4,745 research outputs found
River Discharge, in State of the Climate in 2008
The global mean temperature in 2008 was slightly cooler than that in 2007; however, it still ranks within the 10 warmest years on record. Annual mean temperatures were generally well above average in South America, northern and southern Africa, Iceland, Europe, Russia, South Asia, and Australia. In contrast, an exceptional cold outbreak occurred during January across Eurasia and over southern European Russia and southern western Siberia. There has been a general increase in land-surface temperatures and in permafrost temperatures during the last several decades throughout the Arctic region, including increases of 1Ā° to 2Ā°C in the last 30 to 35 years in Russia. Record setting warm summer (JJA) air temperatures were observed throughout Greenland
U.S. River Discharge for 2008 in State of the Climate in 2008
The global mean temperature in 2008 was slightly cooler than that in 2007; however, it still ranks within the 10 warmest years on record. Annual mean temperatures were generally well above average in South America, northern and southern Africa, Iceland, Europe, Russia, South Asia, and Australia. In contrast, an exceptional cold outbreak occurred during January across Eurasia and over southern European Russia and southern western Siberia. There has been a general increase in land-surface temperatures and in permafrost temperatures during the last several decades throughout the Arctic region, including increases of 1Ā° to 2Ā°C in the last 30 to 35 years in Russia. Record setting warm summer (JJA) air temperatures were observed throughout Greenland
Flux of nutrients from Russian rivers to the Arctic Ocean: Can we establish a baseline against which to judge future changes?
Climate models predict significant warming in the Arctic in the 21st century, which will impact the functioning of terrestrial and aquatic ecosystems as well as alter landāocean interactions in the Arctic. Because river discharge and nutrient flux integrate largeāscale processes, they should be sensitive indicators of change, but detection of future changes requires knowledge of current conditions. Our objective in this paper is to evaluate the current state of affairs with respect to estimating nutrient flux to the Arctic Ocean from Russian rivers. To this end we provide estimates of contemporary (1970sā1990s) nitrate, ammonium, and phosphate fluxes to the Arctic Ocean for 15 large Russian rivers. We rely primarily on the extensive data archives of the former Soviet Union and current Russian Federation and compare these values to other estimates and to model predictions. Large discrepancies exist among the various estimates. These uncertainties must be resolved so that the scientific community will have reliable data with which to calibrate Arctic biogeochemical models and so that we will have a baseline against which to judge future changes (either natural or anthropogenic) in the Arctic watershed
Glaciers and small ice caps in the macro-scale hydrological cycle: an assessment of present conditions and future changes
Glacier and small ice cap melt water contributions to the global hydrologic cycle are an important component of human water supply and for sea level rise. This melt water is used in many arid and semi-arid parts of the world for direct human consumption as well as indirect consumption by irrigation for crops, serving as frozen reservoirs of water that supplement runoff during warm and dry periods of summer when it is needed the most. Additionally, this melt water reaching the oceans represents a direct input to sea level rise and therefore accurate estimates of this contribution have profound economic and geopolitical implications. It has been demonstrated that, on the scale of glacierized river catchments, land surface hydrological models can successfully simulate glacier contribution to streamflow. However, at global scales, the implementation of glacier melt in hydrological models has been rudimentary or non-existent. In this study, a global glacier mass balance model is coupled with the University of New Hampshire Water Balance/Transport Model (WBM) to assess recent and projected future glacier contributions to the hydrological cycle over the global land surface (excluding the ice sheets of Greenland and Antarctica). For instance, results of WBM simulations indicate that seasonal glacier melt water in many arid climate watersheds comprises 40 % or more of their discharge. Implicitly coupled glacier and WBM models compute monthly glacier mass changes and resulting runoff at the glacier terminus for each individual glacier from the globally complete Randolph Glacier Inventory including over 200 000 glaciers. The time series of glacier runoff is aggregated over each hydrological modeling unit and delivered to the hydrological model for routing downstream and mixing with non-glacial contribution of runoff to each drainage basin outlet. WBM tracks and uses glacial and non-glacial components of the in-stream water for filling reservoirs, transfers of water between drainage basins (inter-basin hydrological transfers), and irrigation along the global system of rivers with net discharge to the ocean. Climate scenarios from global climate models prepared for IPCC AR5 are used to explore an expected range of possible future glacier outflow variability to estimate the impacts on human use of these valuable waters and their poorly understood net contribution to sea level change
Lean and Fat Deposition Measurements for Purebred Berkshire Pigs Housed in Hoop Barns in Iowa
Previous research on meat quality of pork has demonstrated that purebred Berkshires have advantages over most commodity based pork. Therefore a Certified Berkshire Pork program has developed and is a vital niche market in Iowa and the United States that provides economic opportunity for a growing number of producers. This research has also documented that Berkshires have a significantly poorer feed conversion than other breeds, thus raising their cost of production. Understanding how feed programs and growth rates affect lean and fat deposition rates is a critical aspect to these niche programs in order to maximize profitability and quality of the Berkshire pork products marketed. From these two trials there are differences between the two trials for both barrows and gilts that may not be accounted for by seasonal affects. Overall, barrows averaged an inch of backfat between 200 and 240 lb body weight whereas gilts approached this backfat depth between 260 and 300 lb. Lean deposition rates were different between barrows and gilts and between trials. This difference makes it critical when selecting animals for marketing and achieving consistency in meat quality within a marketing system. The differences between barrows and gilts indicate it may be more critical that each are fed differently than in commercial production systems
High frequency repetitive transcranial magnetic stimulation over the motor cortex: No diagnostic value for narcolepsy/cataplexy
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Feed Intake and Growth Rate in Purebred Berkshire Pigs Housed in Hoop Buildings in Iowa
Niche marketing continues to grow in Iowa and the United States as the demand for high quality pork increases for both in home and out of home consumption. The majority of pigs in demand for these markets are Berkshires, with many raised in bedded hoop barns. Berkshires have been shown to have significant advantages in meat eating quality, with significantly poorer feed conversion and higher feed costs. However very little information exists as to how these pigs grow and the nutritional needs to optimize both growth and feed efficiency. Producers have little production data to evaluate and adjust feeding programs. These trials were initiated to help characterize these parameters and allow Berkshire producers a means to be more effective within their production and marketing system. This trial demonstrated that Berkshire pigs grow as fast but consume more feed than expected from traditional commodity genetic lines, resulting in a challenging feed conversion ratio. Barrows grow faster, consumed more feed than gilts, but gilts were more efficient converting feed to gain. Although seasonal feed intakes differ for both sexes, growth rates were similar within gilts and barrows. This information can perhaps be used in designing rations and feed budgeting systems that can lower the feed costs for production of Berkshire pork
Coordination and control ā limits in standard representations of multi-reservoir operations in hydrological modeling
Major multi-reservoir cascades represent a primary mechanism for dealing with hydrologic variability and extremes within institutionally complex river basins worldwide. These coordinated management processes fundamentally reshape water balance dynamics. Yet, multi-reservoir coordination processes have been largely ignored in the increasingly sophisticated representations of reservoir operations within large-scale hydrological models. The aim of this paper is twofold, namely (i) to provide evidence that the common modeling practice of parameterizing each reservoir in a cascade independently from the others is a significant approximation and (ii) to demonstrate potential unintended consequences of this independence approximation when simulating the dynamics of hydrological extremes in complex reservoir cascades. We explore these questions using the Water Balance Model, which features detailed representations of the human infrastructure coupled to the natural processes that shape water balance dynamics. It is applied to the Upper Snake River basin in the western US and its heavily regulated multi-reservoir cascade. We employ a time-varying sensitivity analysis that utilizes the method of Morris factor screening to explicitly track how the dominant release rule parameters evolve both along the cascade and in time according to seasonal high- and low-flow events. This enables us to address aim (i) by demonstrating how the progressive and cumulative dominance of upstream releases significantly dampens the ability of downstream reservoir rules\u27 parameters to influence flow conditions. We address aim (ii) by comparing simulation results with observed reservoir operations during critical low-flow and high-flow events in the basin. Our time-varying parameter sensitivity analysis with the method of Morris clarifies how independent single-reservoir parameterizations and their tacit assumption of independence leads to reservoir release behaviors that generate artificial water shortages and flooding, whereas the observed coordinated cascade operations avoided these outcomes for the same events. To further explore the role of (non-)coordination in the large deviations from the observed operations, we use an offline multi-reservoir water balance model in which adding basic coordination mechanisms drawn from the observed emergency operations is sufficient to correct the deficiencies of the independently parameterized reservoir rules from the hydrological model. These results demonstrate the importance of understanding the stateāspace context in which reservoir releases occur and where operational coordination plays a crucial role in avoiding or mitigating water-related extremes. Understanding how major infrastructure is coordinated and controlled in major river basins is essential for properly assessing future flood and drought hazards in a changing world
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