Solar position algorithm for solar radiation applications

Reda, Ibrahim; Andreas, Afshin

doi:10.1016/j.solener.2003.12.003

Cited by 845 publications

(501 citation statements)

References 2 publications

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“…introduced by Reda and Andreas (2004). The sea ice coverage and thickness were estimated from four upward looking sonars (ULS), which were placed at about 100-150 m depth below the sea surface at the top of the oceanographic moorings.…”

Section: Other Environmental Parametersmentioning

confidence: 99%

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Cisewski

Strass

2016

Progress in Oceanography

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The success of any efforts to determine the effects of climate change on marine ecosystems depends on understanding in the first instance the natural variations, which contemporarily occur on the interannual and shorter time scales. Here we present results on the environmental controls of zooplankton distribution patterns and behaviour in the eastern Weddell Sea, Southern Ocean. Zooplankton abundance and vertical migration are derived from the mean volume backscattering strength (MVBS) and the vertical velocity measured by moored acoustic Doppler current profilers (ADCPs), which were deployed simultaneously at 64°S, 66.5°S and 69°S along the Greenwich Meridian from February, 2005, until March, 2008 While these time series span a period of full three years they resolve hourly changes.A highly persistent behavioural pattern found at all three mooring locations is the synchronous diel vertical migration (DVM) of two distinct groups of zooplankton that migrate between a deep residence depth during daytime and a shallow depth during nighttime. The DVM was closely coupled to the astronomical daylight cycles. However, while the DVM was symmetric around local noon, the annual modulation of the DVM was clearly asymmetric around winter solstice or summer solstice, respectively, at all three mooring sites. DVM at our observation sites persisted throughout winter, even at the highest latitude exposed to the polar night. Since the magnitude as well as the relative rate of change of illumination is minimal at this time, we propose that the ultimate causes of DVM separated from the light-mediated proximal cue that coordinates it. In all three years, a marked change in the migration behaviour occurred in late spring (late October/early November), when DVM ceased. The complete suspension of DVM after early November is possibly caused by the combination of two factors: (1) increased availability of food in the surface mixed layer provided by the phytoplankton spring bloom, and (2) vanishing diurnal enhancement of the threat from visually oriented predators when the illumination is quasi-continuous during the polar and subpolar summer. 3Zooplankton abundance in the water column, estimated as the mean MVBS in the depth range 50 -300 m, was highest end of summer and lowest mid to end winter on the average annual cycle. However, zooplankton abundance varied several-fold between years and between locations. Based on satellite and in situ data of chlorophyll and sea ice as well as on hydrographic measurements, the interannual and spatial variations of zooplankton mean abundance can be explained by differences in the magnitude of the phytoplankton spring bloom, which develops during the seasonal sea ice retreat. Whereas the vernal ice melt appears necessary to stimulate the blooming of phytoplankton, it is not the determinator of the blooms magnitude, its areal extent and duration. A possible explanation for the limitation of the phytoplankton bloom in some years is top-down control. We hypothesize that the phytoplankton spring ...

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Section: Other Environmental Parametersmentioning

confidence: 99%

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Cisewski

Strass

2016

Progress in Oceanography

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“…Using different astronomical algorithms 33– 35 it estimates approximate Gregorian Day Number, Decimal Day, Decimal Day of the Year, Fractional Year, Equation of the Time, Declination, Solar Time Offset, Solar Time Solar Zenith Angle, Solar Hour Angle, Solar Azimuth Angle and Solar noon. For any registered ant and its visits to the feeder, it will automatically extract the information about latitude and longitude from the associated experiment.…”

Section: Methodsmentioning

confidence: 99%

Ant-App-DB: a smart solution for monitoring arthropods activities, experimental data management and solar calculations without GPS in behavioral field studies

et al. 2015

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Field studies on arthropod ecology and behaviour require simple and robust monitoring tools, preferably with direct access to an integrated database. We have developed and here present a database tool allowing smart-phone based monitoring of arthropods. This smart phone application provides an easy solution to collect, manage and process the data in the field which has been a very difficult task for field biologists using traditional methods. To monitor our example species, the desert ant Cataglyphis fortis, we considered behavior, nest search runs, feeding habits and path segmentations including detailed information on solar position and Azimuth calculation, ant orientation and time of day. For this we established a user friendly database system integrating the Ant-App-DB with a smart phone and tablet application, combining experimental data manipulation with data management and providing solar position and timing estimations without any GPS or GIS system. Moreover, the new desktop application Dataplus allows efficient data extraction and conversion from smart phone application to personal computers, for further ecological data analysis and sharing. All features, software code and database as well as Dataplus application are made available completely free of charge and sufficiently generic to be easily adapted to other field monitoring studies on arthropods or other migratory organisms. The software applications Ant-App-DB and Dataplus described here are developed using the Android SDK, Java, XML, C# and SQLite Database.

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“…However, the sun is not just any directional light source. Its daily trajectory over the sky has been very well studied, and its position in the sky dome can be computed from the time of the day and the geolocation (latitude and longitude) of the scene (Reda and Andreas 2003). Since these two pieces of information are easily available, the time being provided by the camera and the geolocation by a GPS unit or any of today's webbased mapping engines, we can assume the position of the sun to be known.…”

Section: The Point Light Plus Ambient Illumination Algorithmmentioning

confidence: 99%

Building Illumination Coherent 3D Models of Large-Scale Outdoor Scenes

Troccoli¹,

Allen

2007

Int J Comput Vis

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Systems for the creation of photorealistic models using range scans and digital photographs are becoming increasingly popular in a wide range of fields, from reverse engineering to cultural heritage preservation. These systems employ a range finder to acquire the geometry information and a digital camera to measure color detail. But bringing together a set of range scans and color images to produce an accurate and usable model is still an area of research with many unsolved problems. In this paper we address the problem of how to build illumination coherent integrated texture maps from images that were taken under different illumination conditions. To achieve this we present two different solutions. The first one is to align all the images to the same illumination, for which we have developed a technique that computes a relighting operator over the area of overlap of a pair of images that we then use to relight the entire image. Our proposed method can handle images with shadows and can effectively remove the shadows from the image, if required. The second technique uses the ratio of two images to factor out the diffuse reflectance of an image from its illumination. We do this without any light measuring device. By computing the actual reflectance we remove from the images any effects of the illumination, allowing us to create new renderings under novel illumination conditions.

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Solar position algorithm for solar radiation applications

Cited by 845 publications

References 2 publications

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Ant-App-DB: a smart solution for monitoring arthropods activities, experimental data management and solar calculations without GPS in behavioral field studies

Building Illumination Coherent 3D Models of Large-Scale Outdoor Scenes

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