Changes in Atmospheric Constituents and in Radiative Forcing

Integrating conceptually similar models of the growth of marine and terrestrial primary producers yielded an estimated global net primary production (NPP) of 104.9 petagrams of carbon per year, with roughly equal contributions from land and oceans. Approaches based on satellite indices of absorbed solar radiation indicate marked heterogeneity in NPP for both land and oceans, reflecting the influence of physical and ecological processes. The spatial and temporal distributions of ocean NPP are consistent with primary limitation by light, nutrients, and temperature. On land, water limitation imposes additional constraints. On land and ocean, progressive changes in NPP can result in altered carbon storage, although contrasts in mechanisms of carbon storage and rates of organic matter turnover result in a range of relations between carbon storage and changes in NPP.

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Primary Production of the Biosphere: Integrating Terrestrial and Oceanic Components

A weekly 1° spatial resolution optimum interpolation (OI) sea surface temperature (SST) analysis has been produced at the National Oceanic and Atmospheric Administration (NOAA) using both in situ and satellite data from November 1981 to the present. The weekly product has been available since 1993 and is widely used for weather and climate monitoring and forecasting. Errors in the satellite bias correction and the sea ice to SST conversion algorithm are discussed, and then an improved version of the OI analysis is developed. The changes result in a modest reduction in the satellite bias that leaves small global residual biases of roughly −0.03°C. The major improvement in the analysis occurs at high latitudes due to the new sea ice algorithm where local differences between the old and new analysis can exceed 1°C. Comparisons with other SST products are needed to determine the consistency of the OI. These comparisons show that the differences among products occur on large time- and space scales wit...

An Improved In Situ and Satellite SST Analysis for Climate

The responses of vertebrate neurones to glutamate involve at least three receptor types. One of these, the NMDA receptor (so called because of its specific activation by N-methyl-D-aspartate), induces responses presenting a peculiar voltage sensitivity. Above resting potential, the current induced by a given dose of glutamate (or NMDA) increases when the cell is depolarized. This is contrary to what is observed at classical excitatory synapses, and recalls the properties of 'regenerative' systems like the Na+ conductance of the action potential. Indeed, recent studies of L-glutamate, L-aspartate and NMDA-induced currents have indicated that the current-voltage (I-V) relationship can show a region of 'negative conductance' and that the application of these agonists can lead to a regenerative depolarization. Furthermore, the NMDA response is greatly potentiated by reducing the extracellular Mg2+ concentration [( Mg2+]o) below the physiological level (approximately 1 mM). By analysing the responses of mouse central neurones to glutamate using the patch-clamp technique, we have now found a link between voltage sensitivity and Mg2+ sensitivity. In Mg2+-free solutions, L-glutamate, L-aspartate and NMDA open cation channels, the properties of which are voltage independent. In the presence of Mg2+, the single-channel currents measured at resting potential are chopped in bursts and the probability of opening of the channels is reduced. Both effects increase steeply with hyperpolarization, thereby accounting for the negative slope of the I-V relationship of the glutamate response. Thus, the voltage dependence of the NMDA receptor-linked conductance appears to be a consequence of the voltage dependence of the Mg2+ block and its interpretation does not require the implication of an intramembrane voltage-dependent 'gate'.

Magnesium gates glutamate-activated channels in mouse central neurones

Two new high-resolution sea surface temperature (SST) analysis products have been developed using optimum interpolation (OI). The analyses have a spatial grid resolution of 0.25° and a temporal resolution of 1 day. One product uses the Advanced Very High Resolution Radiometer (AVHRR) infrared satellite SST data. The other uses AVHRR and Advanced Microwave Scanning Radiometer (AMSR) on the NASA Earth Observing System satellite SST data. Both products also use in situ data from ships and buoys and include a large-scale adjustment of satellite biases with respect to the in situ data. Because of AMSR’s near-all-weather coverage, there is an increase in OI signal variance when AMSR is added to AVHRR. Thus, two products are needed to avoid an analysis variance jump when AMSR became available in June 2002. For both products, the results show improved spatial and temporal resolution compared to previous weekly 1° OI analyses. The AVHRR-only product uses Pathfinder AVHRR data (currently available from January 1985 to December 2005) and operational AVHRR data for 2006 onward. Pathfinder AVHRR was chosen over operational AVHRR, when available, because Pathfinder agrees better with the in situ data. The AMSR– AVHRR product begins with the start of AMSR data in June 2002. In this product, the primary AVHRR contribution is in regions near land where AMSR is not available. However, in cloud-free regions, use of both infrared and microwave instruments can reduce systematic biases because their error characteristics are independent.

Daily High-Resolution-Blended Analyses for Sea Surface Temperature

The authors present results of calculations of the low-q behaviour of the liquid structure factor S(q) of the alkali metals for a wide range of thermodynamic states. Assuming that the interionic forces can be modelled by the effective pairwise potential arising in second-order pseudopotential theory, they have calculated S(q) for small q using two different random-phase approximations. The first employs a hard-sphere reference system and the second uses the one-component plasma as the reference system. The second scheme enables them to evaluate S(0) and the coefficient of q2 in S(q) analytically.

https://iopscience.iop.org/article/10.1088/0022-3719/14/22/009/pdf

The long-wavelength behaviour of the structure factor of liquid alkali metals

The purpose of this paper is to demonstrate the ability to meet the need to measure distributions of physical and biological properties of the ocean over large areas synoptically and over long time periods by means of remote sensing utilizing contemporaneous buoy, ship, aircraft, and satellite (i.e., multiplatform) sampling strategies. A mapping of sea surface temperature and chlorophyll fields in a Gulf Stream warm core ring using the multiplatform approach is described. Sampling capabilities of each sensing system are discussed as background for the data collected by means of these three dissimilar methods. Commensurate space/time sample sets from each sensing system are compared, and their relative accuracies in space and time are determined. The three-dimensional composite maps derived from the data set provide a synoptic perspective unobtainable from single platforms alone.

Multiplatform sampling (ship, aircraft, and satellite) of a Gulf Stream warm core ring

D-α-Aminoadipate, α,ε-diominopimelic acid and HA-966 as antagonists of amino acid-induced and synaptic excitation of mammalian spinal neurones in vivo

Small-scale cyclones found around Gulf Stream warm-core ring 82B are investigated by using infrared satellite images and current information obtained with an acoustic-Doppler velocimeter. Currents in these cyclones reveal speeds ranging from 20 to 80 cm/s. One small cyclone or 'ringlet' found in June 1982 was studied extensively by removing the basic rotational velocities of 82B. The azimuthal velocity field for this ringlet was used with the gradient current equation to calculate the absolute dynamic topography at 100 dbar. It was found that the ringlet was 13 dyn-cm lower than its surroundings. In addition, neglect of the centrifugal term would have changed the dynamic topography of the ringlet by 30 percent. From a comparison with CTD data the absolute reference level was determined, and a vertical profile of horizontal currents was calculated for the ringlet. Other cyclones were found throughout the slope water region around warm-core ring 82B with observable lifetimes of 1 to 2 weeks. The northeast quadrant of 82B was a favored generation site for ringlets. Two cyclones were observed to form in this region and were advected anticyclonically around 82B. Typically, at any one time, six cyclones with diameters of approximately 40 to 50 km can be detected north of the Gulf Stream by using satellite images.

Small-scale cyclones on the periphery of a Gulf Stream warm-core ring

We examine the usefulness of the integral equations derived from the HNC and PY closures of the wall-particle Ornstein-Zernike equation for describing the density profile and pairwise distribution function of models of the solid-fluid interface. It is shown that these, and closely related closure approximations, cannot account for complete wetting of a solid-gas interface by liquid or complete wetting by gas of a purely repulsive substrate at a solid-liquid interface. The closure approximation to the first YBG equation which sets the total pairwise correlation function equal to that of the bulk fluid exhibits the same failings. Since none of these approaches can describe liquid-gas coexistence, they cannot be used as a basis for a self consistent theory of contact angle and wetting phenomena. Moreover, they cannot account for the growth of thick, liquid-like, adsorbed films which develop at solid-gas interfaces at temperatures T above the wetting transition temperature Tw. Such approaches also give an inadequate description of pairwise correlations in the interface. This is illustrated by the introduction of a ' surface ' compressibility sum rule which relates an integral over the interracial part of the pairwise distribution function to (SI'/~/~)T, the derivative with respect to chemical potential/~ of the coverage r. For T> T,¢ r and, hence, (er/~,)T diverge as p~ approaches its value at saturation with exponents that reflect the asymptotic behaviour of the attractive part of the solid-gas potential. The sum rule shows that the range of transverse (parallel to the surface) pairwise correlations must diverge in an equivalent fashion. Divergences of this kind are not predicted by the integral equation approaches. The growth of long-ranged transverse correlations has important repercussions for computer simulations of thick adsorbed films. It iS the purpose of this paper to point out the limitations of several widely used theories of solid-fluid interfaces. In particular we show that these theories cannot account for the phenomenon of complete wetting by liquid or by gas. There are three main theoretical approaches employed in calculations of the microscopic structure of simple fluids near model solid substrates. The first of these makes use of closure approximations to the wall-particle OrnsteinZernike equation. This approach was pioneered by Perram and White [I] and Henderson et al. [2] and has been applied to a variety of model systemssee, for example, [3, 4] and references therein. Two of the simplest and most commonly used closures are the hypernetted-chai n (HNC) and Percus-Yevick

Robert Evans

Papers

The long-wavelength behaviour of the structure factor of liquid alkali metals

Multiplatform sampling (ship, aircraft, and satellite) of a Gulf Stream warm core ring

D-α-Aminoadipate, α,ε-diominopimelic acid and HA-966 as antagonists of amino acid-induced and synaptic excitation of mammalian spinal neurones in vivo

Small-scale cyclones on the periphery of a Gulf Stream warm-core ring

On the failure of certain integral equation theories to account for complete wetting at solid-fluid interfaces