Modelling topographic variation in solar radiation in a GIS environment

Kumar, Lalit; Skidmore, Andrew K.; Knowles, E.

doi:10.1080/136588197242266

Cited by 475 publications

(329 citation statements)

References 17 publications

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“…This has already been done in previously developed theory (e.g. Kumar et al [23], Gates [24] or Liu and Jordan [11]). Later, in the methods section, new equations for modifying the clear sky irradiances due to the effects of cloud are developed.…”

Section: Irradiance In Clear Sky Conditionsmentioning

confidence: 89%

A method for generating synthetic hourly solar radiation data for any location in the south west of Western Australia, in a world wide web page

2014

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An algorithm was developed to generate synthetic hourly cloudiness data for any time of the year at any location in the south west region of Western Australia (WA). To enable the algorithm to be used for simulation of the power output of both tilted photovoltaic and concentrating solar power systems, a metric of cloudiness was defined which modifies the clear sky beam, diffuse and reflected solar transmittance. Seasonally and positionally adjusted values of daily cloudiness were generated by roughly mimicking the geographic pattern of annual rainfall in WA. Rather than longitude and latitude, distance along the coastline and distance inland from the coast were used as the positional coordinates. Hourly cloudiness data was generated from the daily values using a first order autoregression algorithm with time varying mean and standard deviation. Two years of measured hourly horizontal solar irradiance data from a network of 31 weather stations was used to calibrate the algorithm. The algorithm was simple enough to run inside a world wide web page and has the potential to be adapted to other regions with a similar pattern of declining inland rainfall.

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Section: Irradiance In Clear Sky Conditionsmentioning

confidence: 89%

A method for generating synthetic hourly solar radiation data for any location in the south west of Western Australia, in a world wide web page

2014

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“…Dubayah and Rich, 1995;Kumar et al, 1997;McKenney et al, 1999). Such calculations would provide more realistic values to use in ET o calculations.…”

Section: Calculation Of Reference Evapotranspirationmentioning

confidence: 99%

Comparison of different procedures to map reference evapotranspiration using geographical information systems and regression‐based techniques

Vicente‐Serrano

Lanjeri

López‐Moreno

2007

Intl Journal of Climatology

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Abstract:This paper compares different procedures for mapping reference evapotranspiration (ET o ) by means of regression-based techniques and geographical information systems (GIS). ET o is calculated following the method of Hargreaves (HG) from a dense database of meteorological stations in the northernmost semi-arid region of Europe, the Ebro valley. The HG method requires the calculation of estimates of extraterrestrial radiation (R a ). We calculated this parameter using two approaches: (1) the common approach that assumes a planar surface and determines the parameter as a function of latitude and (2) using a digital terrain model (DTM) and GIS modelling. The maps were made on a monthly basis using both approaches. We also compared possible propagations of errors in the map calculations for maps derived from modelled layers of maximum and minimum temperatures with those modelled using previously determined local ET o calculations. We demonstrate that calculations of R a from a DTM and GIS modelling provide a more realistic spatial distribution of ET o than those derived by only considering latitude. It is also preferable to model in advance the variables involved in the calculation of ET o (temperature and R a ) and to subsequently calculate ET o by means of layer algebra in the GIS rather than directly model the local ET o calculations. The obtained maps are useful for the purposes of agriculture and ecological and water resources management in the study area.

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“…Note that the temperature factor (F t ) used in this equation is smaller than the commonly used DDFs (Pellicciotti et al, 2005). In our experiments, the potential clear-sky direct solar radiation at the surface corrected for the incidence angle I s in W m −2 is calculated following Kumar et al (1997):…”

Section: Enhanced Temperature Index Model -Etimmentioning

confidence: 99%

“…I r is the radiation reflected from surrounding locations transmitted to the surface, calculated using a constant mean ground reflectance coefficient of 0.2, following Kumar et al (1997).…”

Section: Enhanced Temperature Index Model -Etimmentioning

confidence: 99%

The influence of resolution and topographic uncertainty on melt modelling using hypsometric sub‐grid parameterization

Hebeler

Purves

2008

Hydrological Processes

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Modelling of physical processes such as ablation or runoff at continental or global scales provides a key challenge: a high degree of abstraction is required in order to minimize computational demands, while spatial and temporal variability of key processes, often at the sub‐scale level, need to be adequately captured and reproduced within a lower resolution model. For some approaches, such as temperature index models, downscaling to lower resolutions is straightforward. However a key issue when using these downscaled models is to assess the impact of scaling on model behaviour and results, including the associated uncertainties. We assess the impact of scaling on both a simple and an enhanced temperature index melt model from 100 m to 1, 5 and 10 km resolutions. Different sub‐grid parameterization approaches are applied to both models across all resolutions and tested for their suitability against high‐resolution reference data, with the aim of developing a robust, scalable and computationally undemanding parameterization. Results show patterns of over‐ and underestimation of potential melt rates for both models, with clear dependencies on scale, terrain roughness and variations of temperature thresholds, among other quantities. The sub‐grid parameterizations tested in this article are found to effectively compensate these effects at little additional computational cost. Copyright © 2008 John Wiley & Sons, Ltd.

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Modelling topographic variation in solar radiation in a GIS environment

Cited by 475 publications

References 17 publications

A method for generating synthetic hourly solar radiation data for any location in the south west of Western Australia, in a world wide web page

A method for generating synthetic hourly solar radiation data for any location in the south west of Western Australia, in a world wide web page

Comparison of different procedures to map reference evapotranspiration using geographical information systems and regression‐based techniques

The influence of resolution and topographic uncertainty on melt modelling using hypsometric sub‐grid parameterization

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