Assessment of nocturnal aerosol optical depth from lunar photometry at the Izaña high mountain observatory

Abstract

Abstract. This work is a first approach to correct the systematic errors observed in the aerosol optical depth (AOD) retrieved at nighttime using lunar photometry and calibration techniques dependent on the lunar irradiance model. To this end, nocturnal AOD measurements were performed in 2014 using the CE318-T master Sun-sky-lunar photometer (lunar Langley calibrated) at the Izaña high mountain observatory. This information has been restricted to 59 nights characterized as clean and stable according to lidar vertical profiles. A phase angle dependence as well as an asymmetry within the Moon's cycle of the Robotic Lunar Observatory (ROLO) model could be deduced from the comparison in this 59-night period of the CE318-T calibration performed by means of the lunar Langley calibration and the calibration performed every single night by means of the common Langley technique. Nocturnal AOD has also been compared in the same period with a reference AOD based on daylight AOD extracted from the AErosol RObotic NETwork (AERONET) at the same station. Considering stable conditions, the difference AOD fit , between AOD from lunar observations and the linearly interpolated AOD (the reference) from daylight data, has been calculated. The results show that AOD fit values are strongly affected by the Moon phase and zenith angles. This dependency has been parameterized using an empirical model with two independent variables (Moon phase and zenith angles) in order to correct the AOD for these residual dependencies. The correction of this parameterized dependency has been checked at four stations with quite different environmental conditions (Izaña, Lille, Carpentras and Dakar) showing a significant reduction of the AOD dependence on phase and zenith angles and an improved agreement with daylight reference data. After the correction, absolute AOD differences for day-night-day clean and stable transitions remain below 0.01 for all wavelengths.

Ice-nucleating particle versus ice crystal number concentrationin altocumulus and cirrus layers embedded in Saharan dust:a closure study

“…The instrumentation was run continuously over a 6-week period. The station consisted of a multiwavelength polarization/Raman lidar Polly (PortabLe Lidar sYtsem) (PollyNET, 2019;Baars et al, 2016) from the National Observatory Athens (NOA) (Marinou et al, 2019), a wind Doppler lidar (HALO Photonics) from the Leibniz Institute for Tropospheric Research (TROPOS) , Leipzig, and a sun/lunar photometer (Cimel, CE318-T) from TROPOS, belonging to the Aerosol Robotic Network (AERONET) (Holben et al, 1998;Barreto et al, 2017). Another polarization/Raman lidar and AERONET sun photometer was operated by the Cyprus University of Technology (CUT-TEPAK (Technologiko Panepistimio Kyprou) in Fig.…”

“…Therefore, we begin with a historical overview of published (pioneering) attempts to simultaneously measure the INPC and ICNC and to perform icenucleation-related aerosol-cloud closure studies. The concept of aerosol-related closure experiments (Russel et al, 1979;Bates et al, 1998;Russell and Heintzenberg, 2000;Ansmann et al, 2002) was originally introduced to investigate the complex relationships between physical, chemical, optical, and radiative properties of atmospheric aerosol particles and thus to study the direct effect on climate solely based on aerosol observations (Quinn et al, 1996). In closure experiments, the measured value of a dependent variable is compared with the modeled or predicted value that is calculated from measured values of independent variables by using an appropriate model.…”

Comparative assessment of GRASP algorithm for a dust event over Granada (Spain) during ChArMEx-ADRIMED 2013 campaign

“…Passive remote sensing offers large advances in aerosol characterization with global sun-photometry networks such as the Aerosol Robotic Network (AERONET; Holben et al, 1998) or lunar and/or star photometry measurements Barreto et al, 2016Barreto et al, , 2017. In the last few years, several different inversion methods, based on spectral aerosol optical depth (AOD) measurements, were developed for the retrieval of aerosol microphysical properties such as effective radius (r eff ) and volume concentration (VC) (e.g.…”

The Influence of Heterogeneity on Lunar Irradiance Based on Multiscale Analysis

“…The average influence is greater during the waxing lunar phases than the waning lunar phases and reaches its maximum around the half-moon lunar phases. The heterogeneous correction factor derived using Equations (11) and (12), and the results of six bands (351.2 nm, 474.9 nm, 745.3 nm, 941.9 nm, 1243.2 nm, and 2125.5 nm) at the scale of 8 pixels/degree, are shown as examples in Figure 9. The vertical bars for each lunar phase represent the standard deviation of the heterogeneous correction factors, and the curved line represents the mean heterogeneous correction factor.…”

“…The MT2009 lunar irradiance model accounts for the variation of the lunar phase, however, it takes less consideration of lunar topography, surface heterogeneity, and the libration effect [10]. Both models have been widely used in applications including lunar calibration, night-time aerosol retrieval, and in socioeconomic fields [11][12][13][14][15].…”