6,272 research outputs found

    A Digital Archive of Northern Hemisphere Snow Cover, November 1966 through December 1980

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    The purpose of this article is to acquaint the research community with a new data base—a digitized archive of Northern Hemisphere snow cover. Historically, those researchers who needed snow cover data for climatic and atmospheric boundary layer studies have had to rely on the irregularly spaced (and in some regions, sparse) grid of point observations. Northern Hemisphere Weekly Snow and Ice Cover Charts, which are created from analyzed satellite imagery at the National Earth Satellite Service (NESS), have been available on an operational basis since late 1966. Each of these weekly charts for the period November 1966 through December 1980 was digitized and stored in a new data archive. Snow cover area and snow cover frequency climatologies were created and examples are presented. The significance of this unique data archive is examined by comparing the 14-year mean annual snow cover frequency climatology with several published snow cover climatologies. The potential uses for this data archive in meteorological and climatological studies also are reviewed

    XMM-Newton observations of SNR 1987A. II. The still increasing X-ray light curve and the properties of Fe K lines

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    Aims. We report on the recent observations of the supernova remnant SNR 1987A in the Large Magellanic Cloud with XMM-Newton. Carefully monitoring the evolution of the X-ray light curve allows to probe the complex circumstellar medium structure observed around the supernova progenitor star. Methods. We analyse all XMM-Newton observations of SNR 1987A from January 2007 to December 2011, using data from the EPIC-pn camera. Spectra from all epochs are extracted and analysed in a homogeneous way. Using a multi-shock model to fit the spectra across the 0.2-10 keV band we measure soft and hard X-ray fluxes with high accuracy. In the hard X-ray band we examine the presence and properties of Fe K ines. Our findings are interpreted in the framework of a hydrodynamics-based model. Results. The soft X-ray flux of SNR 1987A continuously increased in the recent years. Although the light curve shows a mild flattening, there is no sudden break as reported in an earlier work, a picture echoed by a revision of the Chandra light curve. We therefore conclude that material in the equatorial ring and out-of-plane HII regions are still being swept-up. We estimate the thickness of the equatorial ring to be at least 4.5x10^16 cm (0.0146 pc). This lower limit will increase as long as the soft X-ray flux has not reached a turn-over. We detect a broad Fe K line in all spectra from 2007 to 2011. The widths and centroid energies of the lines indicate the presence of a collection of iron ionisation stages. Thermal emission from the hydrodynamic model does not reproduce the low-energy part of the line (6.4-6.5 keV), suggesting that fluorescence from neutral and/or low ionisation Fe might be present.Comment: 4 pages, 3 figures, 2 tables. Accepted for publication in Astronomy and Astrophysic

    Persistent, symptomless, systemic, and seed-borne infection of lettuce by Botrytis cinerea

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    Experiments are presented which show that Botrytis cinerea, the cause of gray mould disease, is often present in symptomless lettuce plants as a systemic, endophytic, infection which may arise from seed. The fungus was isolated on selective media from surface sterilized sections of roots, stem pieces and leaf discs from symptomless plants grown in a conventional glasshouse and in a spore-free air-flow provided by an isolation propagator. The presence of B. cinerea was confirmed by immuno-labelling the tissues with the Botrytis-specific monoclonal antibody BC-12.CA4. As plants grew, infection spread from the roots to stems and leaves. Surface sterilization of seeds reduced the number of infected symptomless plants. Artificial infection of seedlings with dry conidia increased the rate of infection in some experiments. Selected isolates were genetically finger-printed using microsatellite loci. This confirmed systemic spread of the inoculating isolates but showed that other isolates were also present and that single plants hosted multiple isolates. This shows that B. cinerea commonly grows in lettuce plants as an endophyte, as has already been shown for Primula. If true for other hosts, the endophytic phase may be as important a component of the species population as the aggressive necrotrophic phase

    Daily Maximum and Minimum Temperature Forecasts and the Influence of Snow Cover

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    Research into the relationship between snow cover and observed maximum and minimum temperatures is reviewed. An example of the importance of snow cover and forecasting max/min temperatures is presented for this past winter (1976-77). It is shown that there was a warm bias in the MOS temperature forecasts for the northern Great Plains following the receipt of a fresh cover of snowfall. it is proposed that snow cover be incorporated as a conditional predictor to be used only during specific synoptic conditions

    Lake Erie Induced Mesosystems- An Operational Forecast Model

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    All Lake Erie lake-effect days for a 10-year period prior to the 1976-77 snowfall season were utilized in the development of an operational lake-effect snowfall forecast model. Upper air and surface observation were combined with overlake data and analyzed, using stepwise multiple-discriminant analysis. A nine-predictor mesoscale forecast model resulted from this statistical test and its performance was evaluated during the 1976-77 and 1977-78 snowfall seasons. The results of this evaluation indicate that it is possible to predict six intensities of the Lake Erie lake-effect snowstorm using this mesoscale model

    Dewey F. Bartlett to President Richard M. Nixon, 19 June 1974

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    Copy typed memorandum from Dewey Bartlett, re: attached letter to Nixon. Attached: Copy typed letter signed dated 19 June 1974 from Eastland fifty-three other senators to Nixon, re: budget deficit & government spending.https://egrove.olemiss.edu/joecorr_f/1088/thumbnail.jp

    A Digital Archive of Northern Hemisphere Snow Cover, November 1966 through December 1980

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    The purpose of this article is to acquaint the research community with a new data base—a digitized archive of Northern Hemisphere snow cover. Historically, those researchers who needed snow cover data for climatic and atmospheric boundary layer studies have had to rely on the irregularly spaced (and in some regions, sparse) grid of point observations. Northern Hemisphere Weekly Snow and Ice Cover Charts, which are created from analyzed satellite imagery at the National Earth Satellite Service (NESS), have been available on an operational basis since late 1966. Each of these weekly charts for the period November 1966 through December 1980 was digitized and stored in a new data archive. Snow cover area and snow cover frequency climatologies were created and examples are presented. The significance of this unique data archive is examined by comparing the 14-year mean annual snow cover frequency climatology with several published snow cover climatologies. The potential uses for this data archive in meteorological and climatological studies also are reviewed

    Selected localities in the Taconics and their implications for the plate tectonic origin of the Taconic region

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    Guidebook for field trips in western Massachusetts, northern Connecticut and adjacent areas of New York: 67th annual meeting October 10, 11, and 12, 1975: Trip B-1; C-
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