Zibordi Optical Radiometry for Ocean Climate Measurements

1. Auflage 2014
ISBN: 978-0-12-416994-4
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, Band Volume 47, 722 Seiten

Reihe: Experimental Methods in the Physical Sciences

This book presents the state-of-the-art of optical remote sensing applied for the generation of marine climate-quality data products, with contributions by international experts in the field. The chapters are logically grouped into six thematic parts, each introduced by a brief overview. The different parts include: i. requirements for the generation of climate data records from satellite ocean measurements and additionally basic radiometry principles addressing terminology, standards, measurement equation and uncertainties; ii. satellite visible and thermal infrared radiometry embracing instrument design, characterization and, pre- and post-launch calibration; iii. in situ visible and thermal infrared radiometry including overviews on basic principles, technology and measurements methods required to support satellite missions devoted to climate change investigations; iv. simulations as fundamental tools to support interpretation and analysis of both in situ and satellite radiometric measurements; v. strategies for in situ radiometry to satisfy mission requirements for the generation of climate data records; and finally, vi. methods for the assessment of satellite data products. Fundamentals of measurement theory are taken through to implementation of practical ground based radiometers and their application to validate satellite data used to generate climate data records. This book presents practical solutions for those involved or contemplating the validation of optical climate measurements from satellite instruments. - Exhaustive coverage of important topics - Fundamental and advanced discussions of many types of instruments - Emphasis on calibration and uncertainty analysis of results

Autoren/Hrsg.

Zibordi, Giuseppe

Inhaltsverzeichnis

1;Front
Cover;1
2;Experimental Methods in the Physical Sciences;3
3;Optical Radiometry
for Ocean Climate
Measurements;4
4;Copyright;5
5;Contents;6
6;List of Contributors;16
7;Volumes in Series;18
8;Foreword;22
9;Preface;24
10;Chapter 1 - Introduction to Optical Radiometry and Ocean Climate Measurements from Space;26
10.1;Chapter 1.1 - Ocean Climate and Satellite Optical Radiometry;28
10.1.1;1. INTRODUCTION;28
10.1.2;2. GLOBAL CLIMATE OBSERVING SYSTEM REQUIREMENTS FOR ECVS AND CDRS;31
10.1.3;3. FROM ESSENTIAL CLIMATE VARIABLES TO CLIMATE DATA RECORDS;35
10.1.4;4. CONCLUSION;36
10.1.5;REFERENCES;36
10.2;Chapter 1.2 - Principles of Optical Radiometry and Measurement Uncertainty;38
10.2.1;1. BASICS OF RADIOMETRY;39
10.2.2;2. RADIOMETRIC STANDARDS AND SCALE REALIZATIONS;55
10.2.3;3. THE MEASUREMENT EQUATION;67
10.2.4;4. SUMMARY;86
10.2.5;ACKNOWLEDGMENTS;87
10.2.6;REFERENCES;87
11;Chapter 2 - Satellite Radiometry;94
11.1;Chapter 2.1 - Satellite Ocean Color Sensor Design Concepts and Performance Requirements;98
11.1.1;1. INTRODUCTION;99
11.1.2;2. OCEAN COLOR MEASUREMENT FUNDAMENTALS AND RELATED SCIENCE OBJECTIVES;100
11.1.3;3. EVOLUTION OF SCIENCE OBJECTIVES AND SENSOR REQUIREMENTS;105
11.1.4;4. PERFORMANCE PARAMETERS AND SPECIFICATIONS;109
11.1.5;5. SENSOR ENGINEERING;118
11.1.6;6. SUMMARY;132
11.1.7;ACRONYMS;133
11.1.8;SYMBOLS AND DIMENSIONS;134
11.1.9;7. APPENDIX. HISTORICAL SENSORS;134
11.1.10;REFERENCES;141
11.2;Chapter 2.2 - On Orbit Calibration of Ocean Color Reflective Solar Bands;146
11.2.1;1. INTRODUCTION;146
11.2.2;2. SOLAR CALIBRATION;149
11.2.3;3. LUNAR CALIBRATIONS;153
11.2.4;4. SPECTRAL CALIBRATION OF GRATING INSTRUMENTS;160
11.2.5;5. VICARIOUS CALIBRATION;162
11.2.6;6. ON-ORBIT CALIBRATION UNCERTAINTIES;167
11.2.7;7. COMPARISON OF UNCERTAINTIES ACROSS INSTRUMENTS;170
11.2.8;8. SUMMARY OF ON-ORBIT CALIBRATION;174
11.2.9;REFERENCES;175
11.3;Chapter 2.3 - Thermal Infrared Satellite Radiometers: Design and Prelaunch Characterization;178
11.3.1;1. INTRODUCTION;179
11.3.2;2. RADIOMETER DESIGN PRINCIPLES;180
11.3.3;3. REMOTE SENSING SYSTEMS;186
11.3.4;4. CALIBRATION MODEL;197
11.3.5;5. ON-BOARD CALIBRATION;201
11.3.6;6. PRE-LAUNCH CHARACTERIZATION AND CALIBRATION;207
11.3.7;7. CONCLUSIONS;222
11.3.8;REFERENCES;223
11.4;Chapter 2.4 - Postlaunch Calibration and Stability: Thermal Infrared Satellite Radiometers;226
11.4.1;1. INTRODUCTION;226
11.4.2;2. ON-BOARD CALIBRATION;228
11.4.3;3. COMPARISONS WITH REFERENCE SATELLITE SENSORS;243
11.4.4;4. VALIDATING GEOPHYSICAL RETRIEVALS;250
11.4.5;5. DISCUSSION;262
11.4.6;6. CONCLUSIONS;264
11.4.7;REFERENCES;264
12;Chapter 3 - In Situ Optical Radiometry;270
12.1;Chapter 3.1 - In situ Optical Radiometry in the Visible and Near Infrared;272
12.1.1;1. INTRODUCTION AND HISTORY;273
12.1.2;2. FIELD RADIOMETER SYSTEMS;274
12.1.3;3. SYSTEM CALIBRATION;279
12.1.4;4. MEASUREMENT METHODS;289
12.1.5;5. ERRORS AND UNCERTAINTY ESTIMATES;298
12.1.6;6. APPLICATIONS;310
12.1.7;7. SUMMARY AND OUTLOOK;319
12.1.8;REFERENCES;320
12.2;Chapter 3.2 - Ship-Borne Thermal Infrared Radiometer Systems;330
12.2.1;1. INTRODUCTION AND BACKGROUND;331
12.2.2;2. TIR MEASUREMENT THEORY;336
12.2.3;3. TIR FIELD RADIOMETER DESIGN;346
12.2.4;4. EXAMPLES OF FRM SHIP-BORNE TIR RADIOMETER DESIGN AND DEPLOYMENTS;388
12.2.5;5. FUTURE DIRECTIONS;418
12.2.6;6. CONCLUSIONS;420
12.2.7;ACKNOWLEDGMENTS;420
12.2.8;REFERENCES;420
13;Chapter 4 - Theoretical Investigations;430
13.1;Chapter 4.1 - Simulation of In Situ Visible Radiometric Measurements;432
13.1.1;1. OVERVIEW;432
13.1.2;2. THE RTE AND ITS SOLUTION METHODS;433
13.1.3;3. SIMULATIONS OF IN SITU RADIOMETRIC MEASUREMENT PERTURBATIONS;438
13.1.4;4. SUMMARY AND REMARKS;466
13.1.5;REFERENCES;467
13.2;Chapter 4.2 - Simulation of Satellite Visible, Near-Infrared, and Shortwave-Infrared Measurements;476
13.2.1;1. INTRODUCTION;477
13.2.2;2. OCEAN–ATMOSPHERIC SYSTEM;480
13.2.3;3. SIMULATIONS;482
13.2.4;4. SUMMARY;503
13.2.5;DISCLAIMER;504
13.2.6;REFERENCES;504
13.3;Chapter 4.3 - Simulation and Inversion of Satellite Thermal Measurements;514
13.3.1;1. INTRODUCTION;514
13.3.2;2. RADIATIVE TRANSFER SIMULATION FOR THERMAL REMOTE SENSING;515
13.3.3;3. PROPAGATION OF THERMAL RADIATION THROUGH CLEAR SKY;518
13.3.4;4. SIMULATION OF INTERACTION WITH AEROSOL AND CLOUD;525
13.3.5;5. SIMULATION OF SURFACE EMISSION AND REFLECTION;527
13.3.6;6. USE OF SIMULATIONS IN THERMAL IMAGE CLASSIFICATION (CLOUD DETECTION);530
13.3.7;7. USE OF SIMULATIONS IN GEOPHYSICAL INVERSION (RETRIEVAL);534
13.3.8;8. USE OF SIMULATIONS IN UNCERTAINTY ESTIMATION;541
13.3.9;9. CONCLUSION;546
13.3.10;REFERENCES;548
14;Chapter 5 - In Situ Measurement Strategies;552
14.1;Chapter 5.1 - Requirements and Strategies for In situ Radiometry in Support of Satellite Ocean Color;556
14.1.1;1. INTRODUCTION;557
14.1.2;2. OVERVIEW OF PAST AND CURRENT FIELD-RELATED RADIOMETRIC ACTIVITIES;558
14.1.3;3. REQUIREMENTS AND STRATEGIES FOR FUTURE SATELLITE OCEAN-COLOR MISSIONS;568
14.1.4;4. SUMMARY AND WAY FORWARD;576
14.1.5;REFERENCES;577
14.2;Chapter 5.2 - Strategies for the Laboratory and Field Deployment of Ship-Borne Fiducial Reference Thermal Infrared Radiomet ...;582
14.2.1;1. INTRODUCTION;583
14.2.2;2. FIDUCIAL REFERENCE MEASUREMENTS FOR SST CDRS AND UNCERTAINTY BUDGETS;584
14.2.3;3. LABORATORY INTERCALIBRATION EXPERIMENTS FOR FRM SHIP-BORNE RADIOMETERS;610
14.2.4;4. SHIP-BORNE RADIOMETER FIELD INTERCOMPARISON EXERCISES;615
14.2.5;5. PROTOCOLS TO MAINTAIN THE SI TRACEABILITY OF FRM SHIP-BORNE TIR RADIOMETERS FOR SATELLITE SST VALIDATION;620
14.2.6;6. SUMMARY AND FUTURE PERSPECTIVES;623
14.2.7;ACKNOWLEDGMENTS;623
14.2.8;REFERENCES;624
15;Chapter 6 - Assessment of Satellite Products for Climate Applications;630
15.1;Chapter 6.1 - Assessment of Satellite Ocean Colour Radiometry and Derived Geophysical Products;634
15.1.1;1. INTRODUCTION;634
15.1.2;2. VALIDATION OF SATELLITE PRODUCTS;635
15.1.3;3. COMPARISON OF CROSS-MISSION DATA PRODUCTS;646
15.1.4;4. CONCLUSIONS;656
15.1.5;ACKNOWLEDGMENTS;657
15.1.6;REFERENCES;657
15.2;Chapter 6.2 - Assessment of Long-Term Satellite Derived Sea Surface Temperature Records;664
15.2.1;1. INTRODUCTION;664
15.2.2;2. BACKGROUND;665
15.2.3;3. ASSESSMENT OF LONG-TERM SST DATASETS;674
15.2.4;4. SUMMARY AND RECOMMENDATIONS;698
15.2.5;REFERENCES;699
16;Index;704

Leseproben

Chapter 1.1

Ocean Climate and Satellite Optical Radiometry

James A. Yoder1,*, Kenneth S. Casey2 and Mark D. Dowell3     1Woods Hole Oceanographic Institution, Woods Hole, MA, USA     2NOAA Oceanographic Data Center, Silver Spring, MD, USA     3European Commission, Joint Research Centre, Ispra, Varese, Italy
* Corresponding author: Email: [e-mail] 

Abstract

There is a growing consensus among global policymakers to accept the conclusions of the scientific community that the Earth and its Ocean are warming, with consequences to ecosystems around the world. Satellite radiometers are one of the most important tools for measuring changes in global ocean temperatures, as well as changes in key biogeochemical parameters, such as phytoplankton chlorophyll-a and particulate carbon. This chapter first describes the rigorous requirements established by the Global Climate Observing System for radiometric measurements for sea surface temperature, and ocean color radiometry to determine oceanic trends. This description is followed by a brief discussion outlining the steps that are required to meet those requirements with details provided in the following chapters. Finally, it is emphasized that sustaining calibrated time series indefinitely into the future across multiple satellite missions is too much for a single space agency or single nation. International organizations now exist to describe and advocate for the type of international cooperation that is required to provide the long records of calibrated satellite radiometric measurements of the ocean that are critical to understanding changes in the physical and biogeochemical state of the ocean.

Keywords

earth observing satellites; sea surface temperature; ocean color radiometry; essential climate variable; climate data record; ocean; climate; observing system; Global Climate Observing System

1. Introduction

The following two statements are from a summary report of the recent Intergovernmental Panel on Climate Change (IPCC) [1].

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.

Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence). It is virtually certain that the upper ocean (0–700m) warmed from 1971 to 2010, and it likely warmed between the 1870s and 1971.

These recent statements of the IPCC point to the importance of determining both the rates of changes to the climate system, as well as the impacts of those changes, including on marine ecosystems. Both tasks require global observing systems of which space-borne radiometers are crucial components.

Earth observation satellites measuring in the visible and infrared spectral domain provide a global perspective for many measurements required to determine the role of the ocean in the global climate system, as well as the effects on the ocean of a changing climate. The focus of this book is on measurements of sea surface temperature (SST) and on ocean color radiometery (OCR). SST is directly related to warming of the ocean and to the oceans role in the hydrologic cycle in general. OCR provides measures of biogeochemical constituents of the upper ocean, including phytoplankton pigments (e.g., Chl a), colored organic matter, particulate carbon and estimates of phytoplankton size and taxonomic composition. Variability or trends in these constituents can be related to changes in ocean productivity and to the taxonomic structure of the organisms responsible for primary production. These changes also have implications for higher tropic levels, including fisheries. Measurements from satellites provide a regional to global scale perspective not possible from in situ and airborne measurements that are more limited in spatial and temporal coverage. Comparing satellite measurements with in situ observations, however, is essential to establish the credibility of satellite-based measurements to be used as essential climate variables (ECVs) leading to climate data records (CDRs) (see Table 1 for definitions).

1.1. Characteristics of a Climate-Observing System

The discussions in the present monograph, on the use of satellite visible and infrared radiometry for studies of ocean climate should be seen in the broader context of the development of a climate observing system, based on determined requirements, which should be adopted systematically. In order to characterize climate and climate change, data need to be accurate and homogeneous over long time scales. The relevant signals for the detection of climate change can easily be lost in the noise of a changing observing system. This enforces the need for continuity in an observing system, where observations can be tied to an invariant reference. Such a system needs to be maintained over at least several decades and preferably indefinitely.

Climate-monitoring principles, requirements, and guidelines for the creation of CDRs have been formulated to increase awareness of the specific observational and procedural needs for establishing a successful approach to climate monitoring. In this respect the task of climate monitoring has specific requirements that go beyond one-time research missions. For instance, it is important that the design of an observing system for climate monitoring, including satellite and in situ systems, takes account of all required observations and legacy instruments, and that it guarantees effective continuity in measurements. At the very least, appropriate transfer standards must be provided to enable robust linkage to an invariant, International System of Units (SI) reference system at an appropriate level of accuracy. The provision of such an observing system requires a global strategy in which agencies agree to collaborate to fulfill such a generic continuity requirement. It is simply too large a task for a single agency or even a single country to implement effectively. Although most space agencies accept the climate-monitoring principles, there is still only limited coordination of the long-term commitment to collect climate observations.

Table 1

Basic Terminology for Data Records Relating to Climate

An understanding of the terminology used when talking about climate-related data records is important. This box therefore lists established definitions, with respect to data records in general and satellite data records in particular:

An essential climate variable (ECV) is a geophysical variable that is associated with climate variation and change as well as the impact of climate change onto Earth. GCOS has defined a set of ECVs for three spheres, atmospheric, terrestrial, and oceanic [2].

A climate data record (CDR) is a series of observations over time that measures variables believed to be associated with climate variation and change. These changes may be small and occur over long time periods (seasonal, interannual, and decadal to centennial) compared to the short-term changes that are monitored for weather forecasting. Thus, a CDR is a time series of a climate variable that tries to account for systematic errors and noise in the measurements [3].

Stability [4] may be thought of as the extent to which the accuracy remains constant with time. Over time periods of interest for climate, the relevant component of total uncertainty is expected to be its systematic component as measured over the averaging period. Stability is therefore measured by the maximum excursion of the difference between a true value and the short-term average measured value of a variable under identical conditions over a decade. The smaller the maximum excursion, the greater the stability of the data set.

The term fundamental climate data record (FCDR) denotes a well-characterized, long-term data record, usually involving a series of instruments, with potentially changing measurement approaches, but with overlaps and calibrations sufficient to allow the generation of products that are accurate and stable, in both space and time, to support climate applications [3]. FCDRs are typically calibrated radiances, backscatter of active instruments, or radio occultation bending angles. FCDRs also include the ancillary data used to calibrate them. The term FCDR has been adopted by GCOS and can be considered as an international consensus definition.

The term thematic climate data record (TCDR) denotes the counterpart of the FCDR in geophysical space [3]. It is closely connected to the ECVs but strictly covers one geophysical variable, whereas an ECV can encompass several variables. For instance, the ECV cloud property includes at least five different geophysical variables, each of them constitutes a TCDR. The term TCDR has been taken up by many space agencies and can be considered as de facto standard.

GCOS, Global Climate Observing System.

Well-calibrated and stable satellite measurements can be used for climate monitoring, studies of trends and variability, climate impacts, and verification of climate models. The following sections specifically address the fundamental requirements for OCR and...