Radiation balance at the surface in the city of S?o Paulo, Brazil: diurnal and seasonal variations     

Mauricio Jonas Ferreira  Amauri Pereira de Oliveira  Jacyra Soares  Georgia Codato  Eduardo Wilde Bárbaro  Jo?o Francisco Escobedo 《Theoretical and Applied Climatology》2012,107(1-2):229-246

The main goal of this work is to describe the diurnal and seasonal variations of the radiation balance components at the surface in the city of S?o Paulo based on observations carried out during 2004. Monthly average hourly values indicate that the amplitudes of the diurnal cycles of net radiation (Q*), downwelling and upwelling shortwave radiation (SW_DW, SW_UP), and longwave radiations (LW_DW, LW_UP) in February were, respectively, 37%, 14%, 19%, 11%, and 5% larger than they were in August. The monthly average daily values indicate a variation of 60% for Q*, with a minimum in June and a maximum in December; 45% for SW_DW, with a minimum in May and a maximum in September; 50% for SW_UP, with a minimum in June and a maximum in September; 13% for LW_DW, with a minimum in July and a maximum in January; and 9% for LW_UP, with a minimum in July and a maximum in February. It was verified that the atmospheric broadband transmissivity varied from 0.36 to 0.57; the effective albedo of the surface varied from 0.08 to 0.10; and the atmospheric effective emissivity varied from 0.79 to 0.92. The surface effective emissivity remained approximately constant and equal to 0.96. The albedo and surface effective emissivity for S?o Paulo agreed with those reported for urban areas in Europe and North America cities. This indicates that material and geometric effects on albedo and surface emissivity in S?o Paulo are similar to ones observed in typical middle latitudes cities. On the other hand, it was found that S?o Paulo city induces an urban heat island with daytime maximum intensity varying from 2.6°C in July (16:00 LT) to 5.5°C in September (15:00 LT). The analysis of the radiometric properties carried out here indicate that this daytime maximum is a primary response to the seasonal variation of daily values of net solar radiation at the surface.  相似文献   

Tropical cyclone hazard assessment using model-based track simulation   总被引：3，自引：1，他引：2  

Jonas Rumpf  Helga Weindl  Peter Höppe  Ernst Rauch  Volker Schmidt 《Natural Hazards》2009,48(3):383-398

A method is introduced for assessing the probabilities and intensities of tropical cyclones at landfall and applied to data from the North Atlantic. First, a recently developed model for the basin-wide Monte-Carlo simulation of tropical cyclone tracks is enhanced and transferred to the North Atlantic basin. Subsequently, a large number of synthetic tracks is generated by means of an implementation of this model. This synthetic data is far more comprehensive than the available historical data, while exhibiting the same basic characteristics. It, thus, creates a more sound basis for assessing landfall probabilities than previously available, especially in areas with a low historical landfall frequency.  相似文献   

A palaeomagnetic investigation of the Ulvö dolerite, Ångermanland,central Sweden     

K.-Å Magnusson  S.Å Larson 《Lithos》1977,10(3):205-211

A palaeomagnetic study of dolerites spread over a large area in the coastal part of Ångermanland, central Sweden, introduces a palaeopole close to poles obtained from Jotnian or post-Jotnian dolerites in Finland, implying that all these rocks belong to the same intrusive phase.  相似文献   

Potassium Doppler-resonance lidar for the study of the mesosphere and lower thermosphere at the Arecibo Observatory     

Jonathan S. Friedman  Craig A. Tepley  Shikha Raizada  Qihou H. Zhou  Jonas Hedin  Rubn Delgado 《Journal of Atmospheric and Solar》2003,65(16-18):1411-1424

We have developed a lidar to study the temperature structure of the nighttime mesopause region over the Arecibo Observatory (18.35°N, 66.75°W) by measuring the lineshape of the fluorescence spectrum of atomic potassium that is deposited in the mesosphere and lower thermosphere (MLT) by meteors. To demonstrate how the potassium lidar can enhance MLT studies at Arecibo, we show recent results for: (1) comparisons with airglow temperature measurements; (2) simultaneous operations with stratospheric and mesospheric temperature profiling by Rayleigh lidar; (3) simultaneous observations of K, Ca⁺, and E-region electron density profiles; and (4) occurrences of sporadic K layers, and relationships to sporadic E layers.  相似文献   

夏季自然水体与大气界面间气态总汞的交换通量   总被引：10，自引：0，他引：10  

冯新斌  S.Jonas  G.Katarina  L.Oliver 《中国科学D辑》2002,32(7):609-616

利用动力学通量箱法与高时间分辨率大气测汞仪的联用技术, 在瑞典西南的Kristineberg海洋观测站(KMRS)和Knobesholm的Hovgårdsån河分别测定了夏季海水和河水表面与大气间汞的交换通量. 在夏季, 河水和海水都是大气汞的源. 河水和海水表面与大气间汞的交换通量在夏季具有一致的昼夜变化规律, 白天由水体向大气排汞且在正午达到最大值; 夜间排汞量相对较小且有时会出现大气汞向水体沉降. 河水与大气间汞的交换通量与光照强度呈线性正相关关系, 与大气相对湿度呈线性负相关性, 同时还与水体温度存在指数相关性. 海水与大气间汞交换通量只与光照强度存在良好的线性正相关关系. 水体中溶解态气汞的过饱和是水体汞向大气释放的驱动力.  相似文献   

Fundamentals of gas containment in unlined rock caverns   总被引：3，自引：0，他引：3  

D. C. Goodall  B. Åberg  T. L. Brekke 《Rock Mechanics and Rock Engineering》1988,21(4):235-258

Summary The criterion for gas entry into idealized, uniform, water-saturated fractures is examined for one-dimensional, elliptical and cylindrical cavern geometries. This limiting criterion is a necessary condition for gas escape from unlined, pressurized gas storages.Gas-entry phenomena were examined using 450-mm-square glass plates in Hele Shaw configuration with nominal apertures of 50 and 200 microns. The fundamentals of gas entry, as first enunciated by Åberg (1977), are confirmed by the experiments; the critical gas-entry pressure is a function of hydraulic flow regime, fracture-mouth capillarity and fracture-mouth profile. Finite-element simulation based on these fundamentals is substantiated by experimental observations and is therefore used for generalization.The gas-entry criterion is found to be sensitive to details of fracture geometry such as aperture, connection of the fractures to the groundwater regime, geometry of the intersection of the fractures with the gas cavern, disturbance of the rock mass as a consequence of excavation, and cavern shape. In view of the inability to predict or even measure these factors, an alternative criterion which ensures no gas migration away from the gas storage is proposed. This simple criterion insists that gas escape will not occur as long as the water pressure along all possible escape paths increases for some small distance in the direction of potential gas escape. This criterion is a generalization of Åberg's (1977) proposal that the vertical hydraulic gradient should exceed one for no gas escape.  相似文献   

Zur Charakterisierung von Aktivkohlen durch die Zersetzung von Wasserstoffperoxid     

K.-H. Radeke  S. Jonas  P. Spitzer  R. Jung  S. Neffe 《洁净——土壤、空气、水》1989,17(3):315-319

In search for a suitable and fast analytical method for assessing kinds of activated carbon for water purification there were carried out investigations with hydrogen peroxide. According to their catalytic activity, the various kinds of activated carbon are capable of decomposing hydrogen peroxide to different degrees and at different rates. The released oxygen can be determined volumetrically. The results of investigation obtained on always fresh carbon samples with acid and basic groups were discussed on the basis of the velocity constants of the oxygen development. An assessment of quality would be possible, in principle, but the surface characteristic of the kinds of carbon is considerably superimposed by influences of morphology, so that applying this method is advised against.  相似文献   

The western border of the Archaean province of the Baltic shield: evidence from northern Sweden   总被引：1，自引：0，他引：1  

Björn Öhlander  Torbjörn Skiöld  P. Joseph Hamilton  Lars -Åke Claesson 《Contributions to Mineralogy and Petrology》1987,95(4):437-450

Restricted areas of acid to intermediate gneisses in northernmost Sweden are known to be Archaean and several other gneissic granodioritic to tonalitic massifs have been suggested to be of this age. To delimit the western border of the Archaean province of the Baltic Shield, and to characterize the Swedish Archaean, we have studied the 2.83 Ga old Soppero gneiss and 8 of the proposed Archaean massifs in northern Sweden by Sm-Nd isotopic analyses, U-Pb zircon dating (in two cases), and geochemistry.Of the Archaean gneisses proposed thus far, only those from the Soppero and Kukkola areas have Archaean ages (2.83 and 2.67 Ga, respectively). These gneisses have geochemical characteristics such as LREE-enrichment, low U-contents, and low K/Na-ratios, which are typical of Archaean TTG (tonalite-trondhjemite-granodiorite) rocks worldwide. The REE results indicate that the Soppero and the Kukkola gneisses were generated by partial melting of basic rocks, presumably amphibolites. According to the Sm-Nd isotopic data for the Soppero gneiss, this process occurred only a short time after initial segregation from the mantle ( _Nd values between +0.9 and +3.5). The Kukkola gneiss, however, has longer crustal residence time as indicated by negative _Nd values (–1.0 and –2.5) at the U-Pb zircon age of 2.67 Ga. Evidence in support of an important event at that time is given by secondary overgrowth on zircon cores in the 2.83 Ga old Soppero gneiss.The Sm-Nd isotope results show that the Proterozoic granitoids in northern Sweden have a decreasing involvement of Archaean source material with increasing distance from the Archaean areas. Before the Proterozoic reworking, the rather small Archaean areas in northern Sweden presumably belonged to a large continuous Archaean craton. The western palaeoboundary of this craton in Sweden probably follows approximately a line extrapolated from the western limit of the Archaean of central Finland, passing west of Kukkola, and then continues to the Lofoten area in northern Norway.  相似文献   

Ore lead isotope variations in the Proterozoic massive pyrite deposit at Näsliden,Skellefte district,Sweden     

D. Rickard  Sven-Åke Svensson 《Mineralium Deposita》1984,19(2):145-151

The ore lead isotope ratios from the Näsliden deposit are mantle-like in terms of the idealized plumbotectonics model. They suggest that the Näsliden deposit was formed in the Proterozoic equivalent of a Phanerozoic primitive island arc. The mantle-like nature of the lead and its homogeneity indicate that crustal lead does not constitute the major component of the ore lead. Crustal lead contamination is suggested to be the cause of divergences in ore lead isotopic compositions associated with later veins in the deposit.  相似文献   

Lagrange multiplier-based domain decomposition methods for a non-linear sedimentary basin problem     

Jonas Koko 《Computational Geosciences》2007,11(4):307-317

We present two Lagrange multiplier-based domain decomposition methods for solving iteratively a non-linear sedimentary basin problem. Both methods are Uzawa-type algorithms derived from saddle point equations of Lagrangian and augmented Lagrangian functionals. Numerical experiments show that both methods are scalable with respect to the mesh size.  相似文献