671 research outputs found
Impact analysis of climate change for an Alpine catchment using high resolution dynamic downscaling of ECHAM4 time slices
International audienceGlobal climate change affects spatial and temporal patterns of precipitation and so has a major impact on surface and subsurface water balances. While global climate models are designed to describe climate change on global or continental scales, their resolution is too coarse for them to be suitable for describing regional climate change. Therefore, regional climate models are applied to downscale the coarse meteorological fields to a much higher spatial resolution to take account of regional climate phenomena. The changes of atmospheric state due to regional climate change must be translated into surface and sub-surface water fluxes so that the impact on water balances in specific catchments can be investigated. This can be achieved by the coupled regional climatic/hydrological simulations presented here. The non-hydrostatic regional climate model MCCM was used for dynamic downscaling for two time slices of a global climate model simulation with the GCM ECHAM4 (IPCC scenario IS92a, "business as usual") from 2.8° × 2.8° to 4 × 4 km2 resolution for the years 1991?1999 and 2031?2039. This allowed derivation of detailed maps showing changes in precipitation and temperature in a region of southern Germany and the central Alps. The performance of the downscaled ECHAM4 to reproduce the seasonality of precipitation in central Europe for the recent climate was investigated by comparison with dynamically downscaled ECMWF reanalyses in 20 × 20 km2 resolution. The downscaled ECHAM4 fields underestimate precipitation significantly in summer. The ratio of mean monthly downscaled ECHAM4 and ECMWF precipitation showed little variation, so it was used to adjust the course of precipitation for the ECHAM4/MCCM fields before it was applied in the hydrological model. The high resolution meteorological fields were aggregated to 8-hour time steps and applied to the distributed hydrological model WaSiM to simulate the water balance of the alpine catchment of the river Ammer (c. 700 km2) at 100 × 100 m2 resolution. To check the reliability of the coupled regional climatic/hydrological simulation results for the recent climate, they were compared with those of a station-based hydrological simulation for the period 1991?1999. This study shows the changes in the temperature and precipitation distributions in the catchment from the recent climate to the future climate scenario and how these will affect the frequency distribution of runoff. Keywords: coupled climate-hydrology simulations, dynamic downscaling, distributed hydrological modelling, ECHAM4 climate scenario, alpine hydrolog
OXIDATION RATES OF MAJOR FATTY ACIDS IN FASTING NEONATAL PIGS
Thirty-two pigs were used to compare the oxidation rates of uniformly labeled (U-14C) palmitic (16:0), stearic (18:0), oleic (18:1) and linoleic (18:2) acids in fasting neonatal pigs. The pigs were allowed to nurse the sow for 24 to 48 h following birth. Subsequently, they were removed, an indwelling catheter was surgically placed in the external iliac vein and the pigs were fasted for 12 h to attain a postabsorptive state. The 14C fatty acids were administered as a single infusion (10 / μCi) via the catheter, and recovery of the label as expired 14CO2 was determined at 45-min intervals for a 6-h period. Blood samples were taken following the infusion (15, 60, 120, 240, 360 min) to monitor activity maintained within the free fatty acid (FFA) fraction of the plasma pool. The oxidation rate of each fatty acid was corrected for the difference in dose dilution using a uniform factor based on plasma concentration of 18:1. The cumulative 6-h 14CO2 recovery rates (percentage of dose) were 19.1, 6.6, 30.1 and 13.1% for 16:0, 18:0, 18:1 and 18:2, respectively. Oleic acid was oxidized at a more (P\u3c.05) rapid rate than the other fatty acids. Palmitic acid and 18:2 were oxidized more rapidly than 18:0, although the difference between 18:0 and 18:2 was not significant. Plasma FFA pools differed with respect to the proportion of infused activity remaining at various times after administration. At 60 and 120 min postinfusion, the greatest (P\u3c.05) proportion of activity was maintained in the 18:1 pool (11.9 and 6.6%, respectively, vs 7.7 and 4.3% for 16:0, 6.9 and 3.9% for 18:2 and 3.6 and 2.2% for 18:0). Palmitic acid and 18:2 had a greater (P\u3c.05) level of activity in the plasma FFA pool at 60 min than did 18:0. This same pattern was observed through 2 h, but by 240 min postinfusion, the proportion of activity remaining in each of the plasma pools was similar. Rate of oxidation appeared to correspond with plasma concentration and proportion of activity remaining in the plasma FFA pool
OXIDATION RATES OF MAJOR FATTY ACIDS IN FASTING NEONATAL PIGS
Thirty-two pigs were used to compare the oxidation rates of uniformly labeled (U-14C) palmitic (16:0), stearic (18:0), oleic (18:1) and linoleic (18:2) acids in fasting neonatal pigs. The pigs were allowed to nurse the sow for 24 to 48 h following birth. Subsequently, they were removed, an indwelling catheter was surgically placed in the external iliac vein and the pigs were fasted for 12 h to attain a postabsorptive state. The 14C fatty acids were administered as a single infusion (10 / μCi) via the catheter, and recovery of the label as expired 14CO2 was determined at 45-min intervals for a 6-h period. Blood samples were taken following the infusion (15, 60, 120, 240, 360 min) to monitor activity maintained within the free fatty acid (FFA) fraction of the plasma pool. The oxidation rate of each fatty acid was corrected for the difference in dose dilution using a uniform factor based on plasma concentration of 18:1. The cumulative 6-h 14CO2 recovery rates (percentage of dose) were 19.1, 6.6, 30.1 and 13.1% for 16:0, 18:0, 18:1 and 18:2, respectively. Oleic acid was oxidized at a more (P\u3c.05) rapid rate than the other fatty acids. Palmitic acid and 18:2 were oxidized more rapidly than 18:0, although the difference between 18:0 and 18:2 was not significant. Plasma FFA pools differed with respect to the proportion of infused activity remaining at various times after administration. At 60 and 120 min postinfusion, the greatest (P\u3c.05) proportion of activity was maintained in the 18:1 pool (11.9 and 6.6%, respectively, vs 7.7 and 4.3% for 16:0, 6.9 and 3.9% for 18:2 and 3.6 and 2.2% for 18:0). Palmitic acid and 18:2 had a greater (P\u3c.05) level of activity in the plasma FFA pool at 60 min than did 18:0. This same pattern was observed through 2 h, but by 240 min postinfusion, the proportion of activity remaining in each of the plasma pools was similar. Rate of oxidation appeared to correspond with plasma concentration and proportion of activity remaining in the plasma FFA pool
Towards integrated regional earth system modeling: a coupled biosphere-hydrosphere-atmosphere model with dynamic vegetation and chemistry
Towards integrated regional earth system modeling: a coupled biosphere-hydrosphere-atmosphere model with dynamic vegetation and chemistry
From regional climate modelling to hydrological impact analysis: current capabilities and future research needs
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