scholarly journals MODELING AND SIMULATION OF RELIEF INFLUENCE ON EUCALYPTUS FORESTS: INTERACTION BETWEEN SOLAR IRRADIANCE AND PRODUCTIVITY

2016 ◽  
Vol 40 (2) ◽  
pp. 319-327
Author(s):  
Yhasmin Paiva Rody ◽  
Aristides Ribeiro ◽  
Aline Santana de Oliveira ◽  
Fernando Palha Leite

ABSTRACT This study aimed to verify the differences in radiation intensity as a function of distinct relief exposure surfaces and to quantify these effects on the leaf area index (LAI) and other variables expressing eucalyptus forest productivity for simulations in a process-based growth model. The study was carried out at two contrasting edaphoclimatic locations in the Rio Doce basin in Minas Gerais, Brazil. Two stands with 32-year-old plantations were used, allocating fixed plots in locations with northern and southern exposure surfaces. The meteorological data were obtained from two automated weather stations located near the study sites. Solar radiation was corrected for terrain inclination and exposure surfaces, as it is measured based on the plane, perpendicularly to the vertical location. The LAI values collected in the field were used. For the comparative simulations in productivity variation, the mechanistic 3PG model was used, considering the relief exposure surfaces. It was verified that during most of the year, the southern surfaces showed lower availability of incident solar radiation, resulting in up to 66% losses, compared to the same surface considered plane, probably related to its geographical location and higher declivity. Higher values were obtained for the plantings located on the northern surface for the variables LAI, volume and mean annual wood increase, with this tendency being repeated in the 3PG model simulations.

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 802
Author(s):  
Kristian Skeie ◽  
Arild Gustavsen

In building thermal energy characterisation, the relevance of proper modelling of the effects caused by solar radiation, temperature and wind is seen as a critical factor. Open geospatial datasets are growing in diversity, easing access to meteorological data and other relevant information that can be used for building energy modelling. However, the application of geospatial techniques combining multiple open datasets is not yet common in the often scripted workflows of data-driven building thermal performance characterisation. We present a method for processing time-series from climate reanalysis and satellite-derived solar irradiance services, by implementing land-use, and elevation raster maps served in an elevation profile web-service. The article describes a methodology to: (1) adapt gridded weather data to four case-building sites in Europe; (2) calculate the incident solar radiation on the building facades; (3) estimate wind and temperature-dependent infiltration using a single-zone infiltration model and (4) including separating and evaluating the sheltering effect of buildings and trees in the vicinity, based on building footprints. Calculations of solar radiation, surface wind and air infiltration potential are done using validated models published in the scientific literature. We found that using scripting tools to automate geoprocessing tasks is widespread, and implementing such techniques in conjunction with an elevation profile web service made it possible to utilise information from open geospatial data surrounding a building site effectively. We expect that the modelling approach could be further improved, including diffuse-shading methods and evaluating other wind shelter methods for urban settings.


Author(s):  
N. Abid ◽  
C. Mannaerts ◽  
Z. Bargaoui

<p><strong>Abstract.</strong> Actual Evapotranspiration (AET) is a key component of the water and energy balance and hydrological regime of catchments. A land surface energy balance system model (SEBS) was used to estimate the AET of the 160100-km² Medjerda river basin in Northern Tunisia. This model uses satellite data in combination with meteorological data. In this study, we investigated the sensitivity of the AET model output to five major input variables: the 30-minute Downward Surface Shortwave solar radiation fluxes (DSSF), and Land Surface Temperatures (LST), the roughness height for momentum transfer z<sub>0m</sub>, and the influence of the spatial resolution of satellite-based Leaf Area Index (LAI) and fraction of Vegetation Cover (FVC) estimates. The DSSF product was validated using a comparison to solar radiation estimates by the Angstrom formula based on in-situ station data. Gaps in the 15-min satellite-based land surface temperature time series were filled using a sinusoidal model on pixels containing meteorological stations. One-half to two standard deviations of the errors of the regression curves were applied to analyse the sensitivity of the SEBS output. Two methods to estimate the near surface aerodynamic parameter z<sub>0m</sub> were applied and compared. Maps of LAI and FVC derived from two sensors alternatively applied as an input to the SEBS model. A sensitivity analysis, performed in the first decade of May 2010, showed that SEBS model parameterization is quite sensitive in the forestland cover type. The difference can be up to 0.3&amp;thinsp;mm&amp;thinsp;day<sup>&amp;minus;1</sup>. For agricultural land areas, representing an important percentage of the Medjerda basin, AET estimations based on the SEBS model proved to be used to satisfy the actual evapotranspiration estimates.</p>


1991 ◽  
Vol 117 (3) ◽  
pp. 339-346 ◽  
Author(s):  
B. A. McKenzie ◽  
G. D. Hill

SUMMARYLentils were grown in 1984/85, 1985/86 and 1988/89 in Canterbury, New Zealand. Results showed that lentil canopies were capable of intercepting a maximum of 95% of incident solar radiation at a leaf area index of 7. Autumn sowings attained canopy closure, but late spring sowings did not. At the highest population density used (500 plants/m2), only 65% of incident solar radiation was intercepted by a late spring-sown crop. In all three growing seasons there was a highly significant positive relationship between cumulative absorbed radiation and dry matter (DM) production. Over all seasons, 1·6 g DM/m2 was produced per MJ of absorbed photosynthetically active radiation (PAR). The final utilization coefficient (u) was not affected by sowing date but in a late-sown, diseased crop, u was 38% less than in a disease free crop. In 1984/85, dryland crops had a utilization coefficient of 1·39 while irrigated crops had a u of 1·54. Growth efficiency of lentils was low, at 2·5%.


2007 ◽  
Vol 8 (4) ◽  
pp. 922-937 ◽  
Author(s):  
Yves Lejeune ◽  
Ludovic Bouilloud ◽  
Pierre Etchevers ◽  
Patrick Wagnon ◽  
Pierre Chevallier ◽  
...  

Abstract To determine the physical processes involved in the melting and disappearance of transient snow cover in nonglacierized tropical areas, the CROCUS snow model, interactions between Soil–Biosphere–Atmosphere (ISBA) land surface model, and coupled ISBA/CROCUS model have been applied to a full set of meteorological data recorded at 4795 m MSL on a moraine area in Bolivia (16°17′S, 68°32′W) between 14 May 2002 and 15 July 2003. The models have been adapted to tropical conditions, in particular the high level of incident solar radiation throughout the year. As long as a suitable function is included to represent the mosaic partitioning of the surface between snow cover and bare ground and local fresh snow grain type (as graupel) is adapted, the ISBA and ISBA/CROCUS models can accurately simulate snow behavior over nonglacierized natural surfaces in the Tropics. Incident solar radiation is responsible for efficient melting of the snow surface (favored by fresh snow albedo values usually not exceeding 0.8) and also for the energy stored in snow-free areas (albedo = 0.18) and transferred horizontally to adjacent snow patches. These horizontal energy transfers (by conduction within the upper soil layers and by turbulent advection) explain most of the snowmelt and prevent the snow cover from lasting more than a few days during the wet season in this high-altitude tropical environment.


2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Maitha Al-Shamisi ◽  
Ali Assi ◽  
Hassan Hejase

The geographical location (Latitude: 24 deg 28′ N and Longitude: 54 deg 22′ E) of Abu Dhabi city in the United Arab Emirates (UAE) favors the development and utilization of solar energy. This paper presents an artificial neural network (ANN) approach for the estimation of monthly mean global solar radiation (GSR) on a horizontal surface in Abu Dhabi. The ANN models are presented and implemented on a 16-yr measured meteorological data set for Abu Dhabi comprising the maximum daily temperature, mean daily wind speed, mean daily sunshine hours, and mean daily relative humidity between 1993 and 2008. The meteorological data between 1993 and 2003 are used for training the ANN and data between 2004 and 2008 are used for testing the estimated values. Multilayer perceptron (MLP) and radial basis function (RBF) are used as ANN learning algorithms. The results attest to the capability of ANN techniques and their ability to produce accurate estimation models.


2010 ◽  
Vol 44-47 ◽  
pp. 1853-1861 ◽  
Author(s):  
W.S. Ou ◽  
K.T. Huang ◽  
Chi Chang Liao

Solar radiation data is an important consideration factor in building environment planning. This study focused on the regional characteristics of global solar radiation of Taiwan. The research utilized the raw meteorological data meseaursed by the Central Weather Bureau to establish reliable solar radiation data of weather stations by means of statistic analysis. A total of weather station’s data are used where their geographical location are evenly distributed from northern to southern Taiwan. The results of this study will presented the diagrams of annual and monthly averaged solar radiation in Taiwan. Geographical distribution of inter-annual trend of global solar radiation during this period was also presented in this paper. It can be used for further study of the climate zoning comparing with other climate conditions. Furthermore, researchers of solar cell design, building energy, shading design, site planning, etc. can utilize the distribution diagram to fetch reliable solar radiation values to carry on reasonable quantitative analysis.


Water SA ◽  
2018 ◽  
Vol 44 (3 July) ◽  
Author(s):  
Onalenna Gwate ◽  
Sukhmani K Mantel ◽  
Anthony R Palmer ◽  
Lesley A Gibson ◽  
Zahn Munch

Accurately measuring evapotranspiration (ET) is important in the context of global atmospheric changes and for use with climate models. Direct ET measurement is costly to apply widely and local calibration and validation of ET models developed elsewhere improves confidence in ET derived from such models. This study sought to compare the performance of the Penman-Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) ET models, over mesic grasslands in two study sites in South Africa. The study used routine meteorological data from a scientific-grade automatic weather station (AWS) to apply the PML and PMP models. The PML model was calibrated at one site and validated in both sites. On the other hand, the PMP model does not require calibration and hence it was validated in both sites. The models were validated using ET derived from a large aperture scintillometer (LAS). The PML model performed well at both sites with root mean square error (RMSE) within 20% of the mean daily observed ET (R2 of 0.83 to 0.91). Routine meteorological data were able to reproduce fluxes calculated using micrometeorological techniques and this increased the confidence in the use of data from sparsely distributed AWSs to derive reasonable ET values. The PML model was better able to simulate observed ET compared to the PMP model, since the former models both transpiration and soil evaporation (ES), while the latter only models transpiration. Hence, the PMP model systematically underestimated ET in a context where the leaf area index (LAI) was < 2.5. Model predictions in the grasslands could be improved by incorporating the ES component in the PMP model while the PML model could be improved by careful choice of the number of days to be used in the determination of the fraction of ES.


Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 8
Author(s):  
Perdinan ◽  
Julie A. Winkler ◽  
Jeffrey A. Andresen

Daily solar radiation is a critical input for estimating plant growth and development, yet this variable is infrequently measured compared to other climate variables. This study evaluates the sensitivity of simulated maize and soybean production from the CERES-Maize and CROPGRO-Soybean modules of the Decision Support System for Agrotechnology Transfer (DSSAT) to daily solar radiation estimates obtained from traditional (stochastic, empirical, and mechanistic models) and non-traditional (satellite estimation, reanalysis datasets, and regional climate model simulations) approaches, using as an example radiation estimates for Hancock, Wisconsin, USA. When compared to observations, radiation estimates obtained from empirical and mechanistic models and a satellite-based dataset generally had smaller biases than other approaches. Daily solar radiation estimates from a reanalysis dataset and regional climate model simulations overestimate incoming daily solar radiation. When the radiation estimates were used as an input to CERES-Maize, no significant differences were found for maize yield obtained from the different radiation estimates compared to yield from observed radiation, even though differences were found in the daily values of leaf area index, crop evapotranspiration, and crop dry weight (biomass). In contrast, significant differences were found in simulated soybean yield from CROPGRO-Soybean for the majority of the radiation estimates.


2021 ◽  
pp. 1-10
Author(s):  
Min Huang ◽  
Zui Tao ◽  
Tao Lei ◽  
Fangbo Cao ◽  
Jiana Chen ◽  
...  

Summary The development of high-yielding, short-duration super-rice hybrids is important for ensuring food security in China where multiple cropping is widely practiced and large-scale farming has gradually emerged. In this study, field experiments were conducted over 3 years to identify the yield formation characteristics in the shorter-duration (∼120 days) super-rice hybrid ‘Guiliangyou 2’ (G2) by comparing it with the longer-duration (∼130 days) super-rice hybrid ‘Y-liangyou 1’ (Y1). The results showed that G2 had a shorter pre-heading growth duration and consequently a shorter total growth duration compared to Y1. Compared to Y1, G2 had lower total biomass production that resulted from lower daily solar radiation, apparent radiation use efficiency (RUE), crop growth rate (CGR), and biomass production during the pre-heading period, but the grain yield was not significantly lower than that of Y1 because it was compensated for by the higher harvest index that resulted from slower leaf senescence (i.e., slower decline in leaf area index during the post-heading period) and higher RUE, CGR, and biomass production during the post-heading period. Our findings suggest that it is feasible to reduce the dependence of yield formation on growth duration to a certain extent in rice by increasing the use efficiency of solar radiation through crop improvement and also highlight the need for a greater fundamental understanding of the physiological processes involved in the higher use efficiency of solar radiation in super-rice hybrids.


2021 ◽  
Vol 29 (Supplement_1) ◽  
pp. i40-i41
Author(s):  
A Hindi ◽  
S Willis ◽  
S Jacobs ◽  
E Schafheutle

Abstract Introduction In 2019/2020, the Pharmacy Integration Fund commissioned delivery of cross-sector pre-registration pharmacist training incorporating 3–6 month placements in general practice (GP). GP placements were managed by Health Education England (HEE) and organised as one (or more) blocks, or as spilt weeks/days across base sector (hospital/community) and GP. Trainees had a pharmacist tutor at base and in GP. Aim to evaluate the implementation of cross-sector pre-registration pharmacy placements in GP in England, and to identify barriers and enablers of a successful placement. Methods A qualitative approach was taken, with case study sites purposively sampled for maximum variation: pharmacy base (hospital/community), number of pre-registration pharmacist trainees in base doing GP placement, length of GP placement, organisation of GP placement and geographical location. With consent, trainees and tutors identified as meeting sampling criteria were emailed invitation letters and participant information sheets. Where the trainee and their tutor(s) agreed to participate, semi-structured telephone interviews were conducted January - July 2020. Questions developed from literature(1, 2) and the HEE handbook were tailored to understanding trainees’ and tutors’ views on the implementation of pre-registration pharmacist placements in GP, including benefits, unintended consequences and impacts. Thematic analysis across sites was undertaken with a focus on exploring inter and intra group themes. Results Thirty-four interviews were completed in 11 study sites (5 GP/hospital; 6 GP/community pharmacy). Trainees and tutors considered GP placements had been successful. Contributing factors were: placement planning (induction, contingency arrangements for cover should GP tutor be unavailable); tutors working together (good communication and collaboration); GP tutor support (regular contact, reflection; identifying learning needs; opportunities for learning); integration of GP placements within training year (specific learning/training activities at base during GP placement); and GP tutors having backing of their organisation to supervise effectively. A lack of these impacted negatively. Trainees completed a wide spectrum of activities and gradually moved from administrative to clinical tasks. They built up confidence to undertake patient-facing activities, with more direct supervision at the beginning moving to indirect supervision using debriefing. Thirteen weeks in GP was considered an appropriate minimum duration by all trainees and tutors; those based in community felt that 26 weeks in GP provided more opportunities for clinical and consultation skills learning. Cross-sector experience facilitated a better understanding of patient pathways and the importance of holistic patient care. All trainees considered working in GP in future but highlighted the lack of a cross-sector GP foundation programme. Base tutors felt the time commitment was comparable to single sector placements. Base and GP tutors felt that a clear set of competencies for GP placements and a broader governance framework would ensure standards and consistency. Conclusion This is the first national evaluation of cross-sector pre-registration pharmacists in general practice placements in England. Sampling as case studies enabled data triangulation and generated a multi-faceted understanding on factors impacting GP placements. A key limitation was the volunteer bias associated with recruitment. Key attributes of a successful pre-registration cross-sector training experience are highlighted and can inform policy reforms including change from pre-registration to foundation year training. References 1. Gray N. Review of Experience of Pre-registration Pharmacist Placements in the General Practice Setting – Final Report. 2019. 2. Jee SD, Schafheutle EI, Noyce PR. Is pharmacist pre-registration training equitable and robust? Higher Education, Skills and Work-Based Learning. 2019;9(3):347–58.


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