High Heat Content Research Articles

Attributes of dynamical events to tropospheric ozone distribution over equatorial africa

Volcanic activity, biological decay, forest fi res, thunderstorm events and stratospheric intrusions are key sources that introduce atmospheric traces to the troposphere. Ozone is one of such traces which can be found in very high concentration than its normal level due to natural factors. Upper and middle tropospheric ozone act as a green house gas while ozone found in high concentration at lower troposphere is a pollutant that harms living organisms. In few ozone and relative humidity data records by measurements of ozone by airbus in service aircraft (MOZAIC), spikes were observed at a fl ying altitude of 250‐200 hPa at equatorial Africa. Equatorial Africa is one of the three thunderstorm hot spot regions (South America, Equatorial Africa and Southeast Asia) of the world. This work discusses how ozone of stratospheric origin produced enhanced ozone over the troposphere of equatorial Africa and its redistribution due to dynamical events. To understand the events that attribute to spiky MOZAIC ozone and relative humidity observations, in addition to MOZAIC ozone and relative humidity, data sets from different sources were used for diagnosis. Meridional cross-section of potential vorticity over the region of interest showed high potential vorticity (PV) intrusion below the tropopause level that induced enhanced ozone into upper troposphere. Vertical wind fi elds in the regions of low outgoing long wave radiation (OLR), very high latent heat and cloud liquid water content transport have indicated presence of convection and thunderstorm events. Enhanced ozone of stratospheric origin, as revealed by GOME satellite data produced during stratospheric intrusion, transported from the stratosphere all the way down to the boundary layer. Convective erosion was found to scavenge ozone concentration mainly at the boundary layers between 1000 and 700 hPa and enhanced ozone volume mixing ratio (VMR) of 60‐100 ppbv which exceeds the WHO guideline limit of 60 ppbv were observed. These events have led to ozone pollution.

INCREASE OF THE THERMOCLINE LAYER DUE TO TSUNAMI 2004 IN NANGRO ACEH DARUSSALAM WATERS

Research of physical oceanographic conditions post-tsunami was carried out and subsequently compared with the pre-tsunami 1998. Measurement of suhu, salinity and light transmission was conducted by CTDSBE911pls Model. Results showed that the flow in the Straits of Malacca flowed into the northwest and turned back into the Strait of Bengal and the next rotation into the flow of waters along the west coast of Nangro Aceh Darusalam (NAD). The mainstream off coast NAD in the Indian Ocean flowed to the northwest. Upper thermocline layer (17 m to 50 m) moved upward in 2005 and 2006 compared with previous data 1998 (90 m to 125 m). The moving upward thermocline in 2006 was allegedly due to the influence of Indian Ocean Dipole (IOD) positive. This requires further verification through long-term data collection to determine the monthly and annual variations, which will be compared with previous research. Light transmission (Tx) in 2005 from the surface to near the bottom (water column) was found lower than the year 1998 and 2006. This result was allegedly caused by resuspension from the seabed by energy turbulent produced by the tsunami. Heat content between 5 to 65 m depth in 2005 was higher than in 1998 and 2006. The higher heat content during the year of 2005 (post tsunami) was caused by friction due to the influence of tsunami energy, which predominantly found in the mixed layer depth. Type of water masses in the study area was a mixing between the local water mass, Malacca Strait Water (MSA), Bay of Bengal Water (BBW) under the influence of Arab Waters (AW), and the Indian Deep Water (IDW).Keywords: current, thermocline, heat content, watermass type, and Nangro Aceh Darusalam

INCREASE OF THE THERMOCLINE LAYER DUE TO TSUNAMI 2004 IN NANGRO ACEH DARUSSALAM WATERS

<p>Research of physical oceanographic conditions post-tsunami was carried out and subsequently compared with the pre-tsunami 1998. Measurement of suhu, salinity and light transmission was conducted by CTDSBE911pls Model. Results showed that the flow in the Straits of Malacca flowed into the northwest and turned back into the Strait of Bengal and the next rotation into the flow of waters along the west coast of Nangro Aceh Darusalam (NAD). The mainstream off coast NAD in the Indian Ocean flowed to the northwest. Upper thermocline layer (17 m to 50 m) moved upward in 2005 and 2006 compared with previous data 1998 (90 m to 125 m). The moving upward thermocline in 2006 was allegedly due to the influence of Indian Ocean Dipole (IOD) positive. This requires further verification through long-term data collection to determine the monthly and annual variations, which will be compared with previous research. Light transmission (Tx) in 2005 from the surface to near the bottom (water column) was found lower than the year 1998 and 2006. This result was allegedly caused by resuspension from the seabed by energy turbulent produced by the tsunami. Heat content between 5 to 65 m depth in 2005 was higher than in 1998 and 2006. The higher heat content during the year of 2005 (post tsunami) was caused by friction due to the influence of tsunami energy, which predominantly found in the mixed layer depth. Type of water masses in the study area was a mixing between the local water mass, Malacca Strait Water (MSA), Bay of Bengal Water (BBW) under the influence of Arab Waters (AW), and the Indian Deep Water (IDW).</p><p>Keywords: current, thermocline, heat content, watermass type, and Nangro Aceh Darusalam</p>

Environmental state of Lake Kariba and Zambezi River Valley: Lessons learned and not learned

Lake Kariba, still the largest reservoir in the world by volume, is 60 years old. It has undergone changes in its thermal properties, associated with global warming, which reflect in turn on its limnology. These changes include a shallower eipilimnion, higher heat content and increased tropicality to near equatorial status. The role of Lake Kariba with regard to its energy characteristics is discussed in light of global warming findings. The lake’s water residence time has increased from 3.7 years to ≈5.7 years, attributable to a reduced inflow from the Zambezi River. The phytoplankton communities have changed towards a cyanophyceae-dominated community, leading to a decline in entomostracan zooplankton, and a near collapse of the planktivorous Limnothrissa miodon fishery. Prolonged use of pesticides to control Glossina has led to measurable ecosystem level impacts on both terrestrial and aquatic biota. The impacts of the forced relocation of the Tonga people were still evident during this study. Siltation from resettlement areas has led to the loss of habitat and biodiversity in the inflowing streams to the lake. Unplanned shoreline development in the early history of the lake poses health problems. It is projected that global warming will cause the lake temperature to rise by ≈4 °C by the end of the century. Higher temperatures will be accompanied by windier conditions, thereby enhancing the risks from storms on the lake. The appropriateness of administrative structures intended to manage the Zambezi River Basin environment also is discussed herein. It is concluded that the management protocol is institutionally a non-inclusive process lacking the capacity to involve other stakeholders in managing the lake’s resources, and even less so in the integrated management of the basin.

Gas-phase ignition of a film of liquid condensed substance by a metal particle heated to high temperatures under mixed-convection conditions

A numerical analysis of the scale of influence of the mixed convection of an oxidant and a fuel vapor on the characteristics of the gas-phase ignition of the film of a typical liquid condensed substance — kerosene — by a small-size metal particle heated to high temperatures has been made. The limiting values of the velocity of air-mass motion for which no ignition conditions are realized in the system “metal particle heated to high temperatures-kerosene films-air” have been established. The ranges of variation in the air temperature and the initial warmed-up-particle temperature in which the ignition conditions are realized have been determined. It has been shown that no ignition occurs even for a high heat content of the heating source when Re > 1.3·10 3 .

Fluid infiltration, heat transport, and healing of microcracks in the damage zone of magmatic veins: Numerical modeling

Alteration halos with sharp boundaries are flanking pegmatitic veins in high‐grade metamorphic and magmatic rocks of Dronning Maud Land, Antarctica. These halos are interpreted to represent the damage zone, formed as the wake of the process zone at the tip of the propagating magma‐filled fracture and infiltrated by the fluid phase liberated from the crystallizing hydrous melt. On the basis of a set of assumptions, our numerical model explores the time scales of the infiltration processes, taking into account the combined effects of fluid flow, heat transfer, and temperature‐dependent decay of interconnected porosity due to microcrack healing. Assuming an initial magma temperature of 700°C, a far field temperature in the host rock of 300°C, an initial porosity range of 0.5–2% in the damage zone, a permeability of 10−16 m2, and a pressure difference of 300 MPa, we find that the fluid infiltration into the damage zone proceeds within seconds to minutes and that the fluid flow contributes significantly to the heat transfer into the host rock. Assuming an initial microcrack aperture of 1 μm, the model predicts that the crack healing time scale is significantly longer than that of fluid infiltration in the case of thin veins with narrow damage zones; in this case, crack healing does not hinder fluid infiltration. Only for thick veins with high heat content and prolonged crystallization history does permeability become reduced by crack healing during progressive fluid infiltration. The results indicate that the formation of the alteration halos flanking pegmatitic veins may be a quasi‐instantaneous process on geological time scales.

Performance improvement of LPG cook stoves through burner and nozzle modifications

Liquefied petroleum gas (LPG) is a popular fuel for domestic and commercial cooking as it offers clean cooking environment as well as high heat content. Large increases in the demand of LPG in developing countries like India, in the face of its dwindling reserve, underscores the need for performance improvement of LPG cook stoves. The present paper investigates the combustion and emission characteristics of the LPG cook stove burners commonly used in India, and have suggested performance improvement through different designs modifications in the burner cap and fuel injection nozzle. It is found that the increase in the diameter of the ports admitting the fuel–primary air mixture and obliquely orienting the ports to impart swirl to the flow enhances the performance through better efficiency and reduced emissions and soot formation. The smaller orifice hole in the fuel injection nozzle also improves the performance through increased efficiency and reduced emission at the expense of decreasing burner loading. The design improvements are easy and economic to implement, and can lead to nearly 3% of improvement in system thermal efficiency and significant reduction in emission.

Economics of biomass fuels for electricity production: A case study with crop residues

In the past, studies on agricultural feedstocks for energy production were motivated by rising fossil fuel prices interpreted by many as caused by resource depletion. However, today’s studies are mainly motivated by concerns for climate change and global warming. Currently, most studies concentrate on liquid fuels with little study devoted toward electricity. This study examines crop residues for electricity production in the context of climate change and global warming. We use sector modeling to simulate future market penetration for biopower production from crop residues. Our findings suggest that crop residues cost much more than coal because they have lower heat content and higher production/hauling costs. For crop residues to have any role in electricity generation either the carbon or carbon dioxide equivalent greenhouse gas price must rise to about 15 dollars per ton or the price of coal has to increase to about 43 dollars per ton. We find crop residues with higher heat content and lower production costs such as wheat residues have greater opportunities in biopower production than the residues with lower heat content and higher production costs. In addition, the analysis shows that improvements in crop yield do not have much impact on biopower production. However, the energy recovery efficiency does have significant positive impact but only if the carbon equivalent price rises substantially. The analysis also indicates the desirability of cofiring biomass as opposed to 100% replacement because this reduces hauling costs and increases the efficiency of heat recovery. In terms of policy implications, imposing carbon emission pricing could be an important step in inducing electric power producers to include agricultural biomass in their fuel-mix power generation portfolios and achieve greenhouse gas emission reductions. 1 Thein Maung is a PhD candidate in the Department of Agricultural Economics at Texas A&M University. 2 Bruce McCarl is a Regents Professor in the Department of Agricultural Economics at Texas A&M University.

Admixture of Used Engine Oil with DPK (Kerosene) as an Alternative Fuel for Foundry Shop

This study presents the experimental results of using admixture of used engine oil and kerosene as an alternative fuel in foundry shops. In this experiment, several proportions of used engine oil (well filtered) and kerosene were measured to make 1000ml per mixture using a calibrated beaker. Each mixture was fired in a furnacensuring atomization, ignition and combustion in a timed set up. Results of the experiment showed that admixtures of 100%, 95% and 90% volume of used engine oil gave low pour point hence were incombustible. 85%, 80% and 75% volume of used engine oil admixtures gave carburized flame. While 55% and below of used engine oil volume of admixtures gave oxygenated flame. 57% - 70% volume of used engine oil admixtures produced neutral flame which is ideal for melting. Of the latter proportions, 70% of used engine oil admixture had the highest heat content 70,780 kj/kg and the lowest cost. Hence this admixture is recommended as an effective admixture for fuel substitution in the foundry shop.

Hydrographic changes in the Labrador Sea, 1960–2005

The Labrador Sea has exhibited significant temperature and salinity variations over the past five decades. The whole basin was extremely warm and salty between the mid-1960s and early 1970s, and fresh and cold between the late 1980s and mid-1990s. The full column salinity change observed between these periods is equivalent to mixing a 6 m thick freshwater layer into the water column of the early 1970s. The freshening and cooling trends reversed in 1994 starting a new phase of heat and salt accumulation in the Labrador Sea sustained throughout the subsequent years. It took only a decade for the whole water column to lose most of its excessive freshwater, reinstate stratification and accumulate enough salt and heat to approach its record high salt and heat contents observed between the late 1960s and the early 1970s. If the recent tendencies persist, the basin’s storages of salt and heat will fairly soon, likely by 2008, exceed their historic highs. The main process responsible for the net cooling and freshening of the Labrador Sea between 1987 and 1994 was deep winter convection, which during this period progressively developed to its record depths. It was caused by the recurrence of severe winters during these years and in its turn produced the deepest, densest and most voluminous Labrador Sea Water (LSW 1987–1994) ever observed. The estimated annual production of this water during the period of 1987–1994 is equivalent to the average volume flux of about 4.5 Sv with some individual annual rates exceeding 7.0 Sv. Once winter convection had lost its strength in the winter of 1994–1995, the deep LSW 1987–1994 layer lost “communication” with the mixed layer above, consequently losing its volume, while gaining heat and salt from the intermediate waters outside the Labrador Sea. While the 1000–2000 m layer was steadily becoming warmer and saltier between 1994 and 2005, the upper 1000 m layer experienced another episode of cooling caused by an abrupt increase in the air-sea heat fluxes in the winter of 1999–2000. This change in the atmospheric forcing resulted in fairly intense convective mixing sufficient to produce a new prominent LSW class (LSW 2000) penetrating deeper than 1300 m. This layer was steadily sinking or deepening over the years following its production and is presently overlain by even warmer and apparently less dense water mass, implying that LSW 2000 is likely to follow the fate of its deeper precursor, LSW 1987–1994. The increasing stratification of the intermediate layer implies intensification in the baroclinic component of the boundary currents around the mid-depth perimeter of the Labrador Sea. The near-bottom waters, originating from the Denmark Strait overflow, exhibit strong interannual variability featuring distinct short-term basin-scale events or pulses of anomalously cold and fresh water, separated by warm and salty overflow modifications. Regardless of their sign these anomalies pass through the abyss of the Labrador Sea, first appearing at the Greenland side and then, about a year later, at the Labrador side and in the central Labrador Basin. The Northeast Atlantic Deep Water (2500–3200 m), originating from the Iceland–Scotland Overflow Water, reached its historically freshest state in the 2000–2001 period and has been steadily becoming saltier since then. It is argued that LSW 1987–1994 significantly contributed to the freshening, density decrease and volume loss experienced by this water mass between the late 1960s and the mid 1990s via the increased entrainment of freshening LSW, the hydrostatic adjustment to expanding LSW, or both.

Variation and Correlations Among Stem Growth and Wood Traits of Calycophyllum spruceanum Benth. from the Peruvian Amazon

Abstract Calycophyllum spruceanum Benth. is an important tree for timber and energy in the western Amazon, with expanding national and international markets for its wood. There is relatively little information, however, about geographic variation in tree growth and wood properties, and correlations among these traits. The first provenance trial was established with farming communities in the Peruvian Amazon. Seven provenances, sampled from regions near the equator, were tested in three planting zones located in one watershed. Variation and correlations were investigated in stem growth at 30 and 42 months, wood density (in the lower and upper parts of the stem) and mean heat content of stem wood at 32 months. Stem height varied significantly among provenances and planting zones, but zones accounted for much more variation than provenances. Stem wood traits did not vary significantly among provenances. Wood density was greater in the lower than in the upper stem. Wood density in the upper stem and the difference in density between the lower and upper stem varied significantly among planting zones: density in the upper stem was lowest, and the difference in density between the lower and upper stem was largest in the zone where trees grew most rapidly. Phenotypic correlations between stem growth and wood density differed in sign among planting zones, suggesting that selecting fastgrowing trees could indirectly reduce wood density in environments where trees grow slowly, and increase the difference in wood density between the lower and upper stem in environments where trees grow very rapidly. Correlations between stem growth and wood heat content were stable across zones, and indicated that larger trees tended to have wood with higher heat content. Stem-wood heat content varied with provenance latitude/ longitude in the sample region, but none of the other traits varied clinally. Results indicate that there is potential to select faster-growing provenances at an early age, but this could affect wood density in certain environments.

Influence of variations in alloy composition on castability and process stability. Part 1: Gravity and pressure casting processes

The influence of variations in alloy composition on the fluidity of three different light metal alloys was investigated. The aluminium alloys AlSi9Cu3 (A380) and AlSi7Mg (A356) as well as the magnesium alloy AZ91 were cast into spiral fluidity test dies at their upper and lower compositional tolerance limits. The test results show significantly varied behaviour, which is explained by microstructural features and heat content. In alloy AlSi7Mg at the upper compositional limit the formation of intermetallic phases in the interdendritic liquid physically blocks the flow and leads to short flow length compared with the same alloy with low iron and manganese content. Alloy AlSi9Cu3 at the upper compositional limit is very close to eutectic composition and flows significantly better than the alloy at the lower tolerance limit. The intermetallic phases are formed simultaneously with the matrix during eutectic solidification and do not block the flow. In the magnesium alloy the intermetallic phase is incorporated in the primary magnesium phase and does not hinder the flow. A higher content of alloying elements increases the flow length owing to a higher heat content of the melt.

A method for measuring the relative particle fire hazard properties of forest species

A simple method was developed to determine the relative particle foliar flammability and heat content of forest fuels. The apparatus used was similar to the one described by the 79/831 European Commission Directive for measuring the relative self-ignition temperature (minimum ambient temperature at which a certain volume of a substance ignites under defined conditions). The forest materials examined were: Cupressus sempervirens (Italian cypress), Olea europaea (Olive tree), Pinus brutia (Calabrian pine), Pinus halepensis (Aleppo pine), Pistacia lentiscus (Mastic tree), Quercus coccifera (Holly oak). These species are very common in the Mediterranean region and frequently devastated by forest fires. The relative data determined (self-ignition temperature, ignition delay times, combustion duration, etc.) provide a simple screening test on the fire hazard properties of forest species, which could be used for comparison purposes. Among the forest species examined, Pinus brutia had the highest relative ignition temperature and the longest ignition delay time, while Pistacia lentiscus had the lowest and shortest ones. Also, Quercus coccifera and Pistacia lentiscus had the highest heat content and Olea europaea the lowest one. Finally, Cupressus sempervirens was the most combustible and Pinus halepensis the most sustainable fuel.

The source of the high heat and freshwater content of the upper ocean at the SHEBA site in the Beaufort Sea in 1997

Measurements of 7Be and oxygen isotope (18O/16O) ratios from the 1997–1998 SHEBA experiment were used to trace the source of the high heat and freshwater content of the upper ocean observed during the initial occupation of the SHEBA site in October 1997. The evidence suggests that the heating resulted from local input primarily through extended lead coverage in the late spring and summer of 1997 with no requirement of advective input. The freshening was derived from a large ice melt (1.2 m) that was consistent with the thin ice and extensive melt pond coverage (by then frozen) observed at the site. However, a significant contribution to the freshwater budget (0.8 m) included enhanced input from river runoff during the melt season. This obviates the requirement for an unrealistically large ice melt (∼2 m) to account for the freshwater content of the mixed layer, and would have increased the stratification stability of the upper ocean that in turn would have promoted local heating. The question then arises, however, as to the fate of the significant upper ocean heat at SHEBA in the fall 1997 which resulted from an active heating season. Similar evaluation of the fall 1998 SHEBA site indicate that the ice melt was comparable to that of 1997, but the riverine input and stored water column heat were less than in the previous year.

Environmental impact of energy recovery from waste tyres

Abstract Accumulation of millions of worn automotive tyres poses a considerable environmental problem. As an important part of the solid waste stream in today’s society, worn tyres have traditionally been discarded in landfills or stored in stockpiles. Over the past several decades, however, innovative alternatives to disposal have been developed, partly as a result of high tipping fees charged by landfill operators. Because of their high heat content and their low levels of moisture and nitrogen compared to coal, tyres are ideally suited for energy recovery through combustion. Utilization of waste tyres as supplemental or alternate fuel in various industrial combustion facilities, thus, has become one of the most important alternatives to disposal. Combustion processes, however, generate gaseous pollutants and solid waste materials, which must be disposed of or re-used as secondary raw materials. It is therefore important to characterize these combustion products in order to assess the environmental impacts of energy recovery from scrap tyres. Studies have shown that substantial reductions of some environmental pollutants can be achieved by partially replacing conventional fuels with waste tyres. On the other hand, using tyres as fuel may lead to considerable increases in the levels of other pollutants. Most notable among the effects of tyre combustion are, relative to conventional fuels, a pronounced decrease in the emission of nitrogen oxides into the atmosphere, and a generally significant increase in atmospheric zinc emissions as well as in the zinc contents of the solid combustion products. The geochemical effects on solid and gaseous combustion products are more or less pronounced depending on fuel composition, conditions of combustion, type of facility, and effectiveness of air pollution control devices. Thus, the use of tyre fuel has environmental impacts that must be weighed against the benefits of reducing the large volume of waste tyres in the global waste stream.

A study on the design of recuperative burner

Waste heat recovery from the exhaust gas of industrial furnaces and kilns that are high energy-consuming equipment is one of the effective energy conservation methods because of its high sensible heat contents. The recuperative burner integrated with a recuperator and burner is one of the combustion equipments with many advantages of simple installation, compactness and easy control which can be applied to various fields of industry. A recuperative burner with the capacity of 400 kW was designed using the design data from experimental results. Performance tests on this burner were made. The exhaust gas analysis, including NO x , the measurement of the flame temperature, velocity, heat flux and heat flux analysis on the recuperative burner were the main topics of hot combustion tests. Design data from the experimental results are gas velocity, air velocity, air velocity, the tip-location of gas nozzle, the dimension of furnace suitable to burner capacity, the dimension of recuperator and the role of cross-shaped steel plate for increasing the energy efficiency in the recuperator. For uniform temperature distribution and good thermal efficiency, it is appropriate to maintain the furnace pressure at 2-3 mm Aq.

Optimal Duration and Temperature of Prewarming

Core hypothermia developing immediately after induction of anesthesia results largely from an internal core-to-peripheral redistribution of body heat. Although difficult to treat, redistribution can be prevented by prewarming. The benefits of prewarming may be limited by sweating, thermal discomfort, and efficacy of the warming device. Accordingly, the optimal heater temperature and minimum warming duration likely to substantially reduce redistribution hypothermia were evaluated. Sweating, thermal comfort, and extremity heat content were evaluated in seven volunteers. They participated on two study days, each consisting of a 2-h control period followed by 2 h of forced-air warming with the heater set on "medium" (approximately 40 degrees C) or "high" (approximately 43 degrees C). Arm and leg tissue heat contents were determined from 19 intramuscular needle thermocouples, ten skin temperatures, and "deep" foot temperature. Half the volunteers started sweating during the second hour of warming. None of the volunteers felt uncomfortably warm during the first hour of heating, but many subsequently did. With the heater set on "high," arm and leg heat content increased 69 kcal during the first 30 min of warming and 136 kcal during the first hour of warming, representing 38% and 75%, respectively, of the values observed after 2 h of warming. The increase was only slightly less when the heater was set to "medium." Neither sweating nor thermal discomfort limited heat transfer during the first hour of warming. Thirty minutes of forced-air warming increased peripheral tissue heat content by more than the amount normally redistributed during the first hour of anesthesia. The large increase in arm and leg heat content during prewarming thus explains the observed efficacy of prewarming.

Analysing the impact of lost coal sales using the illinois remi model

Illinois is the fifth largest producer of coal in the nation. The high BTU or heat content makes it attractive to burn in the generation of electricity. However, the amount of sulfur in Illinois coal has made it a target of environmental legislation. As utilities work to meet the requirements of the 1990 Clean Air Act, it is likely that demand for Illinois coal will decline, thereby leading to a reduction in coal output of the coal-producing counties of the state. The sub-state REMI model was used to determine the impacts of the dramatic reduction of coal demand on the Illinois economy. While coal mining represents a small percentage of total gross state product, to some counties in the state, coal mining represents a significant amount of the regional product and is a principal source of employment for these areas. The impacts of lost coal output on the economy of southern Illinois as predicted by the model were significant. This led to policy prescriptions to provide incentives to utilities to burn Illinois coal. While the short-term outlook for Illinois coal may appear bleak even with incentives, it is expected that Illinois can eventually be competitive in world coal markets due to the high BTU content of the coal, the extensive reserves, and the existence of an excellent transportation network.

Cryostat for neutron investigations on a large volume of liquid ho between 5.2 and 1.2K at pressures up to 30 bars

Investigation of liquid helium-4 by neutrons scattering methods demands special cryogenic equipment. The experimental conditions require a prolonged exhibition of the large liquid helium sample. Besides, helium-4 is one of the difficult subjects for cooling, as it possesses high heat content, the thermal capacity peak in λ-point, and the thermal conductivity in the superfluid state. A cryostat for the inelastic neutron scattering research is described. Cryostat permit to operate with the large liquid helium sample (2600cm 3) at the temperature range 5.2 − 1.2K and pressure up to 30 bars.

Ocean surface topography measured by the Geosat radar altimeter during the Frontal Air‐Sea Interaction Experiment

An objective analysis (OA) technique was used to analyze Geosat Geodetic Mission residual sea height anomalies (RSHA) for the Frontal Air‐Sea Interaction Experiment (FASINEX), conducted in the western North Atlantic. Preprocessing of the Geosat data included removal of a mean sea surface and orbit error and corrections for tides, wave height, inverse barometer, and ionospheric and dry tropospheric effects. Geosat data were not corrected for water vapor. Central to the analysis was the computation of a spatially anisotropic, time‐dependent autocorrelation function directly from the Geosat data. Results show a single autocorrelation function peak, having a diameter of ∼270 km at 0‐day time lag. A 15‐month time series of RSHA topography was constructed at 10‐day intervals, forming a set of 47 OA maps. These maps show a field of topographic features propagating to the west at ∼4 km d−1. The features exhibited spatial and temporal scales of ∼200 km and ∼50 days, respectively. The root‐mean‐square (rms) of the OA‐derived feature amplitudes fluctuated slowly between 0.05 and 0.09 m with a period of ∼200 days over the 15‐month interval. These fluctuations appeared to be related to the passage of large‐scale, northeast‐southwest trending sea surface temperature (SST) anomaly features reported for FASINEX, which were surface manifestations of large‐scale, first‐mode baroclinic Rossby waves. The rms amplitude of the OA‐derived features was maximal (minimal) during periods of negative (positive) SST anomaly, when the depths of the mixed layer and main thermocline in the upper ocean shoaled (deepened). The fluctuations also appeared to be correlated with the structure of the field. Periods of decreased feature amplitudes corresponded to a “closely packed” structure, while during times of increased amplitudes, the field structure became “zonal” with regions of alternating sign. During FASINEX (January–June 1986) the field was characterized by the closely packed structure and decreasing feature amplitudes. This corresponded to the period of positive SST anomaly and high upper ocean heat content reported for FASINEX.