Remote sensing of lunar aureole with a sky camera: Adding information in the nocturnal retrieval of aerosol properties with GRASP code

Abstract

30The use of sky cameras for nocturnal aerosol characterization is discussed in this study. 31Two sky cameras are configured to take High Dynamic Range (HDR) images at and thermal radiation (direct effect), and acting as cloud droplet nuclei that leads to 60 changes in the cloud properties and lifetime (indirect effect). 61At night there is no solar radiation, but aerosol radiative forcing in the longwave 62 range can be significant for large particles like desert dust and sea salt [Stier et al., 2007; 63 Sicard et al., 2014]. In addition, at night the aerosol indirect effect still works and could 64 provide changes on nocturnal cloud properties [Ramanathan et al., 2001; Kaufman et al. 65 2005; Rosenfeld et al. 2006]. These changes could contribute to global warming since 66 clouds at night absorb part of the longwave radiation emitted by Earth, and then, they 67 re-emit radiation back to the Earth surface [Ramanathan et al., 1989; NASA Facts, 68 1999; Wild, 2012]. Moreover, the knowledge of aerosol properties at night is important 69 for the aerosol characterization in polar areas and in winter seasons, which present low 70 sunshine duration values [Stone et al., 2010; Tomasi et al., 2015]. 71Some instruments and techniques are used for the characterization of aerosol 72 properties at night: lidar systems provide backscatter and extinction profiles using Fernald-Sasano retrievals [Klett, 1981[Klett, , 1985 Fernald, 1984;Sasano, 1984] [Ansmann et al., 2001;Pérez-Ramírez et al., 2008Berkoff et al., 2011; Barreto et 79 al., 2013 Barreto et 79 al., , 2016 Barreto et 79 al., , 2017. The AOD measurements at night provide information to 80 discriminate between the extinction of fine and coarse mode [O'Neill et al., 2003] brighter. This information could be combined with the spectral AOD, also obtained 91 from the Moon (lunar photometry) to retrieve aerosol characteristics. 92A sky camera can be used to obtain relative sky radiance near the Moon since it 93 records the full hemispherical sky radiance measuring different wavelength intervals 94 and it can operate at night with an appropriate exposure time (ET). It should be noted 95 also that sky cameras usually present a low signal to noise ratio. Cloud detection is the 96 most spread use of sky cameras [Long et al., 2006; Calbó and Sabburg, 2008; Cazorla et 97 al., 2008a; Ghonima et al., 2012;Kazantzidis et al., 2012; Mandat et al., 2014, Alonso 98 et al., 2014 though they have been used with other purposes [Horváth et al., 2002; 99 Cazorla et al., 2008b;Kreuter et al., 2009; Sigernes et al., 2014], including the 100 retrieval of sky radiances in daytime [Voss and Zibordi, 1989; López-Alvarez et al., 101 2008; Román et al., 2012; Toshing et al., 2013; Chauvin et al., 2015]. The CCD spectral response, given by the manufacturer, is shown in Fig. 1a. This 183 response is only available up to 700 nm, but red channel seems to have certain 184 sensitivity to longer wavelengths. As mentioned above, the camera also co...

Constraining global aerosol emissions using POLDER/PARASOL satellite remote sensing observations

“…In addition, GRASP is a highly versatile algorithm that has been applied for a large variety of different types of satellite, groundbased and airborne remote-sensing measurements by photometers, lidars, satellite sensors, nephelometers, sky cameras, etc. (Benavent-Oltra et al, 2017;Dubovik et al, 2019;Espinosa et al, 2017;Hu et al, 2019;Li et al, 2019;Lopatin et al, 2013;Román et al, 2017Román et al, , 2018Torres et al, 2017;Tsekeri et al, 2017). The spaceborne multidirectional, multispectral polarized POLDER-3 (Polarization and Directionality of the Earth's Reflectances) imager on board PARASOL can measure the global angular distribution of intensity and polarization of solar radiation reflected to space by the earth-atmosphere system (Deschamps et al, 1994;Deuzé et al, 1999Deuzé et al, , 2001Tanré et al, 2011).…”

Retrieval of aerosol properties from ceilometer and photometer measurements: long-term evaluation with in situ data and statistical analysis at Montsec (southern Pyrenees)

“…In this study, we follow the inversion strategy named GRASP pac (with subscript meaning "photometer and ceilometer") introduced by Román et al (2018). A GRASP pac retrieval is done for each sky radiance almucantar sequence available from AERONET if sky radiances and ceilometer measurements satisfy cloud-free conditions.…”

“…One of the recently developed inversion algorithms is the Generalized Retrieval of Aerosol and Surface Properties (GRASP; Dubovik et al, 2014;https://www.grasp-open. com/, last access: 1 May 2019) code that uses the heritage of the AERONET (Aerosol Robotic Network) inversion scheme (e.g., Dubovik et al, 2006). It is a versatile and open-source algorithm capable of obtaining optical and microphysical aerosol properties from different sets of measurements (Kokhanovsky et al, 2015;Espinosa et al, 2017;Torres et al, 2017;Román et al, , 2018. In particular, GRASP allows the user to combine aerosol optical depths (AODs), sky radiances and range-corrected lidar signal (RCS) values to retrieve columnar and vertically resolved aerosol properties.…”

“…In particular, GRASP allows the user to combine aerosol optical depths (AODs), sky radiances and range-corrected lidar signal (RCS) values to retrieve columnar and vertically resolved aerosol properties. Román et al (2018) proposed a similar approach but using the RCS values at only one wavelength measured with ceilometer instead of using multi-wavelength lidar RCS values as done before. The retrieved vertical profiles of aerosol volume concentration showed good agreement with in situ measurements from an aircraft campaign and with in situ measurements from a nearby mountain station during a summer campaign in southern Spain .…”

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

“…Currently, GARRLiC algorithm is included in the Generalized Retrieval of Atmosphere and Surface Properties inversion code (GRASP; Dubovik et al, 2011). However, very few studies have attempted to evaluate this recently developed inversion algorithm Bovchaliuk et al, 2016;Torres et al, 2017;Román et al, 2017), and therefore their evaluation under different atmospheric conditions is still necessary.…”