Annual drought flow and groundwater storage trends in the eastern half of the United States during the past two-third century

Low flow drainage from a river system, in the absence of precipitation or snowmelt, derives directly from the water stored in the upstream aquifers in the basin; therefore, observations of the trends of the annual lowest flows can serve to deduce quantitative estimates of the evolution of the basin-scale groundwater storage over the period of the streamflow record. Application of this method has allowed for the first time to determine the magnitudes of the trends in groundwater storage over the past two-third century in some 41 large prototypical basins in the United States east of the Rocky Mountains. It was found that during the period 1940–2007 groundwater storage has generally been increasing in most areas; these positive trends were especially pronounced in the Ohio and Upper Mississippi Water Resources Regions, but they were weaker in most other regions. Notable exceptions are the northern New England and especially the South Atlantic-Gulf regions, which saw prolonged declines in groundwater levels over this nearly 70-year long period. These observed long-term trends are generally in agreement with previous studies regarding trends of other components of the water cycle, such as precipitation, total runoff, and terrestrial evaporation. Over the most recent 20 years, from 1988 through 2007, except for the Ohio and the Souris-Red-Rainy regions, most regions have experienced declining average groundwater levels to varying degrees, with maximal values of the order of ?0.2 mm a^?1.     

The representation of a synoptic-scale weather system in a thermodynamically adjusted version of the ECHAM4 general circulation model

Summary In this work, a strong cyclone event is simulated by the general circulation model (GCM) ECHAM4 for studying the representation of weather systems in a climate model. The system developed along the East Coast of the U.S.A. between the 12th and 14th of March 1993. The GCM simulation was started from climatological conditions and was continuously forced to the analyzed state by a thermodynamical adjustment based on the Newtonian relaxation technique (nudging). Relaxation terms for vorticity, divergence, temperature, and the logarithm of surface pressure were added at each model level and time step. The necessary forcing files were calculated from the ECMWF re-analysis (ERA15). No nudging terms were added for the components of the water cycle. Using this forcing, the model was able to reproduce the synoptic-scale features and its temporal development realistically after a spin-up period. This is true even for quantities that are not adjusted to the analysis (e.g., humidity). Detailed comparisons of the model simulations with available observations and the forcing ERA15 were performed for the cyclone case. Systematic errors were detected in the simulation of the thermodynamic state of the atmosphere, which can be traced back to deficiencies in model parametrizations. Differences in the representation of the surface fluxes lead to systematic deviations in near-surface temperature and wind fields. The general situation is very similar in both model representations. Errors were detected in the simulation of the convective boundary layer behind the cold front. The observed strong convective activity is missed both by the adjusted ECHAM4 simulation and ERA15. This is most likely caused by weaknesses in the cloud and convection schemes or by a too strong downdraft compensating the frontal lifting and suppressing the vertical transport of moisture from the boundary layer to higher levels. This work demonstrates for the investigated case the value of simulating single weather events in climate models for validating model physics. Correspondence: Hans-Stefan Bauer, Institute of Physics and Meteorology, University of Hohenheim, Garbenstra?e 30, 70599 Stuttgart, Germany     

Web-based geospatial multiple criteria decision analysis using open software and standards

The emerging ubiquity of geospatial information is providing an unprecedented opportunity to apply Geographical Information Systems (GIS)-based multiple criteria decision analysis (MCDA) to a broad spectrum of use cases. Volunteered geographic information, open GIS software, geoservice-based tools, cloud-based virtualized platforms, and worldwide collaboration of both domain experts and general users have greatly increased the quantity and accessibility of geospatially referenced data resources. Currently, there is a lack of GIS-based MCDA tools that integrate this decision-driven process within a widely accessible, robust geoframework environment, designed for user-friendly interaction. In this contribution, we present a conceptual workflow and proof-of-concept software application, Geocentric Environment for Analysis and Reasoning (GEAR), which provides a viable transition path to enhance geospatial MCDA in the age of open GIS. We propose a Web-based platform that leverages open-source geotechnologies to incorporate a wide variety of geospatial data formats in a common solution space to allow for spatially enhanced and time-relevant decision analysis. Through the proposed workflow, a user can ingest and modify heterogeneous data formats, exploit temporally tagged data sources, create multicriteria decision analysis models, and visualize the results in an iterative and collaborative workspace. A sample case study applied to disaster relief is used to demonstrate the prototype and workflow. This proof-of-concept Web-based application provides a notional pathway of how to connect open-source data to open-source analysis through a geospatially enabled MCDA workflow that could be virtually accessible to many levels of decision makers from individuals to entire organizations.     

Carbonation of lignite fly ash at ambient T and P in a semi-dry reaction system for CO2 sequestration

The global rise in atmospheric greenhouse gas concentrations calls for practicable solutions to capture CO₂. In this study, a mineral carbonation process was applied in which CO₂ reacts with alkaline lignite ash and forms stable carbonate solids. In comparison to previous studies, the assays were conducted at low temperatures and pressures and under semi-dry reaction conditions in an 8 L laboratory mixing device. In order to find optimum process conditions the pCO₂ (10-20%), stirring rate (500-3000 rpm) and the liquid to solid ratio (L/S = 0.03-0.36 L kg⁻¹) were varied. In all experiments a considerable CO₂ uptake from the gas phase was observed. Concurrently the solid phase contents of Ca and Mg (hydr)oxides decreased and CaCO₃ and MgCO₃ fractions increased throughout the experiments, showing that CO₂ was stabilized as a solid carbonate. The carbonation reaction depends on three factors: Dissolution of CO₂ in the liquid phase, mobilization of Ca and Mg from the mineral surface and precipitation of the carbonate solids. Those limitations were found to depend strongly on the variation of the process parameters. Optimum reaction conditions could be found for L/S ratios between 0.12 and 0.18, medium stirring velocities and pCO₂ between 10% and 20%.Maximum CO₂ uptake by the solid phase was 4.8 mmol g⁻¹ after 120 min, corresponding to a carbonation efficiency for the alkaline material of 53% of the theoretical CO₂ binding capacity. In comparison to previous studies both CO₂ uptake and carbonation efficiencies were in a similar range, but the reaction times in the semi-dry process were considerably shorter. The proposed method additionally allows for a more simple carbonation setup due to low T and P, and produces an easier to handle product with low water content.     

Gewinnung repräsentativer Wassermischproben mit einem einfachen kontinuierlichen Sammelgerät

The sampling device consists of a weighted wide-necked bottle with a siphon pipe inserted in its top through which water enters the bottle while air escapes out of the bottle through a pipe with a valve that is inserted in the top, too. Due to the variable setting of the valve the period of time for the filling of the bottle can be controlled between few minutes and up to 24 h.     

The stability functions in the bulk similarity formulation for the unstable boundary layer

An update is presented for the functionC in the heat transfer equation and for the functionB _w in the momentum transfer equation of the bulk similarity approach for the atmospheric boundary layer (ABL). Motives for this update are recent developments in the formulation of Monin-Obukhov functions for the surface layer, and the availability of the new data set of FIFE-89, the 1989 phase of the First ISLSCP Field Experiment, which took place over the same hilly prairie terrain in north-eastern Kansas as the 1987 phase, i.e., FIFE-87. Functional forms developed in earlier studies are considered. In addition, a new form is derived based on a simple dual structure of the ABL. The functions are calibrated with the data set obtained during FIFE-87; the results are then verified with the independent data set acquired during FIFE-89.Formerly at Cornell University.     

U.S. Religious Regions Revisited

Religion continues to play an important role in the public and private lives of Americans. Therefore, a reexamination of U.S. religious regions is necessary in light of the rapid demographic changes that have occurred in the past few decades. This article presents a new regionalization of religion in the United States for 1980 and 2000, produced using multivariate cluster analysis. Comparing this new regionalization with earlier attempts, it demonstrates that religious regions continue to exist today and have undergone various levels of stability and change. Furthermore, religious regions continue to be relevant because they provide scholars with a method for identifying and characterizing the societal context in which individual religious communities function.     

Inventory and evolution of glacial lakes since the Little Ice Age: Lessons from the case of Switzerland

Retreating glaciers give way to new landscapes with lakes as an important element. In this study, we combined available data on lake outlines with historical orthoimagery and glacier outlines for six time periods since the end of the Little Ice Age (LIA; ~1850). We generated a glacial lake inventory for modern times (2016) and traced the evolution of glacial lakes that formed in the deglaciated area since the LIA. In this deglaciated area, a total of 1192 lakes formed over the period of almost 170 years, 987 of them still in existence in 2016. Their total water surface in 2016 was 6.22 ± 0.25 km². The largest lakes are > 0.4 km² (40 ha) in size, while the majority (> 90%) are smaller than 0.01 km². Annual increase rates in area and number peaked in 1946–1973, decreased towards the end of the 20th century, and reached a new high in the latest period 2006–2016. For a period of 43 years (1973–2016), we compared modelled overdeepenings from previous studies to actual lake genesis. For a better prioritization of formation probability, we included glacier-morphological criteria such as glacier width and visible crevassing. About 40% of the modelled overdeepened area actually got covered by lakes. The inclusion of morphological aspects clearly aided in defining a lake formation probability to be linked to each modelled overdeepening. Additional morphological variables, namely dam material and type, surface runoff, and freeboard, were compiled for a subset of larger and ice-contact lakes in 2016, constituting a basis for future hazard assessment.