CLIMAP SSTs re-revisited

Since the 1976 publication of the CLIMAP ice age sea surface temperature (SST) reconstruction showing a 1–2 ^∘C tropical cooling a substantial debate has arisen as to whether tropical SSTs may instead have been 4–5^∘ colder than present. Herein I review the arguments for large SST variations and question a number of key findings, particularly the validity of ice-age coral SST estimates and “down-projecting” tropical snowline changes to the surface. GCM results indicate that an intermediate solution requiring ∼2.5 ^∘C warm pool cooling is consistent with most quantitative low elevation surface land data and is small enough to allow the persistence of tropical biota in the ocean during glacial times. The proposal reduces estimated ice-age climate sensitivity (for a doubling of CO₂) from a “high-end” sensitivity of about 4.5 ^∘C (for a 5–6 ^∘C tropical cooling) to a “mid-range” sensitivity of about 3.0 ^∘C for a 2.5 ^∘C warm-pool decrease. Received: 28 July 1999 /Accepted: 12 August 1999     

Laboratory study of deep-water breaking waves

In an attempt to elucidate the mechanics of deep-water wave breaking, a variety of breaking waves, including spilling and plunging waves, of different length scales and geometries was studied. The waves were generated through wave-wave interactions using wave packets with constant-steepness components, constant-amplitude components, and also components following the Pierson-Moskowitz distribution. Wave steepening prior to breaking were found to cause an increase in the high frequency spectral slope of the wave spectrum. The slopes were correlated to the type of breaking and the intensity of the breaking. The energy loss through breaking varied with the spectral characteristics of the wave packet. On the other hand, it was also noted that, irrespective of the wave packet, the losses were from the higher frequency end of the first harmonics.     

Phytoplankton diversity and chlorophyll-A in a polluted estuary

The quantity of phytoplankton in Newark Bay, New Jersey as indicated by chlorophyll-a content of the water, is low in the winter and early spring, and fluctuates greatly during the spring and summer. Chlorophyll-a concentrations are generally less than 20 μg/l until April. Between April and August, three phytoplankton blooms were indicated by chlorophyll-a concentrations as high as 81.4 μg/l. Net phytoplankton diversity values indicated generally eutrophic conditions; however, there was no significant correlation between diversity and chlorophyll-a concentrations. A role of nannoplankton in blooms is indicated.     

Carbon-Oxidizing and Sulfate-Reducing Bacteria in Mozhaisk Reservoir Soils

The population and distribution of carbon-oxidizing and sulfate-reducing bacteria in the soils of the Mozhaisk Reservoir are studied.     

Impact of Earth radiation pressure on GPS position estimates

GPS satellite orbits available from the International GNSS Service (IGS) show a consistent radial bias of up to several cm and a particular pattern in the Satellite Laser Ranging (SLR) residuals, which are suggested to be related to radiation pressure mismodeling. In addition, orbit-related frequencies were identified in geodetic time series such as apparent geocenter motion and station displacements derived from GPS tracking data. A potential solution to these discrepancies is the inclusion of Earth radiation pressure (visible and infrared) modeling in the orbit determination process. This is currently not yet considered by all analysis centers contributing to the IGS final orbits. The acceleration, accounting for Earth radiation and satellite models, is introduced in this paper in the computation of a global GPS network (around 200 IGS sites) adopting the analysis strategies from the Center for Orbit Determination in Europe (CODE). Two solutions covering 9 years (2000–2008) with and without Earth radiation pressure were computed and form the basis for this study. In previous studies, it has been shown that Earth radiation pressure has a non-negligible effect on the GPS orbits, mainly in the radial component. In this paper, the effect on the along-track and cross-track components is studied in more detail. Also in this paper, it is shown that Earth radiation pressure leads to a change in the estimates of GPS ground station positions, which is systematic over large regions of the Earth. This observed “deformation” of the Earth is towards North–South and with large scale patterns that repeat six times per GPS draconitic year (350 days), reaching a magnitude of up to 1 mm. The impact of Earth radiation pressure on the geocenter and length of day estimates was also investigated, but the effect is found to be less significant as compared to the orbits and position estimates.     

The solubility of quartz in aqueous sodium chloride solution at 350°C and 180 to 500 bars

The solubility of quartz in 2, 3, and 4 molal NaCl was measured at 350°C and pressures ranging from 180 to 500 bars. The molal solubility in each of the salt solutions is greater than that in pure water throughout the measured pressure range, with the ratio of solubility in NaCl solution to solubility in pure water decreasing as pressure is increased. The measured solubilities are significantly higher than solubilities calculated using a simple model in which the water activity in NaCl solutions decreases either in proportion to decreasing vapor pressure of the solution as salinity is increased or in proportion to decreasing mole fraction of water in the solvent.     

Guided wave propagation in laterally varying media - II. Lg-waves in north-western Europe

Summary. Lg -wave observations at NORSAR from a sequence of explosions straddling the Central Graben in the North Sea, show that the phase is almost extinguished by passing through this structure. For models of the graben structure, based on seismic refraction experiments, with crustal thinning beneath a zone of thickened sediments, numerical modelling of Lg propagation shows very poor transmission. The inclusion of attenuation simulating the effects of scattering from faults and other complex structures further diminishes the transmittivity. The theoretical effect of a crustal pinch is to redistribute S energy over a wide range of groups velocities, a pattern that fits well with the observations.
Three components recordings at NORSAR of explosive charges fired in water covering a wide range of azimuths, show significant transverse components to the seismograms. The transverse energy builds up with travel time and for Lg is of the same order as the vertical component. These results are consistent with the theoretical prediction of progressive net transfer of energy from Rayleigh to Love modes as the wavetrain propagates through a three-dimensionally heterogeneous medium.