A Two-Axis Tracking System with Datalogger

Seefeldner, M.; Oppenrieder, A.; Rabus, D.; Reuder, Joachim; Schreier, M. M.; Hoeppe, Peter; Koepke, Peter

doi:10.1175/1520-0426(2004)021<0975:attswd>2.0.co;2

Cited by 9 publications

(12 citation statements)

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“…Detailed information on the mechanical construction of the AS-CARATIS system is published in Seefeldner et al (2004). The orientable radiometer is programmed to scan 27 positions-12 positions with vertical orientation and 30 steps of azimuth angle, 12 positions with an inclination of 45 also with 30 azimuth steps, one position facing the zenith, one position facing the nadir and one position facing the sun.…”

Section: Methodsmentioning

confidence: 99%

Visualization of UV exposure of the human body based on data from a scanning UV-measuring system

Hoeppe¹,

Oppenrieder

Erianto

et al. 2004

Int J Biometeorol

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In general, measurements of UV radition are related to horizontal surfaces, as in the case of the internationally standardized and applied UV index, for example. In order to obtain more relevant information on UV exposure of humans the new measuring system ASCARATIS (Angle SCAnning RAdiometer for determination of erythemally weighted irradiance on TIlted Surfaces) was developed and built. Three systems of ASCARATIS have been in operation at different locations in Bavaria for 3 years, providing erythemally weighted UV irradiation data for 27 differently inclined surfaces every 2 min. On the basis of these data virtual three-dimensional models of the human body surface consisting of about 20,000 triangles could be created and each of these triangles coloured according to its UV irradiation. This allowed the UV exposure of the human body to be visualized for any kind of body posture and spatial orientation on the basis of real measuring data. The results of the UV measurements on inclined surfaces have shown that measuring UV radiation on horizontal surfaces, as done routinely worldwide, often underestimates the UV exposure of the human skin. Especially at times of the day or year with low solar elevations the UV exposure of parts of the human skin can be many times higher than that of the horizontal surface. Examples of three-dimensional modelling of the human UV irradiation are shown for different times of the day and year, altitudes above sea level, body postures and genders. In these examples the UV "hotspots" can be detected and, among other things, used to inform and educate the public about UV radiation.

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Section: Methodsmentioning

confidence: 99%

Visualization of UV exposure of the human body based on data from a scanning UV-measuring system

Hoeppe¹,

Oppenrieder

Erianto

et al. 2004

Int J Biometeorol

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“…The AOD data presented in this work were obtained with the Sun‐Sky Automatic RAdiometer (SSARA, Wagner et al, 2003). It is mounted on a two‐axis tracking system, which allows an accurate and fast pointing of the sensor head (Seefeldner et al, 2004). Both systems were developed by the Meteorological Institute of the University of Munich.…”

Section: Site Of Measurements and Instrumentationmentioning

confidence: 99%

Spectral aerosol optical depth characterization of desert dust during SAMUM 2006

Toledano¹,

Wiegner²,

Garhammer³

et al. 2009

Tellus B: Chemical and Physical Meteorology

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The aerosol optical depth (AOD) in the range 340–1550 nm was monitored at Ouarzazate (Morocco) during the Saharan Mineral Dust Experiment (SAMUM) experiment in May–June 2006. Two different sun photometers were used for this purpose. The mean AOD at 500 nm was 0.28, with a maximum of 0.83, and the mean Ångström exponent (AE) was 0.35. The aerosol content over the site changed alternatively from very low turbidity, associated to Atlantic air masses, to moderate dust load, associated to air masses arriving in the site from Algeria, Tunisia and Libya. The dusty conditions were predominant in the measurement period (78% of data), with AOD (500 nm) above 0.15 and AE below 0.4. The spectral features of the AOD under dusty conditions are discussed. Air mass back trajectory analysis is carried out to investigate the origin and height patterns of the dust loaded air masses. The advection of dust occurred mainly at atmospheric heights below 3000 m, where east flow is the predominant. At the 5000 m level, the air masses originate mainly over the Atlantic Ocean. Finally the Optical Properties of Aerosols and Clouds (OPAC) model is used to perform a set of simulations with different aerosol mixtures to illustrate the measured AOD and AE values under varying dust concentrations, and a brief comparison with other measurement sites is presented.

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“…The sensor has to pick up on brightness-differences over the sun. Also, high aerosol loads, cirrus, or thin 30 water clouds blur out the sun disc, resulting in an equally lit quadrant-sensor further away from the sun's center. If the clouds are "streaky", this effect can occur in a certain direction.…”

Section: Mount Calibrationmentioning

confidence: 99%

“…For scans, we therefore wait 6 s to allow for the detector signal to settle, preventing 20 the measurements at different scanning angles from "blurring" into one another. The sensorhead is mounted on a two-axis alt-azimuthal mount (Seefeldner et al, 2004). Its stepper motors have a resolution of 0.009 • (32.4 arcsec).…”

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confidence: 99%

The polarized sun and sky radiometer SSARA: design, calibration, and application for ground based aerosol remote sensing

Grob¹,

Emde²,

Wiegner³

et al. 2019

Preprint

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Recently, polarimetry has been used to enhance classical photometry to infer aerosol optical properties, as polarized radiation contains additional information about the particles. Therefore, we have equipped the SSARA sun and sky photometer with polarizer filters to measure linearly polarized light at 501.5 nm.We have developed a novel radiometric and polarimetric calibration method, which allows us to simultaneously determine the linear polarizers' diattenuation and relative orientation with high accuracy (0.002 and 0.1 • , respectively). Furthermore, 5 we employed a new calibration method for the azimuthal mount capable of correcting the instrument's pointing to within 32 arcmin. So far, this is limited by the accuracy of the sun-tracker. Both these methods are applicable to other sun and sky radiometers, such as Cimel CE318-DP instruments used in AERONET.During the A-LIFE field campaign in April 2017, SSARA collected 22 days of data. Here, we present two case studies: The first demonstrates the performance of an aerosol retrieval from SSARA observations under partially cloudy conditions. In the 10 other case, a high aerosol load due to a Saharan dust layer was present during otherwise perfect clear sky conditions. Copyright statement. CC BY 4.0 IntroductionAccording to the IPCC aerosols have a significant and not entirely understood impact on the earth's climate (IPCC, 2013). In first order, it induces a direct radiative forcing effect. Additionally, it has been established that aerosols have an influence on the 15 development and lifetime of clouds (Albrecht, 1989), which is known as the secondary aerosol effect. In order to study these effects, aerosols have to be retrieved in the vicinity of clouds. To gain insight into processes occuring in or close to the edge of clouds, microphysical properties of the aerosol are required in addition to the total aerosol load, quantified by the aerosol optical depth (AOD). These are, for instance, information about the size distribution of the particles, their index of refraction, and single scattering albedo (related to the absorptance). The combination of these parameters can be used to indentify the 20 chemical composition, and, eventually, source region of the aerosol. This has in turn impact on the aerosol's hygroscopicity, and therefore the microphysical properties of the cloud droplets that might develop from it.Aerosols can be measured from satellites, and from the ground. While the former has the advantage of global coverage, its spatial resolution is still not good enough to properly resolve smaller clouds and the aerosol in between them. Ground based systems are better suited for these studies, e.g. the AErosol RObotic NETwork (AERONET) that has been established as a large network of ground based sun photometers (Holben et al., 1998;Giles et al., 2019).Classically, this information is retrieved from multispectral measurements. Recently, polarimetric measurements started to 5 be included as well. Several studies suggest that including polarimetric information ...

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A Two-Axis Tracking System with Datalogger

Cited by 9 publications

References 1 publication

Visualization of UV exposure of the human body based on data from a scanning UV-measuring system

Visualization of UV exposure of the human body based on data from a scanning UV-measuring system

Spectral aerosol optical depth characterization of desert dust during SAMUM 2006

The polarized sun and sky radiometer SSARA: design, calibration, and application for ground based aerosol remote sensing

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