bluuebunny/crossref_metadata_2025 huggingface dataset:
Spektroskopische und strukturelle Charakterisierung von Tris(2, 6‐di‐t‐butyl‐phenolato)lanthanid(III) (Ln(OAr′)3; Ln = Pr, Nd) sowie parametrische Analyse des Kristallfeld‐Aufspaltungsmusters von Nd(OAr′)3
Authors: Amberger Hanns‐Dieter , Reddmann Hauke , Guttenberger Clemens , Unrecht Bernhard , Zhang Lixin , Apostolidis Christos , Walter Olaf , Kanellakopulos Basil
Published: August 2003

Pr(OAr′)3 und Nd(OAr′)3 kristallisieren (bei ca. 150 K bzw. 200 K) in der monoklinen Raumgruppe P21 mit vier Molekülen pro Elementarzelle. Betrachtet man lediglich die unmittelbar koordinierten Sauerstoffatome, dann ist das effektive Kristallfeld von C3v‐Symmetrie. Die Signale in den optischen Spektren von Pr(OAr′)3 sind selbst bei 80‐90 K sowohl bei Verwendung von Lösungen als auch von Festkörpern ungewöhnlich breit, so daß sie sich nicht für Interpretationszwecke eignen. Nd(OAr′)3 weist dagegen sowohl bei Raumtemperatur als auch bei tiefen Temperaturen scharfe Absorptionsbanden auf, die in Analogie zu den bereits früher auf der Grundlage optischer Polarisationsmessungen identifizierten Absorptionsübergängen von Nd[N(SiMe3)2]3 zugeordnet werden. Das so abgeleitete Kristallfeld‐Aufspaltungsmuster wird durch Anpassung der offenen Parameter eines phänomenologischen Hamilton‐Operators simuliert, wobei eine reduzierte r.m.s.‐Abweichung von 26.4 cm—1 bei 64 Zuordnungen erzielt wurde. Die dabei verwendeten Parameter gestatten die Bestimmung der Ligandenfeldstärke des (OAr′)—‐Liganden, die Einreihung dieses Liganden in empirische nephelauxetische und relativistische nephelauxetische Reihen und die Aufstellung experimentorientierter nichtrelativistischer und relativistischer Molekülorbital‐Schemata im f‐Bereich.
Cs2[MnSnTe4]: Ungewöhnliche Synthese einer quaternären Phase mit eindimensionalen, ternären Anionensträngen
Authors: Zimmermann Christian , Dehnen Stefanie
Published: August 2003

Die Umsetzung eines Methanol‐Solvats des bisher nicht beschriebenen Orthotellurstannat(IV)‐Salzes Cs4[SnTe4] (1) mit MnCl2·4H2O in Wasser führte zur Synthese der quaternären Phase Cs2[MnSnTe4] (2), deren Kristallstruktur mittels Einkristallstrukturanalyse geklärt wurde. 2: Raumgruppe Fddd; Gitterabmessungen bei 203 K: a = 681.9(1), b = 1506.3(3), c = 2596.7(5) pm, V = 2667.2(9)·106pm3; R1 = 0.0655. Mit der Synthese von 2 gelang es erstmals, Orthotellurostannat‐Anionen unzersetzt in die Koordinationssphäre eines 3d‐Übergangsmetallions zu überführen. 2 enthält eine ternäre anionische Substruktur in Form eindimensional ausgedehnter, paralleler 1{[MnSnTe4]2—}‐Stränge. Trotz des nasschemischen Syntheseweges enthält 2 keine Solvensmoleküle im Kristallgitter.
Crystal Structure of LiClO4
Authors: Wickleder Mathias S.
Published: August 2003

Single crystals of LiClO4 were obtained during attempts to prepare lithium containing rare earth perchlorates from a lithium perchlorate melt. In the crystal structure of LiClO4 (ortho‐rhombic, Pnma, Z =4, a = 865.7(1), b = 691.29(9) pm, c = 483.23(6), Rall = 0.0273) the Li+ ions are in distorted octahedral coordination of oxygen atoms. The octahedra are linked via common edges to chains according to 1[LiO2/1O4/2] which run in the [010] direction. The perchlorate ions are almost ideal tetrahedra.
Umsetzungen von Cp*NbCl4 und Cp*TaCl4 mit Trimethylsilyl‐azid, Me3Si‐N3. Molekülstrukturen der bis(azido)‐oxo‐verbrückten Komplexe [Cp*NbCl(N3)(μ‐N3)]2(μ‐O) und [Cp*TaCl2(μ‐N3)]2(μ‐O) (Cp* = Pentamethylcyclopentadienyl)
Authors: Herberhold Max , Goller Achim , Milius Wolfgang
Published: August 2003

Die Chloro‐Liganden in Cp*TaCl4 (1c) lassen sich bei der Umsetzung mit Trimethylsilyl‐azid, Me3Si‐N3 (A), schrittweise durch Azido‐Liganden ersetzen. Dabei entsteht die vollständige Reihe der bis(azido)‐verbrückten Dimeren [Cp*TaCl3‐n(N3)n(μ‐N3)]2 (n = 0 (2c), n = 1 (3c), n = 2 (4c) und n = 3 (5c)). Wenn das Solvens CH2Cl2 Wasserspuren enthält, wird unter Bildung von [Cp*TaCl2(μ‐N3)]2(μ‐O) (6c) oder [Cp*TaCl(N3)(μ‐N3)]2(μ‐O) (7c) eine zusätzliche Oxo‐Brücke eingebaut; 6c und 7c bilden sich auch in stöchiometrischer Reaktion aus [Cp*TaCl2(μ‐OH)]2(μ‐O) (8c) und A. Bei analogen Umsetzungen von Cp*NbCl4 (1b) mit A wurden die azid‐reichen Zweikernkomplexe [Cp*NbCl3‐n(N3)n(μ‐N3)]2 (n = 2 (4b) und n = 3 (5b)) und [Cp*NbCl(N3)(μ‐N3)]2(μ‐O) (7b) isoliert. Aus Cp*Ta(Cl)Me3 und A kann der einkernige Komplex Cp*Ta(N3)Me3 (10c) dargestellt werden. Alle Azido‐Komplexe wurden anhand ihrer IR‐ und 1H‐ bzw. 13C‐NMR‐Spektren charakterisiert; für 6c und 7b liegen Röntgenstrukturanalysen vor.
Synthesis and Structure of an Unusual Carbonyl Ruthenium(II) Complex Containing Neutral NO2 as Ligand: [Ru(NO2)4(CO)(H2O)]Cl2·2H2O
Authors: Wang Wen‐Zhen , Liu Xin , Liao Dai‐Zheng , Jiang Zong‐Hui , Yan Shi‐Ping , Wang Geng‐Lin
Published: August 2003

A new ruthenium(II) complex [Ru(NO2)4(CO)(H2O)]Cl2 · 2H2O has been prepared and characterized structurally. The compound crystallizes in monoclinic space group C2 /m, with the unit cell parameters a = 12.913(2), b = 14.605(2), c = 7.4494(1)Å, ß =121.49(2)°; V = 1198.0(3)Å3, Z = 4, Dc = 2.429 Mgm—3; μ = 1.83 mm—1; R = 0.0455, wR = 0.1552. The complex contains four neutral NO2 ligands. The ruthenium atom is six‐coordinated to four nitrogen atoms of nitrogen dioxide, one carbon atom from carbon monoxide and one oxygen atom from water molecule, forming slightly distorted octahedral coordination. The preparation procedure has been discussed.
Double Carbonyl Substitution in [BrMn(CO)5]: Reaction with Benzoylhydrazine and Synthesis of fac‐[Mn(Br)(CO)3(BHD)]·2THF (BHD = OC(Ph)—NH—NH2)
Authors: de Oliveira Gelson Manzoni , Casagrande Gleison Antonio , Faoro Eliandro , Fernandes Jr. Ramão Marceli , Mayer Peter , Schulz Lang Ernesto
Published: August 2003

[BrMn(CO)5] reacts with benzoylhydrazine in THF occurring substitution of two CO groups by a Metal‐ligand ring to give fac‐[Mn(Br)(CO)3(BHD)]·2THF (BHD = C6H5CONHNH2). The novel compound shows a distorted octahedral arrangement at the manganese atom, with three nearly linear carbonyl ligands in a fac arrangement, illustrating another example that the CO group in position trans to the bromine ligand in [BrMn(CO)5] presents the most intensive metal‐CO backbonding effect of all the CO groups of the parent complex, leading to the formation of a facial (and not meridional) isomer, even in the presence of a bidentate ligand like benzydrazide. X‐ray measures of yellow crystals showed that the title complex belong to space group P21/c, with the asymmetric unit containing one crystallographically independent [Mn(Br)(CO)3(BHD)] complex and two tetrahydrofurane solvate molecules. The new compound represents heretofore the unique occurrence of the complexing single bidentate ligand ‐O=C(Ph)‐N(H)‐N(H)2‐ with an octahedral coordination at the MnI atom supported chiefly by carbonyl groups.
First Homoleptic Rare Earth Carbazolates: Synthesis, Crystal Structures, Spectroscopic and Thermal Investigations of Divalent 1[Ln(NC12H8)2] with Ln = Europium and Ytterbium
Authors: Müller‐Buschbaum Klaus , Quitmann Catharina C.
Published: August 2003

The compounds [Ln(NC12H8)2], Ln = Eu and Yb, were obtained in solvent free reactions of the rare earth elements europium and ytterbium with the amine carbazole. Single crystals of both compounds were grown from the melt syntheses, no recrystallization from solvents was necessary. The new compounds are the first examples of homoleptic carbazolates of the rare earth elements furthermore exhibiting divalent lanthanides. In absence of any solvent, carbazole as the sole coordination partner shows η6‐π‐coordination in addition to the μ1‐ and μ2‐coordination of the nitrogen atoms. This results in a one‐dimensional chain structure of dimers with a formal C.N. of 6 for the rare earth elements and thus being low for divalent lanthanides. The products were investigated by X‐ray single crystal and powder diffraction, Mid IR, Far IR and Raman spectroscopy, and with DTA/TG regarding their thermal behaviour. Both compounds [Ln(NC12H8)2], Ln = Eu (1) and Yb (2), crystallize isotypic in the triclinic space group P1.
HoClTe2O5: Ein tellurdioxidreiches Holmium(III)‐Chlorid‐Oxotellurat(IV)
Authors: Meier Steffen F. , Schleid Thomas
Published: August 2003

Bei Versuchen zur Darstellung von anionisch derivatisierten Holmium‐Oxotelluraten durch Reaktion von Holmiumtrichlorid (HoCl3) mit Tellurtrioxid (TeO3; molares Verhältnis 1:2, 800°C, 10 d) in evakuierten Kieselglasampullen wurden transparente, grünlich gelbe und derbe Einkristalle des Holmium(III)‐Chlorid‐Oxotellurats(IV) HoClTe2O5 (triklin, P1; a = 762, 07(6), b = 796, 79(6), c = 1010, 36(8) pm, α = 100, 987(4), ß = 99, 358(4), γ = 91, 719(4)°; Z = 4) erhalten. Die Kristallstruktur beinhaltet achtfach koordinierte (Ho1)3+‐ (nur umgeben von Oxid‐Anionen) und siebenfach koordinierte (Ho2)3+‐Kationen (umgeben von einem Chlorid‐ und sechs Oxid‐Anionen). Über Kantenverknüpfungen treten beide Sorten von Holmium‐Polyedern jeweils für sich zu Ketten entlang [100] zusammen und kombinieren ihrerseits abwechselnd über O6 und O9 zu 2{[Ho2O10(Cl1)]15—}‐Schichten parallel (001). Alle vier kristallographisch unterschiedlichen Te4+‐Kationen sind jeweils von drei nahen Sauerstoffatomen (d(Te—O) = 188 — 195 pm) und stets auch einem weiter entfernten Sauerstoffteilchen umgeben. Durch die stereochemische Aktivität der nicht‐bindenden Elektronenpaare (“lone pairs”) ergeben sich ψ1‐trigonal‐bipyramidale Koordinationsfiguren. Die ψ1‐tetraedrischen [TeO3]2—‐Primäreinheiten formieren sich durch Eckenverknüpfung zu diskreten [Te2O5]2—‐Doppeln mit ekliptischer Konformation, welche nach Art eines Fischgrätenmusters parallel (001) auf beiden Seiten der 2{[Ho2O10Cl]15—}‐Schichten angeordnet sind. Der Zusammenhalt der 2{[Ho2(Cl1)Te4O10]+}‐Schichten erfolgt ausschließlich über Cl2—Te1‐Kontakte mit einem ungewöhnlich langen Abstand von 335 pm. Da (Cl1)— zur Koordinationssphäre von (Ho2)3+ zählt und (Cl2)— nur von Te4+ umgeben ist, sollte die Verbindung korrekterweise als Holmium(III)‐Chlorid‐Oxochlorotellurat(IV) gemäß Ho2Cl[Te4O10Cl] (Z = 2) formuliert werden.
Zum Chemischen Transport im System Mg/Mo/O ‐ Experimente und Modellrechnungen
Authors: Steiner Udo , Reichelt Werner
Published: August 2003

Einkristalle von MgMoO4 und Mg2Mo3O8 wurden mittels Chemischen Transport im Temperaturgefälle 1273 K nach 1173 K mit den Transportmitteln Cl2 bzw. Br2 dargestellt. Ausgangsmaterial waren sowohl phasenreine Proben der ternären Verbindungen als auch Gemenge dreier koexistierender Phasen aus den unterschiedlichen Koexistenzgebieten des Systems. Das beobachtete Transportverhalten wird verglichen mit den Resultaten von Modellrechnungen zum Chemischen Transport und in Abhängigkeit von Ausgangsbodenkörperzusammensetzung, Transportmittelmenge und Feuchtigkeitsgehalt der Ampulle ausführlich diskutiert.
Synthese und Molekülstruktur des heterobimetallischen sulfidoacetato‐verbrückten Zr, Mo‐Komplexes [Cp°2Zr(OOCCH2S‐κ2O, S)(μ‐O‐OOCCH2S‐κ1O, κ2O′, S)(MoCp′2)] (Cp° = C5EtMe4, Cp′ = C5MeH4)
Authors: Wenzel Barbara , Lönnecke Peter , Hey‐Hawkins Evamarie
Published: August 2003

Die Umsetzung von [Cp°2Zr(OOCCH2SH‐κ1O)(OOCCH2SH‐κ2O, O′)] mit [Cp′2MoH2] liefert den dinuklearen ZrIV/MoIV‐Komplex [Cp°2Zr(OOCCH2S‐κ2O, S)(μ‐O‐OOCCH2S‐κ1O, κ2O′, S)(MoCp′2)] (1) (Cp° = C5EtMe4, Cp′ = C5MeH4). Zum NMR‐spektroskopischen Vergleich wurde [Cp′2Mo(OOCCH2S‐κ2O, S)] (2) ausgehend von [Cp′2MoH2] und Mercaptoessigsäure dargestellt. 1 und 2 wurden spektroskopisch (1H‐, 13C‐NMR‐ und IR‐Spektroskopie), 1 auch röntgenkristallstrukturanalytisch charakterisiert.
Alkali Cation Ligating Chains and Sheets of the Macrocycle 1, 7‐Dithia‐18‐Crown‐6 with Bridging Iodo‐ and Thiocyanatocuprate(I) Units
Authors: Heller M. , Sheldrick W. S.
Published: August 2003

Treatment of an acetonitrile solution of CuI with 1, 7‐dithia‐18‐crown‐6 (1, 7‐DT18C6) at 100°C affords the coordination polymer 1[(CuI)2(1, 7‐DT18C6)2] (1) in which 1, 7‐DT18C6 ligands bridge (CuI)2 rings into double chains. 1D polymers of the type 1[M{(Cu3I4)(1, 7‐DT18C6)}] (M = K, 2; M = Cs, 3) can be isolated under similar conditions in the presence of respectively KI and CsI. Both contain bridging heptacyclic [Cu6I8]2— units but crystallise in different space groups, namely P1 and C2/m. The cesium cation of 3 is markedly displaced from the best plane through the thiacrown ether donor atoms. Reaction of 1, 7‐DT18C6 with CuSCN in the presence of NaSCN yields 2[{Na(CH3CN)2} {(CuSCN)2(1, 7‐DT18C6)}][Cu(SCN)2] (4), in which 1[(CuSCN)2] double chains are linked through macrocycles into sheets. Infinite 1[{Cu(SCN)2}—] chains compensate the charge of the Na+ cations. Complex 1 can imbibe 0.90 mol CsNO3 per mol of 1, 7‐DT18C6 pairs.
Affinity of Divalent Mercury Towards Nitrogen Donor Ligands
Authors: Meyer Gerd , Nockemann Peter
Published: August 2003

As with gold, relativistic effects are important in the chemistry of mercury. Together with the closed‐shell d10 configuration of Hg2+ they account for the special bonding schemes as preferred linear coordination with highly covalent contributions to chemical bonding or special affinities to nitrogen and sulfur that are so prominent in mercuric chemistry. This research report summarizes recent research on coordination compounds with halogen, oxygen and, especially, nitrogen as direct bonding partners of divalent mercury and their competition with each other. In a rather systematic way N‐donor ligands with one, two and more than two nitrogen atoms have been inspected in order to elucidate the influences that lead to the special bonding schemes of HgII‐N compounds.
Zur Kinetik der Bildung von Na2PdC2
Authors: Ruschewitz Uwe , Bähtz Carsten , Knapp Michael
Published: August 2003

Die Kinetik der Bildung von Na2PdC2 aus Na2C2 und Palladium wurde pulverdiffraktometrisch mit Synchrotronstrahlung (Pulverdiffraktometer der Beamline B2, HASYLAB/Hamburg) zeitaufgelöst bei verschiedenen Reaktionstemperaturen zwischen 513 und 533 K untersucht. Durch Rietveld‐Analyse der erhaltenen Diffraktogramme konnte der molare Anteil des Produkts Na2PdC2 in Abhängigkeit von der Zeit bestimmt werden. Die so erhaltenen Kristallisationskurven wurden mit Hilfe der Avrami‐Erofe'ev‐Theorie analysiert. Es zeigte sich, dass die untersuchte Reaktion diffusionskontrolliert abläuft. Die Aktivierungsenergie wurde zu EA = 480(120) KJ/mol bestimmt. Gründe für die relativ hohe Ungenauigkeit bei der Bestimmung der Aktivierungsenergie werden diskutiert.
Magnetotail flows can consume as much solar wind energy as a substorm
Authors: Pulkkinen T. I. , Tanskanen E. I. , Wiltberger M. , Slavin J. A. , Nagai T. , Reeves G. D. , Frank L. A. , Sigwarth J. B.
Published: August 2003

We examine an event on 17 December 1997, during which the Wind and ACE spacecraft measured an extended period of southward interplanetary magnetic field. The high values of the epsilon parameter were interpreted as strong energy input into the magnetotail. Despite this energy input, the polar cap potential and area remained constant over a period of several hours, the inner magnetotail was very quiet, and there were no substorm signatures either in the magnetotail or in the ionosphere. Comparison of data and MHD simulation results show that the energy input to the magnetosphere was enhanced and that this event was not a case where the solar wind monitor would have trouble predicting the interplanetary field reaching the Earth orbit. Both Geotail observations in the tail and the MHD simulations show that a substantial amount of energy was being consumed in the tail flow activity during this period. Order of magnitude estimates indicate that the flows indeed were sufficient to consume the incoming energy in a quasi‐continuous even if bursty manner. Observations from the IMAGE meridional magnetometer network reveal that the substorm that followed several hours later was relatively small, and its size was proportional to the energy input after the substorm onset, not to the total energy input since the southward turning of the interplanetary field. It is argued that the continuous flow activity disturbed the formation of the thin current sheet in the inner magnetotail, which led to the delay in the substorm development. However, the controlling factor which finally led to the global instability remains an open issue.
Why earthquakes correlate weakly with the solid Earth tides: Effects of periodic stress on the rate and probability of earthquake occurrence
Authors: Beeler N. M. , Lockner D. A.
Published: August 2003

We provide an explanation why earthquake occurrence does not correlate well with the daily solid Earth tides. The explanation is derived from analysis of laboratory experiments in which faults are loaded to quasiperiodic failure by the combined action of a constant stressing rate, intended to simulate tectonic loading, and a small sinusoidal stress, analogous to the Earth tides. Event populations whose failure times correlate with the oscillating stress show two modes of response; the response mode depends on the stressing frequency. Correlation that is consistent with stress threshold failure models, e.g., Coulomb failure, results when the period of stress oscillation exceeds a characteristic time tn; the degree of correlation between failure time and the phase of the driving stress depends on the amplitude and frequency of the stress oscillation and on the stressing rate. When the period of the oscillating stress is less than tn, the correlation is not consistent with threshold failure models, and much higher stress amplitudes are required to induce detectable correlation with the oscillating stress. The physical interpretation of tn is the duration of failure nucleation. Behavior at the higher frequencies is consistent with a second‐order dependence of the fault strength on sliding rate which determines the duration of nucleation and damps the response to stress change at frequencies greater than 1/tn. Simple extrapolation of these results to the Earth suggests a very weak correlation of earthquakes with the daily Earth tides, one that would require >13,000 earthquakes to detect. On the basis of our experiments and analysis, the absence of definitive daily triggering of earthquakes by the Earth tides requires that for earthquakes, tn exceeds the daily tidal period. The experiments suggest that the minimum typical duration of earthquake nucleation on the San Andreas fault system is ∼1 year.
Temporal variability of rainwater iron speciation at the Bermuda Atlantic Time Series Station
Authors: Kieber Robert J. , Willey Joan D. , Avery G. Brooks
Published: August 2003

Diurnal and seasonal variations in rainwater iron speciation were investigated during a summer and winter cruise aboard the RV Endeavor at the Bermuda Atlantic Time Series Station. Concentrations of total Fe, Fe(II), and Fe(III) were all higher in rainwater falling at BATS during the summer relative to winter cruise. Iron speciation displayed marked diel variability with a 200‐fold higher Fe(II)(aq)/Fe(III)(aq) ratio in rain received between 1200 and 1800 local time (LT) relative to late evening or early morning summer rain. The higher Fe(II)/Fe(III) ratio in the afternoon indicates Fe(II) is produced at the expense of Fe(III) during the course of the day, suggesting photochemical processes are important in controlling iron speciation in marine rains falling over the open ocean. Experiments utilizing authentic rainwater collected at BATS during both summer and winter cruises demonstrate that rainwater Fe(II)(aq) is stabilized against oxidation and precipitation for more than 4 hours after mixing with BATS seawater. Preliminary results suggest this stabilization is the result of organic complexation of Fe in rainwater. Owing to the isolation of BATS from riverine sources of Fe, rainwater is the predominant source of soluble and stable Fe(II) in this region of the North Atlantic.
How wind‐forcing and air‐sea heat exchange determine the meridional temperature gradient and stratification for the Antarctic Circumpolar Current
Authors: Bryden Harry L. , Cunningham Stuart A.
Published: August 2003

Mesoscale oceanic eddies have a profound effect on the meridional circulation in the Antarctic Circumpolar region. Previous studies have shown that eddies transport heat poleward to balance the heat lost by the ocean to the atmosphere in the waters around Antarctica and also transport eastward momentum downward at a rate comparable to the amount of momentum put into the water column by the wind stress. Using the poleward eddy heat fluxes to relate air‐sea heat loss and wind stress, we find that the meridional temperature gradient in the circumpolar region is determined by the ratio of the air‐sea heat loss to the zonal wind stress. Including a widely used parameterisation where poleward eddy heat fluxes are proportional to the mean meridional temperature gradient, we find that the slope of isotherms (or isopycnals) across the circumpolar zone is determined by the wind stress. Further assuming no cross‐isopycnal mixing in the interior ocean, we find that the stratification in the deep ocean is determined by the ratio of air‐sea heat loss to zonal wind stress squared. The poleward eddy heat fluxes also represent a southward eddy mass transport in the upper water column in density coordinates. The vertical gradient of this eddy mass transport is the meridional component of the eddy Stokes drift which is equal to the difference between the Lagrangian and Eulerian mean velocities in the circumpolar region. Because there can be no zonally averaged geostrophic Eulerian meridional velocity across the circumpolar region above the topography, this southward eddy Stokes drift provides a mechanism by which circumpolar deep water can flow southward across the circumpolar zone. Eddy heat fluxes, which are central to the mass, momentum, heat and energy balances in the circumpolar region, provide a catalyst for relating the roles of wind and buoyancy forcing in setting the overall circulation for the Southern Ocean.
Eurekan transpressive deformation in the Wandel Hav Mobile Belt (northeast Greenland)
Authors: von Gosen W. , Piepjohn K.
Published: August 2003

Besides the ∼W‐E trending Kap Cannon Thrust Zone and Harder Fjord Fault Zone, the 300 km long and NW‐SE striking Wandel Hav Mobile Belt represents the third major fault zone in north Greenland. Structural analyses in several areas of this belt suggest that compressive deformation is characterized by transpressive dextral strike‐slip kinematics. This is demonstrated by a combination of folding around ∼W‐E axes, approximately north and south directed reverse faulting, and dextral strike‐slip displacements along NW‐SE trending fault lines. The initial formation of the long, linear faults is interpreted to be related to deformational events in Late Paleozoic, Triassic‐Jurassic, and Late Cretaceous times. Due to the lack of structural evidence, we assume that deformations led to the generation of extension faults which probably were reactivated during dextral strike‐slip tectonism. It is suggested that dextral transpressive deformation was coeval with ∼N‐S compression at the Harder Fjord Fault Zone and Cap Cannon Thrust Zone and took place during Eocene (Eurekan) times. Dextral strike‐slip tectonism in the Wandel Hav Mobile Belt was the result of ∼N‐S compression due to a general northward movement of the Greenland plate. As a zone of crustal weakness, the belt can be interpreted as the onshore equivalent of the main transcurrent fault zone (De Geer Fault) which caused the intracontinental dextral slip of Svalbard (Barents Shelf) relative to north Greenland during Early Tertiary (Eurekan) times and prior to their separation. In this configuration, it represents one part of the belt of Eurekan deformation which extends from the Canadian Arctic islands over north Greenland to the Barents Shelf where compressive deformation is recorded in the West Spitsbergen Fold‐and‐Thrust Belt.
Ionospheric control of the magnetospheric configuration: Thermospheric neutral winds
Authors: Ridley A. J. , Richmond A. D. , Gombosi T. I. , De Zeeuw D. L. , Clauer C. R.
Published: August 2003

In this study we present the first results from the University of Michigan's coupled magnetosphere‐ionosphere‐thermosphere general circulation model. This code is a combination of the Michigan MHD model with the NCAR thermosphere‐ionosphere‐electrodynamics general circulation model (TIEGCM). The MHD code provides specification of the high‐latitude ionospheric electric potential and the particle precipitation pattern, while the TIEGCM provides the divergence of the height‐integrated neutral wind multiplied by the conductance. This can be easily incorporated into the electric potential solver in the MHD code. We show in this study that the neutral winds cause an approximately 6% increase in the cross polar cap potential when the IMF is strongly southward. This causes the magnetospheric field aligned currents to decrease by a small amount. In the magnetosphere, the flow speeds are increased by only a small amount while the IMF is strongly southward, but when it turns northward the differences become 10–20%. When the IMF is northward, the pressure on the dayside magnetosphere is reduced while the pressure on the nightside is increased by ∼10% of the total pressure.
Energization of relativistic electrons in the presence of ULF power and MeV microbursts: Evidence for dual ULF and VLF acceleration
Authors: O'Brien T. P. , Lorentzen K. R. , Mann I. R. , Meredith N. P. , Blake J. B. , Fennell J. F. , Looper M. D. , Milling D. K. , Anderson R. R.
Published: August 2003

We examine signatures of two types of waves that may be involved in the acceleration of energetic electrons in Earth's outer radiation belts. We have compiled a database of ULF wave power from SAMNET and IMAGE ground magnetometer stations for 1987–2001. Long‐duration, comprehensive, in situ VLF/ELF chorus wave observations are not available, so we infer chorus wave activity from low‐altitude SAMPEX observations of MeV electron microbursts for 1996–2001 since microbursts are thought to be caused by interactions between chorus and trapped electrons. We compare the ULF and microburst observations to in situ trapped electrons observed by high‐altitude satellites from 1989–2001. We find that electron acceleration at low L shells is closely associated with both ULF activity and MeV microbursts and thereby probably also with chorus activity. Electron flux enhancements across the outer radiation belt are, in general, related to both ULF and VLF/ELF activity. However, we suggest that electron flux peaks observed at L ∼ 4.5 are likely caused by VLF/ELF wave acceleration, while ULF activity probably produces the dominant electron acceleration at geosynchronous orbit and beyond.
A volcanotectonic cascade: Activation of range front faulting and eruptions by dike intrusion, Mono Basin‐Long Valley Caldera, California
Authors: Bursik M. , Renshaw C. , McCalpin J. , Berry M.
Published: August 2003

Stratigraphic data suggest that during the North Mono‐Inyo eruption sequence of ∼1350 A.D. a series of strong earthquakes occurred near the end of the North Mono explosive phases and the beginning of the Inyo explosive phases. The temporal proximity of these events suggests the possibility of a causal relationship. Geological and geomorphic features of the Hartley Springs Fault are consistent with rupture of the fault during the eruption sequence. These features include steep central slope segments on several fault scarps and a fault scarp and stratigraphic offset since the deposition of ∼1200‐year‐old tephra. We hypothesize that the Inyo Dike, found by drilling underneath the main Inyo vents, neared the Hartley Springs Fault as it propagated southward from the Mono Basin circa 1350 A.D. We demonstrate that once the lateral distance between dike and fault was sufficiently small, the mechanical interaction between them could have triggered the slip observed on the fault. The slip, in turn, could have reduced the horizontal confining pressure in a region near the southern tip of the fault. The presence of the main Inyo vents in this region suggests that the reduction in confining stress was sufficient to allow magma to propagate to the surface. The results suggest that a volcanotectonic “cascade” of eruptions and earthquakes is a possible mechanism by which a large section of a range front or rift system can be activated because of the positive feedback provided by each element to continued activity.
Crustal anisotropy in the Bohemian Massif, Czech Republic: Observations based on Central European Lithospheric Experiment Based on Refraction (CELEBRATION) 2000
Authors: Růžek Bohuslav , Vavryčuk Václav , Hrubcová Pavla , Zedník Jan
Published: August 2003

We study the azimuthal velocity variation of Pg waves in the Bohemian Massif using data collected during Central European Lithospheric Experiment Based on Refraction (CELEBRATION) 2000. We analyze travel times of waves generated by 28 shots and recorded by 256 portable and 19 permanent seismic stations deployed on the territory of the Czech Republic and in adjacent areas. We use recording offset ranging from 30 to 190 km with azimuths covering the whole interval of angles. The observed travel times are inverted for parameters of a velocity model formed by an isotropic low‐velocity subsurface layer with a varying depth lying on a homogeneous transversely isotropic half‐space with a horizontal axis of symmetry. The recovered velocity displays a systematic azimuthal variation indicating a regional‐scale intrinsic or effective anisotropy in the Bohemian Massif. The mean, minimum and maximum values of the velocity are vmean = 6.03 km/s, vmin = 5.98 km/s, vmax = 6.10 km/s, respectively, indicating an anisotropy of 1.5–2.5%. The direction of the maximum propagation velocity is ∼N35°E being approximately perpendicular to the present maximum compression in the Earth crust in central Europe. The observed anisotropy cannot be induced by stress‐aligned cracks in the crust, because the crack models predict azimuthal velocity variations completely inconsistent with the observed one. Therefore we suggest the crustal anisotropy to be induced by a preferred orientation of rock‐forming minerals and large‐scale intrusion fabrics developed during a tectonic evolution of the Bohemian Massif.
Postseismic relaxation across the Central Nevada Seismic Belt
Authors: Hetland E. A. , Hager B. H.
Published: August 2003

Two GPS geodetic surveys across the Basin and Range (BR) province of western North America have detected an anomalous compression east of the Central Nevada Seismic Belt (CNSB). The first network, installed by the U.S. Geological Survey along an east‐west trending transect across the BR at approximately 40°N, consisted of 63 monuments observed campaign style in 1992, 1996, and 1998. The second network, installed by the California Institute of Technology, consisted of 50 continuously operating GPS receivers, 18 of which were roughly along the same transect as the campaign survey. We have used a viscoelastic postseismic relaxation model of the four largest earthquakes in the CNSB (on the Pleasant Valley fault in 1915, the Cedar Mountain fault in 1932, and on the Fairview Peak and Dixie Valley faults in 1954) to interpret the geodetic velocities observed across the CNSB. A model of postseismic relaxation with a lower crustal Maxwell viscosity of 5–50 × 1018 Pa s can explain the apparent compression regardless of the assumed mantle viscosity. The geodetic velocities that we determined after removing the postseismic contribution indicate that within current GPS detection limits the BR is stable east of the CNSB and is undergoing rapid right‐lateral shear west of the CNSB.
Vertical eddy diffusion and nutrient supply to the surface mixed layer of the Antarctic Circumpolar Current
Authors: Law C. S. , Abraham E. R. , Watson A. J. , Liddicoat M. I.
Published: August 2003

Dispersion of the tracer sulphur hexafluoride (SF6) during the Southern Ocean Iron Enrichment Experiment (SOIREE) provided an estimate of vertical exchange at the base of the surface mixed layer (60 m) at 61°S 140°E. Budget analysis confirmed that the SF6 patch was well constrained by surface mapping, with the decline in total SF6 showing good agreement with that predicted from wind speed parameterizations. Two approaches were used to calculate the mean effective vertical diffusivity Kz from the diapycnal transfer of SF6, with complementary error function and second‐moment fits to the SF6 depth profiles indicating that Kz was less than 0.3 × 10−4 m2s−1. This result was examined using a three‐dimensional diffusion model that incorporated lateral dispersion and air‐sea exchange losses, which confirmed that vertical shear and subpycnocline dispersion did not influence the Kz estimate. Current shear at the base of the mixed layer was generated by wind‐driven inertial oscillation, with a decrease in wind speed and increasing stratification in the latter half of the experiment reducing diapycnal transfer of SF6. A compilation was used to examine the potential of both N (Brunt‐Väisäla frequency) and Ri (gradient Richardson number) on the basis of parameterizations of Kz in the seasonal pycnocline. Application of Kz to nutrient gradients in the seasonal pycnocline suggests that vertical diffusion represents a significant pathway for silicic acid supply in late summer. Furthermore, use of the mean effective Kz (0.11 ± 0.2 × 10−4 m2s−1) indicates that vertical diffusion supplies a large proportion of the iron required for new production in this region.
Seasonal variation in the distribution of suspended particulate matter in the northwest Aegean Sea
Authors: Karageorgis Aristomenis P. , Anagnostou Christos L.
Published: August 2003

CTD/transmissometer profiles were made on four cruises in the northwest Aegean Sea to study seasonal and spatial distribution patterns of particulate matter (PM). Water samples were filtered to obtain particulate matter concentrations and subsequently to calibrate transmissometer readings. Continental runoff is a major particle source during high river discharge seasons (winter and spring). Resuspended particles predominate in the water column during summer and autumn. Particulate matter distribution patterns consist in well‐defined surface, intermediate and bottom nepheloid layers (SNL, INL, and BNL, respectively). The SNL is intense during spring and winter, while it is very weak during summer and autumn. The prevailing wind‐driven cyclonic circulation regulates the PM distribution over the shelf, whereas the pycnocline depth controls mainly the vertical PM distribution. The resuspension of modern loosely consolidated sediments, under the forcing of near‐bottom currents, forms consistent BNLs over the continental shelf throughout the year. The detachment of these BNLs at the shelf break generates weak INLs, which account for an important shelf‐basin transport mechanism during winter and spring. The total particulate standing crop is estimated to be between 484 × 103 and 830 × 103 tons. During summer and autumn, the PM on the shelf results largely from resuspension.
Phytoplankton dynamics within 37 Antarctic coastal polynya systems
Authors: Arrigo Kevin R. , van Dijken Gert L.
Published: August 2003

Antarctic coastal polynyas are areas of reduced sea ice cover within the ice pack and their associated surface waters are noted for sustaining enhanced levels of biological production during the spring and summer. Here we present satellite‐based estimates of interannual changes in the areal extent, phytoplankton abundance, and primary productivity within 37 Antarctic coastal polynya systems over five annual cycles (1997 to 2002). The largest polynya studied was located in the Ross Sea (396,500 km2) while the smallest was located in the West Lazarev Sea (1040 km2). Most polynyas attained maximum areal extents in February of less than 20,000 km2. Mean polynya chlorophyll a from 1 September to 31 March ranged from 0.16 to 2.2 mg m−3, averaging 0.69 mg m−3. Daily production averaged 0.09 to 0.76 g C m−2 d−1. Mean annual primary production ranged from 18 to 161 g C m−2 yr−1, with most coastal polynyas exhibiting annual rates of production between 20 and 80 g C m−2. Total production (the product of the open water area and the spatial mean daily primary production rate) varied by 2 orders of magnitude, from 0.03 to 48 Tg C yr−1. Taken together, the Ross Sea, Ronne Ice Shelf, Prydz Bay, and Amundsen Sea polynyas are responsible for >75% of total polynya production. In eastern Antarctica, where 91% of all Adélie penguin colonies are associated with a coastal polynya, the magnitude of annual production in polynyas explained 65% of the variance in penguin colony size.
Characterizations of tropospheric turbulence and stability layers from aircraft observations
Authors: Cho John Y. N. , Newell Reginald E. , Anderson Bruce E. , Barrick John D. W. , Thornhill K. Lee
Published: August 2003

Velocity, temperature, and specific humidity data collected by aircraft at 20‐Hz resolution are analyzed for stability and turbulence parameters. Over 100 vertical profiles (mostly over the ocean) with a total of over 300 km in vertical airspace sampled are used. The compiled statistics show that anisotropy in the velocity fluctuations prevail down to the smallest spatial separations measured. A partitioning of convective versus dynamical instability indicates that in the free troposphere, the ratio of shear‐produced turbulence to convectively produced turbulence increases from roughly 2:1 for weak turbulence (ϵ < 10−4 m2 s−3) to perhaps 3:1 for strong turbulence (ϵ > 10−4 m2 s−3). For the boundary layer, this ratio is close to 1:1 for weak turbulence and roughly 2:1 for strong turbulence. There is also a correlation between the strength of the vertical shear in horizontal winds and the turbulence intensity. In the free troposphere the turbulence intensity is independent of the degree of static stability, whereas in the boundary layer the turbulence intensity increases with a fall in static stability. Vertical humidity gradients correlate with static stability for strong humidity gradients, which supports the basic notion that stable layers impede vertical mixing of trace gases and aerosols. Vertical shear correlates with vertical humidity gradient, so it appears that the effect of differential advection creating tracer gradients dominates the effect of differential advection destroying tracer gradients through shear‐induced turbulence.
Ground‐based measured and calculated spectra of actinic flux density and downward UV irradiance in cloudless conditions and their sensitivity to aerosol microphysical properties
Authors: Früh Barbara , Eckstein Eva , Trautmann Thomas , Wendisch Manfred , Fiebig Markus , Feister Uwe
Published: August 2003

Ground‐based spectral measurements of actinic flux density (300–660 nm wavelength) and downward UV irradiance (300–324 nm) under cloudless conditions have been compared with the results of one‐dimensional radiative transfer calculations employing concurrent airborne vertical profile measurements of aerosol particle size distributions. Good agreement (within ±10%) between measured and calculated spectra was found. The remaining differences were explained by uncertainties inherent in the aerosol particle microphysical input data and the column ozone content. A respective sensitivity analysis of the calculated spectra, which was based on the observed variability of microphysical properties, has shown that the particle number concentration is the most crucial input uncertainty for both the actinic flux density and the UV irradiance. For the wavelength range investigated, the uncertainty of the column ozone content is of minor importance for both spectral quantities.
Performance and analysis of the constructed analogue method applied to U.S. soil moisture over 1981–2001
Authors: van den Dool Huug , Huang Jin , Fan Yun
Published: August 2003

We have conducted an experiment to assess the real time skill in monthly and seasonal predictions based solely on patterns of antecedent hydrological information over the United States. The hydrological information is contained in a proxy for soil moisture at 102 locations over the lower 48 states. This soil moisture is calculated over the years 1931 to present from a local hydrological equation taking monthly precipitation (P) and temperature (T) as input, and producing soil moisture (w), evaporation (E), runoff (R), and loss to groundwater (G) as output. The initial condition (IC) for the forecast procedure is soil moisture over the United States at the end of the month (w30). We constructed an analogue to the w30 fields, i.e., made linear combinations of soil moisture fields at the same time of year in years past to reproduce the IC to within a small tolerance. The coefficients assigned to the years past are then made to persist, and the subsequent development in the historical years is linearly combined to form a forecast. This method has been running at CPC in real time since 1998, and we added 1981–1997 in “retroactive real time” mode to form a large enough sample. In total, we considered both seasonal and monthly forecasts at leads of −1 to +6 months for 1981–2001, for the elements w30, E, T, and P. From the outset, we wanted to investigate nonlocal forecast methods, considering local effects, on evaporation and temperature mainly, as being established already and well documented [Huang et al., 1996]. In a nonlocal method we entertain the possibility of precipitation (the response) falling downstream of a soil moisture anomaly (forcing). We found that we have about a 0.6 correlation in forecasting monthly soil moisture with a lead of one month (i.e., July at the end of May). This figure is higher in spring and somewhat lower in the early fall. The capability to forecast evaporation anomalies is very seasonal. During the cold half of the year, when E anomalies resemble T anomalies, the correlation is only 0.2–0.3, but in summer, when E anomalies resemble w anomalies, the skill of forecasts goes up to 0.6. We thus have some insight into patterns of anomalous water vapor input from the land surface into the lower atmosphere on a continental scale. Skill of forecasting T is modest, reaching 0.2–0.3 in many months and seasons, but there is no clear seasonal dependence that relates to the presumed physics of land atmosphere interactions. Skill in forecasting P is quite low, barely 0.1 in correlation, but +ve in all months and seasons. We did alternative experiments where the constructed analogue was built on E, T, or P instead of w and verified the forecast of all elements likewise. We found initial w to be the best for forecasting w itself and indeed for forecasting the other fields as well! This is important testimony that soil moisture is indeed the key, as has been suspected by many for ages.
Methane emission from rice fields in mainland China: Amount and seasonal and spatial distribution
Authors: Yan Xiaoyuan , Cai Zucong , Ohara Toshimasa , Akimoto Hajime
Published: August 2003

China is the largest rice producer in the world. Methane (CH4) emission from its rice fields has been widely measured since the late 1980s. This study collected the results of available field research, totaling 204 season‐treatment measurements conducted on 23 sites. Analysis of these data shows that input of organic material, such as green manure, animal waste, and crop straw, increases CH4 emission by a factor of 2. Average CH4 flux from intermittently irrigated rice fields is 53% of that from continuously flooded rice fields; and average CH4 emission flux from late rice fields is 1.6 and 2.3 times greater than flux from early and single rice fields, respectively. There are regional differences in emission factors and a trend of decreasing emission from south to north. On the basis of earlier estimates of CH4 emission from Chinese rice fields, and recent reports on the use of crop residue and green manure, it is presumed that half of the rice fields in China receive organic input. From the frequency of various water management events indicated in the surveyed field experiments, as well as from specific statements in individual reports, it is presumed that 2/3 of irrigated rice fields have been intermittently flooded. On the basis of these assumptions, the region‐specific emission factors, and 1995 data on rice cultivation area, CH4 emission from growing‐season rice fields in Mainland China was estimated to be 7.67 Tg yr−1, ranging from 5.82 to 9.57 Tg yr−1, due to uncertainties in the areas receiving organic inputs, and intermittent irrigation. Generalized seasonal flux patterns were developed for early, late, and single rice. Monthly distributions of emission were estimated from these patterns and rice calendars. The highest emission rate occurred in August. Spatially, emission hot spots included the plains of Dongting Lake in Hunan Province, Boyang Lake in Jiangxi Province, the delta region of Qiantang River in Zhejiang Province, and the Sichuan Basin. Nearly 90% of all Mainland China CH4 emission occurred between 23°N and 33°N.
Actinic flux determination from measurements of irradiance
Authors: Kylling A. , Webb A. R. , Bais A. F. , Blumthaler M. , Schmitt R. , Thiel S. , Kazantzidis A. , Kift R. , Misslbeck M. , Schallhart B. , Schreder J. , Topaloglou C. , Kazadzis S. , Rimmer J.
Published: August 2003

The actinic flux describes the number of photons incident at a point, while the irradiance describes the radiant energy crossing a surface. An algorithm for conversion of irradiance to downwelling actinic flux has been developed and tested. The algorithm uses a simple method to distinguish between a cloudy and a cloudless sky. It is necessary to separate cloudy and cloudless situations, as the irradiance to actinic flux conversion depends on the radiance field which is rather different for cloudy and cloudless skies. Surface UV irradiance and downwelling actinic flux spectra were measured at five European locations which were representative of different climates. A total of 9015 synchronized actinic flux and irradiance spectra were available to test the proposed algorithm. The measured irradiance spectra were used to estimate downwelling actinic flux spectra. The estimated actinic flux spectra were compared with the measured actinic flux spectra for all cloud and aerosol situations encountered, a wide range of solar zenith angles, and surface conditions. The average ratio of the reproduced to measured downwelling actinic flux is 1.021 ± 0.085 in the UV‐B and 1.015 ± 0.105 in the UV‐A. In general, the performance of the algorithm is better at smaller solar zenith angles.
Analysis of surface black carbon distributions during ACE‐Asia using a regional‐scale aerosol model
Authors: Uno Itsushi , Carmichael Gregory R. , Streets David , Satake Shinsuke , Takemura Toshihiko , Woo Jung‐Hun , Uematsu Mitsuo , Ohta Sachio
Published: August 2003

The regional‐scale aerosol transport model (CFORS) is used in the analysis of black carbon (BC) observed at five remote Japanese islands during the ACE‐Asia experiment. BC is modeled online in the regional‐scale meteorological model, using emissions estimates for 2000. Two model experiments are conducted (1) a control run that includes all the BC emission, and (2) a sensitivity run without open biomass burning emissions to clarify the impact of biomass burning on the BC levels in the western Pacific. The regional aerosol model (CFORS) is shown to accurately reproduce many of the important features observed. Model analysis shows that the spatial and temporal distributions of black carbon between the northern sites (Rishiri and Sado; located in the Japan Sea) and the southern stations (Hachijo, Chichijima, and Amami‐Oshima; in the western Pacific Ocean) are under different flow regimes. It is shown that the major synoptic features controlling BC levels are associated with outflow in the warm conveyor belt of traveling cold fronts and the subsequent postfrontal transport. At the northern stations (Rishiri and Sado), elevated BC concentrations are calculated to be mainly below the heights of 2000 m, and the biomass burning fraction is estimated to be below 20%. At the southern sites (e.g., Chichijima) the contribution due to biomass burning reaches 32% at the surface and 52% in the free atmosphere. CFORS results indicate that the major black carbon source and transport height are different between the northern and southern sites.