North Lobe Research Articles

PLAN FOR INJECTION OF COAL COMBUSTION BYPRODUCTS INTO THE OMEGA MINE FOR THE REDUCTION OF ACID MINE DRA1NAGE

The Omega Mine Complex is located outside of Morgantown, West Virginia. The mine is in the Upper Freeport Coal, an acid-producing coal seam. The coal was mined in a manner that has resulted in acid mine drainage (AMD) discharges at multiple points. During the 1990`s, the West Virginia Division of Environmental Protection (WVDEP) assumed responsibility for operating a collection and treatment system for the AMD. Collection and treatment costs are approximately $300,000 per year. An innovative procedure of injecting grout into the mine working to reduce AMD and the resulting treatment costs is proposed. The procedure involves injecting grout mixes composed primarily of coal combustion byproducts (CCB`s) and water, with a small quantity of cement. The intention of the injection program is to fill the mine voids in the north lobe of the Omega Mine (an area where most of the acidity is believed to be generated) with the grout, thus reducing the contact of air and water with potentially acidic material. The grout mix design consists of an approximate 1:1 ratio of fly ash to byproducts from fluidized bed combustion. Approximately 100 gallons of water per cubic yard of grout is used to help achieve flowability. Observation of themore » mine workings via subsurface borings and downhole video camera operation confirmed that first-mined areas were generally open while second-mined areas were generally partially collapsed. The injection program was developed to account for this by utilizing closer injection hole spacing in second-mined areas. Administration of a construction contract for the project is on-going through WVDEP`s Abandoned Mine Lands (AML) program. Funding for the project is coming from the WVDEP; Allegheny Power; Consol, Inc.; United States Office of Surface Mining Reclamation and Enforcement (OSMRE); Anker Energy Corporation; and the Electric Power Research Institute.« less

Spectropolarimetry of the Bipolar Planetary Nebula M2-9

We present optical spectropolarimetry of the young bipolar planetary nebula M2-9. The goal of these observations is to determined the origin of the knots or brightness enhancements seen in the lobes of M2-9. The line spectra of the lobes of M2-9 are composed of two components, one that is produced locally in the lobes and one that is scattered from deep in the nebula. The presence of this scattered radiation means that the total flux line ratios do not accurately describe the local conditions in the lobes. We have obtained spectropolarimetric data of the N2 and S2 knots and the adjacent nebula, and we use our data to separate the scattered and unscattered emission-line components. <P />The spectrum of the core of M2-9 exhibits broad Hα emission lines. In our high-resolution spectra we observe a broad wing on the scattered Hα line profile at all of the positions in the north lobe. This confirms that the scattered line emission originates in the core. In addition, we calculate the outflow velocity of the scatterers, ≍15 km s<SUP>-1</SUP>, based on the observed wavelength shift between the Hα peak in scattered and unscattered flux. <P />Using the unscattered spectra, we derive the local line ratios as a function of position in the north and south lobes. The degree of ionization of the spectra decreases in the off-knot regions. We measure the gas temperature as a function of position and find that it is approximately constant across the lobes. This result rules out the simple recombination tail model proposed by Goodrich for the origin of the knots. We suggest instead that the off-knot positions are ionized by a UV spectrum that is attenuated by material between the off-knot positions and the central UV source. We have used the photoionization code CLOUDY to test this idea and find that attenuation effects alone cannot accurately reproduce the observed unscattered line ratios. To accurately model the observed line ratios in the knots, we require the presence of both high (≥ 10<SUP>5</SUP> cm<SUP>-3</SUP>) and low (≍ 10<SUP>3</SUP> cm<SUP>-3</SUP>) density components. For the off-knot positions both attenuation effects and multiple density components are necessary to reproduce the observed line ratios. <P />We modify the recombination tail model proposed by Goodrich to explain the origin of the knots in M2-9. We propose, as did Goodrich, that at discrete north-south levels, the lobes of M2-9 contain "rings" of higher density material. The UV source illuminates a section of the lobe, causing these rings of material to glow, producing the knots and explaining and naturally leading to their "fixed" north-south positions. Obscuring material near the star keeps one side of the lobe from being illuminated by the full force of UV source, thus explaining the lower excitation off-knot spectra. This model can explain why the knots appear to move only in the east-west plane, while remaining fixed in the north-south direction. In addition, it explains why the observed spectra in the off-knot regions are lower excitation than the knot spectra.

Long duration Pc 5 compressional pulsations inside the Earth's magnetotail lobes

Abstract. Pc 5-type magnetic field pulsations are detected by the IMP-8 spacecraft well inside the Earth's magnetotail lobes. The three studied events with an average duration of 3 h and mean amplitude of ΔB/B=6.6% show a strong longitudinal oscillation. The clockwise polarization sense of the magnetic field arrowheads in the north lobe (as well as the counterclockwise in the south lobe) on the XZ plane is consistent with that expected when periodic solar wind lateral pressures squeeze the magnetotail axisymmetrically while moving tailward. In the two case studies, the latter property has been found to concur with quasi-periodic upstream density fluctuations detected by ISEE-3 and/or ISSE-1. The lobe magnetic field oscillations are classified in two distinct modes. The manifestations of the first mode are tailward-travelling waves detectable along the By and Bz magnetic field traces (i.e., with regard to the Bz the spacecraft encounters constantly the same conspicuous signature of south-then-north tilting of field lines around each local compression region). The second mode is associated with prolonged periods of extremely low geomagnetic activity and exhibits a signature along the By component inconsistent with travelling waves. Thus, the maxima of compressions occur simultaneously with the maxima of By excursions: a feature that is explained in terms of tail-aligned current density flowing at the boundary which separates the stable magnetic field in the tail lobe from the very irregular in the magnetosheath. In this case, the spacecraft was located in the vicinity of the high-latitude tail boundary and the observed By excursions are consistent with those anticipated by the tail-aligned current polarity, which is determined by the dominant By-component of the interplanetary magnetic field (IMF). On the plane YZ we observe an almost linear and circular polarization sense of the vector magnetic field for the first and second mode, respectively.

Long duration Pc 5 compressional pulsations inside the Earth’s magnetotail lobes

<strong class="journal-contentHeaderColor">Abstract.</strong> Pc 5-type magnetic field pulsations are detected by the IMP-8 spacecraft well inside the Earth's magnetotail lobes. The three studied events with an average duration of 3 h and mean amplitude of &#916;<i>B</i>/<i>B</i>=6.6% show a strong longitudinal oscillation. The clockwise polarization sense of the magnetic field arrowheads in the north lobe (as well as the counterclockwise in the south lobe) on the <i>XZ</i> plane is consistent with that expected when periodic solar wind lateral pressures squeeze the magnetotail axisymmetrically while moving tailward. In the two case studies, the latter property has been found to concur with quasi-periodic upstream density fluctuations detected by ISEE-3 and/or ISSE-1. The lobe magnetic field oscillations are classified in two distinct modes. The manifestations of the first mode are tailward-travelling waves detectable along the <i>B_y</i> and <i>B_z</i> magnetic field traces (i.e., with regard to the <i>B_z</i> the spacecraft encounters constantly the same conspicuous signature of south-then-north tilting of field lines around each local compression region). The second mode is associated with prolonged periods of extremely low geomagnetic activity and exhibits a signature along the <i>B_y</i> component inconsistent with travelling waves. Thus, the maxima of compressions occur simultaneously with the maxima of <i>B_y</i> excursions: a feature that is explained in terms of tail-aligned current density flowing at the boundary which separates the stable magnetic field in the tail lobe from the very irregular in the magnetosheath. In this case, the spacecraft was located in the vicinity of the high-latitude tail boundary and the observed <i>B_y</i> excursions are consistent with those anticipated by the tail-aligned current polarity, which is determined by the dominant <i>B_y</i>-component of the interplanetary magnetic field (IMF). On the plane <i>YZ</i> we observe an almost linear and circular polarization sense of the vector magnetic field for the first and second mode, respectively.

Average motion, structure and orientation of the distant magnetotail determined from remote sensing of the edge of the plasma sheet boundary layer with E &gt; 35 keV ions

In this paper, we study gradients of the energetic ion intensity observed at the edge of the plasma sheet boundary layer (PSBL) by the energetic ion anisotropy spectrometer (EPAS) on ISEE 3. In particular, we have determined the velocity of the boundary relative to the spacecraft in the direction perpendicular to the tail axis and the angle which the boundary normal makes to the spacecraft spin axis for 1160 PSBL encounters at XGSM &gt; −240 RE. By assuming that, on average, the edge of the PSBL is parallel to the cross‐tail current sheet, we are then able to determine a number of properties of the structure, orientation and motion of the deep geomagnetic tail. We conclude the following: (1) Most crossings of the edge of the PSBL are caused by transverse motion of the entire tail induced by solar wind direction variations, although some are caused by reconfiguration of the tail due to geomagnetic activity. (2) The typical velocity of the PSBL (and hence of the tail) in a direction perpendicular to the tail axis is 50–85 km s−1. (3) The average twist of the tail is near zero, with the edge of the PSBL (and by inference the cross‐tail current sheet) lying parallel to the ecliptic plane (however, large twists are found in individual events and the distribution of twists is broad, with one standard deviation of ∼50°. (4) The width of the distribution decreases with downtail distance. (5) The variation of the distributions with cross‐tail position reveals that this decrease in width is most likely due to the edge of the PSBL being concave, or significantly flared at the tail flanks, in the near‐Earth region. This flaring is absent further downtail. In fact, at XGSM &lt; −200 RE, the combined thickness of the plasma sheet and PSBL may be greatest at the tail centre and reduced towards the flanks. (6) During days on which the IMF has “away” sector structure, the north lobe of the tail is twisted on average towards dawn by 7.0±2.4°. (7) During days on which the IMF has "toward" sector structure, the north lobe is tilted towards dusk by 3.8±2.3°. (8) A subset of events for which IMP 8 solar wind data are available show that, for southward IMF Bz, the tail has a mean twist of −12.3±5.0° for IMF By &gt; 0 and 5.5±3.8° for IMF By &lt; 0 (positive twist angles correspond to a tilt of the northern lobe towards dusk). (9) For northward IMF Bz, the tail has a twist of −23.9±5.0° for IMF By &gt; 0 and 13.4±6.0° for IMF By &lt; 0. Hence the tail appears more twisted on average for the IMF Bz northward case. (10) The distribution of tail twists is wider for lower levels of geomagnetic activity, indicating that the tail is able to twist more at lower levels of activity. (11) The data set reveals no evident effect of the Earth's dipole wobble; tail orientation appears to be controlled by the solar wind and IMF, such that the GSE coordinate system may be appropriate for the study of field and plasma structures in the distant tail region.

Combining A Volumetric Model With A Pseudo-Miscible Field Simulation To Achieve Uniform Fluid Levelling In The Rainbow Keg River "B" Pool

Abstract A vertical first-contact hydrocarbon miscible flood is being applied to the Rainbow Keg River "B" Pool since June 22, 1984 as a tertiary process to recover additional oil from the previously water-swept oil zone. The "B" Pool is a reef of Middle Devonian age containing the largest oil accumulation in the Rainbow Field. The pool consists of a North Lobe and a South Lobe separated by a saddle. The major EOR target in this pool is represented by the 19 × 106 m3 (120 × 106 STB) of residual oil left unswept in the water flooded region. One of the key operating objectives is to achieve horizontal fluid levels having a uniform solvent bank across the pool at the time when the solvent bank merges at the saddle. A three-dimensional pseudo-miscible reservoir simulation model updated with the latest results from 3-D seismic, geology and petrophysics was constructed to successfully match the pool's 19 years of waterflood and 3 years of tertiary hydrocarbon miscible flood history. An analytical volumetric model was developed to define parameters such as fluid levels and rates in conjunction with the field scale 3-D simulation model. A solvent-in-place cutoff volume was used to determine when the miscible flood ceased and became an immiscible gas flood. Ultimate recovery in the order of 70% to 80% is anticipated depending on the solvent slug size and solvent production. This paper describes how an analytical volumetric model can be run in synergy with a complex full field simulator to achieve the objective of obtaining and maintaining horizontal fluid levels throughout the pool. Introduction The Rainbow Keg River "B" Pool is located in northwestern Alberta (Fig. 1) and contains the largest oil accumulation of the Rainbow Field, having 43 × 106 m3 (270 × 106 STB) of original oil-in-place (OOIP). Total oil production as of March 1990 amounted to 19.7 × 106 m3 (124 × 106 STB) or 46%, of the OOIP. The pool isopach, reef top to original oil-water contact (OOWC), shown in Figure 2, illustrates the reef's geometry as inferred from excellent quality 3-D seismic data and well information. The geological model contains three horizontal zones within the original oil column arranged in a more-or-less "Layer-cake" fashion as shown in Figure 3. The uppermost, the thin "A" zone is largely limestone. Underlying the capping "A" zone is the "B" zone, which is all dolomite. Generally, increased vugginess in the pool coincides with the top of the "B" zone. The "B" zone is also recognized by an absence of the ubiquitous pyrobitumen which characterizes the basal "C" zone. The "C" or pyrobitumen (properly carbon) zone shows an oil-wet tendency. Both the dolomite and the pyrobitumen extend to and below the pool's OOWC. Highly fractured and vuggy intervals were not co relatable from well to well and do not in themselves form a definable zone or zones. Instead, high incidence of fracture and vuggy intervals were reported on an individual well bases for incorporation into the numerical model.

Investigation of six anatomical and four statistical features of bald-cypress ( Taxodium distichum) tree rings

A tree-ring study was conducted to determine if growth rings on core samples from bald cypress ( Taxodium distichum (L.) Rich.) differed significantly in anatomical and statistical features depending on where on the tree the sample was taken. The variables studied were compass direction and surface geometry of the trunk. If significant differences exist, then standardization of core type could provide a higher-quality sample and a more reliable variance measurement for the comparison of tree-core data from different trees. The trunk of bald cypress is often irregular in circumference, forming lobes and furrows. Eight core types were sampled on each tree: north lobe, north furrow, south lobe, south furrow, east lobe, east furrow, west lobe, and west furrow. When anatomical and statistical features were compared, no significant difference in ring-width data was measured that was attributable to compass direction of the core site, with one exception: cores from south furrows had a significantly greater number of missing and merging rings when compared to other furrow cores. Furrow samples were found to have significantly more missing and/or merging rings and significantly fewer false rings than lobe samples. The number of apparent ring-shakes was found to differ significantly among trees. The effect of core type, i.e. compass direction or lobe versus furrow, on ring-width data appears to depend on the year the growth ring was formed.

Plasma electrons as tracers of distant magnetotail structure: ISEE-3

Electrons in the 50–500 eV energy range commonly exhibit strong, field-aligned bidirectional anisotropies in the distant (r > 100 R E) geomagnetic tail lobes and are found to occur predominantly in the lobe directly connected to the sun along the interplanetary magnetic field in the open magnetosphere model (north lobe for away interplanetary sectors and south lobe for toward sectors). Data show the transition from unidirectional (sheath) electron populations to bidirectional (lobe) populations at the distant magnetopause. This demonstrates the open nature of the distant magnetotail and shows that the source of the higher-energy, bidirectional lobe electrons is the tailward-directed electron heat flux population in the magnetosheath. The field-aligned lobe electron phase space densities above ∼ 200 eV at ISEE-3 agree well with DMSP-measured polar rain phase space densities near the polar cap and the spectral slopes above 200 eV also are similar. Below 100–200 eV there is a thermal electron population in the distant tail, arising from local entry of plasma through the distant magnetopause, which is not present at DMSP altitudes. These data show that the suprathermal tail lobe electrons are essentially a test particle population which can move freely along field lines to form polar rain; in contrast, the thermal electrons are bound to the tailward-flowing lobe ion population far down the tail and thus cannot reach the polar cap regions.

Observations of polar rain at low and high altitudes

Observations in the distant magnetotail lobes (r ≳ 100 RE) reveal that electrons in the ∼50‐ to 1000‐eV energy range often exhibit strong, field‐aligned bidirectional anisotropies. Because of large tail motions in the variable flow of the solar wind, ISEE 3 data provide extensive sampling of most tail plasma regions in rapid succession. It is found that bidirectional electron fluxes occur predominantly in the lobe connected directly to the sunward interplanetary magnetic field in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Using data from the low‐altitude DMSP spacecraft, we compare polar rain electron intensities, energy spectra, and time variations at low altitudes with concurrent bidirectional electron properties measured by ISEE 3. The field‐aligned lobe electron phase space densities above ∼200 eV agree well (i.e., to within a factor of ∼2–3) with DMSP‐measured polar rain phase space densities near the polar cap. Furthermore, the spectral slopes above 200 eV also are similar at low and high altitudes. Below 100–200 eV there is a thermal electron population in the distant tail, probably arising from local entry of plasma through the distant magnetopause, which is not present at DMSP altitudes. These data suggest that the suprathermal tail lobe electrons are essentially a test particle population which can move freely along field lines to form polar rain; in contrast, the thermal electrons are bound to the tailward flowing lobe ion population far down the tail and thus cannot reach the polar cap regions.

Molecular hydrogen in S106

Emission from the |$\upsilon=1-0\enspace S(1)$| line of molecular hydrogen at 2.122 μm has been found and mapped in the bipolar nebula S106. The emission is extended along an axis running approximately N–S, similar to the radio and mid-infrared emission. More emission is seen from the north lobe than the south, and generally there is an anti-correlation between the H2 and radio emission. In particular, the strongest H2 emission comes from a peak at the outer boundary of the northern radio lobe. The total luminosity in H2 emission can be accounted for completely either by shock excitation driven by mass loss at a rate close to that calculated by other methods, or by ultraviolet excitation by photons from an O9.0 ZAMS star. Emission line ratios in the 2.0–2.5 μm region are indeed consistent with a combination of shock- and ultraviolet-excitation mechanisms.

Strong electron bidirectional anisotropies in the distant tail: ISEE 3 observations of polar rain

A detailed observational treatment of bidirectional electrons (∼50 to 500 eV) in the distant magnetotail (r ≳ 100 RE) is presented. It is found that electrons in this energy range commonly exhibit strong, field‐aligned anisotropies in the tail lobes. Because of large tail motions, the ISEE 3 data provide extensive sampling of both the north and south lobes in rapid succession. These data demonstrate directly the strong asymmetries that exist between the north and south lobes at any one time. The bidirectional fluxes are found to occur predominantly in the lobe directly connected to the sunward interplanetary magnetic field in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Electron anisotropy and magnetic field data are presented which show the transition from unidirectional (sheath) electron populations to bidirectional (lobe) populations. Thus we demonstrate the open nature of the distant magnetopause and show that the source of the higher‐energy, bidirectional lobe electrons is the tailward directed electron heat flux population in the distant magnetosheath. Taken together, the present evidence suggests that the bidirectional electrons that we observe in the distant tail are closely related to the polar rain electrons observed previously at lower altitudes. Furthermore, these data provide strong evidence that the distant tail is composed largely of open magnetic field lines in contradistinction to some recently advanced models.

PKS 0812+020: a quasar interacting with its environment

Slit spectra have shown optical emission line gas in the vicinity of the radio jet and the north radio lobe of PKS 0812+020. Velocities up to −1000 km/s with respect to the central quasar are seen in the north lobe. The [OII] emission strength becomes comparable to the [OIII] near the north lobe, as would be expected from acceleration by shocks. We suggest this acceleration occurs by interaction with the radio-emitting jet.

North‐south and dawn‐dusk plasma asymmetries in the distant tail lobes: ISEE 3

ISEE 3 plasma measurements made in the distant geomagnetic tail during rapid traversals of the current sheet from one lobe to the other show that the lobe densities on opposite sides of the current sheet often differ by a factor of ∼3–10 or more. On the dawnside of the tail the north lobe plasma has the higher density when the interplanetary magnetic field (IMF) has a +By component, and the south lobe plasma has the higher density when the IMF has a −By component. The sense of this asymmetry is reversed on the duskside of the tail. Such IMF‐controlled asymmetries in lobe plasma density are consistent with earlier observations made much closer to earth and can be interpreted most simply as a consequence of an “open” geomagnetic tail.

The distant magnetotail's response to a strong interplanetary magnetic field By: Twisting, flattening, and field line bending

During an interval of strong interplanetary magnetic field (IMF) By, while ISEE 3 was in the distant magnetotail, the north lobe was observed south of the ecliptic plane. Lobe field lines were strongly bent in the direction of the IMF, and a dense boundary layer plasma was observed. During the interval, magnetopause normals pointed in the z direction, although ISEE 3 was near the dawnside ecliptic plane. The observations are interpreted in terms of field line bending within a twisted and flattened magnetotail.

Entry of solar protons to the plasma sheet and lobe of the magnetotail at r=18 RE in the event of April 22, 1971

Vela satellites of orbit r=18 RE measured the intensity of ≲1‐MeV solar protons at two points in the plasma sheet and one in the north tail lobe during an 8‐hour period on April 22, 1971. Intensities were isotropic, except when a sharp gradient was convected past a satellite. Several such gradients have been interpreted as the boundary between plasma sheet and north lobe. Movement of this plasma sheet surface has been observed in coincidence with substorm and geomagnetic storm activity. It is inferred that the region of open field lines at Vela orbit was very small in this event. A prolonged intensity difference by a factor of almost 2 existed across the surface between plasma sheet and lobe for &gt;8 hours, implying very little cross‐field transport of ≲1‐MeV protons. One gradient‐induced anisotropy was anomalous in direction and has been explained by a tongue‐shaped distortion in the surface separating plasma sheet and lobe. A second case of anomalous anisotropy from another event has been explained in a similar way. Intercomparison between Vela and Imp 6, the latter in interplanetary space, suggests the following. Access of ≲1‐MeV solar protons to the north tail lobe was delayed by 3–4 hours, giving an access point 602–872 RE from earth. The intensity there was a little higher than the mean of the interplanetary distribution. The intensity in the dusk plasma sheet lay between the mean in interplanetary space and the integrated intensity of the backward moving interplanetary particles (−1 &lt; µ &lt; 0). The intensity in the dawn plasma sheet was lower and tracked the integrated intensity of the backward moving particles in interplanetary space. This gradient across the plasma sheet at r=18 RE implies that there was not a thorough mixing of ≲1‐MeV protons, at least on a time scale of hours.

The solar proton event of April 16, 1970, 3. Evolution of pitch angle distribution as ≲1‐MeV protons propagate into the high‐latitude magnetotail

The solar proton event of April 16, 1970 was monitored by Vela satellites, of orbit r=18 RE, in the solar wind and high‐latitude magnetotail (lobe). Intensity structure at ≲1 MeV indicates a delay of 85–102 min in access of protons to near the center of the north lobe, corresponding to entry points at 340–370 RE from the earth. In three sequential periods, of 16, 181, and 124 min duration, the average intensity in the north lobe was lower, higher, and lower, respectively, than that in interplanetary space by factors which varied from 2 to 5. These reversals were a consequence of reversals in field‐aligned anisotropy in interplanetary space, the interplanetary magnetic field remaining southward. Pitch angle distributions were measured in three dimensions in interplanetary space and in the north lobe. In the lobe the distributions were essentially isotropic at r=18 RE. Comparison is made with theoretical propagation of solar particles along field lines in an open tail model, under the following conditions along a trajectory: (1) adiabatic motion all the way (Liouville theorem)—the ‘adiabatic access model’ or (2) isotropization at the magnetopause followed by adiabatic motion—the ‘nonadiabatic access model.’ Neither mode of access explains the observations adequately. A hybrid mode is proposed, in which a minimal amount of scattering occurs as particles enter the tail, followed by amplification (attenuation) of intensity as the pitch distribution is transformed to near 18 RE in the favored (unfavored) lobe. In this mode a large part of the isotropization at Vela orbit is accomplished by the Liouville transformation, since particles entering the tail beyond ≈100 RE will see an increase in magnetic field by a factor of 3 as they propagate along the tail. The amount of scatter at the magnetopause is estimated to be Δµ(rms)=0.3, where µ is cosine of pitch angle. Intensity discrepancies later in the event are interpreted as (1) a brief adjustment in the topology of the magnetotail in which the field line through Vela 6A changed its exit point to ≈530 RE, compared to ≈350 RE before and ≈420 RE after and (2) interconnection between interplanetary and magnetotail fields determined by the radial component of the interplanetary field, as distinct from the southward component during the main portion of the event (the particle access window, however, remained at the same distance from the earth).