Department of Information and Communications Engineering

MAPP (2020-2023)

Metrology Research Institute was involved in project MAPP - "Metrology for aerosol optical properties" financed by the European Metrology Programme for Innovation and Research (EMPIR).

Advancing Aerosol Optical Properties: EMPIR Project MAPP

In the realm of precision metrology, the Metrology Research Institute is a guiding light, leading groundbreaking initiatives like the European Metrology Programme for Innovation and Research (EMPIR) Project MAPP—a monumental endeavor that has transformed our understanding of aerosol optical properties.

Unveiling the Vision

Under the aegis of PMOD (Physikalisch-Meteorologische Observatorium Davos, Switzerland), this transformative project aimed to catalyze SI-traceable measurements of column-integrated aerosol optical properties—a paramount achievement in the realm of passive remote sensing of the atmosphere through solar and lunar radiation measurements. Radiometers from three prominent aerosol monitoring networks were calibrated at NMI laboratories, with innovative portable devices developed for in-field calibration—a feat that invigorated current aerosol optical property retrievals through cutting-edge inversion models. The overarching goal? Standardize aerosol optical properties retrieval, streamlining the calibration chain, reducing network radiometer downtime, and fostering consistent dissemination along with their associated uncertainties.

Optical radiometers monitoring environmental parameters including aerosols in an intercomapison campaign in Teneriffe 2016. (Figure by Tomi Pulli).
Figure 1. Optical radiometers monitoring environmental parameters including aerosols in an intercomapison campaign in Teneriffe 2016. (Figure by Tomi Pulli).

Radiometers at the Forefront

Within the heart of this groundbreaking project, the Metrology Research Institute played an instrumental role in developing and deploying measurement setups, poised to unlock critical insights into radiometer linearity and angular properties—parameters integral to the precision of aerosol measurements. Our contribution laid the foundation for accurate and reliable aerosol data, fundamentally transforming our comprehension of atmospheric constituents.

Pioneering Novel Techniques

Amid prior collaborative projects, the Institute pioneered novel simulation techniques that embraced the complexity of uncertainty estimations, unraveling the intricate web of correlations. Building upon this rich history, we brought our expertise to the project, facilitating nuanced uncertainty evaluations alongside our partners.

Figure 2. Optical setup for measuring the spatial nonuniformity of an integrating sphere mounted on the XY translation stage at 325 nm (HeCd laser) and 543.5 nm (HeNe laser) wavelengths.
Figure 2. Optical setup for measuring the spatial nonuniformity of an integrating sphere mounted on the XY translation stage at 325 nm (HeCd laser) and 543.5 nm (HeNe laser) wavelengths.

Embarking on a Journey of Discovery

Between 2020 and 2021, our tireless efforts gave birth to setups engineered to measure the spatial uniformities of integrating spheres, enhancing the fidelity of aerosol measurements. The ingenious setup harnessed lasers to create an innovative methodology, comparing favorably against traditional direct measurements. This innovation, showcased by our own integrating sphere, resonated with our commitment to progress.

Angular Insights Unveiled

In a pivotal stride towards precision, our angular responsivity measurement setup revealed the intricate angular properties of radiometers. This advancement was put into practice as we meticulously measured the angular responsivities of PMOD's radiometers, orchestrating a symphony of data that harmonized with existing measurements. This pursuit of accuracy was further constrained by the resolution of our gimbal system, imparting a resolution of 9 arcseconds—a testament to our commitment to precision.

Guiding Light for Progress

As the journey unfolded, the Metrology Research Institute stood unwavering, forging paths towards a future illuminated by unprecedented insights into aerosol optical properties. Our legacy stands as a testament to the tireless pursuit of precision, enriching our understanding of atmospheric dynamics, fostering sustainability, and empowering us to navigate a brighter tomorrow.

A Commitment to Excellence

In the grand tapestry of metrology, the MAPP project emerges as a triumph, led by the dedication of the Metrology Research Institute. Our legacy is etched in the data we've unearthed, the uncertainties we've unraveled, and the illumination we've cast upon aerosol optical properties. With each step forward, we're pushing the boundaries of knowledge and fostering a future marked by clarity, accuracy, and unwavering commitment to the advancement of science.

Figure 3. Measured angular responsivity of a lunar radiometer of PMOD. The channel measuring radiation at the wavelength of 778 nm, is one of the four channels characterised.
Figure 3. Measured angular responsivity of a lunar radiometer of PMOD. The channel measuring radiation at the wavelength of 778 nm is one of the four channels characterised.

The setup for measuring angular responsivities of radiometers was used to measure angular responsivities of two radiometers of PMOD (Fig. 3). The results were compared with good agreement with the measurements of PMOD [3]. The maximum resolution of the measurements is 9 arcsec (0.0025 deg) constrained by the gimbal system.

Contact person: Petri Kärhä

References:

1. Iiro Harju, Measurement setup for characterising angular responsivities of optical radiometers, Candidate work, Aalto University School of Electrical Engineering, Espoo, 2020, 20 p. (in Finnish).

2. Kinza Maham, Petri Kärhä, and Erkki Ikonen, “Methodologies to measure spatial uniformities of integrating spheres,” Abstracts of CIE 2021 Conference, September 27 – 29, 2021, pp. 104 – 105. https://malaysia2021.cie.co.at/sites/default/files/cie_2021_abstract_booklet_0.pdf

3. I. Harju, P. Kärhä, E. Ikonen, J. Gröbner, N. Kouremeti, G. Hülsen, and S. Kasadzis, “Angular responsivity measurements of optical radiometers for estimating uncertainties of atmospheric aerosol measurements related to FOV effects,” 20th International Metrology Congress CIM2021, Lyon, September 7 – 9, 2021. https://www.cim2021.com/files/programmes/CIM2021-PapersAbstract-V1.pdf

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