Sea surface temperature changes in the North Sea and their causes   总被引：2，自引：0，他引：2  

Becker  Gerd A.; Pauly  Manfred 《ICES Journal of Marine Science》1996,53(6):887-898

  相似文献   

Thermal history of the westernmost Eastern Alps (Penninic Rhenodanubian Flysch nappes,Helvetic nappes,and Subalpine Molasse thrust sheets)     

Michael Zerlauth  Audrey Bertrand  Gerd Rantitsch  Doris Groß  Hugo Ortner  Hannah Pomella  Bernhard Fügenschuh 《International Journal of Earth Sciences》2016,105(5):1525-1547

  相似文献   

Climatology of noctilucent cloud radii and occurrence frequency using SCIAMACHY     

Charles E. Robert  Christian von Savigny  John P. Burrows  Gerd Baumgarten 《Journal of Atmospheric and Solar》2009,71(3-4):408-423

  相似文献   

Perturbations of the upper atmosphere in the cleft region     

Gerd W. Prlss 《Journal of Atmospheric and Solar》2008,70(18):2374-2380

In the dayside polar region—loosely referred to as the cleft region—particle precipitation and Joule heating cause significant perturbations of the upper atmosphere. Here Dynamics Explorer-2 satellite data are used to present a synopsis of these disturbance effects. Documented are an increase in electron temperature and a decrease in electron density; increases in ion drift speed and ion temperature; an increase in the upward-directed ion velocity; increases in zonal wind speed and neutral gas temperature; and changes in the neutral gas composition and mass density. It is suggested that the increase in electron temperature is partly controlled by the decrease in electron density; that the ion upflow velocity mainly depends on the electron temperature, less frequently on the ion temperature; and that the observed decrease in thermospheric mass density is due to a decrease in the atomic oxygen density, which in turn is caused by diverging wind flows.  相似文献   

Alongshore variation in beach cusp morphology in a coastal embayment     

Gerhard Masselink 《地球表面变化过程与地形》1999,24(4):335-347

The variation in beach cusp characteristics was examined along a 1 km long embayed beach (Pearl Beach, New South Wales, Australia). The beach cusp morphology had formed during the previous day and/or night and displayed a marked alongshore variation in cusp spacing. The edge wave mechanism of beach cusp formation could not account for the observed trend in cusp spacing, because no relationship could be established between the spacing of the cusps and the gradient of the beachface. On the other hand, the cusp spacing was strongly related to the horizontal swash excursion, providing some support for the self-organization model of beach cusp formation. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Optimal planning and operation of irrigation systems under water resource constraints in Oman considering climatic uncertainty     

Niels Schütze  Sebastian Kloss  Franz Lennartz  Ahmed Al Bakri  Gerd H. Schmitz 《Environmental Earth Sciences》2012,65(5):1511-1521

In this contribution, we introduce a stochastic framework for decision support for optimal planning and operation of water supply in irrigation. This consists of (1) a weather generator for simulating regional impacts of climate change on the basis of IPCC scenarios, (2) a tailor-made evolutionary optimization algorithm for optimal irrigation scheduling with limited water supply, (3) a mechanistic model for simulating water transport and crop growth in a sound manner, and (4) a kernel density estimator for estimating stochastic productivity, profit, and demand functions by a nonparametric method. As a result of several simulation/optimization runs within the framework, we present stochastic crop-water production functions (SCWPF) for different crops which can be used as a basic tool for assessing the impact of climate variability on the risk for the potential yield for specific crops and specific agricultural areas. A case study for an agricultural area in the Al Batinah region of the Sultanate of Oman is used to illustrate these methodologies. In addition, microeconomic impacts of climate change and the vulnerability of the agro-ecological system are discussed.  相似文献   

A Tunnel Information System for the Management and Utilization of Geo-Engineering Data in Urban Tunnel Projects     

Klaus Chmelina  Klaus Rabensteiner  Gerd Krusche 《Geotechnical and Geological Engineering》2013,31(3):845-859

The contribution presents the current state and latest capabilities of information technology (particularly tunnel information systems) used for urban tunnel projects. In detail, it informs on the system architecture and the latest data management, monitoring, alarming and reporting functions and services of the tunnel information system KRONOS of Geodata. To assess the systems’ benefits, installation examples and experiences from four currently running, urban European tunnelling projects are described. Finally, the most recent and promising R&D activities in this field are emphasized.  相似文献   

Empirical relationship between leaf wax n-alkane δD and altitude in the Wuyi,Shennongjia and Tianshan Mountains,China: Implications for paleoaltimetry     

Pan Luo  Ping'an Peng  Gerd Gleixner  Zhuo Zheng  Zhonghe Pang  Zhongli Ding 《Earth and Planetary Science Letters》2011,301(1-2):285-296

Estimating past elevation not only provides evidence for vertical movements of the Earth's lithosphere, but also increases our understanding of interactions between tectonics, relief and climate in geological history. Development of biomarker hydrogen isotope-based paleoaltimetry techniques that can be applied to a wide range of sample types is therefore of continuing importance. Here we present leaf wax-derived n-alkane δD (δD_wax) values along three soil altitudinal transects, at different latitudes, in the Wuyi, Shennongjia and Tianshan Mountains in China, to investigate δD_wax gradients and the apparent fractionation between leaf wax and precipitation (ε_wax-p).We find that soil δD_wax track altitudinal variations of precipitation δD along the three transects that span variable environment conditions and vertical vegetation spectra. An empirical δD_wax-altitude relation is therefore established in which the average δD_wax lapse rate of ? 2.27 ± 0.38‰/100 m is suitable for predicting relative paleoelevation change (relative uplift). The application of this empirical gradient is restricted to phases in the mountain uplift stage when the atmospheric circulation had not distinctly changed and to when the climate was not arid. An empirical δD_wax–latitude–altitude formula is also calculated: δD_wax = 3.483LAT ? 0.0227ALT ? 261.5, which gives the preliminary spatial distribution pattern of δD_wax in modern China.Mean value of ε_wax-p in the extreme humid Wuyi Mountains is quite negative (? 154‰), compared to the humid Shennongjia (? 129‰) and the arid (but with abundant summer precipitation) Tianshan Mountains (? 130‰), which suggests aridity or water availability in the growing season is the primary factor controlling soil/sediment ε_wax-p. Along the Tianshan transects, values of ε_wax-p are speculated to be constant with altitude; while along the Wuyi and Shennongjia transects, ε_wax-p are also constant at the low-mid altitudes, but become slightly more negative at high altitudes which could be attributed to overestimates of precipitation δD or the vegetation shift to grass/conifer.Additionally, a reversal of altitude effect in the vertical variation of δD_wax was found in the alpine zone of the Tianshan Mountains, which might be caused by atmospheric circulation change with altitude. This implies that the paleo-circulation pattern and its changes should also be evaluated when stable isotope-based paleoaltimetry is applied.  相似文献   

Relative contribution of foliar and fine root pine litter to the molecular composition of soil organic matter after in situ degradation   总被引：1，自引：0，他引：1  

Stefania Mambelli  Jeffrey A. Bird  Gerd Gleixner  Todd E. Dawson  Margaret S. Torn 《Organic Geochemistry》2011,42(9):1099-1108

The influence of litter quality on soil organic matter (SOM) stabilization rate and pathways remains unclear. We used ¹³C/¹⁵N labeled litter addition and Curie-point pyrolysis gas chromatography–mass spectrometry combustion-isotope ratio mass spectrometry (Py–GC–MS–C–IRMS) to explore the transformation of litter with different composition and decay rate (ponderosa pine needle vs. fine root) to SOM during 18 months in a temperate conifer forest mineral (A horizon) soil. Based on ¹³C Py–GC–MS–C–IRMS the initial litter and bulk soil had ∼1/3 of the total pyrolysis products identified in common. The majority was related either to carbohydrates or was non-specific in origin. In bulk soil, carbohydrates had similar levels of enrichment after needle input and fine root input, while the non-specific products were more enriched after needle input. In the humin SOM fraction (260 yr C turnover time) we found only carbohydrate and alkyl C-derived compounds and greater ¹³C enrichment in the “carbohydrate” pool after fine root decomposition. ¹⁵N Py–GC–MS–C–IRMS of humic substances showed that root litter contributed more than needle litter to the enrichment of specific protein markers during initial decomposition.We found little evidence for the selective preservation of plant compounds considered to be recalcitrant. Our findings suggest an indirect role for decomposing plant material composition, where microbial alteration of fine root litter seems to favor greater initial stabilization of microbially derived C and N in SOM fractions with long mean turnover times, such as humin, compared to needles with a faster decay rate.  相似文献   

The atmospheric boundary layer structure over the open and ice-covered Baltic Sea: in situ measurements compared to simulations with the regional model REMO     

Burghard Brümmer  Amélie Kirchgäßner  Gerd Müller 《Theoretical and Applied Climatology》2014,118(4):641-653

The regional model REMO, which is the atmospheric component of the coupled atmosphere–ice–ocean–land climate model system BALTIMOS, is tested with respect to its ability to simulate the atmospheric boundary layer over the open and ice-covered Baltic Sea. REMO simulations are compared to ship, radiosonde, and aircraft observations taken during eight field experiments. The main results of the comparisons are: (1) The sharpness and strength of the temperature inversion are underestimated by REMO. Over open water, this is connected with an overestimation of cloud coverage and moisture content above the inversion. (2) The vertical temperature stratification in the lowest 200 m over sea ice is too stable. (3) The horizontal inhomogeneity of sea ice concentration as observed by aircraft could not be properly represented by the prescribed ice concentration in REMO; large differences in the surface heat fluxes arise especially under cold-air advection conditions. The results of the comparisons suggest a reconsideration of the parameterization of subgrid-scale vertical exchange both under unstable und stable conditions.  相似文献