Turbulence in Continental Stratocumulus,Part I: External Forcings and Turbulence Structures

Comprehensive, ground-based observations from the US Department of Energy Atmospheric Radiation Measurements program Southern Great Plains site are used to study the variability of turbulence forcings and cloud-scale turbulence structures in a continental stratocumulus cloud. The turbulence observations are made from an upward facing cloud (35 GHz) Doppler radar. Cloud base and liquid water path are characterized using a lidar at the surface and a microwave radiometer. The turbulence characterizations are compared and contrasted with those observed in marine stratocumulus clouds. During the 16-h observation period used in this study the cloud-base and cloud-top heights evolve with time and changes in liquid water path observed by the radiometer are consistent with variations in cloud depth. Unlike marine stratocumulus clouds, a diurnal cycle of cloud thickness and liquid water path is not observed. The observed surface latent, sensible, and virtual sensible heat fluxes and the radiative fluxes exhibit a diurnal cycle with values increasing from sunrise to afternoon and decreasing afterwards. During the night, the sensible heat, virtual sensible heat and the net radiative fluxes at the surface are slightly negative. Solar radiative heating prevails in the cloud layer during the day and strong radiative cooling exists at cloud top even during the day. Unlike marine stratocumulus, surface heating described by the convective velocity scale \(W_\mathrm{s}^{*}\) and cloud-top cooling described by \(W_\mathrm{r}^{*}\) are both important in driving the in-cloud turbulence during the day, whereas cloud-top cooling is the exclusive contributor during the night. The combined \(W_\mathrm{s}^{*}\) and \(W_\mathrm{r}^{*}\) (the total velocity scale \(W_\mathrm{t}^{*})\) provides a useful way to track the evolution of the turbulence structure in the cloud. The variance of the radar-measured radial velocity, which is related to resolved turbulence, follows the diurnal cycle and is consistent with the total velocity scale \(W_\mathrm{t}^{*}\) variations. It is higher during the day and lower during the night, which is contrary to that in marine stratocumulus. The \(W_\mathrm{t}^{*}\) values are lowest around sunset when the radiative cooling is also small due to upper-level clouds observed above the low-level stratus. The vertical distribution of the variance results from the surface heating during the day and cloud-top cooling during the night. The squared spectrum width, which is related to turbulence structures within the radar sampling volume (unresolved turbulence) also follows the diurnal cycle. Its vertical distribution indicates that the unresolved turbulence more closely relates to the processes near cloud top. Turbulence in the cloud requires about an hour to respond to the external forcings of surface heating and cloud-top radiative cooling. Positive skewness prevails during the day and negative skewness prevails at night with a sharp transition around sunset. Resolved turbulence dominates near cloud base whereas unresolved turbulence dominates near cloud top. The turbulence characteristics and variability defined in this study can be used to evaluate the time evolution of turbulence structures in large eddy simulation forced by surface and cloud-top radiative forcings.     

Experimental and numerical investigations on CO2 injection and enhanced gas recovery effects in Altmark gas field (Central Germany)

The feasibility of CO₂ storage and enhanced gas recovery (EGR) effects in the mature Altmark natural gas field in Central Germany has been studied in this paper. The investigations were comprehensive and comprise the characterization of the litho- and diagenetic facies, mineral content, geochemical composition, the petrophysical properties of the reservoir rocks with respect to their potential reactivity to CO₂ as well as reservoir simulation studies to evaluate the CO₂ wellbore injectivity and displacement efficiency of the residual gas by the injected CO₂. The Rotliegend sediments of the Altmark pilot injection area exhibit distinct mineralogical, geochemical, and petrophysical features related to litho- and diagenetic facies types. The reservoir rock reactivity to CO₂ has been studied in autoclave experiments and associated effects on two-phase transport properties have been examined by means of routine and special core analysis before and after the laboratory runs. Dissolution of calcite and anhydrite during the short-term treatments leading to the enhancements of permeability and porosity as well as stabilization of the water saturation relevant for CO₂ injection have been observed. Numerical simulation of the injection process and EGR effects in a sector of the Altmark field coupled with a wellbore model revealed the possibility of injecting the CO₂ gas at temperatures as low as 10 °C and pressures around 40 bar achieving effective inflow in the reservoir without phase transition in the wellbore. The small ratio of injected CO₂ volume versus reservoir volume indicated no significant EGR effects. However, the retention and storage capacity of CO₂ will be maximized. The migration/extension of CO₂ varies as a function of heterogeneity both in the layers and in the reservoir. The investigation of CO₂ extension and pressure propagation suggested no breakthrough of CO₂ at the prospective production well during the 3-year injection period studied.     

Surface studies of asteroids with the Faint Object Camera of the Space Telescope

Minor planets have been observed in the last few years for physical properties using photometry, polarimetry and IR-radiometry. Using the Faint Object Camera (FOC) of the Space Telescope (ST) it will be possible for the first time to observe a large number of asteroids with direct imaging systems.We propose to use the FOC with high resolution mode to examine minor planets with respect to (a) diameters and shapes, (b) surface and detail studies, (c) densities and (d) possible binary nature of selected asteroids.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

New Observing Opportunities in the Far‐Infrared and Submillimeter Range

F01 CONDOR – 1.4 THz Hetrodyne Receiver for APEX and for GREAT on SOFIA F02 FLASH – a First Light APEX Submillimeter Heterodyne instrument F03 GREAT – The German first light heterodyne instrument for SOFIA F04 CHAMP+ – A powerfull submillimeter array for the APEX telescope F05 The JamesWebb Space Telescope (JWST) and its Mid Infrared Instrument (MIRI) F06 CHARM – a Compact Heterodyne Array Receiver Module for KOSMA with Scalable Fully Reflective Focal Plane Array Optics F07 Science with Herschel‐PACS F08 CI/CO Mapping of IC 348 & Cepheus B using SMART on KOSMA F09 The warm and dense interstellar medium observed with Herschel F10 Intelligent Detectors – On‐Board Data Reduction for Future Missions F11 The Herschel Photodetector Array Camera & Spectrometer PACS F12 Why Astromineralogy Should Care about the Far‐infrared Range F13 ESI: A European Imaging Far‐Infrared Spectrometer for the Japanese SPICA space observatory F14 STAR – A 16 Pixel Terahertz Array Receiver for SOFIA F15 FIFI LS, a Field‐Imaging Far‐Infrared Line‐Spectrometer for SOFIA F16 Characterization of high‐ and low‐stressed Ge:Ga array cameras for Herschel's PACS instrument F17 Herschel / PACS Guaranteed Time Programs at MPIA F18 NANTEN2: CI and mid‐J CO surveys of clouds and galaxies of the southern sky     

Geological influences on the Lower Mississippi River and its alluvial valley

Studies of photographs, maps, and channel morphology permit identification of greatly different Mississippi River reaches. From this, it becomes apparent that this large alluvial river is not monotonous in appearance, and therefore, it is not completely controlled by hydrology and hydraulics. In fact, the Mississippi River has reacted to uplift, faults, clay plugs, outcrops of Tertiary clay, and Pleistocene gravel in its bed, and tributaries. This classic example of a large alluvial river has major geological controls on its shape, pattern, and magnitude of change through time. In addition, the same controls plus the effect of plutonic intrusives and fault zones have significantly affected smaller rivers and the alluvial valley of the Mississippi River.     

Prey preferences among the community of deep-diving odontocetes from the Bay of Biscay, Northeast Atlantic

Long-finned pilot whales (Globicephala melas), Risso's dolphins (Grampus griseus), melon-headed whales (Peponocephala electra), Cuvier's beaked whales (Ziphius cavirostris), Sowerby's beaked whales (Mesoplodon bidens), northern bottlenose whales (Hyperoodon ampullatus), sperm whales (Physeter macrocephalus), dwarf sperm whales (Kogia sima) and pygmy sperm whales (Kogia breviceps) make up the large community of deep-diving odontocetes occurring off the Bay of Biscay, northeast Atlantic. The ecology of these toothed cetaceans is poorly documented worldwide. The present study described their prey preferences from stomach content analysis and showed resource partitioning within the assemblage. The majority of the species appeared to be mostly teutophageous. Fish was an important food source only for the Sowerby's beaked whale and, to a lesser extent, for the long-finned pilot whale. In terms of foraging habitats inferred from prey composition, either pelagic oceanic or demersal neritic habitats were exploited by toothed whales in the Bay of Biscay, with only the long-finned pilot whale foraging in the two habitats. Finally, with more than 14,000 identified cephalopods from 39 species, the present study highlighted also the poorly known deep-sea cephalopod community off the Bay of Biscay using top predators as biological samplers.     

Structure and kinematics of the Jungfrau syncline, Faflertal (Valais, Alps), and its regional significance

The formation and structural evolution of the Jungfrau syncline is described, based on excellent outcrops occurring in the Lötschental, in the Central Alps of Switzerland. The quality of the outcrops allows us to demonstrate that the External Massifs of the Swiss Alps have developed due to internal folding. The Jungfrau syncline, which separates the autochtonous Gastern dome from the Aar massif basement gneiss folds, is composed of slivers of basement rocks with their Mesozoic sedimentary cover. In the Inner Faflertal, a side valley of the Lötschental, the 200 m thick syncline comprises four units, the Gastern massif with a reduced Mesozoic sedimentary cover in a normal stratigraphic succession, two units of overturned basement rocks with their Mesozoic sedimentary cover, and the overturned lower limb of the Tschingelhorn gneiss fold of the Aar massif with lenses of its sedimentary cover. Stratigraphy shows that the lower units, related to the Gastern massif, are condensed and that the upper units, deposited farther away from a Gastern paleo-high, form a more complete sequence, linked to the Doldenhorn Meso-Cenozoic basin fill. The integration of these local observations with published regional data leads to the following model. On the northern margin of the Doldenhorn basin, at the northern fringe of the Alpine Tethys, the pre-Triassic crystalline basement and its Mesozoic sedimentary cover were folded by ductile deformation at temperatures above 300 °C and in the presence of high fluid pressures, as the Helvetic and Penninic nappes were overthrusted towards the northwest during the main Alpine deformation phase. The viscosity contrast between the basement gneisses and the sediments caused the formation of large basement anticlines and tight sedimentary synclines (mullion-type structures). The edges of basement blocks bounded by pre-cursor SE-dipping normal faults at the northwestern border of the Doldenhorn basin were deformed by simple shear, creating overturned slices of crystalline rocks with their sedimentary cover in what now forms the Jungfrau syncline. The localisation of ductile deformation in the vicinity of pre-existing SE-dipping faults is thought to have been helped by the circulation of fluids along the faults; these fluids would have been released from the Mesozoic sediments by metamorphic dehydration reactions accompanied by creep and dynamic recrystallisation of quartz at temperatures above 300 °C. Quantification of the deformation suggests a strain ellipsoid with a ratio (1+ e₁ / 1+ e₃) of approximately 1000. The Jungfrau syncline was deformed by more brittle NW-directed shear creating well-developed shear band cleavages at a late stage, after cooling by uplift and erosion. It is suggested that the external massifs of the Alps are basement gneiss folds created at temperatures of 300 °C by detachment through ductile deformation of the upper crust of the European plate as it was underthrusted below the Adriatic plate.     

U–Pb dating, Hf-isotope characteristics and trace-REE-patterns of zircons from Medet porphyry copper deposit, Bulgaria: implications for timing, duration and sources of ore-bearing magmatism

Precise U–Pb geochronology, Hf isotope compositions and trace element distributions in zircons are combined in the present study to define the timing and sources of the magmatism forming the Medet porphyry copper deposit, Bulgaria. ID-TIMS U–Pb-zircon dating demonstrates that ore-bearing magmatism extended for less than 1.12 Ma. As inferred from the field relationships, it started with the intrusion of a quartz-monzodiorite at 90.59?±?0.29 Ma followed by granodiorite porphyries at 90.47?±?0.30 and 90.27?±?0.60 Ma and by crosscutting aplite dykes at 90.12?±?0.36 Ma. These units were overprinted by potassic alteration and host economic copper-(Mo–Au) mineralization. The main magmatic–hydrothermal activity ceased after that, and a later quartz-granodiorite porphyry dyke, dated at 89.26?±?0.32 Ma, only contains an uneconomic quartz–pyrite mineralization. Assimilation of Lower Paleozoic rocks with a mantle to mantle–crust signature is characteristic of the fertile magma in the Medet deposit, as defined by positive ?-Hf values of the inherited zircons. The positive Ce-anomalies and the higher Eu/Eu* ratios of the zircons in the mineralized Cretaceous rocks of Medet deposit argue for crystallization from a generally more oxidized magma compared to the later quartz-granodiorite porphyry dyke. A change in paleostress conditions occurred during the intrusion of the Medet pluton and its dykes. The initial stage reveals E–W extension associated with N–S compression, whereas the younger granodiorite dyke was emplaced during subsequent N–S extension. The large-scale switch of the extensional stress regime during the mineralization was favourable for ore deposition by channelling the fluids and increasing the effective permeability.