Numerical solution of the time-dependent heat energy equations for the magnetosphere

A new solution of the magnetospheric heat equations capable of covering the whole region from 300 km along a field line to the equatorial plane has been achieved by adapting the searching procedure of Murphy (1974). It has been found that the protonospheric heat reservoir is sufficient to maintain T_e >T_n down to the height of the F2-peak electron density all through the night at mid-latitudes. Full solution of the equations has also shown that T_i >T_e in the protonosphere at night and the ions constitute a significant source of heat for the electrons.     

Why the Sun may appear oblate

If the Sun loses angular momentum from its core, due to core contraction, into the solar wind at the observed rate, then an 0.7 day rotational period for the core of the Sun is required for temporal equilibrium. The rotational power released in the core contraction process can equal the observed magnetic energy released in the solar activity cycle if the Sun's core rotates with a period near 1.4 to 4 days. The rotational power released from a rotating object is , where is the torque on the object and is its angular velocity. Fitting this to the solar wind torque and core rotation rate provides an 0.5 to 5 day rotation period for the Sun's core. A gravitational Pannekoek-Rosseland electric field in the Sun makes the Ferraro theorem inapplicable in such a way that rather than a constant angular velocity with radius, an inverse square radial dependence occurs. This results in a two day rotational period for the region in the Sun where most of the angular momentum resides. The consistency of the above four methods suggests that the Sun's observed oblateness is due to a rapidly rotating solar core. The oblateness of the photosphere is estimated to be near 3.4×10^–5.     

A model of ionospheric F-2 region storms in middle latitudes

The proposed ionospheric storm model is based on a heat source located at magnetic noon on Feldstein's auroral oval. The rotation of the Earth produces an apparent motion of the source which is greater than the speed of the disturbance. This gives rise to a wake or front which sweeps over the globe and determines the onset time of the negative phase which results from a change in chemical composition. At the front, focussing will occur which accounts for the sudden drop in electron density (or contents) sometimes observed. The calculated onset times of the negative phase are compared with observations for a number of storms. The local onset times vary from 12 at the latitude of the source to around 24 at 10° geomagnetic latitude. This model predicts that the onset of the negative phase at a given location, for storm which commence between about 2000 LT to about 1000 LT, is independent of the time of storm commencement.     

On the mechanisms behind salinity anomaly signals of the northern North Atlantic

Hydrographic time series from the northern North Atlantic throughout the 20th century show oscillations in temperature and salinity at more or less regular intervals. The Great Salinity Anomalies described during the 1970s [Dickson, R.R., Meincke, J., Malmberg, S.-A., Lee, A.J., 1988. The “Great Salinity Anomaly” in the North Atlantic, 1968-1982. Progress in Oceanography 20, 103-151.], during the 1980s [Belkin, I.M., Levitus, S., Antonov, J., Malmberg, S.-A., 1998. “Great Salinity Anomalies” in the North Atlantic. Progress in Oceanography 41, 1-68.], and during the 1990s [Belkin, I.M., 2004. Propagation of the “Great Salinity Anomaly” of the 1990s around the northern North Atlantic. Geophysical Research Letters 31(8), L08306, doi:10.1029/2003GL019334.] have distinct amplitudes, and all three of them were interpreted as low salinity anomalies propagating downstream through the anti-clockwise circulation system of the northern North Atlantic Ocean. Further inspection of time series from the Northeast Atlantic and the Northwest Atlantic over the past century shows, however, several other distinct negative anomalies of lesser amplitudes. Additionally, a number of high salinity anomalies can be identified. The present paper analyses further the propagation of the negative and positive anomalies and links them together. It is shown that they have varying speeds of propagation, and that the varying speeds are correlated across the North Atlantic. We propose that varying volume fluxes in and out of the Arctic Basin is the causal mechanism behind the anomaly signals, and that the North Atlantic Oscillation (NAO) partly has influence on the flux variations described. Periods of large decadal-scale amplitudes of the NAO coincide with periods of large decadal-scale oscillation in the marine climate.     

Comparative Study of Sand Porosity and a Technique for Determining Porosity of Undisturbed Marine Sediment

Porosity is a fundamental property of marine sediment from which wet bulk density can be easily determined and used in a variety of geoacoustic, geotechnical, and sedimentological studies, analyses, and models. However, methods of sampling marine sands suffer from the common problem of core disturbance making the in situ porosity difficult to obtain. Embedding the sediment within an epoxy resin matrix will minimize the disturbance to the microfabric and preserve the in situ sedimentary structure for subsequent study. Image analysis can then be used on thin sections to study the microfabric and porometry. A comprehensive review and analysis of published data on the porosity of predominantly clean sands has been completed and a simple, accurate, and nondestructive technique is described for preparing and measuring the porosity of marine sediment (siliciclastic sand) that has been infiltrated aboard ship immediately upon sample collection and chemically fixed and infiltrated with epoxy shortly thereafter. The average porosity of 36 samples of marine sand collected offshore Fort Walton Beach, Florida, and embedded with resin was determined to be 41.30%. From the review of published data the average porosity of sand was determined to be 37.7%, 42.3%, and 46.3% for packed, natural (in situ), and loose packing conditions, respectively, for a range of sorting coefficients and grain sizes.     

Organic nitrogen and caloric content of detritus III. Effect on growth of a deposit-feeding polychaete, Capitella capitata

Laboratory experiments showed that individual growth rate of the deposit-feeding polychaete, Capitella capitata (type 1) can be predicted by rate of organic nitrogen supply (ration) of detritus to the animals. The rate at which detritus is available to a deposit-feeder, whether by sedimentation to the bottom, or decomposition of otherwise undigestable components via microbial activity, or production rate of microbes themselves, is important and not just the concentrations of limiting substrate of different detritus sources. Even so, the portion of total caloric content of the detritus that can be utilized by a deposit-feeder—approximated by the ‘available’ caloric content—also contributes to limiting growth. However, available caloric content usually is low when nitrogen content is low, as in the case of vascular plant detritus. Trophic transfer efficiency (net production/food supplied) is a measurement of food chain transfer that is usually calculated in carbon or caloric units. If one is interested in comparing energy or carbon flow in food chains, then use of these parameters is appropriate; if one is interested in comparing the efficiencies of different species, then calculations must be made using nutritional factors limiting growth.     

A flood-dominated mesotidal inlet

Tidal inlets along the mesotidal coast of Maine contrast with those from other parts of the world by being dominated by flood-tidal currents. Analysis of the factors responsible for flood or ebb dominance indicates factors external to the backbarrier environment. We suggest that the flood dominance is caused by both a steepening of the tidal wave in the Gulf of Maine and the shallow depth of the ebb-tidal delta and spit platform. Flood currents are typically 10–20 cm/sec stronger than the ebb at the inlet throat. The flood dominance results in a significant net landward transport of sediment into the backbarrier.