A possibly direct measurement of coronal magnetic field strengths     

Hans Rosenberg 《Solar physics》1972,25(1):188-196

During a unique solar radio event on March 2, 1970, among very diverse features, a very regular pattern was observed in the solar radio spectrographic record between 220 and 320 MHz. The proposed explanation is emission by slightly relativistic electrons at the sum frequency of the plasma frequency ( 160 MHz) and the lower harmonics of the local gyrofrequency (n from 3 to 10), rather than emission at pure harmonics of the gyrofrequency (n from 15 to 20). The derived magnetic field strengths range from 3 to 8 G, and can be determined very accurately. From the simultaneously occurring pulsating structure in the type IV emission and the deduced magnetic field strength a typical size of the emitting region of 2–300 km is derived.  相似文献   

Marine quality assessment by use of benthic species-abundance distributions: a proposed new protocol within the European Union Water Framework Directive   总被引：3，自引：0，他引：3  

Rosenberg R  Blomqvist M  C Nilsson H  Cederwall H  Dimming A 《Marine pollution bulletin》2004,49(9-10):728-739

The aim of this study is to develop a new method for classification of marine benthic quality according to the European Union Water Framework Directive. Tolerance values to environmental disturbance were determined in an objective analysis for benthic species along the Swedish west coast by using 4676 samples from 257 stations. Based on a combination of the species tolerance values, abundance and diversity, a benthic quality index (BQI) was calculated for the assessment of environmental status at a particular station. The qualification of BQI was evaluated in relation to known spatial and temporal gradients of disturbance.  相似文献   

Nutrient transfer from soil to surface waters: Differences between nitrate and phosphate   总被引：3，自引：0，他引：3  

René?G?chterEmail author  Sandra?M.?Steingruber  Miriam?Reinhardt  Bernhard?Wehrli 《Aquatic Sciences - Research Across Boundaries》2004,66(1):117-122

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Ultrahigh temperature deformation microstructures in felsic granulites of the Napier Complex, Antarctica   总被引：3，自引：0，他引：3  

Majbritt D. Lund  Sandra Piazolo  Simon L. Harley 《Tectonophysics》2006,427(1-4):133

Detailed electron microscope and microstructural analysis of two ultrahigh temperature felsic granulites from Tonagh Island, Napier Complex, Antarctica show deformation microstructures produced at  1000 °C at 8–10 kbar. High temperature orthopyroxene (Al 7 wt.% and  11 wt.%), exhibits crystallographic preferred orientation (CPO) and frequent subgrain boundaries which point to dislocation creep as the dominating deformation mechanism within opx. Two different main slip systems are observed: in opx bands with exclusively opx grains containing subgrain boundaries with traces parallel to [010] and a strong coupling of low angle misorientations (2.5°–5°) with rotation axes parallel to [010] the dominating slip system is (100)[001]. Isolated opx grains and grain clusters of 2–5 grains embedded in a qtz–fsp matrix show an additional slip system of (010)[001]. The latter slip system is harder to activate. We suggest that differences in the activation of these slip systems is a result of higher differential stresses imposed onto the isolated opx grains and grain clusters. In contrast to opx, large qtz grains (up to 200 μm) show random crystallographic orientation. This together with their elongate and cuspate shape and the lack of systematic in the rotation axes associated with the subgrain boundaries is consistent with diffusion creep as the primary deformation mechanism in quartz.Our first time detailed microstructural observations of ultrahigh temperature and medium to high pressure granulites and their interpretation in terms of active deformation mechanisms give some insight into the type of rheology that can be expect at lower crustal conditions. If qtz is the mineral phase governing the rock rheology, Newtonian flow behaviour is expected and only low differential stress can be supported. However, if the stress supporting mineral phase is opx, the flow law resulting from dislocation creep will govern the rheology of the rock unit; hence, an exponential relationship between stress and strain rate is to be expected.  相似文献   

An upgraded version of the Eta model   总被引：2，自引：0，他引：2  

Fedor Mesinger  Sin Chan Chou  Jorge L. Gomes  Dusan Jovic  Paulo Bastos  Josiane F. Bustamante  Lazar Lazic  André A. Lyra  Sandra Morelli  Ivan Ristic  Katarina Veljovic 《Meteorology and Atmospheric Physics》2012,116(3-4):63-79

Upgrades implemented over a number of years in an open source version of the Eta model, posted at the CPTEC web site http://etamodel.cptec.inpe.br/, are summarized and examples of benefits are shown. The version originates from the NCEP’s Workstation Eta code posted on the NCEP web site http://www.emc.ncep.noaa.gov/mmb/wrkstn_eta, which differs from the NCEP’s latest operational Eta by having the WRF-NMM nonhydrostatic option included. Most of the upgrades made resulted from attention paid to less than satisfactory performance noted in several Eta results, and identification of the reasons for the problem. Others came from simple expectation that including a feature that is physically justified but is missing in the code should help. The most notable of the upgrades are the introduction of the so-called sloping steps, or discretized shaved cells topography; piecewise-linear finite-volume vertical advection of dynamic variables; vapor and hydrometeor loading in the hydrostatic equation, and changes aimed at refining the convection schemes available in the Eta. Several other modifications have to do with the calculation of exchange coefficients, conservation in the vertical diffusion, and diagnostic calculation of 10-m winds. Several examples showing improved performance resulting from the dynamics changes are given. One includes a case of unrealistically low temperatures in several mountain basins generated by a centered vertical advection difference scheme’s unphysical advection from below ground, removed by its replacement with a finite-volume scheme. Another is that of increased katabatic winds in the Terra Nova Bay Antarctica region. Successful forecast of the severe downslope zonda wind case in the lee of the highest peaks of the Andes is also shown, and some of the recent successful verification results of the use of the upgraded model are pointed out. The code is used at numerous places, and along with setup information it is available for outside users at the CPTEC Eta web site given above.  相似文献   

Very high resolution rainfall patterns measured by TRMM precipitation radar: seasonal and diurnal cycles     

Michela Biasutti  Sandra E. Yuter  Casey D. Burleyson  Adam H. Sobel 《Climate Dynamics》2012,39(1-2):239-258

The TRMM Precipitation Radar is used to construct a high resolution (0.05°?×?0.05°) climatology of rainfall over the latitude band extending to about 36° North and South. This study describes climatological patterns of rainfall frequency and intensity at high spatial resolution, with special focus on the seasonal and diurnal cycles in the frequency of rainfall events. We use this Tropics-wide dataset to highlight small-scale precipitation features that are too fine to be captured by the most widely used satellite-based rainfall datasets. The results shed light on the roles of changes in the wind direction, the land-sea thermal contrast, small-scale variations in sea surface temperature, and orography in shaping the seasonal and diurnal cycles of rainfall. In some regions of the tropics, diurnally locked local circulations are largely responsible for sharp gradients in the spatial distribution of seasonal mean precipitation. In other regions, we show that climatological rainfall frequency changes very sharply at coastlines, even though rainfall in these regions is expected to be controlled by relatively large scale weather systems.  相似文献   

Preparing for climate change in Washington State     

Lara C. Whitely Binder  Jennifer Krencicki Barcelos  Derek B. Booth  Meriel Darzen  Marketa McGuire Elsner  Richard Fenske  Thomas F. Graham  Alan F. Hamlet  John Hodges-Howell  J. Elizabeth Jackson  Catherine Karr  Patrick W. Keys  Jeremy S. Littell  Nathan Mantua  Jennifer Marlow  Don McKenzie  Michael Robinson-Dorn  Eric A. Rosenberg  Claudio O. Stöckle  Julie A. Vano 《Climatic change》2010,102(1-2):351-376

Climate change is expected to bring potentially significant changes to Washington State’s natural, institutional, cultural, and economic landscape. Addressing climate change impacts will require a sustained commitment to integrating climate information into the day-to-day governance and management of infrastructure, programs, and services that may be affected by climate change. This paper discusses fundamental concepts for planning for climate change and identifies options for adapting to the climate impacts evaluated in the Washington Climate Change Impacts Assessment. Additionally, the paper highlights potential avenues for increasing flexibility in the policies and regulations used to govern human and natural systems in Washington.  相似文献   

Quantitative reconstruction of Holocene precipitation changes in southern Patagonia     

Marcela Sandra Tonello  Maria Virginia Mancini  Heikki Sepp 《Quaternary Research》2009,72(3):410-420

Holocene variations in annual precipitation (P_ann) were reconstructed from pollen data from southern Argentinian Patagonia using a transfer function developed based on a weighted-averaging partial least squares (WA-PLS) regression. The pollen–climate calibration model consisted of 112 surface soil samples and 59 pollen types from the main vegetation units, and modern precipitation values obtained from a global climate database. The performance (r² = 0.517; RMSEP = 126 mm) of the model was comparable or slightly lower than in other comparable pollen–climate models. Fossil pollen data were obtained from a sediment core from Cerro Frias site (50°24'S, 72°42'W) located at the forest-steppe ecotone. Reconstructed P_ann values of about 200 mm suggest dry conditions during the Pleistocene–Holocene transition (12,500–10,500 cal yr BP). P_ann values were about 300–350 mm from 10,500 to 8000 cal yr BP and increased to 400–500 mm between 8000 and 1000 cal yr BP. An abrupt decrease in P_ann at about 1000 cal yr BP was associated with a Nothofagus decline. The reconstructed P_ann suggests a weakening and southward shift of the westerlies during the early Holocene and intensification, with no major latitudinal shifts, during the mid-Holocene at high latitudes in southern Patagonia.  相似文献   

Detection of a dry-frozen boundary inside Martian regolith     

Fabio Gori  Sandra Corasaniti 《Planetary and Space Science》2008,56(8):1093-1102

The present work investigates the time oscillations of the temperature at several depths of a Martian soil analogue made of two layers of different physical properties. The maximum temperature-time oscillation inside the Martian soil analogue, DT, and its derivative with depth, d(DT)/dz or DDT, can be analysed to understand the presence of a boundary between dry and frozen soil. The maximum temperature-time oscillation, DT, reduces by about one order of magnitude at the boundary between dry and frozen soil if a frozen layer is present. The reduction of DT at the boundary between two dry soils with different porosity is much smaller. DDT decreases by more than one order of magnitude at the boundary between dry and frozen soil if a frozen layer is present. The reduction of DDT at the boundary between two dry soils with different porosity is much smaller.  相似文献   

Euro-Cordex Regional Projection Models: What Kind of Agreement for Europe?     

Martins  Ana  Rafael  Sandra  Monteiro  Alexandra  Scotto  Manuel  Gouveia  Sónia 《Mathematical Geosciences》2019,51(8):1021-1035

Mathematical Geosciences - EURO-CORDEX is an international initiative which provides regional climate projections based on multiple dynamical and empirical–statistical downscaling models. The...  相似文献