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1.
利用地基GPS测量大气水汽廓线的方法 总被引：6，自引：2，他引：6
GPS倾斜路径的湿延迟反映了大气中水汽的三维非均匀分布,通过准确确定空间各卫星对地面各接收机的倾斜路径湿延迟,就可以利用断层扫描技术,确定大气层中水汽的三维分布和变化,从而增加目前还相对缺乏的大气水汽探测。文章就这方面介绍了国际上利用地基GPS测量倾斜路径大气湿延迟的两类方法(单点定位方法和双差定位方法)以及应用断层扫描技术利用这些观测进行水汽廓线遥感探测的两类方法(附加约束法和卡尔曼滤波法),并对这些方法的优缺点进行了初步的比较和探讨。 相似文献
2.
以岩性相近但气候和土地利用迥异的两个具有高分辨率水文水化学自动监测数据的岩溶水系统——湿润亚热带以土质坡地为主的岩溶水系统(贵州普定后寨岩溶水系统)和高寒冰雪覆盖下以石质坡地为主的岩溶水系统(瑞士阿尔卑斯山区的Tsanfleuron冰川岩溶水系统)作为研究对象,进行岩溶作用碳汇强度对比研究。结果发现,后寨岩溶水系统的[HCO3-]年均值为222mg/L,而Tsanfleuron冰川岩溶水系统的[HCO3-]年均值仅为131mg/L,表明湿润亚热带岩溶水系统具有较高的[HCO3-]特征。然而,湿润亚热带岩溶水系统的碳汇强度(60.82t/(km2·a))与Tsanfleuron冰川岩溶水系统的碳汇强度(59.06t/(km2·a))相当。冰川岩溶水系统同样具有较高岩溶作用碳汇强度的原因主要是在全球变暖的背景下,冰川退缩加剧,冰川固体水库水量释放增多,致使冰川岩溶水系统径流量显著增加效应超出因稀释作用而产生的[HCO3-]降低效应,进而使得山岳冰川岩溶水系统的碳汇强度增大。这也暗示着随着某些冰川融化,径流量逐渐减小将使岩溶作用碳汇强度降低。 相似文献
3.
A. V. Romanov 《Russian Meteorology and Hydrology》2009,34(8):549-555
Results generalizing a cycle of works, connected with formulation and solution of inverse problems for one-dimensional model
of unsteady water flow in rivers are presented. Various procedures allowing determining all basic characteristics of complicated
riverbed using observations of unsteady water flow are considered. Data on restoration, convolution and use of the received
characteristics in numerical schemes of the short-term stream flow forecasting for several reaches of artificial and real
riverbeds with flood plains are analyzed. The main problems connected with development of methods of solution of the inverse
problems for mathematical models of hydrological processes are formulated in general view. 相似文献
4.
Expedition data obtained in the coastal-shelf zone of the East Siberian Sea in September 2003, 2004, and 2008 are generalized.
Studies of carbonate system in water and CO2 fluxes between ocean and atmosphere in this region confirmed that it was reasonable to divide the water area studied into
two biogeochemical provinces and that the ecosystem of its coastal part is mainly of a heterotrophic nature. In different
years, the extent of water supersaturation in carbon dioxide in the East Siberian Sea and the area of the CO2 release significantly changed. Geographic localization of the atmosphere action centers over the Arctic and their intensity
were main determining factors; that told both on the formation of a basic character of the atmospheric and hydrological processes
and on the dynamics of the CO2 exchange between water and air. 相似文献
5.
Yu. A. Fedorov A. E. Ovsepyan V. B. Korobov I. V. Dotsenko 《Russian Meteorology and Hydrology》2010,35(9):611-618
Mercury content in bottom estuarine sediments of the Northern Dvina River and the Dvina Bay of the White Sea is studied. Major
regularities of the behavior of the metal and its compounds in bottom sediments of the water area are defined. The role of
lithological composition, pH and Eh of the environment, the presence of hydrogen sulfide for determining the content and forms
of the mercury presence in the bottom sediments of the region are studied. The sediments related to technogenic formations
are specified. The paths and forms of mercury coming from bottom sediments to the near-bottom water level are detected, and
the methylmercury content in the sediments is calculated. 相似文献
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Direct measurement of turbulent fluxes on a cruising ship 总被引：1，自引：0，他引：1
The result of an attempt at the direct measurement of turbulent fluxes on the top of the mast of a cruising ship is presented. The three-dimensional components of wind relative to the ship measured by a sonic anemometer are corrected for ship motion; from these the fluxes of momentum, sensible heat and water vapor are computed using the outputs of a fine-wire thermocouple psychrometer. The observations were made by this method on the Northwestern Pacific. The results indicate that this technique is usable for determining the distribution of fluxes over the ocean. 相似文献
9.
A. R. Chughtai N. J. Miller D. M. Smith J. R. Pitts 《Journal of Atmospheric Chemistry》1999,34(2):259-279
Previous soot hydration studies have been extended to compare the water uptake properties of soots from selected fuels (JP-8 Jet fuel, kerosene, diesel, and metal containing and S-containing synthetics) prepared under varying conditions with corresponding n-hexane model soots. Adsorption and desorption isotherms have yielded such adsorption parameters as the surface coverages at the limit of chemisorption and at 83% relative humidity (RH). These values increase with soot surface oxidation over the range 35–85% RH, while hydration levels at lower RH down to 22% are a function of fuel composition and combustion conditions, thus determining the extent of water uptake at higher RH. Both S- and metal-containing soots exhibit higher levels of hydration than those of the base fuel soots, a result with its origin in availability of sulfate and metal centers at the surface. 相似文献
10.
N. B. Baryshnikov A. O. Pagin Yu. A. Demidova T. S. Selina 《Russian Meteorology and Hydrology》2011,36(12):826-829
Carried out is the analysis of methods of computation of discharge capacity of channels with floodplains. It is revealed that
the standard technique recommended by the regulatory documents is uneffective. One of the causes for large computation errors
is taking no account of the effect of interaction of the channel and floodplain flows. An empirical technique is recommended
for the calculation, based on field observation data and graphical depth-velocity relations in relative coordinates. The technique
based on the equation of stream motion with lengthwise-variable water discharge. Unfortunately, it requires additional studies
on establishing dependences of the inertial terms of this equation on determining parameters. 相似文献
11.
Knowledge of cloud properties and their vertical structure is important for meteorological studies due to their impact on both the Earth’s radiation budget and adiabatic heating within the atmosphere. The objective of this study is to evaluate bulk cloud properties and vertical distribution simulated by the US National Oceanic and Atmospheric Administration National Centers for Environmental Prediction Global Forecast System (GFS) using three global satellite products. Cloud variables evaluated include the occurrence and fraction of clouds in up to three layers, cloud optical depth, liquid water path, and ice water path. Cloud vertical structure data are retrieved from both active (CloudSat/CALIPSO) and passive sensors and are subsequently compared with GFS model results. In general, the GFS model captures the spatial patterns of hydrometeors reasonably well and follows the general features seen in satellite measurements, but large discrepancies exist in low-level cloud properties. More boundary layer clouds over the interior continents were generated by the GFS model whereas satellite retrievals showed more low-level clouds over oceans. Although the frequencies of global multi-layer clouds from observations are similar to those from the model, latitudinal variations show discrepancies in terms of structure and pattern. The modeled cloud optical depth over storm track region and subtropical region is less than that from the passive sensor and is overestimated for deep convective clouds. The distributions of ice water path (IWP) agree better with satellite observations than do liquid water path (LWP) distributions. Discrepancies in LWP/IWP distributions between observations and the model are attributed to differences in cloud water mixing ratio and mean relative humidity fields, which are major control variables determining the formation of clouds. 相似文献
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Yanfang Wang Yanjun Shen Fubao Sun Yaning Chen 《Theoretical and Applied Climatology》2014,118(3):569-579
Temperature has long been accepted as the major controlling factor in determining vegetation phenology in the middle and higher latitudes. The influence of water availability is often overlooked even in arid and semi-arid environments. We compared vegetation phenology metrics derived from both in situ temperature and satellite-based normalized difference vegetation index (NDVI) observations from 1982 to 2006 by an example of the arid region of northwestern China. From the satellite-based results, it was found the start of the growing season (SOS) advanced by 0.37 days year?1 and the end of the growing season (EOS) delayed by 0.61 days year?1 in Southern Xinjiang over 25 years. In the Tianshan Mountains, the SOS advanced by 0.35 days year?1 and the EOS delayed by 0.31 days year?1. There were almost no changes in Northern Xinjiang. Compared with satellite-based results, those estimates based on temperature contain less details of spatial variability of vegetation phenology. Interestingly, they show different and at times reversed spatial patterns from the satellite results arising from water limitation. Phenology metrics derived from temperature and NDVI conclude that water limitation of onset of the growing season is more severe than the cessation. Phenology spatial patterns of four oases in Southern Xingjiang show that, on average, there is a delay of the SOS of 1.6 days/10 km of distance from the mountain outlet stations. Our results underline the importance of water availability in determining the vegetation phenology in arid regions and can lead to important consequences in interpreting the possible change of vegetation phenology with climate. 相似文献
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15.
Yaping Shao 《Boundary-Layer Meteorology》1992,59(4):363-385
A Lagrangian model is applied to simulate the dispersion of passive tracers (in particular, water vapour) in coastal atmospheric boundary layers under onshore wind conditions. When applied to convective boundary layers over uniform surfaces, the model gives results in agreement with those of similar studies. Numerical simulation of turbulent dispersion in coastal areas also reproduces the basic features known from experimental studies. Under onshore wind conditions, the humidity field is plume-shaped with the maximum vertical transport being over land downstream of the coast line. The model shows that the surface sensible heat flux over land, the static stability of the onshore air flow and the onshore wind speed are the most important factors determining the basic features of turbulent dispersion in coastal areas. 相似文献
16.
Abstract The atmospheric model of Danard et al. (1983) is used to investigate the changes in heat, mass and momentum fluxes at the air‐sea interface in Hudson Bay when the seasonal sea surface temperature is varied. Comparisons of model predictions with data from a meteorological buoy located 400 km offshore showed that the model predicted the variations in wind speed and air temperature fairly well but underestimated their magnitudes. In addition it provided offshore heat and mass fluxes for which no direct observations were available. The most important parameter determining air‐sea fluxes is the temperature difference between air and water. This determines the stability and the degree of vertical convection of the air. In the spring the colder water stabilizes the air, which depresses vertical convection. This reduces wind stress and evaporation while increasing the heat flux into the water. During the fall, the opposite occurs. The sea surface temperature is thus buffered against man‐made changes. When the temperature is decreased, for example, as the result of hydroelectric development in surrounding watersheds, the heat flux into the water increases while the wind stress decreases. Both effects increase the sea surface temperature, opposing the initial decrease. A one‐degree depression of sea surface temperature in summer is slowly offset by increased heating and no noticeable change in temperature remains at the end of the fall. 相似文献
17.
Claudio Tomasi Stefano Marani Vito Vitale Frank Wagner Alessandra Cacciari Angelo Lupi 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):734-749
Measurements of direct solar irradiance were taken employing 4 different sun‐photometers at near infrared wavelengths, suitable for use in atmospheric hygrometry. This technique utilising a set of spectral ratios, in and out of selected water vapour absorption bands, was applied to the measurements to obtain accurate evaluations of precipitable water. For all the hygrometric ratios given by the 4 sun‐photometers used at the 3 stations of Sagres, Monchique and Mt. Foia, during the CLEARCOLUMN experiment, we determined the calibration curves by correcting them for the Rayleigh scattering effects and, then, plotting the natural logarithms of such corrected ratios versus the square root of the water vapour mass present along the atmospheric slant path. The regression lines drawn for the various scatter diagrams were estimated to give evaluations of precipitable water with an uncertainty of less than 5%, 3% and 10% at the 3 stations, respectively. The calibration curves of the sun‐photometer located at the Sagres station were determined using the precipitable water evaluations obtained from the local radiosounding measurements taken on 5 clear‐sky days. Those of the sun‐photometers used at the Monchique and Mt. Foia stations were instead determined through intercomparison between subsets of measurements simultaneously taken with various instruments at Sagres and Mt. Foia. Using these calibration curves, we examined all the field measurements determining the time‐patterns of precipitable water at the 3 stations. During the period from 16 June to 25 July 1997, precipitable water was found to vary between 1.1 and 3.7 g cm−2 at the Sagres station (with an accuracy within ±13%), between 1.0 and 2.8 g cm−2 at Monchique (±11%) and between 0.8 and 3.0 g cm−2 at the top of Mt. Foia (±26%). 相似文献
18.
利用NCEP逐日资料和常规观测资料对2009年7月30~31日一次四川盆地南部强降雨过程进行诊断分析。结果发现:西南涡在700hPa上表现得比较明显,当发展极强时,甚至在500hPa也出现闭合环流;西南低涡涡区内均有降水发生,强降水中心位于涡区东北侧。低层水汽通量散度负值辐合区的分布不仅对相应时段降水落区指示较好,而且对于未来6h雨区分布也有一定参考性,可作为短临预警指标。强降雨区与强正涡度辐合上升运动区有较好的对应关系,对流层低层湿位涡的负值区对降水落区指示较好,强降水区出现在中高层正值MPV1下沿最强区,以及MPV2正负值交界区。 相似文献
19.
基于WOFOST模型的河北省保定市冬小麦最佳灌溉方案研究 总被引：2，自引：1，他引：1
利用WOFOST模型对保定地区冬小麦不同年型灌溉方案进行模拟分析,确定最佳灌溉量及灌溉时间,力争灌溉效益最大化,对缓解农业生产和水资源匮乏的尖锐矛盾尤显重要。文章以河北省保定市为例,应用WO)FOST模型对不同降水年型的2003/2004、2005/2006和2008/2009年3个代表生长季,分别进行一次灌溉、两次灌溉、三次灌溉的不同灌溉方案进行模拟,试图揭示冬小麦产量随灌溉时间及灌溉量的变化规律,选择最佳灌溉方案,为干旱缺水的河北省保定市小麦节水、高产提供理论依据。模拟研究结果表明:在冬小麦全生育期中最佳灌溉时期为拔节—孕穗期和抽穗—灌浆期,这两个时期的灌溉对产量的贡献率最高。与此同时,总结出了既可以满足冬小麦生长又可以获得较大经济效益的两次灌溉及三次灌溉的最佳灌溉方案。 相似文献
20.
Robert G. Ridgeway Jr. Donald C. Thornton Alan R. Bandy 《Journal of Atmospheric Chemistry》1992,14(1-4):53-60
A method has been developed for determining trace quantities of dimethyl sulfoxide (DMSO) in aqueous solutions using isotope dilution gas chromatography/mass spectrometry. The method consisted of first reducing DMSO to dimethyl sulfide (DMS), followed by purge and trap preconcentration of DMS. The concentration of DMSO was determined from the signal ratio obtained for the parent ions of DMS and d6-DMS, and the known aqueous concentration of d6-DMSO. The precision of this method was determined to be ± 2.9 %, based on replicate DMSO determinations of a test solution prepared by adding isotopically unenriched (h6-DMSO) to distilled water. The detection limit was 0.010 nmoles/L for the sampling conditions used in this study. This method was applied to the determination of DMSO concentrations in both rain and sea water. The concentration of DMSO in rain was found to be in the range of 2–4 nmoles/L for samples collected at an inland location (Phila, PA) and 8–11 nmoles/L for samples collected at a coastal location (Lewes, DE). Determination of DMSO in sea water required special sample preparation steps to eliminate positive interferences. A depth profile of DMS, DMSO, and dimethyl sulfoniopropionate (DMSP) concentrations is reported for sea water collected off the coast of Ocean City, Md, in August, 1990 相似文献