THE GATE SQUALL LINE OF 9－10 AUGUST 1974

A tropical squall line that passed over the ship array of the Global Atmospheric Research Programme’s Atlantic Tropical Experiment (GATE) on 9－10 August 1974 is analyzed. This squall line was similar to squall systems that passed over the GATE ship array on four other days. It began as a purely convective cloud line, then developed an associated stratiform cloud and precipitation area. The stratiform rain built up to a maxi-mum amount over a period of 8 h, then gradually diminished over a 6 h period. This stratiform rain is esti-mated to have accounted for 32% of the squall system’s total precipitation. As in other GATE squall lines, the upper-level cloud shield from which the stratiform rain fell, was advected slowly forward of the line during the system’s lifetime, the leading line of corrective clouds consisted of transient smaller-scale convective elements, which lent the line an irregular shape and pulsatory movement, and the stratiform portion of the system was characterized by the development of a mid-level mesoscale vortex similar to that seen in other GATE eases.     

MINI-MACtm—A new generation dual—Band surveyor

Summary Litton Divisions presently produce both high accuracy GPS surveyors and low—cost GPS navigation sets. Aero Service'sMACROMETER ^R Interferometric Surveyors, have become the standard against which GPS surveying equipment is measured. Litton Aero Products has developed a highly digitized, low costL ₁,C/A code GPS card set. The integration of these technologies had led to the development of a low-cost, high-precision, GPS survey system which can be configured with or without a codelessL ₂ capability. TheMINI-MAC surveying system is the first member of the new generation of GPS survey systems resulting from this joint development. The system design is described in this paper, and initial survey test results using a prototypeMINI-MAC surveying system are presented.     

Water chemistry and sedimentological observations in littlefield lake,michigan: Implications for lacustrine marl deposition

A combination of both water chemistry and sedimentological information was used to investigate the carbonate-producing mechanism in Littlefield Lake, a small lake located in Isabella County, central Michigan. Data on temperature, dissolved oxygen, pH, calcium carbonate (CaCO₃) saturation, alkalinity, calcium, and magnesium were obtained on a monthly basis over a 13-month period, with each parameter determined at 1m intervals over a depth range of 20m. The loss of dissolved carbon dioxide (CO₂) from warm surface waters during direct degassing, and to a lesser extent during photosynthetic uptake by lacustrine macrophytes and phytoplankton during the summer, results in massive precipitation of the low-magnesium calcite which predominates in all Littlefield Lake sedimentary facies However, despite the fact that carbonate precipitation in this rather typical temperate-region marl lake is directly related to, and may be driven by, seasonal variation in these physiochemical parameters, most calcite forms as encrustations around cyanophytic and chlorophytic macrophytes. Such relationships demonstrate that carbonate precipitation in marl lakes may result from complex interactions between both biochemical and physiochemical processes. As such, marl formation in this, and probably many other calcareous lake systems, can not be simply ascribed to one or the other of these two general mechanisms.     

Vegetative physiographic analysis of a U.S. northern barrier system

A quantitative analysis of historical aerial photographs and maps coupled with detailed field surveys provided the data necessary to assess the importance of overwash processes and vegetative recovery on Nauset Spit, Cape Cod, Massachusetts Development of all plant communities and physiographic features is extremely rapid on the spit. Dunes are evident from aerial photographic analysis in as little as three years after overwash; salt marshes are apparent in only ten years. Classical ecological succession does not appear to occur on Nauset Spit, since environments are periodically altered by overwash processes. Most dominant species on the barrier can grow in bare sandy substrate. Migration of the Nauset Spit, system proceeds by a cyclic series of events, involving inlet dynamics, overwash processes, and dune building     

Rates of sulfur dioxide and particle emissions from White Island volcano,New Zealand,and an estimate of the total flux of major gaseous species

Airborne correlation spectrometry (COSPEC) was used to measure the rate of SO₂ emission at White Island on three dates, i.e., November 1983, 1230 ± 300 t/d; November 1984, 320 ± 120 t/d; and January 1985, 350 ± 150 t/d (t = metric tons). The lower emission rates are likely to reflect the long-term emission rates, whereas the November 1983 rate probably reflects conditions prior to the eruption of December 1983. The particle flux in the White Island plume, as determined with a quartz crystal microbalance/cascade in November 1983, was 1.3 t/d, unusually low for volcanic plumes. The observed plume particles, as shown from scanning electron microscopy, include halite, native sulfur, and silicates and are broadly similar to other volcanic plumes.Gas analyses from high-temperature volcanic fumaroles collected from June 1982 through November 1984 werde used together with the COSPEC data to estimate the flux of other gas species from White Island. The rates estimated are indicative of the long-term volcanic emission, i.e., 8000–9000 t/d H₂O, 900–1000 t/d CO₂, 70–80 t/d HCl, 1.5–2 t/d HF, and about 0.2 t/d NH₃. The long-term thermal power output at White Island is estimated at about 400 MW.     

Practical Application of Theoretical Models to Magnetometer Surveys on Hazardous Waste Disposal Sites — A Case History

Wastes were to be exhumed and removed from a hazardous and chemical waste disposal site. The major disposal practice was shallow burial of wastes in metal drums in parallel trenches. The actual boundaries of the trenches beneath the landscaped cover were not accurately known.
Theoretical two-dimensional models were used to evaluate the application of magnetic methods to define trench boundaries on the disposal site. The models predicted that both the total field and the vertical component anomalies were diagnostic; however, the vertical component anomaly was more focused on the trench boundaries.
A survey with a vertical component fluxgate magnetometer was successful in defining trench boundaries. Observations made along traverses that trended perpendicular to the long axis of the parallel trenches indicated vertical magnetic intensity values with a cyclical pattern of large positive values over trenches and large negative values over intertrench corridors. Vertical magnetic intensity values determined with theoretical two-dimensional models compared favorably to the observed vertical magnetic values. The models were used to constrain the interpretation of the field observations to define trench boundaries; the magnetic survey defined trench boundaries with an accuracy within ± 2 feet.     

The importance of atmospheric input of terrestrial organic material to deep sea sediments

The concentrations of lipids were determined in atmospheric particle, gas and rain samples collected from the tropical North Pacific to assess lipid sources, transport mechanisms and fluxes to the ocean surface. Four lipid compound classes (aliphatic hydrocarbons, fatty alcohols, fatty acid esters, and salts) all unequivocally show a terrestrial vascular plant source. These aerosol lipids originate from wind erosion of Asian and American soils and direct emission from vegetation. The major fluxes result from rain rather than dry deposition. These fluxes are large enough to have a major potential impact on the inventory of terrestrially derived lipid material found in deep-sea sediments. This has been showm for n-alkanes, fatty alcohols, fatty acids, total lipids and for organic carbon. By comparing atmospheric and sediment trap fluxes with sediment accumulation rates, it is suggested that some biogenic terrestrial material is more protected from degradation than marine-derived material.     

High-Pressure crystal chemistry of spinel (MgAl2O4) and magnetite (Fe3O4): Comparisons with silicate spinels

High-pressure crystal structures and compressibilities have been determined by x-ray methods for MgAl₂O₄ spinel and its isomorph magnetite, Fe₃O₄. The measured bulk moduli, K, of spinel and magnetite (assuming K′=4) are 1.94±0.06 and 1.86±0.05 Mbar, respectively, in accord with previous ultrasonic determinations. The oxygen u parameter, the only variable atomic position coordinate in the spinel structure (Fd3m, Z=8), decreases with pressure in MgAl₂O₄, thus indicating that the magnesium tetrahedron is more compressible than the aluminum octahedron. In magnetite the u parameter is unchanged, and both tetrahedron and octahedron display the 1.9 Mbar bulk modulus characteristic of the entire crystal. This behavior contrasts with that of nickel silicate spinel (γ-Ni₂SiO₄), in which the u parameter increases with pressure because the silicon tetrahedron is relatively incompressible compared to the nickel octahedron.