The Solar Minimum Active Region 7978, Its X2.6/1B Flare,CME, and Interplanetary Shock Propagation of 9 July 1996     

Dryer  M.  Andrews  M. D.  Aurass  H.  DeForest  C.  Galvin  A. B.  Garcia  H.  Ipavich  F. M.  Karlický  M.  Kiplinger  A.  Klassen  A.  Meisner  R.  Paswaters  S. E.  Smith  Z.  Tappin  S. J.  Thompson  B. J.  Watari  S. I.  Michels  D. J.  Brueckner  G. E.  Howard  R. A.  Koomen  M. J.  Lamy  P.  Mann  G.  Arzner  K.  Schwenn  R. 《Solar physics》1998,181(1):159-183

The first X-class flare in four years occurred on 9 July 1996. This X2.6/1B flare reached its maximum at 09:11 UT and was located in active region 7978 (S10° W30°) which was an old-cycle sunspot polarity group. We report the SOHO LASCO/EIT/MDI and SOONSPOT observations before and after this event together with Yohkoh SXT images of the flare, radio observations of the type II shock, and GOES disk-integrated soft X-ray flux during an extended period that included energy build-up in this active region.The LASCO coronagraphs measured a significant coronal mass ejection (CME) on the solar west limb beginning on 8 July at about 09:53 UT. The GOES 8 soft X-ray flux (0.1–0.8 nm) had started to increase on the previous day from below the A-level background (10^-8 W m^-2). At the start time of the CME, it was at the mid-B level and continued to climb. This CME is similar to many events which have been seen by LASCO and which are being interpreted as disruption of existing streamers by emerging flux ropes.LASCO and EIT were not collecting data at the time of the X-flare due to a temporary software outage. A larger CME was in progress when the first LASCO images were taken after the flare. Since the first image of the 'big' CME was obtained after the flare's start time, we cannot clearly demonstrate the physical connection of the CME to the flare. However, the LASCO CME data are consistent with an association of the flare and the CME. No eruptive filaments were observed during this event.We used the flare evidence noted above to employ in real time a simplified Shock-Time-of-Arrival (STOA) algorithm to estimate the arrival of a weak shock at the WIND spacecraft. We compare this prediction with the plasma and IMF data from WIND and plasma data from the SOHO/CELIAS instrument and suggest that the flare - and possibly the interplanetary consequences of the 'big' CME - was the progenitor of the mild, high-latitude, geomagnetic storm (daily sum of Kp=16+, Ap=8) on 12 July 1996. We speculate that the shock was attenuated enroute to Earth as a result of interaction with the heliospheric current/plasma sheet.presently at High Altitude Observatory, Boulder, CO80309, U.S.A.presently at Naval Research Laboratory, Washington DC, 20375, U.S.A.  相似文献   

MTBE—A Long-Term Threat to Ground Water Quality     

Charles Andrews 《Ground water》1998,36(5):705-706

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The petroleum geology of the Unst Basin, North Sea     

Clive R. Johns  Ian J. Andrews 《Marine and Petroleum Geology》1985,2(4):361-372

The Unst Basin is situated in the northern North Sea between the East Shetland Basin and the Shetland Isles. The basin is essentially a three-armed, Permo-Triassic fault-controlled basin containing up to 3600 m of red-beds. This is overlain by a westerly thickening Jurassic and early Cretaceous sequence, the stratigraphy of which is very similar to that of the East Shetland Basin. In particular, the Brent Group (140 m), Humber Group (685 m) and Cromer Knoll Group (300 m) are well represented.As a result of Laramide uplift of the area, the thick Upper Cretaceous and Palaeocene strata of the East Shetland Basin are absent from the Unst Basin. This uplift resulted in substantial erosion within the Unst Basin providing the major source for Palaeocene sands in the Viking Graben and the Faeroes Basin. Late Palaeocene and younger Tertiary strata transgress westwards across this erosion surface.Petroleum exploration within the basin culminated in the drilling of two exploration wells. These wells encountered potential reservoir and source rocks in the Jurassic section. However, geochemical analyses indicate these source rocks are immature for hydrocarbon generation within the Unst Basin. It is concluded that the Unst Basin has a low petroleum potential.  相似文献   

Visit to the British museum (Natural history): March 11th, 1905     

C.W. Andrews 《Proceedings of the Geologists' Association. Geologists' Association》1905,19(3):IN1-101

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The Application Of Electrical Tomography In The Study Of The Unsaturated Zone In Chalk At Three Sites In Cambridgeshire,United Kingdom     

R.J. Andrews  R. Barker  L.M. Heng 《Hydrogeology Journal》1995,3(4):17-31

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Reviews     

George S. Koch Jr.  F. P. Agterberg  Heinrich Siemes  J. T. Andrews  D. F. Merriam  James C. Kelley  S. Henley  Graeme Bonham-Carter  R. B. McCammon 《Mathematical Geosciences》1974,6(3):273-287

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Salt-Water Intrusion in the Costa de Hermosillo, Mexico: A Numerical Analysis of Water Management Proposals   总被引：1，自引：0，他引：1  

Robert W. Andrews 《Ground water》1981,19(6):635-647

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On the mean motion induced by transient inertio-gravity waves     

D. G. Andrews 《Pure and Applied Geophysics》1980,118(1):177-188

Using standard two-scaling techniques we calculate the Eulerian- and Lagrangianmean flows induced at second order in amplitude by small-amplitude, transient, non-dissipative, vertically-propagating inertio-gravity waves on anf-plane. The example is an idealized one, but illustrates a number of important features that are typical of wave, mean-flow interaction in a rotating, stratified fluid. Physical discussion of the solution is given in Section 4 of the review byMcIntyre (1980), which appears elsewhere in this issue.  相似文献   

Magnetic pulsation behaviour in the magnetosphere inferred from whistler mode signals     

M.K. Andrews 《Planetary and Space Science》1977,25(10):957-966

During a long series of recordings of the Doppler shift of signals from NLK, Seattle, which have propagated in ducts in the whistler mode, a number of occasions have been noted where the duct has been acted on by the electric field of micropulsation events in the Pc4–5 range. Large oscillations are produced in the Doppler shift of the received VLF signal.It is shown that the field line has an antinode of motion in the equatorial plane, and that the Doppler shift is responding almost entirely to the radial component of the duct motion. The latter enables a comparison to be made between the magnetic disturbance in the magnetosphere and that seen on the ground. Some support is given to the prediction of Hughes (1974) and Inoue (1973) that the magnetospheric disturbance vector when seen on the ground is rotated 90° by the currents induced in the ionosphere. Models of the oscillating field line enable an estimate to be made of the azimuthal component of the electric field in the equatorial plane. This is typically $\text{1}\text{mV}\text{m}$. The model also predicts the north-south magnetic field strength of the transverse standing wave at the base of the magnetosphere, and this value may be compared with that seen on the ground. Values of the order 1–2 times the ground H-component or 5–10 times the ground D-component were found.  相似文献   

Influence of small-scale gold mining and toxic element concentrations in Bonsa river,Ghana: a potential risk to water quality and public health     

Andrews?Obeng?AffumEmail author  Shiloh?Osae?Dede  Benjamin?Jabes?Botwe?Nyarko  Samuel?Osafo?Acquaah  Edward?Ebow?Kwaansa-Ansah  Godfred?Darko  Adomako?Dickson  Enoch?Acheampong?Affum  Joseph?Richmond?Fianko 《Environmental Earth Sciences》2016,75(2):178

A preliminary assessment of toxic element pollution caused by artisanal and small-scale gold mining in the Bonsa river of Ghana as well as the influence of TOC and SO₄ ^2? concentration on these traces in the sediment has been determined. With the exception of mercury (Hg), manganese (Mn), and arsenic (As), the concentration of aluminum (Al) in filtered river water exceeded the WHO guideline limit of 0.1 mg L^?1 in drinking water. Analyses of toxic element in sediment using Canadian Sediment Quality Criteria, contamination factor, geoaccumulation index, and enrichment factor indicate that river sediment is severely contaminated with Hg confirming the negative impact of the amalgamation technique in gold beneficiation in Ghana. The level of Hg in the surface water exceeded reported values from some rivers in Africa, Asia, and South America. The ranking order of the mean element concentration in both matrices followed the conservative order of traces found in the Earth crust except copper, which was below the detection limit of 0.01 mg kg^?1. A Pearson correlation matrix of the toxic element and geology of the river bedrock indicates that the Hg contamination is of anthropogenic origin whilst As, Mn, and Al are the result of natural enrichment. The partitioning of elements in the sediment compartments is independent of TOC and SO₄ ^2? concentration. Health-risk assessment based on average daily dose, hazard quotient, and cancer risk indicates that Hg is a health risk to the human population. In conclusion, the study has shown that there is a likely anthropic affection of the river and that this situation has worsened since earlier studies. In order to sustain aquatic life and to prevent future human health hazard, an immediate mercury remediation in the river is recommended.  相似文献