On Creating Global Gridded Terrestrial Water Budget Estimates from Satellite Remote Sensing

The increasing availability and reliability of satellite remote sensing products [e.g., precipitation (P), evapotranspiration (ET), and the total water storage change (TWSC)] make it feasible to estimate the global terrestrial water budget at fine spatial resolution. In this study, we start from a reference water budget dataset that combines all available data sources, including satellite remote sensing, land surface model (LSM) and reanalysis, and investigate the roles of different non-satellite remote sensing products in closing the terrestrial water budget through a sensitivity analysis by removing/replacing one or more categories of products during the budget estimation. We also study the differences made by various satellite products for the same budget variable. We find that the gradual removal of non-satellite data sources will generally worsen the closure errors in the budget estimates, and remote sensing retrievals of P, ET, and TWSC together with runoff (R) from LSM give the worst closure errors. The gauge-corrected satellite precipitation helps to improve the budget closure (4.2–9 % non-closure errors of annual mean precipitation) against using the non-gauge-corrected precipitation (7.6–10.4 % non-closure errors). At last, a data assimilation technique, the constrained Kalman filter, is applied to enforce the water balance, and it is found that the satellite remote sensing products, though with worst closure, yield comparable budget estimates in the constrained system to the reference data. Overall, this study provides a first comparison between the water budget closure using the satellite remote sensing products and a full combination of remote sensing, LSM, and reanalysis products on a quasi-global basis. This study showcases the capability and potential of the satellite remote sensing in closing the terrestrial water budget at fine spatial resolution if properly constrained.     

Global Terrestrial Water Storage Changes and Connections to ENSO Events

Improved data quality of extended record of the Gravity Recovery and Climate Experiment (GRACE) satellite gravity solutions enables better understanding of terrestrial water storage (TWS) variations. Connections of TWS and climate change are critical to investigate regional and global water cycles. In this study, we provide a comprehensive analysis of global connections between interannual TWS changes and El Niño Southern Oscillation (ENSO) events, using multiple sources of data, including GRACE measurements, land surface model (LSM) predictions and precipitation observations. We use cross-correlation and coherence spectrum analysis to examine global connections between interannual TWS changes and the Niño 3.4 index, and select four river basins (Amazon, Orinoco, Colorado, and Lena) for more detailed analysis. The results indicate that interannual TWS changes are strongly correlated with ENSO over much of the globe, with maximum cross-correlation coefficients up to ~0.70, well above the 95% significance level (~0.29) derived by the Monte Carlo experiments. The strongest correlations are found in tropical and subtropical regions, especially in the Amazon, Orinoco, and La Plata basins. While both GRACE and LSM TWS estimates show reasonably good correlations with ENSO and generally consistent spatial correlation patterns, notably higher correlations are found between GRACE TWS and ENSO. The existence of significant correlations in middle–high latitudes shows the large-scale impact of ENSO on the global water cycle.     

Scenario Projections of Changes in Snow Water Equivalent Due to Possible Climate Changes in Different Regions of the Earth

Water Resources - The study was carried out under the international Earth System Model–Snow Model Intercomparison Project on ten experimental well-instrumented snow sites in different parts...     

全球大陆末次盛冰期气候和植被研究进展

略述了鄱阳湖围垦的简要历史和现状,分析了近５０年来洪水水位的演变趋势,指出围垦使鄱阳湖面积和容积缩小,调蓄功能衰退,以致水情不断恶化,洪峰水位逐渐上升,高水位的出现频率明显加大,致灾洪水越来越频繁,在此基础上,将围垦对洪水位的影响进行了分析计算,得出了各典型年洪水在不同围垦背景下的围垦效应值。     

Level of Lake Ladoga at Possible Climate Changes

A transfer function model with climatic indices as the input and the lake level as the output is proposed to describe the response of a lake to climate changes. The climate indices include air temperature and atmospheric precipitation. The model is used to assess the response of the Lake Ladoga level to different climate changes. It is shown that the significant deviations of the lake level from the values corresponding to the modern climate are associated with changes in the numerical characteristics of climate indices and can be attributed to the displacement of the boundaries of climatic seasons. In this case, significant changes in the lake level may take place even without visible deviations of the annual averages of temperature and precipitation from their long-term standards.     

Projected Changes in Water Balance Components of 11 Large River Basins during the 21st Century and Their Uncertainties

Water Resources - Changes in the water balance components of 11 large-scale river basins due to possible climate change during the 21st century were simulated with the land surface model SWAP and...     

Potential Changes in Aquatic Biota in the Period of Global Climate Warming

The results of investigations of water bodies subjected to constant many-year thermal pollution are proposed to use for the prediction of the consequences of climate warming. General tendencies in changes in the aquatic biota and the distribution of aquatic organisms under the effect of thermal pollution are established by analyzing the materials collected at different cooling ponds of nuclear and thermal power stations.     

Incorporating Natural Changes in Global Climate in Very-Long-Range Forecasting of River Runoff

A method is proposed for incorporating possible global changes in the state of the atmosphere, basing on K. Hasselmann’s theory of stochastic climate models, for assessing the significance of forecasts of variations of annual river runoff depth in the XXI century. The data used includes the results of river runoff simulation at warming, obtained using 21 IPCC climate models along with six IPCC scenarios of greenhouse gas emission, and MEI scenario. The significance index of forecasted runoff variations, i.e., the values of runoff depth increments divided by the standard error of forecasts was mapped. To demonstrate the role of the maps of significance index, which have been constructed taking into account forecast uncertainty because of the natural changes in global climate, those maps were compared with the maps of significance index calculated basing on other sources of errors. At large time scales, the uncertainty of runoff forecasts owing to natural changes in global climate plays the main role in assessing the reliability of forecasts in areas where greenhouse effect is strongest. Estimates of the significance index show that statistically significant changes in the annual runoff depth in the extreme northeast of Eurasia can be expected to occur not earlier than the late XXI century. In other RF regions, as well as in the majority of world areas, the forecasted changes in the annual runoff depth are comparable with the standard errors of the respective estimates or are less than they are.     

Modelling Water Balance Components of River Basins Located in Different Regions of the Globe

Water Resources - Three river basins—the Lena, Ganges, and Darling—were selected to study the possibility of reproducing water balance components of river basins, located in different...     

A Scenario of Possible Effect of Changes in the Hydrological Conditions on the Medical and Environmental Situation: On the Problem of Global Hydroclimatic Changes

The effect of transformation of the human habitat on the medical and ecological situation is considered in the context of anticipated changes in the hydrological situation. The results of earlier studies of environmental crises (transgression of the Caspian Sea and degression of the Aral Sea) are used to show the possibility of a considerable increase in the rates of infectious and noninfectious diseases caused by a direct or indirect effect of significant changes in the hydrological and hydrogeological conditions. Regularities in the dynamics of this process have been established, which allows us to discuss possible changes in public health under new hydroclimatic conditions, in particular, under global climate changes. It is shown that the scientific principles and methods for prediction of the consequences of changes in the regime, quantity, and quality of continental waters should be improved in order to allow the assessment of their effect on public health and the development of timely preventive measures.     

Modeling Water and Heat Balance Components for Large Agricultural Region Utilizing Information from Meteorological Satellites

The method has been developed to evaluate water and heat balance components for vegetation covered area of regional scale based on the refined physical-mathematical model of vertical water and heat exchange between land surface and atmosphere (Land Surface Model, LSM) for vegetation season adapted to satellite information on land surface and meteorological conditions. The LSM is accommodated for utilizing satellite-derived estimates of vegetation and meteorological characteristics as model parameters and input variables. Estimates of these characteristics presented as distributions of their values over the study area have been obtained from AVHRR/NOAA, MODIS/EOS Terra and Aqua, SEVIRI/Meteosat-9, -10 data. To build such estimates methods and technologies have been developed and refined using results of thematic processing measurement data from these sensors. Among them the original Multi Threshold Method (MTM) has been developed and tested to calculate daily precipitation sums using rainfall intensity estimates retrieved from AVHRR and SEVIRI data with subsequent replacement of ground-measured rainfall amounts by these daily rainfalls. All technologies have been adapted to the study area with square of 227300 km² being the part of the Central Black Earth Region of European Russia. Developed earlier procedures of utilizing satellitederived estimates of vegetation and meteorological characteristics (including precipitation) in the model have been refined and verified. Final result of modeling is the fields of soil water content, evapotranspiration and other water and heat balance components of the region under study for years 2012–2014 vegetation seasons.     

Local Ionospheric Modeling Using the Localized Global Ionospheric Map and Terrestrial GPS

global ionosphere maps are generated on a daily basis at CODE using data from about 200 GPS/GLONASS sites of the IGS and other institutions. The vertical total electron content is modeled in a solargeomagnetic reference frame using a spherical harmonics expansion up to degree and order 15. The spherical Slepian basis is a set of bandlimited functions which have the majority of their energy concentrated by optimization inside an arbitrarily defined region, yet remain orthogonal within the spatial region of interest. Hence, they are suitable for decomposing the spherical harmonic models into the portions that have significant strength only in the selected areas. In this study, the converted spherical harmonics to the Slepian bases were updated by the terrestrial GPS observations by use of the least-squares estimation with weighted parameters for local ionospheric modeling. Validations show that the approach adopted in this study is highly capable of yielding reliable results.     

湖南对全球变暖的区域响应

本文通过长沙近百年和湖南区域近百站40a来的气象资料统计,分析了在全球气候变暖条件下湖南气候变化事实,揭示了湖南洪水灾害加剧的情况,并提出了应加以重视的问题.     

Climate Variability in NW Spain and its Relationship with Water Balance and Streamflow in a Small Headwater Catchment: Preliminary Results

This paper presents preliminary results from an analysis of hydrological variability of a catchment located in Galicia (NW Spain), with particular focus on the effects of climate variability (temperature and precipitation), using daily streamflow data for the period October 2004 to September 2009. The climate variability has been studied by means of data obtained in a meteorological station on the area. The analysis is based on the examination of statistical parameters, flow duration characteristics, baseflow separation and the relationship between measured streamflow and precipitation. The results show that daily, monthly and annual streamflow are highly variable in this catchment. At seasonal scale about 65% of the water flows in winter (33%) and spring (32%) months, although with significant differences between years. This seasonality essentially relates to distribution and characteristics of precipitation episodes. However, there is not a narrow relationship between precipitation and streamflow, because soil moisture conditions have an important role in the hydrological behaviour of the catchment. The baseflow contribution to total streamflow is quite high, with baseflow index values above 0.69, which is consistent with the characteristics of the study area, such as geology (dominated by schist), soils (Umbrisols and Cambisols), vegetation cover (over 65% forest area) and precipitation characteristics (heavy, long duration and low intensity). The flow duration analysis also reveals that the flow regime is dominated by baseflow, recording high flow peaks during a limited period of the year. The study reveals that the major cause of streamflow variability in this catchment is related to precipitation distribution and soil moisture conditions. The results suggest that the Corbeira stream undergoes a reduction in low streamflows and an increase in the frequency of high flows, hence producing an increase in the risks associated with these changes.     

青海湖水量平衡分析与水资源优化配置研究

在充分收集有关资料的基础上研究青海湖1959-2000年间降水径流蒸发湖泊水位地下水补给量的动态变化建立水量平衡分析方程.青海湖水位在波动中持续下降42年来年平均水位累计下降了 3.32 m平均每年下降了0.079 m近年来下降的幅度减小. 同时青海湖储水量不断减少而湖区降水呈增加的趋势河川径流量地下水的入湖补给量 蒸发量呈现下降的趋势. 根据青海湖水平衡分析计算结果预测2010年青海湖流域耗水量将达1.27108m3为维护生态平衡和社会经济持续发展需要跨流域调水量引大济湖4.1108m3.     

Background Factors of Global Climate Warming in the Coastal Zone of the Black Sea

Mechanisms of the positive changes in the heat budget of the active layer when its surface is cooling down and at its current eustasy are proposed. The proposed mechanisms are based on the analysis of long series of observations of the Black Sea temperature and level. The basic factors determining the vulnerability of the coastal infrastructure are established and a simplified scheme for assessing the possible damage is given. The development of the background factors in the near future is predicted and the necessity for the Black Sea countries to implement individual redemption plans is substantiated.     

全球气候变化模拟结果数据的远程抽取及其可视化

本文针对气候模式在超大规模数值模拟中产生的Tb至Pb量级的四维体数据的可视化和分析诊断方法, 提出了基于Server-Client方式的远程数据抽取和并行可视化解决方案。 针对气候模拟数据中的海洋模式和大气模式数值模拟结果数据的抽取和可视化数值试验分析, 验证了解决方案的可行性和抽取算法的高效性、 可靠性和灵活性。 本文提出的远程数据抽取方法对于帮助气候模式领域中的专家快速抽取、 快速可视化和实现实时交互式模拟结果的诊断分析具有重要的应用价值。     

Control of Ion Balance in Water by Determining the Cation Content

Presented is an analytical method which enables a quick determination of the total cation content in water. In this method, total alkalinity is determined before passage, and mineral acidity after passage through the ion exchange bed. The sum of the two parameter values gives the total cation content in the water. Verification was carried out with model solution and natural water samples. The method makes it possible to verify the ion balance of the electrolytes, as well as to determine the salinity level (i.e. the concentration of dissolved substances) in the sample.     

The Effect of Stage on Flow and Components of the Local Force Balance

Flow fields and water and bed surface topography were measured at two different stages as flow shoals over a submerged mid-channel bar in a straight reach downstream of a bend in Solfatara Creek, Wyoming. The data allow calculation and comparison of the magnitude of the component terms in the downstream and cross-stream force balance at the different stages. At the lower stage, corresponding to a discharge that is 30 per cent of the bankfull discharge, the convective acceleration terms in the equations describing the force balance are important, particularly the terms associated with the cross-stream transport of momentum. These terms are large because of the large accelerations and cross-stream flow forced by the shallow flow over the bar. At the higher stage, corresponding to a discharge that is 45 per cent of the bankfull discharge, flow is more directly downstream and cross-stream velocity is generally less in most of the channel. Downstream flow velocities at the higher stage are larger, but the acceleration is more gradual. Consequently, the convective accelerations at the higher stage tend to be less important than at the lower stage. Results from the two different stages suggest that some of the difference in conclusions reached by various workers on the significance of the various terms in the governing equations may be associated with the relative depth of flow. © 1997 John Wiley & Sons, Ltd.