UNFILTERED TRAP-BASED PHOTOMETER CALIBRATION

LED-based light sources have replaced massively traditional sources. The metrology traceability chains realised in leading European NMIs utilise the absolutely calibrated broadband radiometers (three-element silicon trap detectors) for calibrating primary photometers. Specific spectral properties of white LED allow to apply the trap detectors directly as new primary photometers. The unfiltered technique (Dӧnsberg at al., 2014) is used and the calibration of spectral irradiance responsivity is needed. We have a long experience in detector-based spectral irradiance responsivity calibrations declared by particular CMC’s published in BIPM KCDB. The aim of this work was to revise the uncertainty budget in order to reduce the measurement uncertainties for specific application of calibration of the trap-based unfiltered primary photometers UPP. The two calibration methods were used to analyse the occasional back-reflection effect of the UPP front aperture. The measurement was performed using our reference spectral responsivity facility in spectral range 350 nm – 900 nm.

CÆLIS: software for assimilation, management and processing data of an atmospheric measurement network

Given the importance of the atmospheric aerosol, the number of instruments and measurement networks which focus on its characterization are growing. Many challenges are derived from standardization of protocols, monitoring of the instrument status to evaluate the network data quality and manipulation and distribution of large volume of data (raw and processed). CÆLIS is a software system which aims at simplifying the management of a network, providing tools by monitoring the instruments, processing the data in real time and offering the scientific community a new tool to work with the data. Since 2008 CÆLIS has been successfully applied to the photometer calibration facility managed by the University of Valladolid, Spain, in the framework of Aerosol Robotic Network (AERONET). Thanks to the use of advanced tools, this facility has been able to analyze a growing number of stations and data in real time, which greatly benefits the network management and data quality control. The present work describes the system architecture of CÆLIS and some examples of applications and data processing.

CÆLIS: Software for assimilation, management and processing data of an atmospheric measurement network

Given the importance of the atmospheric aerosol, the number of instruments and measurement networks which focus at its characterization are growing. Many challenges are derived from that: standardization of protocols, monitoring of the instrument status to evaluate the network data quality, manipulation of large volume of data and distribution of data (raw and processed). CÆLIS is a software system which aims at simplifying the management of a network monitoring the instruments, processing the data in real time and offers to the scientific community new tools to work with the data. CÆLIS has been successfully applied to the management of the photometer calibration facility managed by the University of Valladolid in the frame of AERONET. The present work describes the system architecture of CÆLIS and some examples of applications and data processing.

Auroral meridian scanning photometer calibration using Jupiter

Observations of astronomical sources provide information that can significantly enhance the utility of auroral data for scientific studies. This report presents results obtained by using Jupiter for field cross calibration of four multispectral auroral meridian scanning photometers during the 2011–2015 Northern Hemisphere winters. Seasonal average optical field-of-view and local orientation estimates are obtained with uncertainties of 0.01 and 0.1°, respectively. Estimates of absolute sensitivity are repeatable to roughly 5 % from one month to the next, while the relative response between different wavelength channels is stable to better than 1 %. Astronomical field calibrations and darkroom calibration differences are on the order of 10 %. Atmospheric variability is the primary source of uncertainty; this may be reduced with complementary data from co-located instruments.

Auroral meridian scanning photometer calibration using Jupiter

Observations of astronomical sources provides information that can significantly enhance the utility of auroral data for scientific studies. Jupiter is used for field cross-calibration of 4 multi-spectral auroral meridian scanning photometers during 2011–15 northern hemisphere winters. Seasonal average optical field-of-view and local orientation estimates are obtained with uncertainties of 0.01° and 0.1° respectively. Estimates of absolute photometric sensitivity are repeatable to roughly 5 % from one month to the next, while the relative response between different wavelength channels is stable to better than 1 %. Astronomical field calibrations and darkroom calibration differences are on the order of 10 %. Atmospheric variability is the primary source of uncertainty; this may be reduced with data from co-located instruments such as all-sky imagers.