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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.09.008 Byline: Christian B. Rodehacke (a)(b), Wolfgang Roether (a), Hartmut H. Hellmer (c), Timothy Hall (d) Abstract: The knowledge of chlorofluorocarbon (CFC11, CFC12) concentrations in ocean surface waters is a prerequisite for deriving formation rates of, and water mass ages in, deep and bottom waters on the basis of CFC data. In the Antarctic coastal region, surface-layer data are sparse in time and space, primarily due to the limited accessibility of the region. To help filling this gap, we carried out CFC simulations using a regional ocean general circulation model (OGCM) for the Southern Ocean, which includes the ocean-ice shelf interaction. The simulated surface layer saturations, i.e. the actual surface concentrations relative to solubility-equilibrium values, are verified against available observations. The CFC surface saturations driven by concentration gradients between atmosphere and ocean are controlled mainly by the sea ice cover, sea surface temperature, and salinity. However, no uniform explanation exists for the controlling mechanisms. Here, we present simulated long-term trends and seasonal variations of surface-layer saturation at Southern Ocean deep and bottom water formation sites and other key regions, and we discuss differences between these regions. The amplitudes of the seasonal saturation cycle vary from 22% to 66% and their long-term trends range from 0.1%/year to 0.9%/year. The seasonal surface saturation maximum lags the ice cover minimum by two months. By utilizing observed bottle data the full seasonal CFC saturation cycle can be determined offering the possibility to predict long-term trends in the future. We show that ignoring the trends and using instead the saturations actually observed can lead to systematic errors in deduced inventory-based formation rates by up to 10% and suggest an erroneous decline with time. Author Affiliation: (a) Universitat Bremen, Institut fur Umweltphysik (IUP), Abteilung Ozeanographie, Otto-Hahn-Allee, D-28359 Bremen, Germany (b) Columbia University, Department for Applied Physics and Applied Mathematics, 2880 Broadway, New York, NY 10025, USA (c) Alfred Wegener Institut, Department Climate Science, BussestraAe 24, D-27570 Bremerhaven, Germany (d) NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA Article History: Received 20 March 2008; Revised 29 August 2009; Accepted 22 October 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.10.003 Byline: Alonso Hernandez-Guerra (a), Terrence M. Joyce (b), Eugenio Fraile-Nuez (c), Pedro Velez-Belchi (c) Keywords: Meridional Overturning Circulation; Argo floats; Objective analysis; Box inverse model Abstract: Using a variety of oceanographic data, including direct volume transports in the Florida Strait, and Argo float profiles and drift velocities at 24[degrees]N and 36[degrees]N in the North Atlantic, inverse calculations are presented in which the net meridional transport, down to a depth of approximately 1600m, is estimated at both latitudes for a 5-year period 2003-2007. The upper ocean is divided into seven layers using neutral density, and mass conservation constraints have been applied to a closed box bounded by these latitudes, including the Florida Strait. Ekman layer transports have been included in the top-most layer, and the inverse calculation has solved for changes from the initial reference velocities, Ekman and Florida Strait transports, given a priori estimates on the accuracy of each of these quantities. Solutions with and without transformations due to Mediterranean Water (MW) formation are made. Our results indicate that (1) time-averaged transport estimates derived from Argo have significant less eddy noise than individual hydrographic sections, (2) Argo drift velocities provide information to the inverse solution for the ocean interior, and (3) comparison of the total integrated interior mass transports in the thermocline waters for the period 2003-2007 with the previous estimates based on trans-ocean hydrographic sections shows that, within the errors of our estimation, the upper limb of the Atlantic Meridional Overturning Circulation has not significantly changed since 1957. Author Affiliation: (a) Facultad de Ciencias del Mar, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas, Spain (b) Department of Physical Oceanography, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Mail Stop 21, Woods Hole, MA 02543, USA (c) Instituto EspaA[+ or -]ol de Oceanografia, Avenida Tres de Mayo, 73, 38005 Santa Cruz de Tenerife, Spain Article History: Received 4 April 2009; Revised 29 September 2009; Accepted 2 October 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.07.001 Byline: A. Srinivasan (a)(b), Z. Garraffo (a)(b), M. Iskandarani (a) Abstract: Abyssal pathways and volume transports in the Indian Ocean obtained from a 1/12.sup.a global data assimilative hindcast for the years 2004-2006 are presented. The known features of bottom water circulation such as boundary currents and inter-basin exchanges are well represented in the hindcast solution. Further, the hindcast solution reveals a basin-wide, anti-cyclonic deep circulation pattern with the main inflow located in the east, in the Perth Basin, and outflow in the west along the African continent and Madagascar. Inter-basin westward transport at 10.sup.aS across the Ninetyeast Ridge and along the Mascarene Plateau connect the inflow and outflow locations. The model develops a net bottom water inflow of 10[+ or -]8Sv (mean[+ or -]standard deviation) across 32.sup.aS, below approximately 3500m of which 4[+ or -]7Sv are returned south across the same latitude in the deep layers between 2000 and 3500m. Significant variability on intra-seasonal, semi-annual and annual time scales is present in the abyssal flow fields. The vertical mixing algorithm, based on resolved vertical shear, suggests enhanced diapycnal upwelling in the vicinity of the Central Indian Ridge. Author Affiliation: (a) Meteorology and Physical Oceanography Division, RSMAS, University of Miami, FL 33149, USA (b) Center for Computational Science, University of Miami, FL 33124, USA Article History: Received 26 May 2008; Revised 23 June 2009; Accepted 3 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.05.010 Byline: Dagmar Kieke (a), Birgit Klein (b), Lothar Stramma (c), Monika Rhein (a), Klaus Peter Koltermann (b) Keywords: Subpolar North Atlantic; Ocean circulation; Water mass spreading; Labrador Sea Water; Mid-Atlantic Ridge Abstract: The variability of two modes of Labrador Sea Water (LSW) (upper and deep Labrador Sea Water) and their respective spreading in the interior North Atlantic Ocean are investigated by means of repeated ship surveys carried out along the zonal WOCE line A2/AR19 located at 43-48[degrees]N (1993-2007) and along the GOOS line at about 48-51[degrees]N (1997-2002). Hydrographic section data are complemented by temperature, salinity, and velocity time series recorded by two moorings. They have been deployed at the western flank of the Mid-Atlantic Ridge (MAR) in the Newfoundland Basin during 1996-2004. The analysis of hydrographic anomalies at various longitudes points to a gradual eastward propagation of LSW-related signals, which happens on time scales of 3-6 years from the formation region towards the MAR. Interactions of the North Atlantic Current (NAC) with the Deep Western Boundary Current (DWBC) close to Flemish Cap point to the NAC being the main distributor of the different types of LSW into the interior of the Newfoundland Basin. Comparisons between the ship data and the mooring records revealed that the mooring sites are located in a region affected by highly variable flow. The mooring time series demonstrate an elevated level of variability with eddy activity and variability associated with the NAC considerably influencing the LSW signals in this region. Hydrographic data taken from Argo profiles from the vicinity of the mooring sites turned out to mimic quite well the temporal evolution captured by the moorings. There is some indication of occasional southward flow in the LSW layer near the MAR. If this can be considered as a hint to an interior LSW-route, it is at least of minor importance in comparison to the DWBC. It acts as an important supplier for the interior North Atlantic, distributing older and recently formed LSW modes southward along the MAR. Author Affiliation: (a) Institut fur Umweltphysik, Abt. Ozeanographie, Universitat Bremen, Postfach 330440, 28334 Bremen, Germany (b) Bundesamt fur Seeschifffahrt und Hydrographie, Hamburg, Germany (c) Leibniz-Institut fur Meereswissenschaften an der Universitat Kiel, IFM-GEOMAR, Kiel, Germany Article History: Received 18 July 2008; Revised 11 May 2009; Accepted 18 May 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.04.007 Byline: Daniel M. Sigman (a), Peter J. DiFiore (a), Mathis P. Hain (b), Curtis Deutsch (c), Yi Wang (a), David M. Karl (d), Angela N. Knapp (e), Moritz F. Lehmann (f), Silvio Pantoja (g) Keywords: Nitrate; Stable isotope; Biogeochemistry; Numerical model; Nutrients Abstract: We compare the output of an 18-box geochemical model of the ocean with measurements to investigate the controls on both the mean values and variation of nitrate [delta].sup.15N and [delta].sup.18O in the ocean interior. The [delta].sup.18O of nitrate is our focus because it has been explored less in previous work. Denitrification raises the [delta].sup.15N and [delta].sup.18O of mean ocean nitrate by equal amounts above their input values for N.sub.2 fixation (for [delta].sup.15N) and nitrification (for [delta].sup.18O), generating parallel gradients in the [delta].sup.15N and [delta].sup.18O of deep ocean nitrate. Partial nitrate assimilation in the photic zone also causes equivalent increases in the [delta].sup.15N and [delta].sup.18O of the residual nitrate that can be transported into the interior. However, the regeneration and nitrification of sinking N can be said to decouple the N and O isotopes of deep ocean nitrate, especially when the sinking N is produced in a low latitude region, where nitrate consumption is effectively complete. The [delta].sup.15N of the regenerated nitrate is equivalent to that originally consumed, whereas the regeneration replaces nitrate previously elevated in [delta].sup.18O due to denitrification or nitrate assimilation with nitrate having the [delta].sup.18O of nitrification. This lowers the [delta].sup.18O of mean ocean nitrate and weakens nitrate [delta].sup.18O gradients in the interior relative to those in [delta].sup.15N. This decoupling is characterized and quantified in the box model, and agreement with data shows its clear importance in the real ocean. At the same time, the model appears to generate overly strong gradients in both [delta].sup.18O and [delta].sup.15N within the ocean interior and a mean ocean nitrate [delta].sup.18O that is higher than measured. This may be due to, in the model, too strong an impact of partial nitrate assimilation in the Southern Ocean on the [delta].sup.15N and [delta].sup.18O of preformed nitrate and/or too little cycling of intermediate-depth nitrate through the low latitude photic zone. Author Affiliation: (a) Department of Geosciences, Princeton University, Princeton, NJ 08544, USA (b) Institute of Geosciences, University of Potsdam, PO Box 60 15 53, Potsdam D-14415, Germany (c) Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095, USA (d) Department of Oceanography, 1000 Pope Rd. MSB 629, University of Hawaii, Honolulu, HI 96822, USA (e) Department of Marine and Environmental Biological Sciences, University of Southern California, University of Southern California, 3616 Trousdale Parkway, AHF 108, Los Angeles, CA 90089-0371, USA (f) Institute for Environmental Geosciences, Bernoullistrasse 30, Universitat Basel, CH-4056 Basel, Switzerland (g) Department of Oceanography and Center for Oceanographic Research in the Eastern South Pacific, University of Concepcion, Casilla 160-C, Concepcion, Chile Article History: Received 21 January 2008; Revised 4 April 2009; Accepted 21 April 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.03.005 Byline: Martin Saraceno (a)(b), Christine Provost (c), Uriel Zajaczkovski (b)(d) Keywords: Zapiola Rise; South Atlantic circulation; Interannual variability Abstract: The Zapiola Rise (ZR) is a singular sedimentary deposit about 1200m in height and 1500km in width located in the Argentine Basin. In situ and satellite observations have revealed the presence of an intense counterclockwise circulation around the feature, with a volume transport comparable to those of the major ocean currents. The existence of a very low-frequency variability of the transport associated with the anticyclonic circulation is documented for the first time. As the Zapiola anticyclonic circulation plays a significant role in the mixing of the strongly contrasted water masses of the South Atlantic, variations in the anticyclonic transport can have a major impact on the mixing, hence a role in global climate variability. The circulation was clearly anticyclonic in the periods 1993-1999 and 2002-2007. In contrast, the 1999-2001 period did not show evidence of an anticyclonic flow in the mean surface velocity field. Moreover, the analysis of the weekly fields during that period of time revealed a cyclonic pattern from time to time. Previous work has shown that the flow can be considered as purely barotropic over the ZR region. A 15-year time-series of the transport was produced using absolute altimeter-derived geostrophic velocities. The estimated transport presents high-frequency variability associated with mesoscale activity superimposed on a low-frequency signal. The amplitude of the estimated transport is in good agreement with the only in situ-derived estimation available (80Sv, January 1993). The low-frequency signal presents a minimum during the period 1999-2001, further suggesting that at times the Zapiola anticyclonic flow may have significantly decreased in strength or even vanished. Possible causes of the low-frequency variability are discussed. Author Affiliation: (a) Centro de Investigaciones del Mar y la Atmosfera (CIMA), Intendente Guiraldes 2160, Ciudad Universitaria, Pab. II, 2do piso, Ciudad de Buenos Aires C1428EGA, Argentina (b) Departamento de la Atmosfera y los Oceanos, FCEyN, Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. II, 2do piso, Ciudad de Buenos Aires C1428EGA, Argentina (c) Laboratoire d'Oceanographie et du Climat: Experimentation et Approche Numerique (LOCEAN), Universite Pierre et Marie Curie, Tour 45/55, 5eme etage, BoA[R]te 100, 4 Place Jussieu, 75252 Paris cedex 05, France (d) Departamento de Oceanografia, Servicio de Hidrografia Naval, Av. Montes de Oca 2124, Ciudad de Buenos Aires C1270ABV, Argentina Article History: Received 8 October 2008; Revised 3 March 2009; Accepted 11 March 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.01.003 Byline: R.E. Roman, J.R.E. Lutjeharms Keywords: Ocean circulation; Western Boundary Current; Mesoscale eddies; Intermediate water masses; Water types; Mixing Abstract: Red Sea Intermediate Water (RSIW) has been shown to move down the Agulhas Current as distinct lenses. It has been assumed that this intermittency is the result of variable input. To clarify and quantify the nature of RSIW contributions from the source regions of the Agulhas Current observations at 15 hydrographic sections were examined using a multi-parameter analysis. In the northern Mozambique Channel RSIW is found to be layer-like, but with patches of distinctly different contributions. In the southern part of the channel the layer-like distribution disappears with RSIW mostly confined within anticyclonic and cyclonic eddies exhibiting varying maximum contributions ranging from 15-20% to 25-30% purity. Net transports across the channel ranged from -0.45 to -0.7Sv. At the southern tip of Madagascar RSIW contributions exhibited similar purity variability ranging from 10-15% to 15-20%. The net southward transport of RSIW in the East Madagascar Current displayed an even greater variability due to changes in the flux of the undercurrent ranging from negligible to -0.3Sv. Indications therefore were that the transport of RSIW to the Agulhas Current occurs in both cyclones and anti-cyclones through the Mozambique Channel whilst from the East Madagascar Current it is mostly confined to anti-cyclones. This variability in the inflow was also reflected in the northern part of the Agulhas Current proper. The maximum contributions of RSIW range here from 10-15% to 20-25% purity and net transports from -0.75 to -1.39Sv off Durban. As it was east of Madagascar RSIW was mostly confined to the slope. Author Affiliation: Department of Oceanography, University of Cape Town, Rondebosch 7700, South Africa Article History: Received 22 August 2008; Revised 8 January 2009; Accepted 15 January 2009

Oceanic overflows are bottom-trapped density currents originating in semienclosed basins, such as the Nordic seas, or on continental shelves, such as the Antarctic shelf. Overflows are the source of most of the abyssal waters, and therefore play an important role in the large-scale ocean circulation, forming a component of the sinking branch of the thermohaline circulation. As they descend the continental slope, overflows mix vigorously with the surrounding oceanic waters, changing their density and transport significantly. These mixing processes occur on spatial scales well below the resolution of ocean climate models, with the result that deep waters and deep western boundary currents are simulated poorly. The Gravity Current Entrainment Climate Process Team was established by the U.S. Climate Variability and Prediction (CLIVAR) Program to accelerate the development and implementation of improved representations of overflows within large-scale climate models, bringing together climate model developers with those conducting observational, numerical, and laboratory process studies of overflows. Here, the organization of the Climate Process Team is described, and a few of the successes and lessons learned during this collaboration are high-lighted, with some emphasis on the well-observed Mediterranean overflow. The Climate Process Team has developed several different overflow parameterizations, which are examined in a hierarchy of ocean models, from comparatively well-resolved regional models to the largest-scale global climate models.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2008.12.001 Byline: Ali Harzallah Keywords: Ocean circulation; Tide; Velocity; Density; Mediterranean Sea; Strait of Gibraltar Abstract: The vertical structure of the flow variability through the Strait of Gibraltar is studied based on the Gibraltar Experiment and the Word Ocean Circulation Experiment data sets. An analysis of the leading modes of velocity and density variability at the Strait of Gibraltar showed an adjustment of the water masses exchanged through the Strait. Mediterranean mass variations resulting from the water exchanged by barotropic tidal oscillations generate changes of the baroclinic component of the flow that damp these mass variations. This adjustment explains the previously observed fortnightly variation of the shear. Moreover, the adjustment is found to operate for the subinertial time scale flow variability forced by the atmospheric pressure. An analytical model aimed at reproducing variations of the velocity with time and in the vertical is derived. The model includes a depth-varying parameterisation of friction and takes into account density gradient fluctuations across the Strait. The model reproduces the main features of the flow, in particular the shear and the interface depth variations with the tide phase. Author Affiliation: Institut National des Sciences et Technologies de la Mer, 28, rue du 2 mars 1934, 2025 SalammbA[acute accent], Tunisia Article History: Received 1 March 2007; Revised 28 November 2008; Accepted 3 December 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2008.05.016 Byline: Oliver Huhn, Wolfgang Roether, Reiner Steinfeldt Keywords: Transient tracers; Tracer ages; Transit time distributions; North Atlantic Deep Water; Tropical Atlantic; South Atlantic Abstract: An extensive set of transient-tracer observations has been used to determine age spectra in Upper and Lower North Atlantic Deep Water (UNADW, LNADW) along the western continental margin between [approximately equal to]10[degrees]N and 30[degrees]S. The tracers are CFC-11, CFC-12, CCl.sub.4, and tritium, and the observations cover 20 years. The procedure was to deduce from the data the free parameters of a transit time distribution (TTD; mean age or transit time I, age dispersion I, and dilution factor by tracer-free water f) of the common functional form (Inverse Gaussian). A novel northern boundary condition for the tracers was employed; it allows for enhanced halocarbon input during convective deep-water formation in winter and yields minimized biases between observed and TTD-based tracer concentrations in downstream NADW. We found that the common boundary condition of time-invariant apparent saturations gave inconsistent results. The TTD parameter fits covered the entire region and used all tracer data jointly, the parameters being prescribed to increase linearly along-stream and the Peclet number (Pe=2I.sup.2 I.sup.-2) to be constant. For the southward transit up to the equator, we obtained for UNADW I=54 years, I=33 years, and f=1.4, with uncertainties of about [+ or -]20% estimated on the basis of a thorough error analysis. A limiting factor was a significant scatter in the NADW tracer fields. The LNADW parameter values are similar but less well constrained than for UNADW. The age spectra are broad; they correspond to large-scale along-core diffusivities on the order of 10.sup.4 m.sup.2/s. The TTD-based mean NADW flow velocities are less than 1cm/s. The relative southward increases of the TTD-based ages exceed those of CFC-11 to CFC-12 ratio ages about three-fold. An additional result is an improved CCl.sub.4 decomposition rate of 0.011[+ or -]0.002year.sup.-1 at UNADW temperatures. Our TTDs can be used to estimate the NADW-related transfer of dissolved constituents. We present such estimates for.sup.3He generated by tritium decay from the pre-nuclear period onward and for anthropogenic dissolved inorganic carbon (DIC) as examples. The latter estimate yields a NADW-related transport of anthropogenic DIC southward across the equator of about 50Mt in 1994. A critical aspect of the TTD methodology is that the older part of the age spectra is essentially unconstrained by observations. The TTDs can furthermore be used as a diagnostic tool to check certain aspects of NADW transfer in numerical ocean circulation models. Author Affiliation: Institut fur Umweltphysik (IUP), Abt. Ozeanographie, Universitat Bremen, D-28359 Bremen, Germany Article History: Received 17 October 2007; Revised 14 May 2008; Accepted 27 May 2008

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1523-1739.2008.01029.x Keywords: agroecosystem; biodiversity; coffee production systems; meta-analysis; shade-grown coffee; site characteristic; sun-grown coffee Abstract: Abstract: Studies have documented biodiversity losses due to intensification of coffee management (reduction in canopy richness and complexity). Nevertheless, questions remain regarding relative sensitivity of different taxa, habitat specialists, and functional groups, and whether implications for biodiversity conservation vary across regions. We quantitatively reviewed data from ant, bird, and tree biodiversity studies in coffee agroecosystems to address the following questions: Does species richness decline with intensification or with individual vegetation characteristics? Are there significant losses of species richness in coffee-management systems compared with forests? Is species loss greater for forest species or for particular functional groups? and Are ants or birds more strongly affected by intensification? Across studies, ant and bird richness declined with management intensification and with changes in vegetation. Species richness of all ants and birds and of forest ant and bird species was lower in most coffee agroecosystems than in forests, but rustic coffee (grown under native forest canopies) had equal or greater ant and bird richness than nearby forests. Sun coffee (grown without canopy trees) sustained the highest species losses, and species loss of forest ant, bird, and tree species increased with management intensity. Losses of ant and bird species were similar, although losses of forest ants were more drastic in rustic coffee. Richness of migratory birds and of birds that forage across vegetation strata was less affected by intensification than richness of resident, canopy, and understory bird species. Rustic farms protected more species than other coffee systems, and loss of species depended greatly on habitat specialization and functional traits. We recommend that forest be protected, rustic coffee be promoted, and intensive coffee farms be restored by augmenting native tree density and richness and allowing growth of epiphytes. We also recommend that future research focus on potential trade-offs between biodiversity conservation and farmer livelihoods stemming from coffee production. Abstract (Spanish): Perdida de Biodiversidad en Paisajes Cafetaleros en Latinoamerica: Revision de la Evidencia en Hormigas, Aves y Arboles Resumen: Diversos estudios han documentado las perdidas de biodiversidad debido a la intensificacion del manejo de cafe (disminucion de la riqueza y complejidad del dosel). Sin embargo, persisten preguntas sobre la sensibilidad relativa de diferentes taxa, especialistas de habitat y grupos funcionales, y si las implicaciones para la conservacion de la biodiversidad varian entre regiones. Revisamos cuantitativamente los datos de estudios de biodiversidad de hormigas, aves y arboles en agroecosistemas de cafe para abordar las siguientes preguntas: La riqueza de especies declina con la intensificacion o con las caracteristicas individuales de la vegetacion? Hay perdidas significativas de riqueza de especies en los sistemas cafetaleros en comparacion con los bosques? Es mayor la perdida en especies de bosque o en grupos funcionales particulares? y Las aves o las hormigas son mas afectadas por la intensificacion? En los estudios revisados, la riqueza de hormigas y aves declino con la intensificacion del manejo y con los cambios de vegetacion. La riqueza de especies de todas las hormigas y aves y la de especies de hormigas y aves de bosque fue menor en la mayoria de los agroecosistemas cafetaleros que en los bosques, pero el cafe rustico (cultivado bajo dosel de bosque nativo) sustento la mayor perdida de especies, y la perdida de especies de hormigas, aves y arboles de bosque aumento con la intensificacion del manejo. Las perdidas de especies de hormigas y aves fueron similares, aunque las perdidas de hormigas de bosque fueron mas drasticas en el cafe rustico. La riqueza de especies de aves migratorias y de aves que forrajean en varios estratos de vegetacion fueron menos afectadas por la intensificacion que las especies residentes de dosel y de sotobosque. Las fincas rusticas protegieron mas especies que otros sistemas cafetaleros, y la perdida de especies dependio mayormente de la especializacion de habitat y de los atributos funcionales. Recomendamos que el bosque sea protegido, se promueva el cafe rustico y se restauren las fincas intensivas mediante el incremento de la densidad y riqueza de arboles nativos y permitiendo el crecimiento de epifitas. Tambien recomendamos que las futuras investigaciones enfoquen las compensaciones potenciales entre la conservacion de la biodiversidad y la forma de vida de los campesinos que producen cafe. Author Affiliation: (*)Smithsonian Migratory Bird Center, Washington, D.C. 20013, U.S.A. ([dagger])USDA Forest Service, International Institute of Tropical Forestry, San Juan 00773, Puerto Rico ([double dagger])Departamento de Biologia, Universidad del Valle, Cali 25360, Colombia (s.)Center for Tropical Research, University of California, Los Angeles, CA 90095, U.S.A. (**)Department of Biology, Lake Forest College, Lake Forest, IL 60045, U.S.A. ([dagger][dagger])School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI 48109, U.S.A. ([double dagger][double dagger])Instituto Nacional de Investigaciones Forestales, Agricolas, and Pecuarias Pacifico SUR, Ocozocoautla, Chiapas 29140, Mexico (s.s.)El Colegio de la Frontera Sur, San Cristobal de las Casas, Chiapas 29200, Mexico (***)Instituto de Ecologia, Xalapa, Veracruz 91070, Mexico ([dagger][dagger][dagger])Fundacion Cocibolca, A.P. C-212 Managua, Nicaragua Article History: Paper submitted August 6, 2007; revised manuscript accepted April 3, 2008. Article note: ([double dagger][double dagger][double dagger]) Current address: Department of Environmental Sciences, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606, U.S.A., email stacy.philpott@utoledo.edu

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.earscirev.2006.03.005 Byline: D. Soudry (a), C.R. Glenn (b), Y. Nathan (a), I. Segal (a), D. VonderHaar (b) Keywords: phosphogenesis; south Tethys margins; Cretaceous-Eocene; I[micro].sub.Nd(T); [delta].sup.44/42Ca; P accumulation rates; paleoceanography; TCC; deep water formation Abstract: The evolution of Tethyan phosphogenesis during the Cretaceous-Eocene is examined to try to explain fluctuations of phosphogenesis through time, and whether or not they reflect long-term changes in ocean circulation or in continental weathering. Twenty-seven time-stratigraphic phosphate levels in various Tethyan sites, covering a time span of about 90 Myr from the Hauterivian to the Eocene, were analyzed for.sup.44Ca/.sup.42Ca and.sup.143Nd/.sup.144Nd in their carbonate fluorapatite (CFA) fraction. P and Ca accumulation rates and bulk sedimentation rates were quantified throughout the Cretaceous-Eocene Negev sequence to examine how changes in.sup.44Ca/.sup.42Ca and.sup.143Nd/.sup.144Nd are reflected in the intensity of phosphogenesis. A clear-cut change occurs in I[micro].sub.Nd(T) and [delta].sup.44Ca and in the rates of P and Ca accumulation and bulk sedimentation through the time analyzed. I[micro].sub.Nd(T) is much lower in the Hauterivian-Lower Cenomanian (-12.8 to -10.9) than in the Upper Cenomanian-Eocene (-7.8 to -5.9). Much lower [delta].sup.44Ca values occur in the Hauterivian-Turonian (-0.22 to +0.02) than in the Coniacian-Eocene (+0.23 to +0.40). P accumulation rates in the Negev steeply increase from The culmination of P accumulation rates in the Negev during the Campanian, occurring with a high in I[micro].sub.Nd(T) and [delta].sup.44Ca and a low in sedimentation rates, indicates that paleoceanographic and paleogeographical factors mostly governed phosphorite accumulation in this area. The abrupt I[micro].sub.Nd(T) rise after the Cenomanian is attributed to increased incursion of Pacific (radiogenic) water masses into the Tethys, driven by the Late Cretaceous global sea-level rise, the connection between North and South Atlantic, the global post-Santonian cooling, and the progressive widening of the Caribbean threshold, all acting in combination to significantly intensify the Tethyan circumglobal current (TCC). It also reflects a weakening of the continental Nd signal due to a reduction of exposed landmasses caused by increased flooding of continental shelves. High [delta].sup.44Ca values at those times also point to a decrease in weathering Ca.sup.+2 fluxes and expansion of carbonate sedimentation in shelves, both enriching seawater with isotopically heavy Ca.sup.+2. Deep ocean circulation intensified by the post-Santonian cooling of high latitudes increased P inventory in the Tethys basin, whereas the strengthened TCC and the folded shelf likely resulted in coastal and topographically-induced upwelling, supplying P-rich intermediate waters to southeastern Tethys shelves. Only in the Paleocene-Eocene, following major changes in global circulation produced by narrowing of Tethys and widening of the Atlantic, did phosphogenesis shifts its locus of high intensity to the western (Atlantic) Tethys and West African Atlantic coasts. This change in paleocirculation is expressed by distinctly differing I[micro].sub.Nd(T) in the Middle East and the North and West African phosphorites, suggesting different oceanic P sources and current systems for these two major groups of phosphorites. Our Nd isotope results further suggest a weaker TCC during the Mid-Cretaceous, becoming more intense in Late Cretaceous times. They also point to the North Pacific Ocean as major source of deep water formation for the intermediate-deep waters in the Tethys Basin during the Late Cretaceous. Author Affiliation: (a) Geological Survey Israel, 30 Malkhe Israel St., Jerusalem 95501, Israel (b) Department of Geology and Geophysics, University of Hawaii, Honolulu, Hawaii 96822, USA Article History: Received 19 September 2005; Accepted 27 March 2006

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2006.03.007 Byline: Bettina A. Fach (a), Eileen E. Hofmann (b), Eugene J. Murphy (c) Abstract: A time-dependent, size-structured, physiologically based krill growth model was used in conjunction with a circulation model to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia are sustained by import of individuals from upstream regions. Surface phytoplankton concentrations along the simulated drifter trajectories were extracted from historical Coastal Zone Color Scanner (CZCS) measurements and sea ice biota concentrations were calculated from sea ice concentration and extent extracted along drifter trajectories from Special Sensor Microwave/Imager measurements. As additional food sources, a time series of heterotrophic food was constructed from historical data, and time series of detritus concentrations were calculated using phytoplankton concentrations extracted from CZCS measurements together with measured particulate organic carbon to chlorophyll a ratios. These food resources along specified drifter trajectories were then input to the krill growth model to determine the size and viability of krill during transport from the source region to South Georgia. The krill growth model simulations showed that no single food source can support continuous growth of krill during the 58-306 days needed for transport to South Georgia. However, under the current assumptions results indicate that combinations of food sources during the transport time enhanced krill survival, with heterotrophic food and detritus being particularly important during periods of low phytoplankton concentrations. The growth model simulations also showed that larval and juvenile krill originating along the western Antarctic Peninsula can grow to 1+ (14-36mm) and 2+ (26-45mm) age and size classes observed at South Georgia during the time needed for transport to this region. Krill originating in the Weddell Sea need 20 months for transport, which allows retention in a potentially high food environment, provided by sea ice, for almost 1 year. Krill then complete transport to South Georgia in the following year and larval and juvenile krill grow to 2+ (26-45mm) and 3+ (35-60mm) age and size classes during transport. The results of this study show that the successful transport of krill to South Georgia depends on a multitude of factors, such as the location of the spawning area and timing of spawning, food concentrations during transport, predation, and variations in the location of the Southern Antarctic Circumpolar Current Front (SACCF) and in sea ice extent. Author Affiliation: (a) Woods Hole Oceanographic Institution, Mail Stop 25, 266 Woods Hole Road, Woods Hole, MA 02543, USA (b) Center for Coastal Physical Oceanography, Crittenton Hall, Old Dominion University, Norfolk, VA 23529, USA (c) British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK Article History: Received 1 October 2004; Revised 23 September 2005; Accepted 7 March 2006

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2006.03.006 Byline: Bettina A. Fach (a), John M. Klinck (b) Abstract: The Harvard Ocean Prediction System (HOPS) is configured to simulate the circulation of the Scotia Sea and environs. This is part of a study designed to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia in the eastern Scotia Sea are sustained by import of individuals from upstream regions, such as the western Antarctic Peninsula. Comparison of the simulated circulation fields obtained from HOPS with observations showed good agreement. The surface circulation, particularly through the Drake Passage and across the Scotia Sea, matches observations, with its northeastward flow characterized by three high-speed fronts. Also, the Weddell Sea and the Brazil Current, and their associated transports match observations. In addition, mesoscale variability, an important component of the flow in this region, is found in the simulated circulation and the model is overall well suited to model krill transport. Drifter simulations conducted with HOPS showed that krill spawned in areas coinciding with known krill spawning sites along the west Antarctic Peninsula continental shelf can be entrained into the Southern Antarctic Circumpolar Current Front (SACCF). They are transported across the Scotia Sea to South Georgia in 10 months or less. Drifters originating on the continental shelf of the Weddell Sea can reach South Georgia as well; however, transport from this region averages about 20 months. Additional simulations show that such transport is sensitive to changes in wind stress and the location of the SACCF. The results of this study show that krill populations along the Antarctic Peninsula and the Weddell Sea are possible source populations that can provide krill to the South Georgia population. However, successful transport of krill to South Georgia is shown to depend on a multitude of factors, such as the location of the spawning area and timing of spawning, and variations in the location of the SACCF. Therefore, this study provides insight into which environmental factors control the successful transport of krill across the Scotia Sea and with it a better understanding of krill distribution in the region. Author Affiliation: (a) Woods Hole Oceanographic Institution, Mail Stop 25, 266 Woods Hole Rd, Woods Hole, MA 02543, USA (b) Center for Coastal Physical Oceanography, Crittenton Hall, Old Dominion University, Norfolk, VA 23529, USA Article History: Received 1 October 2004; Revised 23 September 2005; Accepted 7 March 2006

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.09.009 Byline: Yuan-Hui Li (a), Laurie Menviel (a), Tsung-Hung Peng (b) Keywords: Remineralization ratios; Nitrification; Partial nitrification; Denitrification; Anammox; Nitrate deficit; Indian Ocean Abstract: The three-end-member mixing model of Li and Peng [Latitudinal change of remineralization ratios in the oceans and its implication for nutrient cycles. Global Biogeochemical Cycles 16, 1130-1145] was applied to the World Ocean Circulation Experiment (WOCE) data from Indian Ocean to obtain additional estimates on the remineralization ratios (Pas.[sup.1]Nas.[sup.1]C.sub.orgas.[sup.1]aO.sub.2) of organic matter in the oxygenated regions. The results show systematic changes of the remineralization ratios with latitude and depth in the Indian Ocean. The average remineralization ratios for Indian warm water masses (potential temperature I[cedilla][approximately equal to]10.sup.aC) are Pas.[sup.1]Nas.[sup.1]C.sub.orgas.[sup.1]aO.sub.2=1as.[sup.1](15.6[+ or -]0.7)as.[sup.1](110[+ or -]9)as.[sup.1](159[+ or -]8). These are comparable to the traditional Redfield ratios (Pas.[sup.1]Nas.[sup.1]C.sub.orgas.[sup.1]aO.sub.2=1as.[sup.1]16as.[sup.1]106as.[sup.1]138), and are in good agreement with Anderson's [On the hydrogen and oxygen content of marine phytoplankton. Deep-Sea Research I 42, 1675-1680.] values of Pas.[sup.1]Nas.[sup.1]C.sub.orgas.[sup.1]aO.sub.2=1as.[sup.1]16as.[sup.1]106as.[sup.1]150 within the given uncertainties. Separation of nitrate deficits resulting from aerobic partial nitrification (dN) and anaerobic denitrification (dNa[sup.3]) processes using empirical equations is shown to be useful and consistent with other observations. The dN maximum coincides with the phosphate and nitrate maximums, lies within the oxycline below the oxygen minimum zone, and is in contact with the continental slope sediments. The dNa[sup.3] maximum lies within the oxygen minimum zone with O.sub.2 Author Affiliation: (a) Department of Oceanography, University of Hawaii, Honolulu, Hawaii 96822 (b) NOAA/AOML, Ocean Chemistry Division, Miami, Florida 33149, USA Article History: Received 3 March 2005; Revised 12 September 2005; Accepted 19 September 2005

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.08.003 Byline: Monika Rhein, Kerstin Kirchner, Christian Mertens, Reiner Steinfeldt, Maren Walter, Ulrich Fleischmann-Wischnath Keywords: Ocean circulation; Water mass spreading; Western tropical Atlantic; Western Atlantic; Caribbean Abstract: CTD, vessel-mounted ADCP and LADCP measurements in the Caribbean passages south of Guadeloupe (three repeats) and along 16[degrees]N (five repeats) were carried out between December 2000 and July 2004. The CTD data were used to calculate the contribution of South Atlantic water (SAW) in the upper 1200m between the isopycnals I.sub.I[cedilla]=24.5 and 27.6. Northern and southern source water masses are defined and an isopycnal mixing approach is applied. The SAW fractions are then combined with the ADCP flow field to calculate the transport of SAW into the Caribbean and across 16[degrees]N. The SAW inflow into the Caribbean through the passages south of Guadeloupe ranges from 7.6 to 11.6Sv, which is 50-75% of the total inflow. The mean (9.1[+ or -]2.2Sv) is in the range of previous estimates. Ambiguities in the northern and southern source water masses of the salinity maximum water permitted us only to calculate the contribution of SAW from the eastern source in this water mass. We estimated the additional SAW transport by the western source to be of the order of 1.9[+ or -]0.7Sv. The calculation of the SAW transport across 16[degrees]N was hampered by the presence of several anticyclonic rings from the North Brazil Current (NBC) retroflection region, some of the rings were subsurface intensified. Provided that the rings observed at 16[degrees]N are typical rings and that all rings which are annually produced in the NBC retroflection area (6.5-8.5 per year) reach 16[degrees]N, the SAW ring transport across 16[degrees]N is calculated to 5.3[+ or -]0.7Sv. From the 5 repeats at 16[degrees]N, only two showed a net northward flow, suggesting that the mean northward SAW transport is dominated by ring advection. The joint SAW transports of the Caribbean inflow (9.1Sv) and the flow across 16[degrees]N (5.3Sv) sum up to 14.4Sv. The transport increases to 16.3Sv if the additional SAW transport from the western source of SMW (1.9[+ or -]0.7Sv) is included. These transport estimates and the following implications depend strongly on the assumption that the surface water in the Caribbean inflow is of South Atlantic origin. The transport estimates are, however, in the range of the inverse model calculations for the net cross-hemispheric flow. About 30-40% of this transport is intermediate water from the South Atlantic, presumably supporting studies which found the contributions of intermediate and upper warm water to be of a comparable magnitude. For the upper warm water (I.sub.I[cedilla] Author Affiliation: Institut fur Umweltphysik, FB1, Abt. Ozeanographie, Universitat Bremen, Postfach 330 440, D-28334 Bremen, Germany Article History: Received 10 November 2004; Revised 2 May 2005; Accepted 2 August 2005

Nineteen uranium-lead zircon ages of lower crustal gabbros from Atlantis Bank, Southwest Indian Ridge, constrain the growth and construction of oceanic crust at this slow-spreading midocean ridge. Approximately 75% of the gabbros accreted within error of the predicted seafloor magnetic age, whereas ~25% are significantly older. These anomalously old samples suggest either spatially varying stochastic intrusion at the ridge axis or, more likely, crystallization of older gabbros at depths of ~5 to 18 kilometers below the base of crust in the cold, axial lithosphere, which were uplifted and intruded by shallow-level magmas during the creation of Atlantis Bank., Slow- and ultraslow-spreading ridges with spreading rates of The SWIR separates the Antarctic and African plates (Fig. 1, inset). Atlantis Bank lie ~100 km south of the SWIR rift valley, [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.01.010 Byline: A. Elmoussaoui, M. Arhan, A.M. Treguier Abstract: The seasonal regime associated with the eastern part of the cyclonic tropical gyre in the North Atlantic is studied using a high-resolution model. The model reproduces a vertical water mass transition (between South and North Atlantic Central Water) previously observed near I.sub.0=26.8, which approximately coincides with the base of the North Equatorial Undercurrent (NEUC). The same density may be taken as the lower limit of the large-scale cyclonic flow. The gyre southern flank is formed of the North Equatorial Countercurrent (NECC) in the near-surface layer, and of the NEUC and deep NECC (when this current is developed) in the Central Water. Its poleward limb is made up from the Ekman drift of the trade winds, a northeastward extension of the NEUC/deep NECC, and reinforced by an extension of the Guinea undercurrent along the African continental slope. Model experiments with two different wind forcings were carried out to estimate the transports across 12[degrees]N, an approximate gyre central latitude. The time-averaged transport for densities lower than I.sub.1=32.3 and to the east of 35[degrees]W is around 4Sv northward, about one-third of the basin-wide net value which measures the Meridional Overturning Circulation. The near-surface layer accounts for about 3Sv, and the Central Water for more than 1Sv, in keeping with the presence of South Atlantic Central Water in the tropical eastern basin. The eastern basin near-surface flow is lowest in summer, when the trade winds nearly vanish at this latitude. In this season the NECC, though having entered its phase of intensification, leaves the region of positive wind stress curl, and temporarily does not act as the tropical gyre southern limb. At the subsurface, most of the NEUC folds up westward at [approximately equal to]10[degrees]N in winter, thus forming an inner circulation of the basin-wide gyre, previously reported from observations. The cyclonic flow associated with the Guinea Dome is another inner circulation, which the model found to be permanent below the surface down to 400-500m, but masked in the Ekman layer, except in summer. Author Affiliation: Laboratoire de Physique des Oceans, CNRS/IFREMER/UBO, Brest, France Article History: Received 15 March 2004; Revised 20 December 2004; Accepted 13 January 2005

Rhodoliths (free-living coralline red algae) can thrive under a wide range of temperatures, reduced light, and increased nutrient levels, and often form a distinct so-called rhodalgal lithofacies that is an important component of Cenozoic shallow-water carbonates. Global distributions illustrate that from the late-early to early-late Miocene (Burdigalian-early Tortonian), rhodalgal facies reached peak abundances and commonly replaced coral-reef environments, accompanied by a decline in other carbonate-producing phototrophs. We argue that the dominance of red algae over coral reefs was triggered in the Burdigalian by enhanced trophic resources associated with a global increase in productivity, as evidenced by a long-term shift toward higher carbon isotope values. Rhodalgal lithofacies expanded further in the middle Miocene when strengthened thermal gradients associated with the establishment of the East Antarctic Ice Sheet led to enhanced upwelling while climate change generated increased weathering rates, introducing land-derived nutrients into the oceans. Globally cooler temperatures following a climatic optimum in the early-middle Miocene contributed to sustain the dominance of red algae and prevented the recovery of coral reefs. The global shift in nearshore shallow-water carbonate producers to groups tolerant of higher levels of trophic resources provides further evidence for increased nutrient levels during that time interval and shows the sensitivity of shallow-water carbonate facies as indicators of past oceanographic conditions. Keywords: rhodolith, coralline red algae, Miocene, coral, nutrients.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2004.11.005 Byline: Alvaro Peliz (a), Jesus Dubert (a), A. Miguel P. Santos (b), Paulo B. Oliveira (b), Bernard Le Cann (c) Abstract: An overview of the winter circulation and upper ocean structure offshore of Western Iberia is presented. The focus is on winter slope currents, fronts and mesoscale eddies, as well as on the connection of these local features to the large-scale circulation of the region. Satellite sea surface temperature; sea surface elevation data from altimetry; cross-shore and meridional hydrological surveys and current meter observations, mainly obtained during winter periods, are used to illustrate features of the winter upper ocean structure and of the generation and evolution of the Iberia Poleward Current. A schematic/hypothetical model of winter upper ocean circulation on the scale of the Western Iberian Basin is given which attempts to systematize and resolve certain ambiguities in the existing circulation schemes and in the concepts and terminology used to describe observed features in the area. Author Affiliation: (a) Departamento de Fisica (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, 3810-194 Aveiro, Portugal (b) Instituto Nacional de Investigacao Agraria e das Pescas-IPIMAR, Av.Brasilia s/n, 1449-006 Lisboa, Portugal (c) Laboratoire de Physique des Oceans, CNRS/IFREMER/UBO, UFR Sciences 6, Av. Le Gorgeu, C.S. 93837, 29238 Brest Cedex 3, France Article History: Received 10 November 2003; Revised 13 August 2004; Accepted 1 November 2004

The physical oceanography and chlorophyll distribution in Willapa Bay and the adjacent coastal ocean were measured during an upwelling-downwelling wind cycle in late May 1999. Coastal conditions were determined shipboard during two sets of five cross-shelf transects conducted 4 d apart, and instrument moorings simultaneously recorded wind velocity in the nearshore zone and biophysical water properties within Willapa Bay. The results demonstrate that estuarine physical oceanography and chlorophyll concentrations were determined by processes occurring in the nearshore ocean, and these in turn were forced by variation in wind stress. At the start of the study period, southerly winds produced downwelling conditions that forced the Columbia River plume against the coast, and low salinity water was advected into Willapa Bay. This water was relatively low in chlorophyll (

Abnormally colored yellow and red Calanus spp. occurred in the Oslofjord (southeast Norway)in late summer. These specimens were infected with an extensive parasitic growth consisting of large branched hyphae-like tubes filled with spores. This parasite has previously been referred to as Ichthyosporidium sp. (now Ichthyophonus, Ichthyosporea), and suspected to be a stage in the life cycle of the fish pathogen Ichthyophonus hoferi. This assumption was not supported by our examination. Infected copepods were virtually confined to the upper meter, while distribution of the uninfected specimens was much deeper. We argue that the change in color and distribution is induced by the parasite, facilitating near-surface, visual predation, dispersal of spores, and, hence, increasing transmission to new hosts.

Sediment resuspension has a major ecological role in many coastal habitats, lakes, and marine environments. Waves and currents are generally thought to be the major control on sediment resuspension. In this study, the temporal and spatial distributions of suspended sand concentrations (SSAC) were measured at five coral reefs in the northern Gulf of Aqaba, Red Sea, by directly filtering seawater through 100-[micro]m mesh nets. Levels of near-bottom SSAC were twice as high during the day (4.8-9.7 mg [m.sup.-3]) than at night (2.3-5.2 mg [m.sup.-3]). Vertical profiles showed a sharp increase of SSAC (2-6-fold) toward the bottom during the daytime but not at night. The contributions of wind, waves, and currents to variations in SSAC were nonsignificant except during rare southern storms. Temporal and spatial changes in the level of SSAC during the day corresponded with the abundance of benthivorous fish and their activity pattern. Resuspension activities by fish numbered > 1.5 resuspension events [m.sup.-2] [h.sup.-1] and were confined to daytime. An in situ experiment in which fish were excluded from a large section (250 [m.sup.2]) of the reef resulted in elimination of the day-night differences and a significant decrease in daytime SSAC over the treated reef section in comparison to the open, control sites. This study is the first report of a daily pattern of suspended sediment at coral reefs with fish activity as its causative agent.

The bounded derivative theory (BDT) for hyperbolic systems with multiple timescales was originally applied to the initialization problem for large-scale shallow-water flows in the midlatitudes and near the equator. Concepts from the theory also have been used to prove the existence of a simple reduced system that accurately describes the dominant component of a midlatitude mesoscale storm forced by cooling and heating. Recently, it has been shown how the latter results can be extended to tropospheric flows near the equator. In all of these cases, only a single type of flow was assumed to exist in the domain of interest in order to better examine the characteristics of that flow. Here it is shown how BDT concepts can be used to understand the dependence of developing mesoscale features on a balanced large-scale background flow. That understanding is then used to develop multiscale initialization constraints for the three-dimensional diabatic equations in any domain on the globe.

A delay/Doppler-mapping receiver system, developed specifically for global positioning system (GPS)-reflection remote sensing, is described, and example delay/Doppler waveforms are presented. The high-quality data obtained with this system provide a more accurate and detailed examination of ground-based and aircraft GPS-reflection phenomenology than has been available to date. As an example, systematic effects in the reflected signal delay waveform, due to nonideal behavior of the C/A-code auto-correlation function, are presented for the first time. Both a single-channel open-loop recording system and a recently developed 16-channel recorder are presented. The open-loop data from either recorder are postprocessed with a software GPS receiver that performs the following functions: signal detection; phase and delay tracking; delay, Doppler, and delay/Doppler waveform mapping; dual-frequency (L1 and L2) processing; C/A-code and Y-code waveform extraction; coherent integrations as short as 125 [micro]s; navigation message decoding; and precise observable time tagging. The software can perform these functions on all detectable satellite signals without dead time, and custom signal-processing features can easily be included into the system. Data collected with this system can, in principle, be processed to extract 1) over an ocean: mean sea height, wind speed and direction, and significant wave height; 2) over land: soil moisture, biomass, and bistatic imaging; and 3) over ice: ice age, thickness, and surface ice density.

Research estimates the rate of global sea-level rise for the past century as approximately 2 mm rather than 1 mm per year. Data indicate that the oceans contribute 0.6 mm per year of thermal expansion to the global sea-level rise with additional contribution from melting of small ice sheets and glaciers.

The authors have used dissolved silicate, oxygen, and a ternary mixing model to distinguish between diagenetic release and remineralization as sources for Antarctic bottom water's silicate concentrations. These data combined with earlier research produce an estimate for deep water silicates and contribute to future estimates of global silicate balance.

The authors describe their discovery of 4 bottom water flows from the Antarctic's Weddell Sea into the Southwest Indian Ocean. These routes include flows through a gap in the Southwest Indian Ridge, two through the Del Cano Rise, and one passing into the Crozet Basin by the Crozet-Kerguelen Gap.

Instrumentation and retrieval algorithms are described which use the forward scattered range-coded signals from the global positioning system (GPS) radio navigation system for the measurement of sea surface roughness. This roughness has long been known to be dependent upon the surface wind speed. Experiments were conducted from aircraft along the TOPEX ground track and over experimental surface truth buoys. These flights used a receiver capable of recording the cross-correlation power in the reflected signal. The shape of this power distribution was then compared against analytical models, which employ a geometric optics approach. Two techniques for matching these functions were studied. The first recognized the most significant information content in the reflected signal is contained in the trailing edge slope of the waveform. The second attempted to match the complete shape of the waveform by approximating it as a series expansion and obtaining the nonlinear least squares estimate. Discussion is also presented on anomalies in the receiver operation and their identification and correction. Index Terms--Bistatic radar, global positioning system (GPS), oceanography, retrievals, scatterometry.

The Sea-viewing Wide Field-of View Sensor (SeaWiFS) Mission has initiated a new era of ocean color remote sensing and has established performance benchmarks that will be emulated by subsequent missions. An integral element of the SeaWiFS mission is the data component, performed by the Goddard Earth Sciences Distributed Active Archive Center (GES DAAC), NASA Goddard Space Flight Center, Greenbelt, MD. Since the beginning of data distribution in September 1997, the GES DAAC has managed the data archive and improved data distribution capability. SeaWiFS data products are archived in a primary, secondary, and tertiary archive structure, ensuring data preservation. Data distribution utilizes a World Wide Web (WWW)-based ordering interface, allowing distribution either electronically or on magnetic tape media. Automatic data subscriptions, supplying user-tailored data product selections, have yielded a high archive-to-distribution ratio. System improvements have increased efficiency and redundancy. The user interface has added features designed to facilitate data access and data usage, enhanced by WWW information resources and comprehensive online dataset documentation. As SeaWiFS enters the latter half of its five-year mission, a system performance assessment provides useful information for other Earth remote sensing missions and allows consideration of future usage objectives for the SeaWiFS data archive. Index Terms--Data systems, ocean color, remote sensing.

Upwelling predicted by a reduced-gravity model is compared with remotely sensed primary productivity data through the tropical Atlantic and Pacific. The model upper layer thickness, an indicator of vertical motion, is correlated with primary productivity. We suggest that the Atlantic basin is more efficient than the Pacific in its production for the same degree of upwelling. This is a characteristic of the tropical Pacific ecological provinces being featured by low salinity in the western tropics and high nutrient, but low chlorophyll in the eastern equatorial region. A comprehensive relationship between model upper layer thickness and primary productivity is established through the tropical basins, with emphasis on the equatorial strip. Our work has implications for the application of reduced-gravity models to estimate productivity in palaeocean studies.

A knowledge of the balance between plankton gross primary production (GPP) and community respiration (CR) in the open ocean is vital to the accurate determination of the global carbon cycle, yet the paucity of open ocean measurements severely limits our understanding. This study measured GPP, net community production, dark CR, and size-fractionated primary production in the upper 200 m of a 12,100 km latitudinal (32 [degrees] S-48 [degrees] N) transect in the Eastern Atlantic Ocean during May and June 1998. This comprehensive data set, which spans five contrasting plankton regimes, including two open ocean oligotrophic provinces, is used to derive a GPP: CR relationship, which suggests that net heterotrophy (GPP < CR) prevails in the eastern Atlantic when primary production falls below ~100 mmo1 [O.sub.2] [m.sup.-2] [d.sup.-1]. The predictive capability of this relationship is compared with that of the only other published relationship based on similar methodologies and is found to give a more representative description of the autotrophic (GPP > CR) to heterotrophic seasonal cycle in the Bay of Biscay. This improved predictive power is attributed to the increased representativeness of the current data set. Specifically, the interpretation suggests that the influence of community structure on net ecosystem metabolism implies that prediction of GPP: CR balances in pelagic ecosystems can be best achieved by use of a data set that covers a wide range of community structure and not only a wide range in the magnitude of primary production.

Bacteria (and possibly archaea) accelerate silica dissolution in the sea by colonizing and enzymatically degrading the organic matrix of diatom frustules. We tested whether colonizer species composition and ectohydrolase profiles critically control silicon regeneration by allowing diatom (Thalassiosira weissflogii and Chaetoceros simplex) detritus to be colonized by natural bacterial assemblages and 12 phylogenetically characterized marine isolates. We characterized the colonizers' ectohydrolase profiles and rates of silicon regeneration. The colonizers' cell-specific protease activity was consistently the dominant ectohydrolase, and it strongly correlated with silica dissolution rates. Cell-specific glucosidase, lipase, and chitinase activities showed no correlation with silicon regeneration. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes was used to monitor colonization of detritus by natural microbial assemblages and to identify colonizing phylotypes. Representatives from gammaproteobacteria and sphingobacteria-flavobacteria classes dominated colonizer populations by comprising 65% and 25% of detected phylotypes, respectively. Archaea were not detected among colonizer populations. All bacterial isolates accelerated silica dissolution, but individual rates varied by >300%. Significant variability was observed within the Altero-monadaceae, which indicates different abilities to process diatom organic matter. Isolates that displayed enhanced colonization and protease activities were the most effective at regenerating silicon. The most effective isolate belonged to the sphingobacteria-flavobacteria, a group specialized in colonizing marine particles. Other effective isolates grouped with Pseudoalteromonas, Alteromonas, and Vibrio genera. One isolate caused intense aggregation of diatom detritus, significantly reducing silicon regeneration. Our results indicate that bacterial species identity strongly controlled silicon regeneration by influencing the colonization potential and ectohydrolytic profiles of bacteria as well as aggregate formation. Mechanistic models of oceanic silica cycling should incorporate species composition and ectohydrolase profiles of bacteria involved in silicon regeneration.

Sinking aggregates are the major component of the vertical particulate flux in most regions of the ocean. Controlling factors for aggregate remineralization rates and solute exchange with the surrounding water, however, are poorly quantified because of few empirical data. To study the role of flow and diffusion on aggregate remineralization rates, oxygen distributions were mapped within and around aggregates by use of microelectrodes in a flow field similar to that experienced by sinking aggregates. The oxygen distribution was asymmetrical with a wake of undersaturated water at the rear (downstream) of the aggregates. Oxygen concentrations within the aggregates were >80% of air saturation. The diffusive fluxes of oxygen at the aggregate-water interface were similar along the equator and at the downstream pole for a wide range of different aggregate sources (field-sampled diatom aggregates, lab-made diatom aggregates, aggregates formed from freeze-thawed diatoms, and zooplankton detritus aggregates) measured at various temperatures. Remineralization rates were reaction limited and, hence, determined by substrate quality and quantity rather than by transport-limited oxygen supply during sedimentation at ambient oxygen concentrations above ~25 [micro]M.

An inversion algorithm for inferring the surface velocity field of buoyant plume frontal features from observed radar imagery has been developed [7]-[9]. The inversion technique is based upon an assumption, suggested by Alpers and Hennings' (AH) relaxation model [1], that near strongly convergent fronts, the radar cross-section (RCS) should be proportional to the component of the local current gradient that is directed along the radar-look direction. However, at X-band, the technique only works when wave-breaking (WB) effects, which are not included in AH model, are incorporated using a recently developed model [2], [3]. This WB model successfully reproduces the magnitude of the signature in images of the plume front at higher frequencies (X-band), where it is known [3]-[5] that the AH model is deficient. WB effects play a dominant role in the backscatter associated with frontal regions with strong surface convergence fields. These results suggest that the enhancements of radar backscatter in the vicinity of strongly-convergent fronts are proportional to the local current-convergence but that the underlying scattering process involves WB in a manner that cannot be understood from the AH model. Results are presented for the estimated velocity field derived from radar imagery of the Chesapeake Bay plume front [6]. Preliminary considerations [7] of the convergence and uniqueness of the inversion technique are extended by means of a controlled numerical experiment involving the inversion of a prescribed input velocity field. Index Terms--Convergence, inversion, ocean fronts, velocity field, wave breaking.

The Water Inclination Topography and Technology Experiment (WITTEX) consists of three TOPEX-class radar altimeters on individual satellites in the same orbit plane. If built with delay-Doppler radar altimeter technology, the WITTEX satellites will be sufficiently small that all three can be launched simultaneously by one vehicle. Even though the WITTEX satellites will be in a common inertial orbit plane, Earth rotation separates their tracks at nadir. Cross-track separation will be proportional to intersatellite spacing. WITTEX will provide near-simultaneous and accurate measurement of sea surface heights along three parallel tracks, providing oceanographic data not previously available, including the two-dimensional (2-D) surface gradient. WITTEX offers a variety of beneficial solutions to the classic time/space sampling tradeoff that confronts oceanic radar altimetry. Index Terms--Geostrophic current, ocean topography, radar altimeter, satellite formation.

The phenomenon of ocean wave-shoaling, and the associated reduction of ocean wave phase speed with decreased water depth, provides useful information for inferring water depth D (bathymetry) in coastal environments. One strategy for relating D to phase speed C and wave-vector K of long wave length ocean waves involves using the one-dimensional (1-D) linear (gravity wave) dispersion relationship [C.sup.2] = g*tanh(KD)/K. In principle, this approach has limitations because the approach is based on a WKB approximation, so it cannot be applied when D varies appreciably over the wavelength of a shoaling wave. Also, the approach is restricted to waves that have small wave height. In the present paper, we use a set of marine radar image sequences and apply this linear approximation, using a three-dimensional (3-D) FFT analysis of 88 sets of image sequences spaced half an hour apart. We invert the dispersion relation to solve for D. Depths between 3.6 and 5.8 m were tested, for root mean square (RMS) wave heights offshore between 8 and 3 m. We show that for low to moderate wave heights, the approach does generally retrieve the correct depth in water depths of 5 m and greater for moderate wave RMS heights. However, an increase in the RMS wave height from 1 m to 3.5 m produced a much poorer depth estimate, proving the need for an application of a nonlinear wave model to the problem. The errors also increase with shallower depths as expected, as the error dependence on depth and wave height is determined. Index Terms--Coastal bathymetry, microwave radar, shoaling waves.

Results from a Monte Carlo simulation of backscattering from one-dimensional (1-D) time-evolving sea surface models are reported. A numerical electromagnetic method based on an accelerated forward-backward approach is used to calculate backscattered returns from impedance surface profiles at incidence angles of 0 [degrees] (normal), 40 [degrees], and 80 [degrees]. Surfaces are initialized as realizations of a Pierson-Moskowitz spectrum and then stepped in time through a numerical hydrodynamic method. Results from three distinct hydrodynamic methods are compared: a linear evolution, the 'improved linear representation' of Creamer et al. [7], and the 'Watson-West' approach of West et al. in [8]. Instabilities in the West model due to formation of steep wave features limit the study to L-band backscattering for wind speeds less than 2 m/s, so that the surfaces considered are only slightly rough on an electromagnetic scale. The small slope approximation for electromagnetic scattering is shown to provide reasonable predictions in this limit. Statistics of the resulting surface profiles and backscattered fields are compared for the three models and are found to be similar in most respects. Backscattered field Doppler spectra, however, show differences, with the West model apparently capturing more nonlinear interactions in the surface evolution. Index Terms--Doppler spectrum, rough surface scattering, sea scattering.

Results show that the oxygen consumption rate by the deep-waters of the Eastern Mediterranean is much higher, which may be due to high temperature conditions prevailing in deep waters. However, the circulation model shows only moderate differences from the previous data.

The oceanic upwelling areas of the Philippine archipelago exhibit unusual cold subsurface temperature rendering them not detectable by satellite imagery. The temperature field data at standard depths, extending up to 500 meter, reveal a change in heat content to be greater than 300 Watts per meter square in upwelling areas.

Research demonstrates that the depletion of the dissolved iodine and enrichment of the surface iodine are associated with nitrate uptake. Data indicate that iodine and nitrate are taken up in definite ratios to each other with almost all the dissolved iodine being exuded as surface iodine.

Tracer-derived 'age' and the transit-time probability density function analyses of oceanic fluid parcels' contact with the surface demonstrate that the former manifests towards the leading part of the latter and the ideal 'age' is more sensitive to the 'tail'.

Determination of vertical velocity for calculating heat and salt exchanges between the ocean surface and interior is presented. Computation of pseudo-synoptic data set gathered from a non-synoptic data set, along with a geostrophic relocation of the stations, corrects the synopticity errors in hydrographic data.

Results demonstrate significant ascending and descending particle fluxes from hydrothermal plumes at all depths and mooring sites off Endeavour Segment, Juan de Fuca Ridge. Data show that the ascending particle organic carbon comes from mid to deep-depth zooplankton and the descending type from the surface of the sea.

The distribution pattern of zooplankton biomass in the Canary Island waters reveal vertical profiles of two sizes, with higher biomass in the shallow layers by night and at a depth of 0-200m by day. The electron transfer system and fluorescence of the biomass are higher by day than in night.

Research demonstrates that the physical variability of the Pacific Ocean spans a wide range of time scales from interannual El Nino conditions to oscillations on a weekly periodicity. These currents affect biological events as revealed by variability in the phytoplankton chlorophyll, zooplankton biomass, rate of primary production, and mineral concentration.

The deep currents in the Northwest Pacific Basin reveal that the currents enter from south in a northward direction along the western boundary at a longitude of 148 degrees E and in the deep passage near a longitude of 170 degrees E, and from the north in the Kamchatka Current.

Research describes hydrography and quantifies transport and flow structure of the Atlantic inflow to the Nordic Seas in both time and space using SeaSoar-CTD and VM-ADCP shipboard equipment. The Norwegian Atlantic current is a two-branched system, eastern and western, with annual mean transport of 4.2Sv and 3.4Sv, respectively.

Temporal variation in terms of short-term and inter-annual in zooplankton community structure together with the Marion Island Oceanographic Survey on the long-term environmental changes and their ecological impact on the mesozooplankton community structure near the Prince Edward Islands are presented.