scholarly journals A two-layer canopy with thermal inertia for an improved modelling of the sub-canopy snowpack energy-balance

2015 ◽  
Vol 8 (1) ◽  
pp. 209-262 ◽  
Author(s):  
I. Gouttevin ◽  
M. Lehning ◽  
T. Jonas ◽  
D. Gustafsson ◽  
M. Mölder
Keyword(s):  
Energy Balance ◽  
Temperature Drop ◽  
Model Performance ◽  
Thermal Inertia ◽  
Thermal Response ◽  
Canopy Temperature ◽  
Night Time ◽  
The Difference ◽  
Snow Model ◽  
The Impact

Abstract. A new, two-layer canopy module with thermal inertia as part of the detailed snow model SNOWPACK (version 3.2.1) is presented and evaluated. This module is designed to reproduce the difference in thermal response between leafy and woody canopy elements, and their impact on the underlying snowpack energy balance. Given the number of processes resolved, the SNOWPACK model with its enhanced canopy module constitutes a very advanced, physics-based atmosphere-to-soil-through-canopy-and-snow modelling chain. Comparisons of modelled sub-canopy thermal radiation to stand-scale observations at an Alpine site (Alptal, Switzerland) demonstrate the improvements of the new canopy module. Both thermal heat mass and the two-layer canopy formulation contribute to reduce the daily amplitude of the modelled canopy temperature signal, in agreement with observations. Particularly striking is the attenuation of the night-time drop in canopy temperature, which was a key model bias. We specifically show that a single-layered canopy model is unable to produce this limited temperature drop correctly. The impact of the new parameterizations on the modelled dynamics of the sub-canopy snowpack is analysed and yields consistent results but the frequent occurrence of mixed-precipitation events at Alptal prevents a conclusive assessment of model performance against snow data. The new model is also successfully tested without specific tuning against measured tree temperatures and biomass heat storage fluxes at the boreal site of Norunda (Sweden). This provides an independent assessment of its physical consistency and stresses the robustness and transferability of the parameterizations used.

scholarly journals A two-layer canopy model with thermal inertia for an improved snowpack energy balance below needleleaf forest (model SNOWPACK, version 3.2.1, revision 741)

2015 ◽  
Vol 8 (8) ◽  
pp. 2379-2398 ◽  
Author(s):  
I. Gouttevin ◽  
M. Lehning ◽  
T. Jonas ◽  
D. Gustafsson ◽  
M. Mölder
Keyword(s):  
Energy Balance ◽  
Temperature Drop ◽  
Model Performance ◽  
Ground Surface ◽  
Thermal Inertia ◽  
Thermal Response ◽  
Canopy Temperature ◽  
Current Form ◽  
The Impact ◽  
Canopy Model

Abstract. A new, two-layer canopy module with thermal inertia as part of the detailed snow model SNOWPACK (version 3.2.1) is presented and evaluated. As a by-product of these new developments, an exhaustive description of the canopy module of the SNOWPACK model is provided, thereby filling a gap in the existing literature. In its current form, the two-layer canopy module is suited for evergreen needleleaf forest, with or without snow cover. It is designed to reproduce the difference in thermal response between leafy and woody canopy elements, and their impact on the underlying snowpack or ground surface energy balance. Given the number of processes resolved, the SNOWPACK model with its enhanced canopy module constitutes a sophisticated physics-based modeling chain of the continuum going from atmosphere to soil through the canopy and snow. Comparisons of modeled sub-canopy thermal radiation to stand-scale observations at an Alpine site (Alptal, Switzerland) demonstrate improvements induced by the new canopy module. Both thermal heat mass and the two-layer canopy formulation contribute to reduce the daily amplitude of the modeled canopy temperature signal, in agreement with observations. Particularly striking is the attenuation of the nighttime drop in canopy temperature, which was a key model bias. We specifically show that a single-layered canopy model is unable to produce this limited temperature drop correctly. The impact of the new parameterizations on the modeled dynamics of the sub-canopy snowpack is analyzed. The new canopy module yields consistent results but the frequent occurrence of mixed-precipitation events at Alptal prevents a conclusive assessment of model performance against snow data. The new model is also successfully tested without specific tuning against measured tree temperature and biomass heat-storage fluxes at the boreal site of Norunda (Sweden). This provides an independent assessment of its physical consistency and stresses the robustness and transferability of the chosen parameterizations. The SNOWPACK code including the new canopy module, is available under Gnu General Public License (GPL) license and upon creation of an account at https://models.slf.ch/.

scholarly journals Evaluation of Cardiac Circadian Rhythm Deconditioning Induced by 5-to-60 Days of Head-Down Bed Rest

2021 ◽  
Vol 11 ◽  
Author(s):  
Sarah Solbiati ◽  
Alba Martin-Yebra ◽  
Pierre Vaïda ◽  
Enrico G. Caiani
Keyword(s):  
Circadian Rhythms ◽  
Recovery Period ◽  
Oscillation Amplitude ◽  
Bed Rest ◽  
Heart Beat ◽  
Night Time ◽  
Mission Success ◽  
The Difference ◽  
Orthostatic Position ◽  
The Impact

Head-down tilt (HDT) bed rest elicits changes in cardiac circadian rhythms, generating possible adverse health outcomes such as increased arrhythmic risk. Our aim was to study the impact of HDT duration on the circadian rhythms of heart beat (RR) and ventricular repolarization (QTend) duration intervals from 24-h Holter ECG recordings acquired in 63 subjects during six different HDT bed rest campaigns of different duration (two 5-day, two 21-day, and two 60-day). Circadian rhythms of RR and QTend intervals series were evaluated by Cosinor analysis, resulting in a value of midline (MESOR), oscillation amplitude (OA) and acrophase (φ). In addition, the QTc (with Bazett correction) was computed, and day-time, night-time, maximum and minimum RR, QTend and QTc intervals were calculated. Statistical analysis was conducted, comparing: (1) the effects at 5 (HDT5), 21 (HDT21) and 58 (HDT58) days of HDT with baseline (PRE); (2) trends in recovery period at post-HDT epochs (R) in 5-day, 21-day, and 60-day HDT separately vs. PRE; (3) differences at R + 0 due to bed rest duration; (4) changes between the last HDT acquisition and the respective R + 0 in 5-day, 21-day, and 60-day HDT. During HDT, major changes were observed at HDT5, with increased RR and QTend intervals’ MESOR, mostly related to day-time lengthening and increased minima, while the QTc shortened. Afterward, a progressive trend toward baseline values was observed with HDT progression. Additionally, the φ anticipated, and the OA was reduced during HDT, decreasing system’s ability to react to incoming stimuli. Consequently, the restoration of the orthostatic position elicited the shortening of RR and QTend intervals together with QTc prolongation, notwithstanding the period spent in HDT. However, the magnitude of post-HDT changes, as well as the difference between the last HDT day and R + 0, showed a trend to increase with increasing HDT duration, and 5/7 days were not sufficient for recovering after 60-day HDT. Additionally, the φ postponed and the OA significantly increased at R + 0 compared to PRE after 5-day and 60-day HDT, possibly increasing the arrhythmic risk. These results provide evidence that continuous monitoring of astronauts’ circadian rhythms, and further investigations on possible measures for counteracting the observed modifications, will be key for future missions including long periods of weightlessness and gravity transitions, for preserving astronauts’ health and mission success.

Impact of centrally applied biogenic amines upon the energy balance of fowl

1977 ◽  
Vol 232 (5) ◽  
pp. R137-R144
Author(s):  
P. E. Hillman ◽  
N. R. Scott ◽  
A. van Tienhoven
Keyword(s):  
Energy Balance ◽  
Body Temperature ◽  
Biogenic Amines ◽  
Thermal Response ◽  
Evaporative Heat Loss ◽  
Ambient Temperatures ◽  
Body Temperature Change ◽  
Intraventricular Injections ◽  
Reducing Activity ◽  
The Impact

The impact of intraventricular injections of 100 microng of the biogenic amines, norepinephrine or dopamine, upon the energy balance of white leghorn hens Gallus domesticus was examined. Both drugs reduce metabolic heat production (about 35% at 9 and 20 degrees C, and about 15% at 35 degrees C) by inhibiting shivering or by reducing activity or both. Also the drugs inhibit the opposing thermal response, evaporative heat loss (about 3% at 9 and 20 degrees C, and about 20% at 35 degrees C) by reducing respiration rate. The relative balance of inhibiting these opposing responses by the drugs results in hypothermia at 9 and 20 degrees C, and hyperthermia or no change in body temperature at 35 degrees C. Both drugs usually caused an initial vasodilation of the feet and comb at all temperatures tested but did not persist long enough to have much of an impact on body temperature. It was concluded that differing ambient temperatures do not alter the action of the biogenic amines upon the modes of physical thermoregulation in chickens even though the direction of body temperature change is reversed at different ambient temperatures.

scholarly journals Evaluating the impact of spatial variability of precipitation on streamflow simulation using a SWAT model

Water Policy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 178-196 ◽  
Author(s):  
Feng Xue ◽  
Peng Shi ◽  
Simin Qu ◽  
Jianjin Wang ◽  
Yanming Zhou
Keyword(s):  
Spatial Variability ◽  
Assessment Tool ◽  
Swat Model ◽  
Model Performance ◽  
Coefficient Of Determination ◽  
Interpolation Methods ◽  
Monthly Streamflow ◽  
Areal Precipitation ◽  
The Difference ◽  
The Impact

Abstract The spatial variability of precipitation is often considered to be a major source of uncertainty for hydrological models. The widely used Soil and Water Assessment Tool (SWAT) is insufficient to calculate a sub-basin's mean areal precipitation (MAP) since it only uses data from the rainfall station nearest to the centroid of each sub-basin. Therefore, Inverse Distance Weighting (IDW), Thiessen Polygons (TP) and Ordinary Kriging (OK) were applied as alternative interpolation methods in this study to calculate sub-basin MAP. The MAP results from the four methods used for the Xixian Basin were quite different in terms of amount and spatial distribution. The SWAT model performance was then assessed at monthly and daily timescales, based on Nash–Sutcliffe efficiency (NSE), the Coefficient of Determination (R2) as well as Percentage Bias (PBIAS) at the basin outlet. The results under different network densities and spatial distributions of gauge stations indicated that the modified MAP models did not have an advantage over the default Nearest Neighbour (NN) method in simulating monthly streamflow. However, the modified areal precipitation obtained through IDW and TP showed relatively high accuracy in simulating daily flows as the applied rainfall stations changed. The difference in terms of estimated rainfall and streamflow in this study confirmed that evaluation of interpolation methods is necessary before building a SWAT model.

scholarly journals Non-Spatial Impairments Affect False-Positive Neglect Diagnosis Based on Cancellation Tasks

2020 ◽  
Vol 26 (7) ◽  
pp. 668-678 ◽  
Author(s):  
Hanne Huygelier ◽  
Margaret Jane Moore ◽  
Nele Demeyere ◽  
Céline R. Gillebert
Keyword(s):  
Test Performance ◽  
False Positive ◽  
Standard Procedure ◽  
Model Performance ◽  
False Positives ◽  
Spatial Bias ◽  
Multiple Tests ◽  
Left And Right ◽  
The Difference ◽  
The Impact

AbstractObjective:To diagnose egocentric neglect after stroke, the spatial bias of performance on cancellation tasks is typically compared to a single cutoff. This standard procedure relies on the assumption that the measurement error of cancellation performance does not depend on non-spatial impairments affecting the total number of cancelled targets. Here we assessed the impact of this assumption on false-positive diagnoses.Method:We estimated false positives by simulating cancellation data using a binomial model. Performance was summarised by the difference in left and right cancelled targets (R-L) and the Centre of Cancellation (CoC). Diagnosis was based on a fixed cutoff versus cutoffs adjusted for the total number of cancelled targets and on single test performance versus unanimous or proportional agreement across multiple tests. Finally, we compared the simulation findings to empirical cancellation data acquired from 651 stroke patients.Results:Using a fixed cutoff, the rate of false positives depended on the total number of cancelled targets and ranged from 10% to 30% for R-L scores and from 10% to 90% for CoC scores. The rate of false positives increased even further when diagnosis was based on proportional agreement across multiple tests. Adjusted cutoffs and unanimous agreement across multiple tests were effective at controlling false positives. For empirical data, fixed versus adjusted cutoffs differ in estimation of neglect prevalence by 13%, and this difference was largest for patients with non-spatial impairments.Conclusions:Our findings demonstrate the importance of considering non-spatial impairments when diagnosing neglect based on cancellation performance.

scholarly journals ESCIMO.spread (v2): parameterization of a spreadsheet-based energy balance snow model for inside-canopy conditions

2016 ◽  
Vol 9 (2) ◽  
pp. 633-646 ◽  
Author(s):  
T. Marke ◽  
E. Mair ◽  
K. Förster ◽  
F. Hanzer ◽  
J. Garvelmann ◽  
...  
Keyword(s):  
Energy Balance ◽  
Snow Cover ◽  
Forest Canopy ◽  
Model Performance ◽  
Snow Accumulation ◽  
Meteorological Conditions ◽  
Mountain Range ◽  
Point Energy ◽  
Snow Model ◽  
Mean Square Errors

Abstract. This article describes the extension of the ESCIMO.spread spreadsheet-based point energy balance snow model by (i) an advanced approach for precipitation phase detection, (ii) a method for cold content and liquid water storage consideration and (iii) a canopy sub-model that allows the quantification of canopy effects on the meteorological conditions inside the forest as well as the simulation of snow accumulation and ablation inside a forest stand. To provide the data for model application and evaluation, innovative low-cost snow monitoring systems (SnoMoS) have been utilized that allow the collection of important meteorological and snow information inside and outside the canopy. The model performance with respect to both, the modification of meteorological conditions as well as the subsequent calculation of the snow cover evolution, are evaluated using inside- and outside-canopy observations of meteorological variables and snow cover evolution as provided by a pair of SnoMoS for a site in the Black Forest mountain range (southwestern Germany). The validation results for the simulated snow water equivalent with Nash–Sutcliffe model efficiency values of 0.81 and 0.71 and root mean square errors of 8.26 and 18.07 mm indicate a good overall model performance inside and outside the forest canopy, respectively. The newly developed version of the model referred to as ESCIMO.spread (v2) is provided free of charge together with 1 year of sample data including the meteorological data and snow observations used in this study.

Ambient Temperature And Nest Temperature Variation In Enclosed Nests (Spanish Sparrow) And Open-Cup Nests (Iberian Azure-Winged Magpie)

2013 ◽  
Vol 37 (1) ◽  
pp. 14-24
Author(s):  
Paulo A. M. Marques
Keyword(s):  
Ambient Temperature ◽  
Temperature Variation ◽  
Life Histories ◽  
The Body ◽  
Nest Temperature ◽  
Buffer Effect ◽  
Night Time ◽  
The Difference ◽  
The Impact ◽  
Positive Effect

Abstract Temperature plays a central role in the life of birds, especially during egg incubation and nestling thermal brooding. I investigated nest temperature variation relative to ambient temperature during incubation in an enclosed nest-builder species (Spanish sparrow Passer hispaniolensis) and an open-cup nest-builder species (Iberian azure-winged magpie Cyanopica cooki). The data for empty enclosed nests showed that the nest structure acted as a temperature buffer which reduced the impact of night-time temperature variation within the nest. The buffer effect was reduced as ambient temperature increased at dawn. The presence of an adult increased the difference between nest temperature and ambient temperature, and dissociated its variation from the ambient temperature variation. The enclosed nest also retained the body heat released by an adult in the nest. Both effects had a positive effect on the temperature balance in the nest. By contrast, open-cup nest temperature was more affected by the ambient temperature, although it did not affect the egg temperature directly. Thus the absence of an incubating parent would endanger the hatchability in open-cup nests more rapidly than in enclosed nests. The life histories of the investigated species correspond to these findings, i.e. a more pronounced presence of the female in the Iberian azure-winged magpie nests.

scholarly journals Uncertainty in the Number of Calibration Repetitions of a Hydrologic Model in Varying Climatic Conditions

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2362
Author(s):  
Patrik Sleziak ◽  
Ladislav Holko ◽  
Michal Danko ◽  
Juraj Parajka
Keyword(s):  
Differential Evolution Algorithm ◽  
Model Performance ◽  
Hydrologic Model ◽  
Climatic Conditions ◽  
Data Set ◽  
Climate Conditions ◽  
Daily Data ◽  
Model Efficiency ◽  
The Difference ◽  
The Impact

The objective of this study is to examine the impact of the number of calibration repetitions on hydrologic model performance and parameter uncertainty in varying climatic conditions. The study is performed in a pristine alpine catchment in the Western Tatra Mountains (the Jalovecký Creek catchment, Slovakia) using daily data from the period 1989–2018. The entire data set has been divided into five 6-years long periods; the division was based on the wavelet analysis of precipitation, air temperature and runoff data. A lumped conceptual hydrologic model TUW (“Technische Universität Wien”) was calibrated by an automatic optimisation using the differential evolution algorithm approach. To test the effect of the number of calibrations in the optimisation procedure, we have conducted 10, 50, 100, 300, 500 repetitions of calibrations in each period and validated them against selected runoff and snow-related model efficiency criteria. The results showed that while the medians of different groups of calibration repetitions were similar, the ranges (max–min) of model efficiency criteria and parameter values differed. An increasing number of calibration repetitions tend to increase the ranges of model efficiency criteria during model validation, particularly for the runoff volume error and snow error, which were not directly used in model calibration. Comparison of model efficiencies in climate conditions that varied among the five periods documented changes in model performance in different periods but the difference between 10 and 500 calibration repetitions did not change much between the selected time periods. The results suggest that ten repetitions of model calibrations provided the same median of model efficiency criteria as a greater number of calibration repetitions and model parameter variability and uncertainty were smaller.

The Influence of Thermal Inertia Index on the Residential External Walls in Hot-Summer and Cold-Winter Areas

2013 ◽  
Vol 368-370 ◽  
pp. 562-565
Author(s):  
Min Xiao ◽  
Guo Qiang Zhang
Keyword(s):  
Power Consumption ◽  
Thermal Performance ◽  
Evaluation Method ◽  
Thermal Inertia ◽  
Building Envelope ◽  
Heating Power ◽  
Cold Winter ◽  
The Difference ◽  
The Impact ◽  
Inertia Index

The evaluation method of residential building envelope thermal performance in hot-summer and cold-winter area is different from the method of the cold northern regions, that is, the merit of the thermal performance of walls and roofs should not be determined only by the heat transfer coefficient K or thermal resistance R, the impact of the thermal inertia index on the thermal performance of building envelope should also be considered. The analysis results show that, with the different values of thermal inertia index D, the difference of residential summer air-conditioning power consumption is not big, but the difference of residential winter heating power consumption is bigger, therefore, the high thermal inert wall is more conductive to reduce the winter heating power consumption than the low thermal inert wall.

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