The method of time-resolved photoacoustic spectroscopy is applied to study the weak aerosol absorption of shortwave radiation in the atmospheric air. Using synchronous measurements of aerosol light absorption coefficients by a pulsed photoacoustic spectrometer and mass concentration of black carbon by an Aethalometer, we determine the values of the efficiency of aerosol light absorption in the atmospheric air in the shortwave spectral range for three wavelengths: ͑0.532 m͒ = ͑5.49± 3.57͒m 2 g −1 ,͑0.694 m͒ = ͑4.46± 2.61͒m 2 g −1 , and ͑1.064 m͒ = ͑2.87± 1.84͒m 2 g −1 . The experimental results are approximated by the spectral dependence ͑͒ = 3.1 −0.92 , where wavelength is expressed in micrometers. We discuss the calibration procedure for the pulsed photoacoustic spectrometer in studying the aerosol absorption.

No abstract

Here we report the first results of a search of a signature for picosecond time stamps of the interaction between ionizing particles and transparent crystalline media. The induced absorption with sub-picosecond rise time observed in a cerium fluoride scintillation single crystal under UV excitation is directly associated with the ionization of Ce 3+ atoms in CeF 3 crystals, and the very fast occurrence thereof can be used to generate picosecond-precise time stamps corresponding to the interaction of ionizing particles with the crystal in high energy physics experiments.

We present the result of a design study for X-Spec, a multi-beam, R=400-700 survey spectrometer covering 190-520 GHz under development for CCAT. It is designed to measure the bright atomic fine-structure and molecular rotational transitions that cool galaxies' interstellar gas, in particular, the 158 µm rest-frame [CII] transition, in thousands to tens of thousands of galaxies ranging from z=9 to z=3.5. With the wide bandwidth and multi-object capability, X-Spec / CCAT will be more powerful than ALMA for redshift-blind galaxy surveys and tomographic intensity mapping. X-Spec uses SuperSpec filterbank spectrometer technology with TiN KIDs described by Hailey-Dunsheath et al. in this conference. Because the density of sources is small, galaxy follow-up will be most efficient with a front-end steering unit which we have prototyped, also described in a separate paper (Chapman et al. in this conference). Our baseline instrument concept has 84 steered beams arrayed over the 1 degree CCAT field, each beam couples to 4 chips (2 bands x 2 polarizations) each chip with approximately 500 detectors, making a total of ∼170,000 KIDs in the full instrument. A direct imaging spectrometer (integral-field spectrometer) with a comparably-sized backend is also considered.

Abstract. The absence of sunlight during the winter in the High Arctic results in a strong surface-based atmospheric temperature inversion, especially during clear skies and light surface wind conditions. The inversion suppresses turbulent heat transfer between the ground and the boundary layer. As a result, the difference between the surface air temperature, measured at a height of 2 m, and the ground skin temperature can exceed several degrees Celsius. Such inversions occur very frequently in polar regions, are of interest to understand the mechanisms responsible for surface–atmosphere heat, mass, and momentum exchanges, and are critical for satellite validation studies. In this paper we present the results of operations of two commercial remotely piloted aircraft systems, or drones, at the Polar Environment Atmospheric Research Laboratory, Eureka, Nunavut, Canada, at 80∘ N latitude. The drones are the Matrice 100 and Matrice 210 RTK quadcopters manufactured by DJI and were flown over Eureka during the February–March field campaigns in 2017 and 2020. They were equipped with a temperature measurement system built on a Raspberry Pi single-board computer, three platinum-wire temperature sensors, a Global Navigation Satellite System receiver, and a barometric altimeter. We demonstrate that the drones can be effectively used in the extremely challenging High Arctic conditions to measure vertical temperature profiles up to 75 m above the ground and sea ice surface at ambient temperatures down to −46 ∘C. Our results indicate that the inversion lapse rates within the 0–10 m altitude range above the ground can reach values of ∼ 10–30 ∘C(100m)-1 (∼ 100–300 ∘Ckm-1). The results are in good agreement with the coincident surface air temperatures measured at 2, 6, and 10 m levels at the National Oceanic and Atmospheric Administration flux tower at the Polar Environment Atmospheric Research Laboratory. Above 10 m more gradual inversion with order-of-magnitude smaller lapse rates is recorded by the drone. This inversion lapse rate agrees well with the results obtained from the radiosonde temperature measurements. Above the sea ice drone temperature profiles are found to have an isothermal layer above a surface-based layer of instability, which is attributed to the heat flux through the sea ice. With the drones we were able to evaluate the influence of local topography on the surface-based inversion structure above the ground and to measure extremely cold temperatures of air that can pool in topographic depressions. The unique technical challenges of conducting drone campaigns in the winter High Arctic are highlighted in the paper.