前兆地电阻率资料处理的剥皮法   总被引：2，自引：1，他引：2       下载免费PDF全文

毛先进  钱家栋 《地震学报》2001,24(6):645-650

在台址下电阻率分层均匀的前提下，针对我国绝大多数前兆地电台单极距观测的事实与现状，提出一种试图从这种观测所获得的视电阻率时间序列中识别电阻率表层变化和深部变化的等效模型方法．分析表明，在保持布极方式和观测结果不变的前提下，任意多层的地电结构都可以视为一个二层地电结构——等效模型．本文中，等效模型上层的地电参数（电阻率和厚度）与实际模型第一层相同，下层的地电参数（电阻率）则根据等效要求，由实际模型第二层及其以下各层的地电参数经计算得到，因此，等效模型的下层包含了实际模型第二层及其以下各层的综合影响．初步研究表明，这种方法是可行的．   相似文献   

An Assessment of HOx Chemistry in the Tropical Pacific Boundary Layer: Comparison of Model Simulations with Observations Recorded during PEM Tropics A     

G. Chen  D. Davis  J. Crawford  B. Heikes  D. O'Sullivan  M. Lee  F. Eisele  L. Mauldin  D. Tanner  J. Collins  J. Barrick  B. Anderson  D. Blake  J. Bradshaw  S. Sandholm  M. Carroll  G. Albercook  A. Clarke 《Journal of Atmospheric Chemistry》2001,38(3):317-344

Reported are the results from a comparison of OH,H₂O₂CH₃OOH, and O₃ observationswithmodel predictions based on current HO_x–CH₄reaction mechanisms. The field observations are thoserecorded during the NASA GTE field program, PEM-Tropics A. The major focus ofthis paper is on thosedata generated on the NASA P-3B aircraft during a mission flown in the marineboundary layer (MBL) nearChristmas Island, a site located in the central equatorial Pacific (i.e.,2° N, 157° W). Taking advantage of thestability of the southeastern trade-winds, an air parcel was sampled in aLagrangian mode over a significantfraction of a solar day. Analyses of these data revealed excellent agreementbetween model simulated andobserved OH. In addition, the model simulations reproduced the major featuresin the observed diurnalprofiles of H₂O₂ and CH₃OOH. In the case ofO₃, the model captured the key observational feature whichinvolved an early morning maximum. An examination of the MBL HO_xbudget indicated that the O(¹D) + H₂Oreaction is the major source of HO_x while the major sinks involveboth physical and chemical processes involving the peroxide species,H₂O₂ and CH₃OOH. Overall, the generally goodagreement between modeland observations suggests that our current understanding ofHO_x–CH₄ chemistry in the tropical MBL isquite good; however, there remains a need to critically examine this chemistrywhen both CH₂O and HO₂are added to the species measured.  相似文献   

An Actively Controlled Wind Tunnel And Its Application To The Reproduction Of The Atmospheric Boundary Layer     

Cao Shuyang  Akira Nishi  Kimitaka Hirano  Shigehira Ozono  Hiromori Miyagi  Hiromori Kikugawa  Yuji Matsuda  Yasuo Wakasugi 《Boundary-Layer Meteorology》2001,101(1):61-76

An actively controlled wind tunnel equipped with multiple fansand airfoils has been developed, mainly for the purpose of reproducing the atmospheric boundary layer (ABL) for wind engineering applications. Various fluctuating flows can be achieved in this wind tunnel by altering the input data of the fans and airfoils through computer control. In this study, the ABL is physically simulated in this wind tunnel, and particular attention ispaid to the simulation of the profile of Reynolds stress. The method of generating the fluctuating flow and the experimental results of reproducing the ABL are presented. As the results show, the spatial distribution of Reynolds stress is satisfactorily simulated, and the profiles of other statisticalturbulent parameters, such as mean velocity, turbulent intensity, integral scale and power spectrum are successfully reproduced simultaneously.  相似文献   

Isoprene and Its Oxidation Products Methyl Vinyl Ketone, Methacrolein, and Isoprene Related Peroxides Measured Online over the Tropical Rain Forest of Surinam in March 1998   总被引：2，自引：0，他引：2  

C. Warneke  R. Holzinger  A. Hansel  A. Jordan  W. Lindinger  U. Pöschl  J. Williams  P. Hoor  H. Fischer  P. J. Crutzen  H. A. Scheeren  J. Lelieveld 《Journal of Atmospheric Chemistry》2001,38(2):167-185

Airborne measurements of volatile organic compounds (VOC) were performed overthe tropical rainforest in Surinam (0–12 km altitude,2°–7° N, 54°–58° W) using the proton transferreaction mass spectrometry (PTR-MS) technique, which allows online monitoringof compounds like isoprene, its oxidation products methyl vinyl ketone,methacrolein, tentatively identified hydroxy-isoprene-hydroperoxides, andseveral other organic compounds. Isoprene volume mixing ratios (VMR) variedfrom below the detection limit at the highest altitudes to about 7 nmol/molin the planetary boundary layer shortly before sunset. Correlations betweenisoprene and its product compounds were made for different times of day andaltitudes, with the isoprene-hydroperoxides showing the highest correlation.Model calculated mixing ratios of the isoprene oxidation products using adetailed hydrocarbon oxidation mechanism, as well as the intercomparisonmeasurement with air samples collected during the flights in canisters andlater analysed with a GC-FID, showed good agreement with the PTR-MSmeasurements, in particular at the higher mixing ratios.Low OH concentrations in the range of 1–3 × 10⁵molecules cm^-3 averaged over 24 hours were calculated due to lossof OH and HO₂ in the isoprene oxidation chain, thereby stronglyenhancing the lifetime of gases in the forest boundary layer.  相似文献   

Regional Fluxes Of Momentum And Sensible Heat Over A Sub-Arctic Landscape During Late Winter     

Ekaterine Batchvarova  Svan-Erik Gryning  Charlotte Bay Hasager 《Boundary-Layer Meteorology》2001,99(3):489-507

Based on measurements at Sodankylä Meteorological Observatory the regional (aggregated) momentum and sensible heat fluxes are estimated for two days over a site in Finnish Lapland during late winter. The forest covers 49% of the area. The study shows that the forest dominates and controls the regional fluxes of momentum and sensible heat in different ways. The regional momentum flux is found to be 10–20% smaller than the measured momentum flux over the forest, and the regional sensible heat flux is estimated to be 30–50% of the values measured over a coniferous forest.The regional momentum flux is determined in two ways, both based on blending height theory. One is a parameterised method, the other represents a numerical solution of an aggregation model. The regional sensible heat flux is determined from the theory of mixed-layer growth. At near neutral conditions the regional momentum flux can be determined independently of the regional sensible heat flux. At unstable conditions the two models become coupled.The information that is needed by the parameterised blending height method and by the mixed-layer evolution method in order to derive the regional fluxes of momentum and sensible heat can be obtained from radiosonde profiles of wind speed and temperature.  相似文献   

Temporal Surface Ozone Patterns in Urban Manitoba, Canada   总被引：1，自引：0，他引：1  

R. L. Raddatz  J. D. Cummine 《Boundary-Layer Meteorology》2001,99(3):411-428

This study examined temporal surface ozone patternsfor two urban centres in Manitoba,Canada by analyzing hourly concentrations at theWinnipeg downtown (1995–1999), Winnipegresidential (1995–1999) and Brandon industrial(1998–1999) monitoring sites. The characteristicannual ozone cycle and diurnalcycles for June and December were attributable to: (1) theannual and diurnal solar radiation cycles,(2) temporal variations in the emissions of precursorchemical compounds, in particular the source strength ofnitrogen oxides, (3) temporal variationsin the height of the mixed layer, which determinethe degree of dilution of these emissions byatmospheric dispersion, and (4) an in situvolatile organic compound sensitive photochemicalregime, which resulted in decreased concentrations ofozone in response to increasedconcentrations of nitrogen oxides. Onlyone exceedance of the maximum acceptable level of82 ppb was recorded in the study period; itoccurred at the Brandon monitoring site on June 6, 1999.The sequence of weather and the hourly concentrationsof ozone and nitrogen oxides indicatedthat: (1) ozone fumigation, with the transition fromthe nocturnal boundary layer to the daytime mixed layer, mayhave supplemented photochemical ozone formation duringthe morning hours, and (2) during theevening hours, the post cold-frontal downward flux ofozone rich air, which was in the region dueto atmospheric transport, stratosphere-troposphere-exchangeor, possibly, due to the multiplicityof thunderstorms in the area in lateafternoon – early evening, may have been the main cause ofthis rare exceedance event.  相似文献   

ON THE PHYSICS OF FLOW-DRIVEN SEDIMENTS (BED-LOAD)     

Ulrich C. E. ZANKE Prof  Institute of Hydraulic Engineering  University of Technology  Darmstadt  Germany 《国际泥沙研究》2001,16(1)

l PROBLEMS AND AlMSSediments may be transported close to the bed, rolling and sliding, as we1l as susPended in the flow. Forvarious reasons the theoretical treatment of the bed-load problem has been exceptionally difficult. Noanalytical solution had been fOund uP to now, beginning with Du Buat (l786), Huebbe (l86l) and DuBoys (I 879). Since the aPProach of Du Boys numerous new attemPts have been catried out, mostly of anempirical nature. Consequently they are not generally valid an…  相似文献   

MODELING OF THE HIGH CONCENTRATION LAYER OF COHESIVE SEDIMENT UNDER THE ACTION OF WAVES AND CURRENTS     

Qinghe ZHANG Yongsheng WU  Jijian LIANand Pingxing DING School of Civil Engineering  Tianjin University  Tianjin  China Dept. Hydraulic Engineering  Tsinghua University  Beijing  China State Key Lab. of Estuarine  Co 《国际泥沙研究》2001,16(2)

MODELING OF THE HIGH CONCENTRATION LAYEROF COIIESIVE SEDMNT UNDER Tus ACTIONOF WAVES AND CURRENTSQinghe ZHANG', Yongsheng WU', Jiian LIAN1 and Pingxing DING3Abstract:High concenhation layer of cohesive sediment frequenhy occurs in muddy estUaries and coastalzones, and causes raPid siltation of the waterways. A one dimensional vertical coupled modeldescribing the interactions betWeen waves, currentS and suspended cohesive sediment is develoPed inthe pre…  相似文献   

亚洲中东部岩浆岩网络状分布与塑性流动网络   总被引：3，自引：2，他引：3       下载免费PDF全文

王绳祖  张宗淳 《地震地质》1997,19(3):44-247

亚洲中东部的岩浆岩分布具有明显的网络状特征，共轭相交的岩浆岩带构成了晚古生代、中生代和新生代不同的岩浆岩网络系统。岩浆岩网络受岩石圈下层塑性流动网络的控制，是塑性流动带剪切变形、摩擦热效应及带内介质弱化、轻化，以至促成地幔上隆和岩浆上涌的结果。根据“塑性流动－岩浆岩”网络，推测了不同地质时期大陆构造变形的驱动边界、驱动力方向和古构造应力场，并探讨了网络构造的演变等问题  相似文献   

TURBULENCE CHARACTERISTICS OF THE ATMOSPHERIC SURFACE LAYER OVER AN OPEN GRASSLAND^*          下载免费PDF全文

Liu Shuhu  Liu Heping  Liang Fuming  Wu Fenglei  M. Y. Lecler  Xu Mei  Hong Zhongxiang  Li Jun  Liu Huizhi  Na Jingyang 《Acta Meteorologica Sinica》1997,11(3):328-337

Described in this paper is an experiment on atmosphere-surface turbulent exchange and boundary layer turbulence properties conducted in July 1994 over the Kerqin Grassland,Jilin,China.The characteristics of the turbulent spectrum,and the relationships of the standard deviation of the turbulent velocity components and sensible heat flux with the atmospheric stability are studied using data from a sonic anemometer and a fast-response platinum resistance thermometer mounted on a 100 m tower.The results show that in the surface layer over a flat,uniform and open grassland,for a broad stability range(-22.12≤Z_iL≤17.98),the velocity spectra obey the-2/3 power law in the inertial subrange,and 1 power law at low frequencies.Under near neutral stratification,σ_u/u_*=1.20,σ_v/u_*=1.23 and σ_w/u_*=1.02.For Z_i/L≤-0.2,the standard deviations of the turbulent velocity components follow a 1/3 power law.For Z_i/L≤-0.1,the standard deviation of the temperature fluctuations follows a-1/3 power law,and as Z_i/L≤-0.08,it exhibits nonlinear behavior.Sensible heat flux is well correlated to the stability parameter.  相似文献