processing. This will provide an introductory treatment of remote sensing technology to readers who have not been previously exposed to the field. Chapters 5 through 12 each present an important environmental application that:

i is relevant to global change or the status of the biosphere; and

ii lends itself to remote monitoring. Each case study offers insights into new EO techniques.

The work presents the fundamental mechanisms of environmental change and the technology underpinning each sensor relevant for its detection and measurement. An in-depth mathematical treatment of the science is purposely avoided, which should make the text especially appealing to many students and professionals with a non-numerate science background. The final chapter provides a look into the near and more distant future of EO as a tool for monitoring global change, before closing with a sombre but pragmatic look at how climate change has become the defining issue of our time.

The book’s framework is based on using examples from the recent literature, via a gap-bridging cross-disciplinary approach, rather than presenting a classical ‘textbook’ that simply projects the author’s understanding or perception of the use of remote sensing for the study of global environmental change. This inevitably leads to the citation of numerous references that may be of considerable value to those readers desiring to pursue a topic in more detail, and also ensures that these sources will be duly credited and that readers have direct access to them.

Given its emphasis on transmitting concepts rather than techniques, the book does not include problems or exercises. At the end of each chapter, however, a series of ‘key concepts’ are presented that summarize the most crucial points covered. These provide appropriate material that can be developed into challenging exercises, even for advanced courses, if the instructor chooses to elaborate on the themes with a more mathematical underpinning of the technologies illustrated.

Samuel J. Purkis National Coral Reef Institute Nova Southeastern University Dania Beach, Florida, USA

Victor V. Klemas College of Earth, Ocean and Environment University of Delaware Newark, Delaware, USA

Acknowledgements

We wish to thank Dr. Ian Francis for the opportunity to undertake this project and his guidance of the text from conception to birth. Invaluable comments, for which we are extremely grateful, were provided by two anonymous reviewers. Throughout this endeavour, Sam Purkis was supported by the National Coral Reef Institute and Nova Southeastern University’s Oceanographic Center. Similarly, support was provided to Vic Klemas by the College of Earth, Ocean and Environment, University of Delaware. We are indebted to Chris Purkis for his patient and unwavering assistance with the artwork. The text draws upon large numbers of images and illustrations from the work of others, and we appreciate the generosity of the many individuals and publishers who have made available source materials and gave permission for their use.

Our children and grandchildren, Isis, Grace, Andy, Paul, Tom, John Paul and Asta, provided an oft-needed distraction and perspective on the priorities of life. Writing this book demanded considerable time and energy, a burden that was shared as much by family as by the authors. We thank our respective wives, Lotte Purkis and Vida Klemas, for their support, which stretched far beyond the call of duty.

It is our hope that the publication of this book will provide stimulation to a new generation of students and researchers to perform in-depth work and analysis of our changing Earth using remote sensing.

Chapter 1

Introduction

The Earth’s climate is now clearly changing and getting warmer. Many components of the climate system are changing at rates and in patterns that are not natural and are best explained by the increased atmospheric abundances of greenhouse gases and aerosols generated by human activity during the 20th century. These changes include temperatures of the atmosphere, land and ocean; the extent of sea ice and mountain glaciers; the sea level; the distribution of precipitation; and the length of the seasons (AGU, 2008).

The Intergovernmental Panel on Climate Change (IPPC), made up of hundreds of scientists from 113 countries, reached a consensus in 2007 that, based on new research concluded in the last decade, it is 90 per cent certain that human-generated greenhouse gases account for most of the global rise in temperatures. The IPPC was very specific, predicting that, even under the most conservative scenario, the global increase of temperature will be between 1.1 C and 6.4 C by 2100, and the sea level will rise between 18 cm and 58 cm during that same time period (Collins et al., 2007; IPCC, WMO/UNEP, 2007).

The Earth has warmed consistently and unusually over the past few decades in a manner that can be explained only when a greenhouse process is overlaid on orbital variation, solar variation, volcanic eruptions and other natural disturbances. Observational evidence, complex modelling and simple physics all confirm this. Whatever the proportion of human-induced rise in global temperature versus natural rise, there is no doubt that the temperature and the sea level are rising, the Greenland and Antarctic ice sheets are disintegrating, and major weather patterns and ocean currents are shifting (Figs. 1.1 and 1.2.). The Earth’s warming is already causing severe droughts and flooding, major vegetation transformations in deserts and forests, massive tundra methane releases and the degradation of the Amazon rainforest and Saharan vegetation (Gates, 1993). It is also starting to impact the Indian Ocean Monsoon, the Atlantic Conveyor Belt and El Niño weather patterns. The economic impacts of droughts in the USA alone cause $68 billion in losses per year (Chagnon, 2000).

Figure 1.1 The projected range of global averaged sea level rise, re-plotted from the IPCC 2001 Third Assessment Report for the period 1990 to 2100.

Figure 1.2 The atmospheric concentration of carbon dioxide versus the occurrence of temperature anomalies from 1950 to 2001 (IPCC, 2007). An anomaly, in this case, is expressed as the difference between the observed annual global land-surface air temperature and the 1961 to 1990 mean.

Decision-makers and scientists need reliable science-based information to make informed judgements regarding policy and actions in order to be able to address the risks of such changes and variability in climate and related systems. To have any hope of mitigating or adapting to these mostly undesirable changes, we must be able to monitor them continuously and over large global regions. Ship and field observations have provided important data on these phenomena in the past and will do so in the future. However, to be able to observe environmental changes globally, it is necessary to use remote sensors on satellites and aircraft in order to extend local measurements to large areas.

For example, without satellite remote sensing we could not have mapped accurately the changes in the Antarctic ozone hole or the disintegration of ice sheets in Greenland and other areas. In fact, it was the ability to view these global changes with remote sensors from satellite altitudes that brought the enormity and severity of these environmental changes to the attention of scientists, politicians and the general public. Many such important datasets are now available in near-real time at no cost, through web portals such as Google Earth and Google Ocean, allowing ‘citizen’ scientists to accomplish research objectives and promoting public engagement with science in general.

Remote sensing is now a mature enough technology to answer some of the fundamental questions in global environmental change science, namely:

1. How and at what pace is the Earth system changing and what are the forces causing these changes?

2. How does the Earth system respond to natural and human-induced changes?

3. How well can we predict future perturbations to the Earth system and what are the consequences of change to human civilization?

Ice sheets, ocean currents and temperatures, deserts and tropical forests each have somewhat different remote sensing requirements. For instance, ocean temperatures are measured by thermal infrared sensors, while ocean currents, winds, waves, and sea level require various types of radar instruments on satellites. Most ocean features are large and require spatial resolutions of kilometres, while observations of desert or forest changes may require resolutions of tens of metres and many bands within the visible and near-infrared region of the electromagnetic spectrum. Monitoring of coral reefs demands even finer spatial resolution and multiple bands pooled in the short-wavelength visible spectrum.

Fortunately, by the turn of this century, most of these requirements had been met by NASA (the National Aeronautics & Space Administration) and NOAA (the National Oceanic & Atmospheric Administration) satellites and aircraft, the European Space Agency (ESA) and the private sector (Jensen, 2007). Furthermore, new satellites are being launched, carrying imagers with fine spatial (0.64 m) and spectral (200 narrow bands) resolutions, as well as other environmental sensors. These provide a capability to detect changes in both the local and the global environment even more accurately. For the first time, constellations of satellites are being launched with the sole aim of quantifying aspects of the Earth’s climate synergistically. With such technology available, governments are no longer alone in being able to monitor the extent of tropical forests and coral reefs, the spread of disease and the destruction caused by war.

Advances in the application of Geographical Information Systems (GIS) and the Global Positioning System (GPS) help to incorporate geo-coded ancillary data layers in order to improve the accuracy of satellite image analysis. When these techniques for generating, organizing, sorting and analyzing spatial information are combined with mathematical climate and ecological models, scientists and managers can improve their ability to assess and predict the impact of global environmental changes and trends (Lunetta & Elvidge, 1998).

To handle the vast quantities of information being generated by today’s Earth observation programmes, there have been significant advances made in the use of the Internet to store and disseminate geospatial data to scientists and the public. The Internet is set to play an even greater role in the handling of products delivered by future missions.

This book is intended to provide the reader with a broad grounding in the science of Earth observation of our changing planet. It contains a comprehensive sequenced discussion that covers the significant themes of global change, their cause, and how they can be monitored through time. In doing so, it represents a good source of basic information and a general overview of the status of remote sensing technology.

The text will serve as an invaluable reference for managers and researchers, regardless of their specialty, while also appealing to students of all ages. The scope of the work yields a reference book that presents the science of remote sensing through a series of pertinent real-world environmental case studies. It offers excellent background material for a course curriculum, being tuned in terms of its length, and the material covered, to fit a variety of teaching scenarios. Each chapter presents an important environmental phenomenon that:

i is relevant to global change or the status of the biosphere; and

ii lends itself to remote monitoring.

Each case study offers insights into new remote sensing techniques. The work presents the fundamentals of the technology underpinning each sensor type and delivers sufficient detail for the reader to grasp the mode of operation of the instrument and how it can be used to detect and measure the environmental parameters at hand. Thus, the book is aimed at a broad audience concerned with the application of remote sensing in Earth science, biological science, physical geography, oceanography and environmental science programmes. It is designed for a reader who does not require an in-depth knowledge of the technology of remote sensing, but who needs to understand how it is used as a key tool for mapping and monitoring global change.

1.1 Key concepts

1. The Earth’s climate is getting warmer and the patterns of the weather and ocean currents are changing. Severe droughts and flooding are becoming more prevalent and the ice sheets of Greenland and at the poles are disintegrating.

2. The global sea level is rising by about 2 to 3 mm per year, threatening to inundate many coastal areas by the end of this century.

3. Remote sensors on satellites offer an effective way for monitoring environmental trends on a global scale. They can detect physical and biological changes in the atmosphere, in the oceans and on land. Satellite systems have become the defining technology in our ability to quantify global change.

4. The accuracy and applicability of satellite imagery is constantly improving due to technological advances, such as finer spectral/spatial resolution, more powerful computers, the Global Positioning System (GPS) and Geographical Information Systems (GIS).

5. When these techniques for generating, organizing and analyzing spatial information are combined with mathematical and environmental models, scientists and managers have a means for assessing and predicting the impact of global environmental changes.

Remote Sensing and Global Environmental Change, First Edition. Samuel Purkis and Victor Klemas. © 2011 Samuel Purkis and Victor Klemas. Published 2011 by Blackwell Publishing Ltd.

Chapter 3

Remote sensors and systems

3.1 Introduction

Aerial photography started approximately in 1858 when the famous photographer, Gaspard Tournachon, obtained the first aerial photographs from a balloon near Paris. Since then, aerial photography has advanced, primarily during wartime, first to include colour infrared films (for camouflage detection) and later to use sophisticated digital cameras. Aerial photography and other remote sensing techniques are now used successfully in agriculture, forestry, land use planning, fire detection, mapping wetlands and beach erosion, and many other applications. For example, in agriculture it has been used for land use inventories, soil surveys, crop condition estimates, yield forecasts, acreage estimates, crop insect/pest/disease detection, irrigation management and, more recently, precision agriculture (Jensen, 2007).

Since the 1960s, ‘remote sensing’ has been used to describe a new field of information collection that includes aircraft and satellite platforms carrying electro-optical and antenna sensor systems (Campbell, 2007). Up to that time, camera systems dominated image collection and conventional photographic media dominated the storage of the spatially varying visible (VIS) and near-infrared (NIR) radiation intensities reflected from the Earth.

Beginning in the 1960s, electronic sensor systems were increasingly used for collection and storage of the Earth’s reflected radiation and satellites were developed as an alternative to aircraft platforms. Advances in electronic sensors and satellite platforms were accompanied by an increased interest and use of electromagnetic radiant energy, not only from the VIS and NIR wavelength regions, but also from the thermal infrared (TIR) and microwave regions. For instance, the thermal infrared region is used for mapping sea surface temperatures and microwaves (radar) are used for measuring sea surface height, currents, waves and winds on a global scale (Martin, 2004).