下垫面非均匀流域的幂指数TOPMODEL的模拟研究

利用取消流域土壤表层饱和导水率0K、土壤饱和导水率有效衰减系数m和地下水补给速率R为空间均匀假设的幂指数TOPMODEL,对流域水量平衡各分量进行敏感性研究试验,揭示空间非均匀性对幂指数TOPMODEL模拟结果的影响。从特定研究流域所得结果中可得的主要结论有:1)0K、m和R的空间变化对流域的逐日地表径流和基流以及逐日总径流有影响,针对设定的0K、m和R的空间变化,其中m的空间变化较明显地增加了逐日地表径流和洪峰流量。2)就设定的0K、m和R的空间变化而论,对流域多年平均年总径流以及蒸发模拟结果影响不大,但改变了径流在地表径流和基流之间的分配;其中R的空间变化影响最显著,m和0K的空间变化影响则较小。     

Integrative Monitoring Analysis Aiming at the Detection of Spatial and Temporal Trends of Metal Accumulation in Mosses

Goal and Scope. The UNECE heavy metals in Mosses Surveys provide data on the accumulation of metals in naturally growing mosses throughout Europe. Using Germany as an example, this article concentrates on the elaboration and application of methods of data analysis that are necessary for a comprehensive interpretation of spatial and temporal trends in metal accumulation.Methods and Results. The sampling of mosses, and the chemical analysis of Cr, Cu, Fe, Ni, Pb, Ti, V and Zn in 1990, 1995 and 2000 are summarized briefly. The variogram analyses detect distinct autocorrelation structures in the sample data which may consequently be estimated for all sites in Germany without monitoring metal accumulation by means of ordinary kriging. A procedure for the geostatistical detection of spatial outliers was developed and applied and, after the elimination of the spatial outliers, several measurements were seen to indicate an adequate quality of the geostatistical estimations. The cluster analyses of the z-transformed estimation data result in a nominal multi-element index that indicates regional metal accumulation types over time. Percentile statistics serve for computation of an ordinal, scaled, multi-element accumulation index which is spatially differentiated over time in terms of multivariate, statistically defined ecoregions. The integrative statistical analysis reveals, from 1990 to 2000, that the metal accumulation declines up to 80% in some of the ecoregions. Hot spots of metal accumulation are mapped and interpreted by means of metadata analysis.Conclusions. Dot maps depict the spatial structure of the metal accumulation without spatial bias. This information, detailed with respect to metal species and space, should be generalized for better supporting the interpretation. The combination of geostatistical analysis and estimation, percentile and multivariate statistics is suitable for the calculation of indices that serve for a comprehensive mapping of metal accumulation in the ecoregions over time, for quantifying the bias of the surface estimation, and for mapping spatial outliers and hot spots of metal accumulation.     

江淮流域旱涝年夏季E-P通量特征分析

利用 1 958～ 1 997年NCAR/NCEP全球再分析资料和 1 951～ 1 998年全国 1 6 0站月降水资料研究了江淮流域旱涝年夏季E P通量的分布状况 ,旱年E P通量在4 0°N附近呈强辐合特征 ,涝年在 30°N附近呈强辐合特征 ,其分布形式与降水的对应关系显著。旱涝年E P通量不同的分布形式促使江淮流域旱年 4 0°N附近的高空西风急流得到加强 ,涝年 30°N附近的高空西风急流得到加强 ,使得相应地区的风场高层辐散、低层辐合得到加强 ,形成了有利于降水生成的动力条件 ,是江淮流域及中国区域不同形式的降水分布形成的重要因素。     

Evolution of the fogwater composition in Strasbourg (France) from 1990 to 1999

The chemical composition of fogwater has been studied in the city of Strasbourg (France) from 1990 to 1999. During these years, fogwater samples have been collected and analysed for major ions and trace metals. This paper reports on the analysis of the collected dataset. The analysis revealed a significant decrease in acidity of approximately one pH unit over the course of the study. This decrease in acidity appears to be linked to a decrease in SO_2(g) and the resulting SO₄²⁻. Trace metal concentrations have also strongly decreased over the 10-year period. Pb concentrations, following the elimination of leaded gasoline, decreased by more than one order of magnitude.     

Power spectrum analysis of the annual rainfall series for Massachusetts (NE,U.S.A.)

Maximum Entropy Spectral Analysis of the annual rainfall series for 1887–1976 (90 years) for Massachusetts (northeastern USA.) shows T = 17.8 (very near the 18.6 year luni-solar signal) as the most prominent periodicity. However, it explains only 12% variance. Also, the next prominent periodicity is T = 2.72 years, i.e. in the QBO (Quasi-Biennial Oscillation, T = 2–3 years) region. Also, regular periodicities account for only 50% variance, leaving 50% as a random component. Hence, predictions are unreliable. Roughly, excess rainfall during 1990–1994 and droughts during 1992–2002 are indicated; but occasional years of opposite behavior cannot be ruled out.     

Lichen as quantitative biomonitors of atmospheric heavy metals deposition in Central India

Three different growth forms of lichens belonging to six species; Phaeophyscia hispidula, Parmotrema praesorediosum (foliose); Caloplaca subsoluta, Diploschistes candidissmus (crustose) and Peltula euploca, Phylliscum indicum (squamulose) were studied comparatively for the biomonitoring of Al, Cd, Cr, Cu, Fe, Ni and Zn in Mandav city in central India. Based on the anthropogenic activities three sites were selected for lichen collection. To identify the sources of heavy metal pollution, their concentration was analyzed in thallus as well as in their respective substrates. The thallus of studied lichens showed higher concentration of metals such as Cd, Cr, Ni and Zn, while most of the metals were absent or present in negligible amount in substrates (Fe, Al, Cu), which proves that the accumulated metals were air borne. The foliose lichens (P. hispidula and P. praesorediosum) found highly significant in metal accumulation at each sites followed by crustose and squamulose forms. Lichen samples collected from site 2, adjacent to road side accumulated maximum quantities of Zn, Ni, Cd and Cr whereas the city centre (Site 1) had maximum concentrations of Fe, Cu and Al. The site 3 situated away from the city had lowest amount of all the metals. The analysis of variance and LSD indicated that the metal concentrations among lichen species as well as between substratum is significant at p < 0.05% and P < 0.01% level respectively.     

Changes in Element Concentrations in Moss Segments After Cross-Transplanting Between a Polluted and Non-Polluted Site

To test the ability of Hylocomium splendens segments to retain absorbed heavy metals (Fe, V and Pb) and some physiological elements (Ca, Mg and K) over a period of some years, moss turf was cross-transplanted between polluted and background sites. Thereby it was possible to determine how quickly the concentrations in moss can reach chemical equilibrium with the atmospheric inputs. At a particular site (background or polluted), the physiological elements in transplanted material quickly reached the levels in the non-transplanted moss. For the heavy metals, the concentrations remained stable over 3 years in moss cross-transplanted from a polluted to a background site. There appeared to be inherent differences between moss at the background and polluted sites in the ability to absorb and accumulate heavy metals.     

Climatic change evidence and lacustrine varves from maar lakes,Germany

Annually laminated, non-glacial lake sediments from Lake Holzmaar (Eifel, western Germany) were investigated using large Merkt thin sections. The absolute age of varve intervals with variations in thickness and composition were correlated to climatic changes recorded by glacier fluctuations in the Alps. Back to 8800 years VT (varve time = varve years before 1950) glacier advances coincide with sedimentation rate minima; prior to 8800 years VT they coincide with sedimentation rate maxima. The early and middle Holocene sediments suggest a periodicity of about 1000 years for cold/warm cycles. A sequence of 512 varve-thickness measurements was subjected to spectral analysis. These provide apparent evidence for a 11-year sun-spot cycle.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program.     

Field and Laboratory Exposures of Two Moss Species to Low Level Metal Pollution

Moss transplants of the species Rhytidiadelphus squarrosus and Pleurozium schreberi were used as active biomonitoring organisms as a part of a monitoring study to assess the impact of metals associated with ambient particles on mosses at roadsides.The moss samples were exposed at a semi-urban and roadside site for 3 months for subsequent analysis of metal concentration (Cu, Pb and Zn). This field experiment was carried out to investigate the accumulation of the metals over a period of 0, 4, 8 and 12 weeks at the two sites. The metal concentration in the moss samples generally increased with the length of exposure and was higher at the roadside site. The two species, however, showed slightly different accumulation patterns. In addition to the metal analysis chlorophyll concentrations were analysed as a measure of stress response in the moss samples of the above mentioned field exposures. The chlorophyll concentrations of exposed mosses showed no or only weak correlations to the concentration of the three metals measured in the moss, which suggests that other conditions have a greater influence on the chlorophyll concentration.The effect of a single metal on the moss was studied in laboratory experiments exposing R. squarrosus to the metals copper, lead and zinc at concentrations based on the above field data. At the concentrations used there was a significant reduction in the chlorophyll a concentration after exposure to copper.     

Atmospheric Deposition of Trace Elements in Romania Studied by the Moss Biomonitoring Technique

The first systematic study in Romania of atmospheric pollution from heavy metals and other toxic elements based on moss analysis was undertaken as a Romanian–Russian–Norwegian collaboration, primarily in order to assess the general state of heavy metal pollution in Romania. An additional goal was to contribute to the European heavy metals in mosses survey, conducted under the auspices UNECE ICP Vegetation which reports to the Working Group of Effects of the Long-range Transboundary Air Pollution Convention. Samples of the moss species Hypnum cupressiforme, Hylocomium splendens and Brachytechium salebrosum and B. rutabulum were collected during the period 1995–2001. A total of 40 elements were determined using NAA and AAS. The total concentrations of arsenic, cadmium, copper, nickel, vanadium and zinc are presented in the form of contour maps. Generally, the observed concentrations in Romania are markedly higher than those observed in most other countries of Europe using the moss technique.     

The Turbulent Lagrangian Time Scale in Forest Canopies Constrained by Fluxes,Concentrations and Source Distributions

One-dimensional Lagrangian dispersion models, frequently used to relate in-canopy source/sink distributions of energy, water and trace gases to vertical concentration profiles, require estimates of the standard deviation of the vertical wind speed, which can be measured, and the Lagrangian time scale, T _L , which cannot. In this work we use non-linear parameter estimation to determine the vertical profile of the Lagrangian time scale that simultaneously optimises agreement between modelled and measured vertical profiles of temperature, water vapour and carbon dioxide concentrations within a 40-m tall temperate Eucalyptus forest in south-eastern Australia. Modelled temperature and concentration profiles are generated using Lagrangian dispersion theory combined with source/sink distributions of sensible heat, water vapour and CO₂. These distributions are derived from a multilayer Soil-Vegetation-Atmospheric-Transfer model subject to multiple constraints: (1) daytime eddy flux measurements of sensible heat, latent heat, and CO₂ above the canopy, (2) in-canopy lidar measurements of leaf area density distribution, and (3) chamber measurements of CO₂ ground fluxes. The resulting estimate of Lagrangian time scale within the canopy under near-neutral conditions is about 1.7 times higher than previous estimates and decreases towards zero at the ground. It represents an advance over previous estimates of T _L , which are largely unconstrained by measurements.     

Evidence for cryptic northern refugia among high- and temperate-latitude species in Beringia

Stewart and Dalén (2008) argue that only temperate species were locked in cryptic northern refugia during Pleistocene glacial cycles, while species presently found at high latitudes had much wider distributions during glaciations. We present evidence supporting the existence of cryptic northern refugia that likely harbored both high- and temperate-latitude species in the Bering Sea region. Genetic signals of refugial isolation are found in island populations of rock ptarmigan (Lagopus muta), rock sandpiper (Calidris ptilocnemis), common raven (Corvus corax), and winter wren (Troglodytes troglodytes). These species have high-latitude, a mixture of high- and temperate-latitude, and temperate-latitude distributions. In addition, there are no data showing historically larger distributions of the high-latitude rock sandpiper or rock ptarmigan in North America during the Pleistocene. Although exact dating of isolation events is not possible using molecular genetic data, the species we examined have similar genetic signals and thus were isolated at similar times. It is evident that Pleistocene glaciations produced refugial genetic signatures among multiple bird species in the North Pacific Ocean.     

黄河流域夏季旱涝变化及气候物理因素的影响

利用1951-2008年NCAR/NCEP再分析资料及中国气象局整编的160站降水资料,探讨了黄河流域夏季降水气候分布范围,在此基础上研究了黄河流域夏季降水旱涝的年代际变化特点。结果表明：20世纪90年代以前,黄河流域夏季旱涝变化为9-11 a和2-3 a周期,20世纪90年代后周期变化不明显。对导致黄河流域夏季旱涝的气候物理因素分析表明,东亚高度场负距平异常直接造成中国黄河流域的夏季偏旱,而亚洲高度距平场东高西低的配置造成黄河流域偏涝;夏季南亚季风、东亚季风在黄河流域的辐合是流域降水偏多的关键。在同期OLR距平场,涝年黄河流域处在大的负距平中,对流强盛有利于水汽的辐合。影响大气的主要下垫面要素海温场,赤道东太平洋海温指数与夏季黄河流域降水同期呈负相关关系。流域旱年赤道东太平洋海温多为正位相,对应流域涝年赤道东太平洋海温多为负位相。本研究提出了一个寻找旱涝成因方法并为预测旱涝提供了科学参考。     

An evaluation of autocatalytic ozone production from vibrationally excited oxygen in the middle atmosphere

The possibility of significant autocatalytic ozone production in the middle atmosphere has been demonstrated by Toumi et al. A detailed framework including five processes previously not considered is presented here. When these processes are included, particularly wavelength-dependent vibrational distributions of O₂, calculated ozone enhancements are less than 10% in the upper stratosphere and lower mesosphere. The vibrational distributions and the rate of vibrational quenching are identified as key issues which need to be addressed by experiments.     

Reconstructing sea level from paleo and projected temperatures 200 to 2100 ad

We use a physically plausible four parameter linear response equation to relate 2,000 years of global temperatures and sea level. We estimate likelihood distributions of equation parameters using Monte Carlo inversion, which then allows visualization of past and future sea level scenarios. The model has good predictive power when calibrated on the pre-1990 period and validated against the high rates of sea level rise from the satellite altimetry. Future sea level is projected from intergovernmental panel on climate change (IPCC) temperature scenarios and past sea level from established multi-proxy reconstructions assuming that the established relationship between temperature and sea level holds from 200 to 2100 ad. Over the last 2,000 years minimum sea level (−19 to −26 cm) occurred around 1730 ad, maximum sea level (12–21 cm) around 1150 ad. Sea level 2090–2099 is projected to be 0.9 to 1.3 m for the A1B scenario, with low probability of the rise being within IPCC confidence limits.     

Subsonic aircraft and ozone trends

Growth in subsonic air traffic over the past 20 years has been dramatic, with an annual increase of }6.1% over the decade between 1978 and 1988. Furthermore, aircraft activities in the year 2000 are predicted to be double those of 1990, with a shift towards more high-flying, longhaul subsonics. Aircraft exhaust gases increase the amount of nitrogen oxides (NO _x ) in the upper troposphere/lower stratosphere through injection at cruise altitudes. Given that NO _x is instrumental in tropospheric ozone production and stratospheric ozone destruction, it is important to determine the influence of subsonic aircraft NO _x emissions on levels of atmospheric ozone. This paper describes calculations designed to investigate the impact that subsonic aircraft may already have had on the atmosphere during the 1980s, run in a 2-D chemical-radiative-transport model. The results indicate a significant increase in upper tropospheric ozone over the decade arising from aircraft emissions. However, when comparing model results with observational data, certain discrepancies appear. Lower stratospheric ozone loss over the 1980s does not appear to be greatly altered by the inclusion of aircraft emissions in the model. However, given the trend in greater numbers of long-haul subsonic aircraft, this factor must be considered in any further calculations.     

Calibration of Four Species of Tillandsia as Air Pollution Biomonitors

Many organisms have been used as bioindicators of atmospheric contamination, with moss and lichen species being the most common. However, studies using epiphytic vascular species of Tillandsia have shown a good correlation between the presence of pollutants and the bioindicator's response. Therefore, the aim of our investigation was to calibrate and compare the response of four Tillandsia species of Argentina to ascertain whether they could be used as atmospheric contamination biomonitors. For this, we analysed the correlation between the levels of heavy metals in total atmospheric deposition samples and: a) their rate of enrichment; b) the physiological response of the plant samples. Tillandsia samples collected from a non contaminated area in the province of Córdoba were transplanted to four areas in the capital city with different sources of pollution (industrial or traffic emissions). They were exposed for a period of 3 to 6 months after which the concentrations of Pb, Ni, Fe, Zn, Cu and S as well as the physiological parameters of foliar damage were determined. Simultaneously samples of total atmospheric deposition were also taken.The highest level of metal enrichment was found in T. capillaris followed by T. tricholepis, T. permutata and T. retorta. Also, the use of a foliar damage index proved to be effective and could be a useful tool to evaluate different levels of atmospheric quality in these species. The rate of heavy metal deposition was higher in the industrial area for all metals except for Zn whose values were higher in areas with high levels of traffic.     

Dimethylsulfide oxidation and the ratio of methanesulfonate to non sea-salt sulfate in the marine aerosol

A box model of DMS oxidation in the clean, low-NO _x marine atmospheric boundary layer has been used to predict the latitude dependence of the aerosol methanesulfonate to non sea-salt sulfate ratio. The observed latitude dependence of this ratio in the Southern Hemisphere can be reproduced reasonably well if the full suite of reactions proposed by Yin et al. (1990a) is employed, and a strong temperature dependence is specified in the rates of decomposition of CH₃SO₂ and CH₃SO₃ radicals.     

Climate change scenarios: Comparisons of paleoreconstructions with recent temperature changes

Paleoclimatic reconstructions for the Mid-Holocene, Eemian, Mid-Pliocene and the Last Glacial Maximum are used to test the paleoanalog hypothesis and develop a regional climate change scenario based on a linear scaling by one parameter - the mean Northern Hemispheric temperature change with respect to present, ΔT _NH. The empirical verification of the paleoanalog hypothesis is extended to a cold epoch for zonal means and to regional distributions of temperature in warm epochs. The best agreement among the scaled paleoanomalies from different epochs is obtained if the seasonal temperature anomalies are scaled with ΔT _NH of the corresponding season. Preferential areas are identified where the paleoanalog hypothesis works relatively well; these areas coincide with the areas of the most pronounced warming. It is shown that the geographical distributions of the winter temperature anomalies over land in the paleodata are similar to those in the 1980–1990 period. From the three warm epochs, a paleodata-based scenario is deduced for the spatial distribution of temperature in a future climate, on the scale of continents. The conditions under which scenarios based on paleodata can be applied are discussed.     

Vertical motion diagnostics related to Q-vectors,and the reorganisation of a cold frontal system

Summary Estimates of vertical motion obtained by explicit solution of the quasi-geostrophic omega equation expressed in terms of Q-vectors (Hoskins et al., 1978) were compared with qualitative estimates based on the divergence of Q-vectors. The horizontal distributions of each were broadly similar, but differed in their detail. At any level, the relative magnitudes of centres of vertical motion varied between the parameters. The precise locations of the main centres also differed. Greater differences existed in the vertical distributions of the parameters. The divergence ofQ andF _Q of Hoskins et al. (1978) both reached maximum values in upper levels, whereas peak values of occurred in middle levels. A vertical distribution similar to was achieved ifF _Q was divided by a stability parameter. The diagnosed vertical velocities appeared consistent with the restructuring of a summertime cold front as it crossed waters south of Australia.With 6 Figures