Implications of solar flare dynamics for reconnection in magnetospheric substorms

From observations of two-ribbon solar flares, we present a new line of evidence that magnetic reconnection is of key importance in magnetospheric substorms. We infer that in substorms reconnection of closed field lines in the near-Earth thinned plasma sheet both initiates and is driven by the overall MHD instability that drives the tailward expulsion of the reconnected closed field (0 loops). The general basis for this inference is the longstanding notion that two-ribbon flares and substorms are essentially similar phenomena, driven by similar processes. We give an array of observed similarities that substantiate this view. More specifically, our inference for substorms is drawn from observations of filament eruptions in two-ribbon flares, from which we conclude that the heart of the overall instability consists of reconnection and eruption of the closed magnetic field in and around the filament. We propose that essentially the same overall instability operates in substorms. Our point is not that the magnetic field configuration or the microphysics in substorms is identical to that in two-ribbon flares, but that the overall instability results from essentially the same combination of reconnection and eruption of closed magnetic field.     

Thorium and radium isotopic relationships in manganese nodules and sediments at MANOP Site S

Relationships among Th and Ra isotopes in nodule, sediment and water phases at MANOP Site S establish the most likely source for Th in the nodules, the frequency of nodule turning, and the similarity of micro and macro nodules. Manganese nodules and bottom waters have ${}^{230}\text{Th}{}^{232}\text{Th}$ activity ratios considerably higher than other phases at this site suggesting that sea water is the likely source of Th for the nodules. Similar ${}^{230}\text{Th}{}^{232}\text{Th}$ activity ratios in nodule tops and bottoms and in certain cases departure from expected ${}^{226}\text{Ra}{}^{230}\text{Th}$ activity ratios in nodule tops and bottoms indicate that the nodules rotate every one to ten thousand years. The micro nodules have diffusion coefficients of Ra similar to macro nodule bottoms. I suggest that they may act as a carrier phase for transporting metals through oxic sediments to nodules.     

Geochemistry of barium in pelagic sediments

High concentrations and accumulation rates of Ba occur on active (spreading) ridges, and in some areas of high biological productivity. These patterns show that Ba is deposited on the deep sea floor by both volcanic and biological processes.     

Carbon and its isotopes in mid-oceanic basaltic glasses

Three carbon components are evident in eleven analyzed mid-oceanic basalts: carbon on sample surfaces (resembling adsorbed gases, organic matter, or other non-magmatic carbon species acquired by the glasses subsequent to their eruption), mantle carbon dioxide in vesicles, and mantle carbon dissolved in the glasses. The combustion technique employed recovered only reduced sulfur, all of which appears to be indigenous to the glasses. The dissolved carbon concentration (measured in vesicle-free glass) increases with the eruption depth of the spreading ridge, and is consistent with earlier data which show that magma carbon solubility increases with pressure. The total glass carbon content (dissolved plus vesicular carbon) may be controlled by the depth of the shallowest ridge magma chamber. Carbon isotopic fractionation accompanies magma degassing; vesicle CO₂ is about 3.8‰ enriched in ¹³C, relative to dissolved carbon. Despite this fractionation, δ¹³C_PDB values for all spreading ridge glasses lie within the range ?5.6 and ?7.5, and the δ¹³C_PDB of mantle carbon likely lies between ?5 and ?7. The carbon abundances and δ¹³C_PDB values of Kilauea East Rift glasses apparently are influenced by the differentiation and movement of magma within that Hawaiian volcano. Using ³He and carbon data for submarine hydrothermal fluids, the present-day mid-oceanic ridge mantle carbon flux is estimated very roughly to be about 1.0 × 10¹³ g C/yr. Such a flux requires 8 Gyr to accumulate the earth's present crustal carbon inventory.     

A switched continuous-wave sonic anemometer for measuring surface heat fluxes

A one-dimensional sonic anemometer system suitable for use in measuring near surface heat fluxes is described. It operates by transferring continuous sound waves in alternate directions between a matched pair of cheap ultrasonic transducers. The design and development of the anemometer is described, together with wind tunnel tests, and field experiments, in which the performances of several prototypes are compared with those of other anemometers over stubble and over forest. The results indicate that the device is suitable for measuring eddy correlation heat fluxes to an accuracy better than 5%.