Modeling Total Solar Irradiance Variations Using Automated Classification Software on Mount Wilson Data     

R. K. Ulrich  D. Parker  L. Bertello  J. Boyden 《Solar physics》2010,261(1):11-34

We present the results using the AutoClass analysis application available at NASA/Ames Intelligent Systems Div. (2002) which is a Bayesian, finite mixture model classification system developed by Cheeseman and Stutz (1996). We apply this system to Mount Wilson Solar Observatory (MWO) intensity and magnetogram images and classify individual pixels on the solar surface to calculate daily indices that are then correlated with total solar irradiance (TSI) to yield a set of regression coefficients. This approach allows us to model the TSI with a correlation of better than 0.96 for the period 1996 to 2007. These regression coefficients applied to classified pixels on the observed solar surface allow the construction of images of the Sun as it would be seen by TSI measuring instruments like the Solar Bolometric Imager recently flown by Foukal et al. (Astrophys. J. 611, L57, 2004). As a consequence of the very high correlation we achieve in reproducing the TSI record, our approach holds out the possibility of creating an on-going, accurate, independent estimate of TSI variations from ground-based observations which could be used to compare, and identify the sources of disagreement among, TSI observations from the various satellite instruments and to fill in gaps in the satellite record. Further, our spatially-resolved images should assist in characterizing the particular solar surface regions associated with TSI variations. Also, since the particular set of MWO data on which this analysis is based is available on a daily basis back to at least 1985, and on an intermittent basis before then, it will be possible to estimate the TSI emission due to identified solar surface features at several solar minima to constrain the role surface magnetic effects have on long-term trends in solar energy output.  相似文献   

Solution of the MoMaS reactive transport benchmark with MIN3P—model formulation and simulation results     

K. Ulrich Mayer  Kerry T. B. MacQuarrie 《Computational Geosciences》2010,14(3):405-419

This paper summarizes the governing equations as implemented in the MIN3P multicomponent flow and reactive transport code (Mayer et al., Water Resour Res 38:1174, 2002) and introduces the equations in discretized form. Linearization and solution methods are presented including adaptive time stepping and update modification schemes. Code-specific details for the implementation of the GdR MoMaS benchmark simulations (Carrayrou et al., Comput Geosci, 2009) are presented. The standard version of the MIN3P code was used to solve the Easy, Medium, and Hard Test Cases, in one and two spatial dimensions, for both advection- and diffusion-dominated conditions. An analysis of the sensitivity of the solution in relation to spatial and temporal discretization parameters is provided for the Easy Test Case, selected results are presented for the Medium and Hard Test Cases, and the performance of the code as a function of discretization parameters is evaluated for all test cases.  相似文献   

Milankovic’s theory: multidimensional visualisation of the change of insolation and indicators of climatic change from 100000 before present to 100000 after present (in intervals of 1,000 years)     

Ulrich Wieczorek 《International Journal of Earth Sciences》2010,99(1):201-205

The deviation of the insolation on the earth’s surface from the past to the present and the present to the future for cloudless days is calculated in intervals of 1,000 years from 100000 years before present (BP) to 100000 years after present (AP), its basis being Milankovic’s theory. But the result are not the well-known Milankovic-curves, which are calculated for different latitudes and in which the x-axis represents years and the y-axis represents the insolation difference to present during the North-summer half-year. The calculations are made for each day of the selected years from the South Pole to the North Pole. Thus, two temporal dimensions are represented, that of a year and that of a day, furthermore the spatial dimension “latitude” and the dimension “energy” (insolation deviation). The performance of modern PCs allows the results of the calculations to be presented by a graphical animation. A determined deviation pattern of the insolation is obtained for each year. δ¹⁸O data, the mean global temperature and the additional ice volume on the continents are added to the graphic representations of those patterns for the period from 100000 years BP to the present. During that period insolation deviation patterns can be recognised which correlate with cool climates or climates getting cooler, and others which correlate with relatively warm climates or climates getting warmer. Correlations between the patterns are calculated and groups of similar patterns can be composed which can be associated in most cases with specific climatic conditions or specific climatic change. Comparison of patterns between 100000 years and present BP with patterns between present and 100000 years AP can help to estimate climatic change during the 100000 years ahead.  相似文献   

A new method in palaeoecology: fish community structure indicates environmental changes     

Ulrich Schmölcke  Kenneth Ritchie 《International Journal of Earth Sciences》2010,99(8):1763-1772

A new method to reconstruct aquatic palaeoenvironments is presented. It is based on a non-metrical ‘fish environment reconstruction index’ (FERI), calculated for the total fish community recorded at an archaeological site. As an example, a FERI is generated for the Baltic Sea using the ecological requirements of northern European fish species. The present study evaluates the proposed method by using fish bone assemblages from a region (the middle Holocene Baltic Sea coast) with well-studied hydrographic history. The bones originate from consecutive human riparian and coastal settlements of hunter-gatherers. The results obtained for the parameters salinity and sediment structure correlate well with geological knowledge. The new method shows a successive change from freshwater to brackish and finally to nearly marine conditions before, during, and towards the end of the marine transgression that created the present Baltic Sea. Additionally, a shift in the sediment structure from muddy to sandy/rocky conditions is recognisable.  相似文献   

Crater floor topography and impact melt sheet geometry of the Sudbury impact structure,Canada     

René Dreuse  Daniel Doman  Tasca Santimano  Ulrich Riller 《地学学报》2010,22(6):463-469

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Letter to the Editor: Comment on “Logratio Analysis and Compositional Distance” by J. Aitchison, C. Barceló-Vidal, J. A. Martín-Fernández, and V. Pawlowsky-Glahn     

Sönke Rehder  Ulrich Zier 《Mathematical Geology》2001,33(7):845-848

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Limnological description of the Lakes Zürich, Lucerne, and Cadagno     

Peter Bossard  Sonja Gammeter  Christine Lehmann  Ferdinand Schanz  Reinhard Bachofen  Hans-Rudolf Bürgi  Daniel Steiner  Ulrich Zimmermann 《Aquatic Sciences - Research Across Boundaries》2001,63(3):225-249

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Über das Vorkommen verschiedener Arten der GattungCyclops (s. restr.) in schweizerischen Seen     

Friedrich Kiefer  Ulrich Einsle 《Aquatic Sciences - Research Across Boundaries》1962,24(1):44-48

Ohne Zusammenfassung  相似文献   

Heavy metal accumulation in river sediments: A response to environmental pollutionSchwermetall-anreicherung in fluviatilen sedimenten als ausdruck der verschmutzung unserer umwelt     

Ulrich Förstner  German Müller 《Geoforum》1973,4(2):53-61

As evidenced by catastrophic cadmium and mercury poisonings in japan, heavy metals belong to the most toxic environmental pollutants. Through the investigation of sediments, the extent, distribution and provenance of heavy metal contamination in rivers and lakes can be determined and traced. Eight heavy metals from the clay fraction of sediments from major rivers within the Federal Republic of Germany were determined by means of atomic adsorption spectrometry. Heavy metals especially known for their high toxicity are enriched most: mercury, lead and zinc by a factor of 10; cadmium by a factor of 50, as compared with the natural background of these elements. A mobilisation of heavy metals from the suspended load and from the sediments, as to be observed in rivers approaching the marine enviromment, could endanger marine organisms, thus negatively influencing the acquatic food chain. With a further increase of heavy metal pollution, a threat to the drinking water supplied by rivers and lakes cannot be excluded.  相似文献   

Untersuchungen zur Morphologie des Schelfrandes vor Mozambique nordöstlich der Sambesi-Mündung     

Dr. Johannes Ulrich  Dr. Horst Pasenau 《Ocean Dynamics》1973,26(5):216-225

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