DOAS Zenith Sky Observations: 2. Seasonal Variation of BrO Over Bremen (53°N) 1994-1995

Zenith sky observations of BrO over Bremen (53°N) are reported for the period of September 1994 to January 1996. BrO differential slant columns between 90° and 80° solar zenith angle showed a strong seasonal variation between a winter maximum of 1.9·1014 molec/cm2 and a summer minimum of 0.6·1014 molec/cm2. The seasonal variation in BrO twilight values is shown to be inversely correlated with NO2 columns in agreement with current knowledge of gas phase chemistry of bromine. In contrast to model predictions, no significant difference between morning and evening BrO measurements was observed. During a 6 day polar vortex excursion to mid-latitudes OClO could be measured above Bremen indicating chlorine activation in the vortex air. No significant increase in BrO differential slant columns was detected during this time.     

Slant Column Measurements of O3 and NO2 During the NDSC Intercomparison of Zenith-Sky UV-Visible Spectrometers in June 1996

In June 1996, 16 UV-visible sensors from 11 institutes measured spectra of the zenith sky for more than 10 days. Spectra were analysed in real-time to determine slant column amounts of O3 and NO2. Spectra of Hg lamps and lasers were measured, and the amount of NO2 in a cell was determined by each spectrometer. Some spectra were re-analysed after obvious errors were found. Slant columns were compared in two ways: by examining regression analyses against comparison instruments over the whole range of solar zenith angles; and by taking fractional differences from a comparison instrument at solar zenith angles between 85° and 91°. Regression identified which pairs of instruments were most consistent, and so which could be used as universal comparison instruments. For O3, regression slopes for the whole campaign agreed within 5% for most instruments despite the use of different cross-sections and wavelength intervals, whereas similar agreement was only achieved for NO2 when the same cross-sections and wavelength intervals were used and only one half-day's data was analysed. Mean fractional differences in NO2 from a comparison instrument fall within ±7% (1-sigma) for most instruments, with standard deviations of the mean differences averaging 4.5%. Mean differences in O3 fall within ±2.5% (1- sigma) for most instruments, with standard deviations of the mean differences averaging 2%. Measurements of NO2 in the cell had similar agreement to measurements of NO2 in the atmosphere, but for some instruments measurements with cell and atmosphere relative to a comparison instrument disagreed by more than the error bars.     

The equidensitometric determination of angular diameters of compact galaxies

On Tautenburg Schmidt plates in system V taken at seeings of about 2″ the determination of real angular diameters of compact galaxies down to 4″ is possible. Diameter-magnitude diagrams of objects in four fields around the globular cluster M₃ show the possibility for getting homogeneous material concerning both the uniformity of the equidensitometric copying process and the measuring process with the iris photometer in order to determine the integral brightness of single galaxies from their limiting equidensities.     

Bottom-moored acoustic array to monitor density and vertical movement of deep-sea benthopelagic animals

A bottom-moored vehicle, employing a 36-kHz acoustic array, is described. Its purpose is to census benthopelagic populations at abyssal depths and detect vertical movement of these animals. It is argued that an acoustic census offers particular advantages over traditional sampling methods, and when used in conjunction with these methods, offers powerful insight into abyssal community dynamics.     

Individual geopotential coefficients of order 15 and 30, from resonant satellite orbits

The analysis of variations in satellite orbits when they pass through 15th-order resonance (15 revolutions per day) yields values of lumped geopotential harmonics of order 15, and sometimes of order 30. The 15th-order lumped harmonics obtained from 24 such analyses over a wide range of orbital inclinations are used here to determine individual harmonic coefficients of order 15 and degree 15,16,…35; and the 30th-order lumped harmonics (from eight of the analyses) are used to evaluate individual coefficients of order 30 and degree 30,32,…40. The new values should be more accurate than any previously obtained. The accuracy of the 15th-order coefficients of degree 15, 16,…23 is equivalent to 1 cm in geoid height, while the 30th-order coefficients of degree 30, 32 and 34 are determined with an accuracy which is equivalent to better than 2 cm in geoid height. The results are used to assess the accuracy of the Goddard Earth Model 10B.     

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Relative sea level changes during the Holocene in the Sisimiut area,south‐western Greenland

Holocene relative sea level (RSL) changes have been investigated by analysing and dating isolation sequences from five lakes near Sisimiut in south‐western Greenland. The transitions between marine and lacustrine sediments were determined from elemental analyses and analyses of macroscopic plant and animal remains. Radiocarbon dating was used to provide minimum ages for the transitions and to construct a RSL curve. Dating of a shell of the marine bivalve Macoma balthica indicates that deglaciation of the lowlands occurred in the early Holocene, at around 10 900 cal a BP. The RSL curve shows initial rapid regression from the marine limit at around 140 m, implying strong glacio‐isostatic rebound. We suggest that the margin of the Greenland Ice Sheet was located at the shelf break during the Last Glacial Maximum. Frequent remains of the ostracode Sarcypridopsis aculeata, which is a thermophilous brackish water species that is unknown from the extant fauna of Greenland, in one of the basins around 8500 cal a BP may mark the beginning of the Holocene thermal maximum in the region. Copyright © 2011 John Wiley & Sons, Ltd.     

Neue Daten zur Biostratigraphie und zur tektonischen Lagerung der Phyllit-Gruppe und der Trypali-Gruppe auf der Insel Kreta (Griechenland)

Based on many new fossil discoveries mainly conodonts and ostracodes an attempt has been made to determine the stratigraphic range of the high pressure/low temperature metamorphic Phyllite Group in West Crete (Greece). The numerous conodont findings indicate — in spite of strong supply of clastic material — a fully marine environment from the Upper Carboniferous up to the end of the Lower Triassic. The prevailing part of the Middle Triassic cannot yet covered by fossils. The upper Triassic shows in the lower (invers) part of the Phyllite Group a shallow water facies with ostracodes, bivalves and at the Triassic/Lias boundary a saliniferous facies, however in the upper (in original position lying) part a conodonts-foraminiferes bearing littoral facies. The present biostratigraphic data point out that the lower part of the Phyllite Group lies in inverted order and the upper part in original position. Thus the Phyllite Group on the whole seems (in West Crete) to form a huge recumbent isoclinal fold analogous to the isoclinal folding on a smaller scale as frequently exposed. The carbonate Trypali Group can be interpreted as either the recumbent limb of this fold structure or as part of the underlying Talea Ori Group. The Trypali Group seems not to be a particular unit. For the reconstruction of the paleogeographic and geodynamic evolution of the South Aegean region the following evidence may be important:

1. the marine sedimentation in the Upper Palaeozoic and the Lower Triassic, especially the marine Upper Permian (Dorashamian), an isolated occurrence 2000 km away from comparable sediments further east and
2. the obvious termination of deposition at the Triassic/Lias boundary. A future interpretation of these results may be the key to a better understanding of the geodynamic process which led to the high pressure/low temperature metamorphism of the Phyllite Group.

     

Aubrites and diogenites: Trace element clues to their origin

We have analyzed by RNAA 25 aubrite and 9 diogenite samples for 13 to 29 siderophile, volatile, and lithophile trace elements. Both meteorite classes show a typically igneous siderophile element pattern, with Ir, Os, Re, Ge more depleted than Au, Ni, Pd, Sb. But aubrites tend to have about 10 × higher abundances (10^?3 ? 10 ^{? 4} × Cl for the first 4 and 10^?2?10^?3 × Cl for the last 4 siderophiles), apparently reflecting smaller metal/silicate distribution coefficients at lowerf(O₂), or less complete segregation of metal. Se is surprisingly abundant in aubrites (up to 0.4 × Cl), but Te is less so ($\text{Se}\text{Te}\text{? 5 × Cl}$), apparently due to its stronger siderophile character. Other volatiles (Ag, Zn, In, Cd, Bi, T1) show depletions intermediate between lunar dunite and the Earth's mantle.Of 7 aubrites analyzed for REE (Ce, Nd, Eu, Tb, Yb, Lu), 6 are depleted in REE (0.08?0.5 × Cl) and 5 show negative Eu anomalies (the exceptions are Bishopville and Mt. Egerton silicate). This supports an igneous origin, as already noted by Boynton and Schmitt (1972). No samples of the complementary, basaltic and feldspathic rocks have been found thus far, but one of our samples of Khor Temiki dark is a candidate for the basalt. It is 5?7 × enriched in REE and only slightly less so in Rb, Cs, and U. Though shocked and enriched in siderophiles to ~0.05 × Cl, it apparently represents a new meteorite class.Three diogenites analyzed for REE show very diverse patterns, from strongly depleted in light REE for Tatahouine (Ce = 0.01 × Cl) to flat for Garland (~2.5 × Cl). The data confirm the trends found by Fukuokaet al. (1977) as well as their interpretations.Factor analysis shows several parallel groupings for aubrites and diogenites: siderophiles (Re, Ir, Os, Pd, Ge), chalcophiles (Se, Te), volatiles (Ag, In, Tl) and incompatibles (U, REE, and Cs or Rb). But there are some differences for elements such as Ni, Sb, Cd, Bi, Au, and Zn, most of which behave more sensibly in aubrites than in diogenites.Several element pairs that differ greatly in volatility (Cs-U, Ge-Ir) correlate closely in aubrites, in approximately Cl-chondrite proportions. These correlations, and other lines of evidence, suggest strongly that aubrites originated by igneous processes in their parent body, not by direct nebular condensation. The source material may have resembled EL chondrites in oxidation state and depletion of refractories, metal, and volatiles.     

Interannual fluctuations in the density of sand lance,Ammodytes americanus,larvae in Long Island Sound, 1951–1983

Enumeration data from over 2,300 ichthyoplankton samples collected during 17 yr, spanning a 32-yr interval (1951–1983), were compiled to determine interannual variations in density of sand lance larvae. Years of relatively high densities were noted during the winters of 1965–1966 and 1978–1979 and low densities in 1971–1974. A regular increase in numbers during the late 1970’s and the peak in 1978–1979 coincided with increases in population size found throughout the coastal northwest Atlantic Ocean. Densities in Long Island Sound began to decline in 1980 and this continued through 1983. In contrast, densities throughout coastal Atlantic areas during the 1980’s remained at least as high as they were 1976–1978. Interannual fluctuations in density of sand lance larvae could be partially explained by water temperatures in December. Warm Decembers were associated with low larval densities.