Ocean Colour Theory And Applications In A Decade Of Czcs Experience

Optical remote sensing is of invaluable help in understanding the marine environment and its biogeochemical and physical processes. The Coastal Zone Color Scanner (CZCS), which operated on board the Nimbus-7 satellite from late 1978 to early 1986, has been the main source of ocean colour data. Much work has been devoted to CZCS data processing and analysis techniques throughout the 1980s. After a decade of experience, the Productivity of the Global Ocean (PGO) Activity - which was established in the framework of the International Space Year 1992 (ISY '92) by SAFISY, the Space Agency Forum of ISY - sponsored a workshop aimed at providing a reference in ocean colour science and at promoting the full exploitation of the CZCS historical data in the field of biological oceanography. The present volume comprises a series of state-of-the-art contributions on theory, applications and future perspectives of ocean colour. After an introduction on the historical perspective of ocean colour, a number of articles are devoted to the CZCS theoretical background, on radiative transfer and in-water topics, as well as on calibration, atmospheric correction and pigment concentration retrieval algorithms developed for the CZCS. Further, a review is given of major applications of CZCS data around the world, carried out in the past decade. The following part of the book is centered on the application of ocean colour to the assessment of marine biological information, with particular regard to plankton biomass, primary productivity and the coupling of physical/biological models. The links between global oceanic production and climate dynamics are also addressed. Finally, the last section is devoted to future approaches and goals of ocean colour science, and to planned sensors and systems. The book is required reading for those involved in ocean colour and related disciplines, providing an overview of the current status in this field as well as stimulating the debate on new ideas and developments for upcoming ocean colour missions.

Since the pioneering work of Clarke et a1. (1970) it has been known that chlorophyll a (or. more generally. pigments) contained in phytoplankton in near-surface waters produced systematic variations in the color of the ocean which could be observed from aircraft. As a direct result of this work. NASA developed the Coastal Zone Color Scanner (CZCS). which was launched on Nimbus-G (now Nimbus-7) in October 1978. (A short description of the CZCS is provided in Appendix I. ) Shortly before launch. at the IUCRM Colloquium on Passive Radiometry of the Ocean (June 1978). a working group on water color measurements was formed to assess water color remote sensing at that time. A report (Morel and Gordon. 1980) was prepared which summarized the state-of-the-art of the algorithms for atmospheric correction. and phytoplankton pigment and seston retrieval. and which included recommendations concerning the design of next generation sensors. The water color session of the COSPAR/SCOR/IUCRM Symposium 'Oceanography from Space' held in Venice (May 1980. i. e •• in the post-launch period) provided the opportunity for a reassessment of the state-of-the-art after having gained some experience in the analysis of the initial CZCS imagery. Such an assessment is the purpose of this review paper. which will begin with an outline of the basic physics of water color remote sensing and the fundamentals of atmospheric corrections. The present state of the constituent retrieval and atmospheric correction algorithms will then be critically assessed.

The ocean is a fundamental component of the earth's biosphere. It covers roughly 70 percent of Earth's surface and plays a pivotal role in the cycling of life's building blocks, such as nitrogen, carbon, oxygen, and sulfur. The ocean also contributes to regulating the climate system. Most of the primary producers in the ocean comprise of microscopic plants and some bacteria; and these photosynthetic organisms (phytoplankton) form the base of the ocean's food web. Monitoring the health of the ocean and its productivity is critical to understanding and managing the ocean's essential functions and living resources. Because the ocean is so vast and difficult for humans to explore, satellite remote sensing of ocean color is currently the only way to observe and monitor the biological state of the surface ocean globally on time scales of days to decades. Ocean color measurements reveal a wealth of ecologically important characteristics including: chlorophyll concentration, the rate of phytoplankton photosynthesis, sediment transport, dispersion of pollutants, and responses of oceanic biota to long-term climate changes. Continuity of satellite ocean color data and associated climate research products are presently at significant risk for the U.S. ocean color community. Assessing Requirements for Sustained Ocean Color Research and Operations aims to identify the ocean color data needs for a broad range of end users, develop a consensus for the minimum requirements, and outline options to meet these needs on a sustained basis. The report assesses lessons learned in global ocean color remote sensing from the SeaWiFS/MODIS era to guide planning for acquisition of future global ocean color radiance data to support U.S. research and operational needs.

Aquatic systems play a salient role in the complex processes of energy and matter exchange between the geosphere and the atmosphere. For example, reactions taking place in cloud water droplets can substantially alter the atmospheric budget and chemistry of trace gases; pollution induced weathering reactions at water/soil interfaces can affect the availability of nutrients and increase the concentration of potentially toxic metals in groundwaters. Moreover, the inextricable links between the water cycle, the geosphere and the atmosphere ensure that apparently localized environmental problems have increasingly impacts in other parts of the world. To identify local-to-global scale variables associated with environmental changes, a focus must be placed on the recognition of processes, rather than a continued reliance on monitoring state variables. However, in heterogeneous aquatic systems, small scale aspects of a process under observation may not be summed directly to obtain regional estimates because of process nonlinearities with change in scale. To understand this, the integrated use of measurements across a range of scales is required.

A wide variety of marginal basins, ranging from polar to equatorial regions, and a few sizeable enclosed basins, can all be included among the Asian Seas. The Arctic Ocean shelf seas off Siberia; the sheltered basins along the Pacific Ocean’s western rim; the coastal seas of the northernmost Indian Ocean, including the semi-enclosed Red Sea and Persian Gulf; the Caspian Sea, the remnants of the Aral Sea and a score of brackish or freshwater lakes, such as Lake Balkhash and Lake Baykal; all exhibit a multiplicity of environmental features and processes. Understanding the peculiarities of such a large and varied collection of marine and coastal types requires integrated observation systems, among which orbital remote sensing must play an essential role. This volume reviews the current potential of Earth Observations in assessing the many Asian seascapes, using both passive and active techniques in diverse spectral regions, such as measuring reflected visible and near-infrared sunlight and surface emissions in the thermal infrared and microwave range, or surface reflection of transmitted radar pulses in the microwave range. An in-depth evaluation of the available spectral regions and observation techniques, as well as of novel multi-technique methods, ensures that suitable tools are indeed accessible for exploring and managing the wealth of resources that the Asian Seas have to offer.

A variety of biophysical applications (e.g. leaf area index and gross primary productivity) have been derived from measurements of the Earth system obtained remotely by NASA’s MODIS sensors and other satellite platforms. In Biophysical Applications of Satellite Remote Sensing, the authors describe major applications of satellite remote sensing for studying Earth's biophysical phenomena. The focus of the book lies on the broad palette of specific applications (metrics) of biophysical activity derived using satellite remote sensing. With in-depth discussions of satellite-derived biophysical metrics that focus specifically on theory, methodology, validation, major findings, and directions of future research, this book provides an excellent resource for remote sensing specialists, ecologists, geographers, biologists, climatologists, and environmental scientists.