Investigating Fast- and Slow-settling Phosphorus Fractions in Lakes using Steady-state Modeling

2021 ◽  
Author(s):  
Hamed Khorasani ◽  
Zhenduo Zhu
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
Large Scale ◽  
Hydraulic Residence Time ◽  
Simple Method ◽  
Retention Models ◽  
Mass Balance Models ◽  
Limiting Nutrient ◽  
Fast Settling ◽  
P Retention

<p>Phosphorus (P) is the key and limiting nutrient in the eutrophication of freshwater resources. Modeling P retention in lakes using steady-state mass balance models (i.e. Vollenweider-type models) provides insights into the lake P management and a simple method for large-scale assessments of P in lakes. One of the basic problems in the mass balance modeling of P in lakes is the removal of P from the lake water column by settling. A fraction of the incoming P into the lake from the watershed is associated with fast-settling particles (e.g. sediment particles) that result in the removal of that fraction of P quickly at the lake entrance. However, existing models considering a constant fraction of fast-settling TP for all lakes are shown to result in overestimation of the retention of P in lakes with short hydraulic residence time. In this study, we combine a hypothesis of the fast- and slow-settling P fractions into the steady-state mass balance models of P retention in lakes. We use a large database of lakes to calibrate the model and evaluate the hypothesis. The results of this work can be used for the improvement of the prediction power of P retention models in lakes and help to better understand the processes of P cycling in lakes.</p>

Impact of the choice of surface mass balance models and their calibration on large-scale glacier change projections

2021 ◽  
Author(s):  
Lilian Schuster ◽  
David Rounce ◽  
Fabien Maussion
Keyword(s):  
Mass Balance ◽  
Large Scale ◽  
Model Complexity ◽  
Model Parameters ◽  
Glacier Change ◽  
Surface Mass Balance ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Mass Balance Models ◽  
Intercomparison Study

<p>A recent large model intercomparison study (GlacierMIP) showed that differences between the glacier models is a dominant source of uncertainty for future glacier change projections, in particular in the first half of the century.  Each glacier model has their own unique set of process representations and climate forcing methodology, which makes it impossible to determine the model components that contribute most to the projection uncertainty. This study aims to improve our understanding of the sources of large scale glacier model uncertainty using the Open Global Glacier Model (OGGM), focussing on the surface mass balance (SMB) in a first step. We calibrate and run a set of interchangeable SMB model parameterizations (e.g. monthly vs. daily, constant vs. variable lapse rates, albedo, snowpack evolution and refreezing) under controlled boundary conditions. Based on ensemble approaches, we explore the influence of (i) the parameter calibration strategy and (ii) SMB model complexity on regional to global glacier change. These uncertainties are then put in relation to a qualitative selection of other model design choices, such as the forcing climate dataset and ice dynamics model parameters. </p>

Understanding monsoon controls on the energy- and mass-balance of glaciers in High Mountain Asia

2020 ◽  
Author(s):  
Stefan Fugger ◽  
Evan Miles ◽  
Michael McCarthy ◽  
Catriona Fyffe ◽  
Marin Kneib ◽  
...  
Keyword(s):  
Mass Balance ◽  
Large Scale ◽  
Balance Model ◽  
Large Temperature ◽  
High Mountain ◽  
Glacier Surface ◽  
Weather Patterns ◽  
Mass Balance Models ◽  
High Precipitation ◽  
Study Sites

<p>The Indian Summer Monsoon (ISM) shapes the melt and accumulation patterns of glaciers in large parts of High Mountain Asia (HMA) in complex ways due to the interaction of persistent cloud-cover, large temperature amplitudes, high atmospheric water content and high precipitation rates. While the ISM dominates in the southern and eastern regions, it progressively loses influence westward towards the Karakoram, where the influence of westerlies is predominant. Previous applications of energy- and mass-balance models for glaciers in HMA have been limited to single study sites (in Khumbu, Langtang and Parlung) and a few attempted to link model results to large-scale weather patterns. While these studies have helped to understand the energy- and mass-balance of glaciers in HMA under specific local climates, a regional perspective is still missing. In this study, we use a full energy- and mass-balance model together  with eight on-glacier AWS datasets around HMA to investigate how ISM conditions influence glacier-surface energy and mass balance. In particular, we look at how debris-covered and debris-free glaciers respond differently to the ISM, validating our results against independent in-situ measurements. This work is fundamental to the development of parameterizations of glacier melt for long-term hydrological studies and to the understanding of the present and future HMA cryosphere and water budget evolution.</p>

scholarly journals Unraveling the hydrological budget of isolated and seasonally contrasted subtropical lakes

2019 ◽  
Vol 23 (3) ◽  
pp. 1705-1724 ◽  
Author(s):  
Chloé Poulin ◽  
Bruno Hamelin ◽  
Christine Vallet-Coulomb ◽  
Guinbe Amngar ◽  
Bichara Loukman ◽  
...  
Keyword(s):  
Surface Water ◽  
Isotopic Composition ◽  
Mass Balance ◽  
Water Budget ◽  
Large Scale ◽  
Satellite Mission ◽  
Simple Method ◽  
Lake Chad ◽  
Aquifer Systems ◽  
The Impact

Abstract. Complete understanding of the hydrological functioning of large-scale intertropical watersheds such as the Lake Chad basin is becoming a high priority in the context of climate change in the near future and increasing demographic pressure. This requires integrated studies of all surface water and groundwater bodies and of their quite-complex interconnections. We present here a simple method for estimating the annual mean water balance of sub-Sahelian lakes subject to high seasonal contrast and located in isolated regions with no road access during the rainy season, a situation which precludes continuous monitoring of in situ hydrological data. Our study focuses for the first time on two lakes, Iro and Fitri, located in the eastern basin of Lake Chad. We also test the approach on Lake Ihotry in Madagascar, used as a benchmark site that has previously been extensively studied by our group. We combine the δ18O and δ2H data that we measured during the dry season with altimetry data from the SARAL satellite mission in order to model the seasonal variation of lake volume and isotopic composition. The annual water budget is then estimated from mass balance equations using the Craig–Gordon model for evaporation. We first show that the closed-system behavior of Lake Ihotry (i.e., precipitation equal to evaporation) is well simulated by the model. For lakes Iro and Fitri, we calculate evaporation to influx ratios (E∕I) of 0.6±0.3 and 0.4±0.2, respectively. In the case of the endorheic Lake Fitri, the estimated output flux corresponds to the infiltration of surface water toward the surface aquifer that regulates the chemistry of the lake. These results constitute a first-order assessment of the water budget of these lakes, in regions where direct hydrological and meteorological observations are very scarce or altogether lacking. Finally, we discuss the implications of our data on the hydro-climatic budget at the scale of the catchment basins. We observe that the local evaporation lines (LELs) obtained on both lake and aquifer systems are slightly offset from the average rainfall isotopic composition monitored by IAEA at N'Djamena (Chad), and we show that this difference may reflect the impact of vegetation transpiration on the basin water budget. Based on the discussion of the mass balance budget we conclude that, while being broadly consistent with the idea that transpiration is on the same order of magnitude as evaporation in those basins, we cannot derive a more precise estimate of the partition between these two fluxes, owing to the large uncertainties of the different end-members in the budget equations.

PROTOTIPE APLIKASI PENYIRAMAN TANAMAN MENGGUNAKAN SENSOR KELEMBABAN TANAH BERBASIS MICRO CONTOLLER ATMEGA 328

2019 ◽  
Vol 5 (1) ◽  
pp. 97-106
Author(s):  
Rudi Budi Agung ◽  
Muhammad Nur ◽  
Didi Sukayadi
Keyword(s):  
Soil Moisture ◽  
Growth And Development ◽  
Large Scale ◽  
Simple Method ◽  
Moisture Sensor ◽  
Sensor Development ◽  
Soil Moisture Sensor ◽  
Application Systems ◽  
Harvesting Systems ◽  
Working Principle

The Indonesian country which is famous for its tropical climate has now experienced a shift in two seasons (dry season and rainy season). This has an impact on cropping and harvesting systems among farmers. In large scale this is very influential considering that farmers in Indonesia are stilldependent on rainfall which results in soil moisture. Some types of plants that are very dependent on soil moisture will greatly require rainfall or water for growth and development. Through this research, researchers tried to make a prototype application for watering plants using ATMEGA328 microcontroller based soil moisture sensor. Development of application systems using the prototype method as a simple method which is the first step and can be developed again for large scale. The working principle of this prototype is simply that when soil moisture reaches a certainthreshold (above 56%) then the system will work by activating the watering system, if it is below 56% the system does not work or in other words soil moisture is considered sufficient for certain plant needs.

Combining SAR interferometry and the equation of continuity to estimate the three-dimensional glacier surface-velocity vector

1999 ◽  
Vol 45 (151) ◽  
pp. 533-538 ◽  
Author(s):  
Niels Reeh ◽  
Søren Nørvang Madsen ◽  
Johan Jakob Mohr
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
Vertical Velocity ◽  
Velocity Vector ◽  
Thickness Distribution ◽  
Vertical Surface ◽  
Horizontal Velocity ◽  
Sar Interferometry ◽  
Surface Velocity ◽  
Ice Thickness

AbstractUntil now, an assumption of surface-parallel glacier flow has been used to express the vertical velocity component in terms of the horizontal velocity vector, permitting all three velocity components to be determined from synthetic aperture radar interferometry. We discuss this assumption, which neglects the influence of the local mass balance and a possible contribution to the vertical velocity arising if the glacier is not in steady state. We find that the mass-balance contribution to the vertical surface velocity is not always negligible as compared to the surface-slope contribution. Moreover, the vertical velocity contribution arising if the ice sheet is not in steady state can be significant. We apply the principle of mass conservation to derive an equation relating the vertical surface velocity to the horizontal velocity vector. This equation, valid for both steady-state and non-steady-state conditions, depends on the ice-thickness distribution. Replacing the surface-parallel-flow assumption with a correct relationship between the surface velocity components requires knowledge of additional quantities such as surface mass balance or ice thickness.

Cyclic Breathing Simulations in Large Scale Models of the Lung Airway From the Oronasal Opening to the Terminal Bronchioles

2012 ◽  
Author(s):  
D. Keith Walters ◽  
Greg W. Burgreen ◽  
Robert L. Hester ◽  
David S. Thompson ◽  
David M. Lavallee ◽  
...  
Keyword(s):  
Steady State ◽  
Boundary Conditions ◽  
Large Scale ◽  
Whole Body ◽  
Patient Specific ◽  
Cfd Simulations ◽  
Reduced Order ◽  
Scale Models ◽  
Steady State Simulation ◽  
Conducting Zone

Computational fluid dynamics (CFD) simulations were performed for unsteady periodic breathing conditions, using large-scale models of the human lung airway. The computational domain included fully coupled representations of the orotracheal region and large conducting zone up to generation four (G4) obtained from patient-specific CT data, and the small conducting zone (to G16) obtained from a stochastically generated airway tree with statistically realistic geometrical characteristics. A reduced-order geometry was used, in which several airway branches in each generation were truncated, and only select flow paths were retained to G16. The inlet and outlet flow boundaries corresponded to the oronasal opening (superior), the inlet/outlet planes in terminal bronchioles (distal), and the unresolved airway boundaries arising from the truncation procedure (intermediate). The cyclic flow was specified according to the predicted ventilation patterns for a healthy adult male at three different activity levels, supplied by the whole-body modeling software HumMod. The CFD simulations were performed using Ansys FLUENT. The mass flow distribution at the distal boundaries was prescribed using a previously documented methodology, in which the percentage of the total flow for each boundary was first determined from a steady-state simulation with an applied flow rate equal to the average during the inhalation phase of the breathing cycle. The distal pressure boundary conditions for the steady-state simulation were set using a stochastic coupling procedure to ensure physiologically realistic flow conditions. The results show that: 1) physiologically realistic flow is obtained in the model, in terms of cyclic mass conservation and approximately uniform pressure distribution in the distal airways; 2) the predicted alveolar pressure is in good agreement with previously documented values; and 3) the use of reduced-order geometry modeling allows accurate and efficient simulation of large-scale breathing lung flow, provided care is taken to use a physiologically realistic geometry and to properly address the unsteady boundary conditions.

The Research of Production Process Statistical Steady-State Based on the Hypothesis Test

2011 ◽  
Vol 314-316 ◽  
pp. 2433-2438
Author(s):  
Wei Zhi Wang
Keyword(s):  
Quality Control ◽  
Steady State ◽  
Production Process ◽  
Quantitative Method ◽  
Large Scale ◽  
Hypothesis Test ◽  
Influence Factors ◽  
Normal Operation ◽  
Scale Production ◽  
Large Scale Production

By only applying a after the event exam in the quality control of the batch production is not enough to meet the needs of modern large-scale production. To a certain extent, modern quality control is a dynamic process of the steady-state judge and adjustment. A simple and reliable steady-state judge rule and method is the premise to guarantee the normal operation. This paper provides a quantitative method to evaluate production process steady-state by analyzing influence factors based on mathematical statistics. The method is both suitable for simple production process and complex production process with sub-processes.

Comparison between energy balance and mass balance models for actual evapotranspiration assessment

2009 ◽  
Author(s):  
A. Gentile ◽  
L. Pierce ◽  
G. Ciraolo ◽  
G. Zhang ◽  
G. La Loggia ◽  
...  
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Actual Evapotranspiration ◽  
Mass Balance Models
Sign in / Sign up

Export Citation Format

Share Document