Proyecto de Investigación: VOCS, HALOGENOS, OZONO Y DIOXIDO DE NITROGENO EN LA ATMOSFERA ANTARTICA
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CTM2017-83199-P
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Polar Stratospheric Clouds Detection at Belgrano II Antarctic Station with Visible Ground-Based Spectroscopic Measurements
(Multidisciplinary Digital Publishing Institute (MDPI), 2021-04-07) Gómez Martín, L.; Toledo, D.; Prados Roman, C.; Adame, J. A.; Ochoa, H.; Yela González, M.; Agencia Estatal de Investigación (AEI); Gómez Martín, L. [0000-0002-6655-7659]; Prados Roman, C. [0000-0001-8332-0226]; Adame, J. A. [0000-0002-6302-7193]
By studying the evolution of the color index (CI) during twilight at high latitudes, polar stratospheric clouds (PSCs) can be detected and characterized. In this work, this method has been applied to the measurements obtained by a visible ground-based spectrometer and PSCs have been studied over the Belgrano II Antarctic station for years 2018 and 2019. The methodology applied has been validated by full spherical radiative transfer simulations, which confirm that PSCs can be detected and their altitude estimated with this instrumentation. Moreover, our investigation shows that this method is useful even in presence of optically thin tropospheric clouds or aerosols. PSCs observed in this work have been classified by altitude. Our results are in good agreement with the stratospheric temperature evolution obtained by the global meteorological model ECMWF (European Centre for Medium Range Weather Forecasts) and with satellite PSCs observations from CALIPSO (Cloud-Aerosol-Lidar and Infrared Pathfinder Satellite Observations). To investigate the presence and long-term evolution of PSCs, the methodology used in this work could also be applied to foreseen and/or historical observations obtained with ground-based spectrometers such e. g. those dedicated to Differential Optical Absorption Spectroscopy (DOAS) for trace gas observation in Arctic and Antarctic sites.
Cirrus-induced shortwave radiative effects depending on their optical and physical properties: Case studies using simulations and measurements
(Elsevier BV, 2020-12-01) Córdoba Jabonero, C.; Gómez Martín, L.; Del Águila, A.; Vilaplana, J. M.; López Cayuela, M. A.; Zorzano, María Paz; Agencia Estatal de Investigación (AEI); European Research Council (ERC); Ministerio de Economía y Competitividad (MINECO); 000-0002-6655-7659; 0000-0002-4492-9650; 0000-0002-8825-830X; 0000-0003-4859-471X; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Cirrus (Ci) clouds play an important role in the atmospheric radiative balance, and hence in Climate Change. In this work, a polarized Micro-Pulse Lidar (P-MPL), standard NASA/Micro Pulse NETwork (MPLNET) system, deployed at the INTA/El Arenosillo station in Huelva (SW Iberian Peninsula) is used for Ci detection and characterization for the first time at this site. Three days were selected on the basis of the predominantly detected Ci clouds in dependence on their cloud optical depth (COD). Hence, three Ci cloud categories were examined at day-times for comparison with solar radiation issues: 19 cases of sub-visuals (svCi, COD: 0.01-0.03) on 1 October 2016, 7 cases of semitransparents (stCi, COD: 0.03-0.30) on 8 May 2017, and 17 cases of opaques (opCi, COD: 0.3-3.0) on 28 October 2016. Their radiative-relevant optical, macro- and micro-physical properties were retrieved. The mean COD for the svCi, stCi and opCi groups was 0.02 +/- 0.01, 0.22 +/- 0.08 and 0.93 +/- 0.40, respectively; in overall, their lidar ratio ranged between 25 and 35 sr. Ci clouds were detected at 11-13 km height (top boundaries) with geometrical thicknesses of 1.7-2.0 km. Temperatures reported at those altitudes corresponded to lower values than the thermal threshold for homogenous ice formation. Volume linear depolarization ratios of 0.3-0.4 (and normalized backscattering ratios higher than 0.9) also confirmed Ci clouds purely composed of ice particles. Their effective radius was within the interval of 9-15 mu m size, and the ice water path ranged from 0.02 (svCi) to 9.9 (opCi) g m(-2). The Cirrus Cloud Radiative Effect (CCRE) was estimated using a Radiative Transfer (RT) model for Ci-free conditions and Ci-mode (Ci presence) scenarios. RT simulations were performed for deriving the CCRE at the top-of-atmosphere (TOA) and on surface (SRF), and also the atmospheric CCRE, for the overall shortwave (SW) range and their spectral sub-intervals (UV, VIS and NIR). A good agreement was first obtained for the RT simulations as validated against solar radiation measurements under clean conditions for solar zenith angles less than 75 degrees (differences were mainly within +/- 20 W m(-2) and correlation coefficients close to 1). By considering all the Ci clouds, independently on their COD, the mean SW CCRE values at TOA and SRF were, respectively, -30 +/- 26 and -24 +/- 19 W m(-2), being the mean atmospheric CCRE of -7 +/- 7 W m(-2); these values are in good agreement with global annual estimates found for Ci clouds. By using linear regression analysis, a Ci-induced enhancing cooling radiative effect was observed as COD increased for all the spectral ranges, with high correlations. In particular, the SW CCRE at TOA and SRF, and the atmospheric CCRE, presented COD-dependent rates of -74 +/- 4, -55 +/- 5, -19 +/- 2 W m(-2) tau(-1), respectively. Additionally, increasing negative rates are found from UV to NIR for each Ci category, reflecting a higher cooling NIR contribution w.r.t. UV and VIS ranges to the SW CCRE, and being also more pronounced at the TOA w.r.t. on SRF, as expected. The contribution of the SW CCRE to the net (SW + LW) radiative balance can be also potentially relevant. These results are especially significant for space-borne photometric/radiometric instrumentation and can contribute to validation purposes of the next ESA's EarthCARE mission, whose principal scientific goal is focused on radiation-aerosol-cloud interaction research.
