Proceedings of the Symposium on Global and Environmental Monitoring: Proceedings of the Symposium on Global and Environmental Monitoring

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Persistent identifier:: 856665355

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts ; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856665355

Language:: English

Document type:: Multivolume work

Volume

Persistent identifier:: 856669164

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Scope:: XIV, 912 Seiten

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856669164

Illustration:: Illustrationen, Diagramme, Karten

Signature of the source:: ZS 312(28,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [TP-3 OCEAN/COASTAL ZONE MONITORING]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: MONITORING THE OCEANS WITH SATELLITE ALTIMETRY TECHNIQUES. Demitris Delikaraoglou, Nicholas Christou and Mario Berube

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Structure type:: Chapter

85 GEOSAT MEAN SEA SURFACE ERM 1 TO 12 60 30 0 -30 -60 -110 -50 0 50 90 Figure 5 - Global Mean Sea Surface as computed from GEOSAT observations collected over the first six months of the Exact Repeat Mission (ERM 1 to 12: November 1986 to May, 1987). al., 1988; Marsh et al., 1989). The orbit error of the GEM- T1-derived GEOSAT ephemerides is estimated to be at the 1-m level, while the respective accuracy of the GEM-T2 improved ephemerides is estimated to be at the 50 cm level or better (Haines et al., 1990). The algorithm portion of the operational system currently being developed at CCS includes: • the development of software to make an assessment of the accuracies of the latest computed orbits of GEOSAT, and to study the stability of sea surface solutions through comparisons with the latest available high degree and order geoidal solutions (e.g. OSU89); and • the design of optimum methodologies for the simultaneous crossover and collinear arc solutions, which are necessary in order to remove various unmodelled significant errors (e.g. orbit, ocean dynamic state errors etc.) inherent in the altimetry observations. Along with precise orbit information, an enhanced processing of radar altimeter data allows the generation of sea surface heights on a global or regular scale with high spatial and temporal resolution. Figure 5 illustrates a typical solution for the global mean sea surface using roughly six months of data from the first twelve GEOSAT 17-day ERMs (November 8, 1986 to May 30, 1987). Subsequent analyses with oceanographic and geodetic data provides the additional capability to derive improved models of the marine geoid and to estimate large scale features of the sea surface topography. The primary goal of the current studies is to provide a homogeneous intermediate-wavelength (100-500 km) and long-wavelength (>500 km) gravity database over the global oceans, particularly for the support of: • • mesoscale oceanographic tasks (e.g. detection of current boundaries and mesoscale eddies); • generating improved maps of geoid height, gravity anomalies, and deflections of the vertical; and • the definition of specific geophysical/geologic areas for more detailed follow-up gravity surveys or resource exploration studies. Figure 6 illustrates typical world maps of altimetry-derived Significant Wave Heights (SWH) computed over two adjacent 5-day periods during ERM 1. They clearly portray the early November rough seas in both the middle North Atlantic and the Southern seas. The maps also reveal that most of the oceans experience SWHs less than 4 metres. In addition, like many other 5-day average maps we have computed, they clearly slow that the sea state is predominantly latitudinally structured and that is has long wavelength nature. Christou (1990) in an extensive treatment of GEOSAT data to study the space-time ocean variability and its effects on the length of day has demonstrated even more clearly the capability of satellite altimetry to depict related space/time ocean surface current variability. Figure 7 is just a "snap-shot" of zonally averaged sea-level-slope time series within a longer (2-year long) record of the mean surface ocean current velocity fields (ibid). Each time series represents the zonal average of current velocity fluctuations with respect to the 2-year long mean (Nov. '86 to Nov. '89) for every 1° latitude band between 65° S and 65° N. The most obvious observation that can be drawn from Figure 7 is that most of the zonal velocity variability is confined within the north and south tropical zones (i.e., between 23° S and 23° N), while significant variability is observed in the northern mid-latitudes (i.e., between 30° N and 50° N) and southern higher latitudes (i.e., between 50° S and 60° S). The northern mid-latitude zonal velocity fluctuations are likely related to the large mid-latitude oceanic gyres (i.e. Gulf

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