Gap flow measurements during the Mesoscale Alpine Programme     

G. J. Mayr  L. Armi  S. Arnold  R. M. Banta  L. S. Darby  D. D. Durran  C. Flamant  S. Gaberšek  A. Gohm  R. Mayr  S. Mobbs  L. B. Nance  I. Vergeiner  J. Vergeiner  C. D. Whiteman 《Meteorology and Atmospheric Physics》2004,86(1-2):99-119

Summary The lowest pass through the Alpine crest, the Brenner Pass, was heavily instrumented with ground-based and air-borne in-situ and remote sensors during the Special Observation Period (SOP) of the Mesoscale Alpine Programme (MAP) in the fall of 1999 to study gap flow. The main objectives were to study the combined effects of changes of terrain height and changes of width in altering the flow characteristics, to investigate the coupling of the gap flow to the flow aloft, and to provide high-density measurements in the along- and cross-gap directions.Gap flows occurred during one third of the 70-day SOP, a frequency above the long term average. Gap flows took place with and without accompanying cross-barrier flow and with and without a capping inversion. A case study demonstrates the hydraulic jump-like features that occurred in gap flow on 30 October 1999 and illustrates the types of data available for further analyses.  相似文献   

Boron isotopes as an artificial tracer     

Quast KW  Lansey K  Arnold R  Bassett RL  Rincon M 《Ground water》2006,44(3):453-466

A field study was conducted using a combination of intrinsic and artificial tracers to estimate travel times and dilution during transport of infiltrate from a reclaimed water infiltration basin to nearby monitoring wells. A major study objective was to validate boric acid enriched in (10)B as an artificial tracer. Basin 10E at the Rio Hondo Spreading Grounds in Whittier, California, was the site of the test. The basin normally receives a mixture of treated municipal waste water, purchased State Project water, and local runoff from the San Gabriel River. Approximately 3.5 kg of (10)B-enriched boric acid was dispersed among 2.05 x 10(5) m(3) of basin water to initiate the experiment. The resultant median delta(11)B in the infiltration basin was -71 per thousand. Prior to tracer addition, the basin water had an intrinsic delta(11)B of +2 per thousand. Local monitoring wells that were used to assess travel times had delta(11)B values of +5 per thousand and +8 per thousand at the time of tracer addition. Analytic results supported an assumption that boron is conserved during ground water transport and that boron enriched in (10)B is a useful artificial tracer. Several intrinsic tracers were used to reinforce the boric acid tracer findings. These included stable isotopes of oxygen (delta(18)O) and hydrogen (deltaD), sulfate concentration, and the boron to chloride ratio. Xenon isotopes, (136)Xe and (124)Xe, also supported boron isotope results. Xenon isotopes were added to the recharge basin as dissolved gases by investigators from the Lawrence Livermore National Laboratory.  相似文献   

Numerical experiment to revisit micrometeorology and sound speed calculations in forests     

Arnold Tunick 《Meteorology and Atmospheric Physics》2010,107(3-4):103-108

A recent paper (Tunick and Swearingen in Appl Acoustics 70:857–867, 2009) presented a finite-difference computer model to calculate the microphysical influences on sound wave propagation in forests. Several numerical tests were conducted to assess model code capabilities using micrometeorological and acoustic field data. Calculated wind, temperature, and specific humidity profile data compared favorably to measured data. Nevertheless, we recommended investigation of alternate numerical schemes to determine the best formulation for micrometeorological-acoustic research applications in forests. Hence, in this paper, we conduct a numerical experiment that focuses on the pressure gradient term in the conservation of momentum equation. In particular, we implement a numerical iteration of this term at each time step of the calculation. This modification yields a more nearly incompressible flow, thus producing an alternative representation of the physics for the simulation of interest. Differences in the computed wind, temperature, and sound speed fields for the runs with and without implementing the iteration scheme are illustrated graphically and discussed.  相似文献   

The Effect of Surface Heterogeneity on the Temperature–Humidity Correlation and the Relative Transport Efficiency     

Arnold F. Moene  Dirk Schüttemeyer 《Boundary-Layer Meteorology》2008,129(1):99-113

We derive a conceptual model of the flow over heterogeneous terrain consisting of patches with contrasting Bowen ratios. Upward moving eddies are assumed to carry heterogeneous properties, whereas downward moving eddies carry homogeneous properties. This results in a decorrelation of temperature and humidity as the contrast between the patches increases. We show that this model is able to reproduce the relationship developed by Lamaud and Irvine (Boundary-Layer Meteorol. 120:87–109, 2006). Some details differ from their expression but are in accordance with data obtained over African savannah. We extend the conceptual model to a combination of any scalars, not necessarily linked through the surface energy balance (as is the case for temperature and humidity). To this end we introduce a new parameter that describes the surface heterogeneity in surface fluxes. The results of the current model can be used to predict the discrepancy between similarity relationships for different scalars over heterogeneous terrain.  相似文献   

Solar cosmic ray records in lunar rock 64455     

K. Nishiizumi  J.R. Arnold  M.W. Caffee  J. Masarik 《Geochimica et cosmochimica acta》2009,73(7):2163-449

Cosmic ray produced ¹⁰Be (half-life = 1.36 × 10⁶ yr), ²⁶Al (7.05 × 10⁵ yr), and ³⁶Cl (3.01 × 10⁵ yr) were measured in a depth profile of 19 carefully-ground samples from the glass-coated lunar surface rock 64455. The solar cosmic ray (SCR) produced ²⁶Al and ³⁶Cl in this rock are present in high concentrations, which in combination with the low observed erosion rate, <0.5 mm/Myr, provide well defined depth profiles characterizing the SCR component of the cosmic rays. In conjunction with new experimentally determined excitation functions, the ³⁶Cl concentrations suggest a softer solar-proton spectral shape than that derived from most previous measurements. The fact that no SCR-produced ¹⁰Be activity could be detected in 64455 is in good agreement with observations in 68815 and also indicates a softer SCR spectrum. Comparison of observed SCR profiles in 64455 with theoretical calculations indicates that the average solar-proton spectrum over the past 2 Myr (based on ²⁶Al) has an exponential rigidity parameter (R₀) of about 90 MV with a proton flux (J) of 73 protons/cm²/s·4π above 10 MeV. Over the last ∼0.5 Myr (based on ³⁶Cl) R₀ is about 70 MV with a flux of ∼196 protons/cm²/s·4π above 10 MeV. These SCR fluxes are consistent with most previous work.  相似文献   

Neuere Veröffentlichungen     

Arnold Schumacher  K. Kalle 《Ocean Dynamics》1949,2(1-3):111-116

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In memoriam     

H. C. Freiesleben  Arnold Schumacher  Otto Steppes 《Ocean Dynamics》1948,1(1):41-44

Ohne Zusammenfassung  相似文献   

PHOENIX-2: A New Broadband Spectrometer for Deci- metric and Microwave Radio Bursts – First Results     

Messmer  Peter  Benz  Arnold O.  Monstein  Christian 《Solar physics》1999,187(2):335-345

A broadband radio spectrometer has been put into operation at Bleien, Switzerland, to register the flare emission of the full Sun. In the frequency range of operation, 0.1 to 4.0 GHz, both modes of circular polarization are recorded continuously. The new system, Phoenix-2, has been developed from the experience with the previous Phoenix spectrometer. Improved, computer-controlled focal hardware allows now a complete daily calibration, a more sophisticated calibration procedure, and monitoring of all essential instrumental and environmental parameters. Calibrated data are now usually available the day after observation and are accessible through the Internet. The scientific improvements include a larger frequency range of observation, a larger number of completely recorded events due to full-day registration, more accurate measurements, particularly in circular polarization, and more reliable operation. First observations are presented and quantitative results comparing the calibration with single frequency instruments are reported. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005194314845  相似文献   

Trace metals and radionuclides reveal sediment sources and accumulation rates in Jordan Cove, Connecticut     

Gaboury Benoit  Tim F. Rozan  Peter C. Patton  Chester L. Arnold 《Estuaries and Coasts》1999,22(1):65-80

Many small estuaries are influenced by flow restrictions resulting from transportation rights-of-way and other causes. The biogeochemical functioning and history of such systems can be evaluated through study of their sediments. Ten long and six short cores were collected from the length of Jordan Cove, Connecticut, a Long Island Sound subestuary, and analyzed for stratigraphy, radionuclides (¹⁴C, ²¹⁰Pb, ²²⁶Ra, ¹³⁷Cs, and ⁶⁰Co), and metals (Ag, Cd, Cu, Pb, Zn, Fe, and Al). For at least 3,800 yr, rising sea level has gradually inundated Jordan Cove, filling it with mud similar to that currently being deposited there. Long-term sediment accumulation in the cove averaged close to 0.1 cm yr⁻¹ over the last three millennia. Recent sediment accumulation rates decrease inland from 0.84 cm yr⁻¹ to 0.40 cm yr⁻¹, and are slightly faster than relative sea-level rise at this site (0.3 cm yr⁻¹). Similarity of depth distributions of trace metals was used to confirm relative sediment accumulation rates. ⁶⁰Co and Ag are derived from sources outside the cove and its watershed, presumably the Millstone nuclear power plant and regional contaminated sediments, respectively. The combined data suggest that Long Island Sound is an important source of sediment to the cove; a minor part of total sediment is supplied from the local watershed. Trace metal levels are strongly correlated with Fe but not with either organic matter or Al. Sediment quality has declined in the cove over the past 60 yr, but only slightly. Cu, Pb, and Zn data correlate strongly with Fe but not with either organic matter or aluminum. Ratios of Ag to Fe and to trace metals suggest that Ag in the cove is derived almost entirely from Long Island Sound. This result supports the notion that Fenormalized Ag can serve as a better tracer of some kinds of contamination than more common and abundant metals, like Cu, Pb, and Zn. *** DIRECT SUPPORT *** A01BY085 00008  相似文献   

Book Review: Glacial Geology: Ice Sheets and Landforms by Matthew R. Bennett and Neil F. Glasser,John Wiley and Sons Ltd,Chichester, 1996. No. of pages: x+364. Price: £19.99 (pb). ISBN 0-471-963445-3     

Neil Arnold 《地球表面变化过程与地形》1997,22(11):1084-1085

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