南海季风区地域性大气环流的结构     

周发琇  张涛  高荣珍 《中国海洋大学学报(自然科学版)》2001,31(4):467-472

作者使用 NCEP/ NCAR再分析资料 ,在热带 30°S～ 30°N纬带用谐波分析方法分离出超长波之后 ,再采用环流诊断方法 ,发现南海季风区存在地域性环流系统。文中给出冬、夏季风期该系统的三维空间结构和相应的热源分布 ,讨论了该地域性环流系统对南海季风气候及其异常的作用 ,并探讨夏季风爆发北部先于南部的一种可能的气候原因。  相似文献   

电磁波信号在对流层中路径弯曲改正的级数展开式     

卢小平 《测绘学报》2008,37(2):0-249

大气折射延迟是空间大地测量中的一个主要误差源。本文严格地给出了中性大气路径弯曲改正的原理性公式。通过对各种因素量级的分析,在亚毫米量级的精度上给出了一个以视天顶距正切和正割乘积为参数的级数展开模型。新模型在球对称大气模型下,级数展开模型的精度达到了毫米量级,理论上可以展开到任意阶次,且可允许观测高度角小到5°。  相似文献   

CHRIS／PROBA高光谱数据的预处理   总被引：1，自引：0，他引：1  

盖利亚  刘正军  张继贤 《测绘工程》2008,17(1):40-43

针对CHRIS／PROBA高光谱遥感数据的特点,对CHRIS影像进行去条带处理、辐射校正、大气校正等预处理,获得较好质量的影像,为影像的进一步分析和实际应用提供保障。  相似文献   

河流活性物质入海通量:概念与方法   总被引：1，自引：0，他引：1  

周国华  孙彬彬  刘占元  魏华玲  曾道明 《地质通报》2008,27(2):182-187

河流水体中呈溶解态和悬浮物结合态的元素活动性强,具有生态环境意义,查明其入海通量是当前生态地球化学评价的重要任务。通过总结前人的相关研究成果,确定了影响河流水体悬浮物的浓度及其矿物、化学组成的主要因素。从沿海经济带区域生态地球化学评价的实际需要出发,拟定了开展中国主要入海河流水溶态和悬浮物结合态元素入海通量调查的基本框架。  相似文献   

太原盆地农田区大气降尘对土壤重金属元素 累积的影响及其来源探讨   总被引：1，自引：0，他引：1  

赖木收  杨忠芳  王洪翠  周继华  王建武 《地质通报》2008,27(2):240-245

通过研究太原盆地大气干湿沉降中重金属元素的含量分布特征及年输入通量,讨论其对土壤中重金属元素累积的影响。同时采用富集因子法探讨降尘物质的来源。研究结果表明,降尘中重金属元素As、Cd主要来源于人为活动,Pb的来源可能是人为源和自然源。而Hg则主要来源于自然源。  相似文献   

Trace metals in suspended particulate matter and in sediment trap material from a permanently anoxic fjord — Framvaren, South Norway     

Jens M. Skei  Douglas H. Loring  Reijo T. T. Rantala 《Aquatic Geochemistry》1996,2(2):131-147

Geochemical studies of the trace metal concentrations in suspended particulate matter (SPM) and sediment trap material from a permanently anoxic fjord, Framvaren, South Norway in 1989 and 1993 indicate that extremely high concentrations of zinc (max = 183920 mg/kg), copper (max = 4130 mg/kg), lead (max = 2752 mg/kg), and cadmium (max= 8.1 mg/kg) sometimes (1993) occur in the SPM collected in the anoxic water layer. The highest concentrations of Zn occur just below the redoxcline at 22 m water depth (in 1993), and copper, lead and cadmium have maximum concentrations between 30 and 80 m depth, where the amount of total SPM is at a minimum (about 0.3 mg/L). On a mass per volume (g/L) basis, the maximum concentrations of Cd, Cu and Fe occur at the interface (21m) and those of Zn occur just below the redoxcline (22 m depth). The SPM and sediment trap data suggest that the metals are precipitated as sulfide minerals in the anoxic water. The presence of particulate sulfides was confirmed by SEM studies that show the occurrence of discrete metal (Cu, Fe, Pb, and Zn) sulfide particles in size from 10–20 m as well as framboidal pyrites (1–5 m in size). Higher levels of metal sulfides at intermediate depths rather than in the deep water of Framvaren (> 100 m), may be due to input of trace metals by water exchange over the sill in the upper part of the water column. In the deep water, less metal sulfide precipitation takes place due to depletion of trace metals, and the dilution of particulate metal concentrations by organic matter and by the chemogenic formation of calcite.  相似文献   

Whistler observations of the quiet time plasmasphere-ionosphere coupling fluxes at low latitude     

Lalmani  R. P. Singh  Rajesh Singh  Altaf Ahmad 《Earth, Moon, and Planets》1996,74(1):7-15

Observations of whistlers during quiet times made at low-latitude ground station Nainital (geomag. lat. 19 1 N) are used to deduce plasmasphere-ionosphere coupling fluxes. The whistler data from 3 magnetically quiet days are presented that show a smooth decrease in dispersion with time. This decrease in dispersion is interpreted in terms of a corresponding decrease in electron content of tubes of ionization. The electron densities, electron tube contents (10¹⁶ el/m²-tube) and coupling fluxes (10 el m^–1 s^–2) are computed by means of an accurate curve fitting method developed by Tarcsai (1975) and are in good agreement with the results reported by other workers.  相似文献   

The effects of solar and ionospheric parameters on seasonal variation of 6300 Å line emission at Calcutta     

S. K. Midya  R. Chattopadhyay 《Earth, Moon, and Planets》1996,74(2):123-129

The purpose of this paper is to find correlation between OI 6300 Å line intensity with solar and ionospheric parameters. A critical study have been made and the following important results are obtained:

(i)	Solar flare index plays more important role for the emissions of 6300 Å line than other solar parameters.
(ii)	Intensity of 6300 Å line increases linearly with the increase of solar flare index.
(iii)	Virtual height plays more important role than critical frequency for the emission of 6300 Å line-intensity.
(iv)	Possible explanation of this type of variation is also presented.

  相似文献   

A dynamic box model of bioactive elements in the southern Taiwan Strait   总被引：3，自引：0，他引：3  

洪华生  商少凌 《中国海洋湖沼学报》1994,12(2):120-129

A dynamic box model was applied to study the characteristics of biogeochemical cycling of PO_4-P,NO_3-N,AOU,POC and PON in the southern Taiwan Strait region based on field data of the"Minnan Taiwan Bank Fishing Ground Upwelling Ecosystem Study" during the period of Dec.1987-Nov.1988.According to the unique hydrological and topographical features of the region,six boxesand three layers were considered in the model.The variation rates and fluxes of elements induced by hor-izontal current,upwelling,by diffusion,sinking of particles and biogeochemical processes were estimatedrespectively.Results further confirmed that upwellings had important effects in this region.Thenearshore upwelling areas had net input fluxes of nutrients brought by upwelling water,also had high de-pletion rates of nutrients and production rates of particulate organic matter and dissolved oxygen.Theabnormal net production of nutrients in the middle layer(10-30m) indicated the important role of bacte-ria in this high production region.Th  相似文献   

Laboratory study of the rates and products of the phototransformations of naphthalene adsorbed on samples of titanium dioxide,ferric oxide,muscovite, and fly ash     

Chantal Guillard  Hervé Delprat  Can Hoang-van  Pierre Pichat 《Journal of Atmospheric Chemistry》1993,16(1):47-59

The photodegradation of naphthalene (NPH), chosen as a model of polynuclear aromatic pollutants, has been studied in the presence of a layer of four water-insoluble inorganic solids which can be found in the troposphere (TiO₂, Fe₂O₃, muscovite, and a fly ash sample). Direct photolysis of NPH is negligible at >340 nm. Dark adsorption of NPH on TiO₂ (mainly anatase, nonporous, 50 m² g^–1) at 293 K corresponds to a surface coverage ofca. 50% at equilibrium. Under these conditions (saturated surface), the stationary-state photocatalytic degradation reaches 0.4 molecule nm^–2 h^–1 (>340 nm, radiant fluxca. 22 mW cm^–2). Dioxygen is required and its partial pressure in air is such that the degradation is zero order in O₂. Water vapor markedly increases the rate. The other particulates have also an effect, less important than that of TiO₂, however quite noticeable with respect to surface area unit for the fly ash sample which contains 3.2% Fe₂O₃. Apart from 1,4-naphthoquinone, which is the main intermediate product in all cases, 2-naphthol, phthalide, phthaldialdehyde, phthalic acid, acetophenone, benzaldehyde, benzoic acid are also formed on dry TiO₂. Depending on their volatility, these compounds are transferred to the gas phase or remain principally adsorbed on the solid particles where they are further transformed. For instance, phthalic acid (or anhydride) and benzoic acid are generated from 1,4-naphthoquinone. Degradation mechanisms are briefly discussed.  相似文献