Proyecto de Investigación: ACTRIS-2 654109
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654109
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Intercomparison of MAX-DOAS vertical profile retrieval algorithms: studies on field data from the CINDI-2 campaign
(European Geoscience Union (EGU), 2021-01-04) Tirpitz, J. L.; Frieb, U.; Hendrick, F.; Alberti, C.; Allaart, M.; Apituley, A.; Bais, A.; Beirle, S.; Berkhout, S.; Bognar, K.; Bösch, T.; Bruchkouski, I.; Cede, A.; Lok Chan, K.; Den Hoed, M.; Donner, S.; Drosoglou, T.; Fayt, C.; Friedrich, M. M.; Frumau, A.; Gast, L.; Gielen, C.; Gómez Martín, L.; Hao, N.; Hensen, A.; Henzing, B.; Hermans, C.; Jin, J.; Kreher, K.; Kuhn, J.; Lampel, J.; Li, A.; Liu, C.; Liu, H.; Ma, J.; Merlaud, A.; Peters, E.; Pinardi, G.; Piters, Ankie.; Platt, U.; Puentedura, O.; Richter, A.; Schmitt, S.; Spinei, E.; Stein Zweers, D.; Strong, K.; Swart, D.; Tack, F.; Tiefengraber, M.; Van der Hoff, R.; Van Roozendael, M.; Vlemmix, T.; Vonk, J.; Wagner, T.; Wang, Y.; Wang, Z.; Wenig, M.; Wiegner, M.; Wittrock, F.; Xie, P.; Xing, C.; Xu, J.; Yela González, M.; Zhang, C.; Zhao, X.; European Space Agency (ESA); European Commission (EC); Canadian Space Agency; National Natural Science Foundation of China (NSFC); Natural Sciences and Engineering Research Council of Canada; Deutsche Forschungsgemeinschaft (DFG); European Research Council (ERC); Ministerio de Economía y Competitividad (MINECO); Frieß, U. [0000-0001-7176-7936]; Alberti, C. [0000-0002-1574-5393]; Apituley, A. [0000-0001-8821-6348]; Bais, A. [0000-0003-3899-2001]; Beirle, S. [0000-0002-7196-0901]; Berkhout, S. [0000-0001-5447-8868]; Bognar, K. [0000-0003-4619-2020]; Bösch, T. [0000-0003-4230-8129]; Donner, S. [0000-0001-8868-167X]; Frumau, A. [0000-0001-5940-0285]; Gómez Martín, L. [0000-0002-6655-7659]; Henzing, B. [0000-0001-6456-8189]; Lampel, J. [0000-0001-7370-9342]; Liu, C. [0000-0002-3759-9219]; Ma, J. [0000-0002-9510-5432]; Peters, E. [0000-0002-8380-3137]; Pinardi, G. [0000-0001-5428-916X]; Puentedura, O. [0000-0002-4286-1867]; Richter, A. [0000-0003-3339-212X]; Stein Zweers, D. [0000-0002-1180-5790]; Strong, K. [0000-0001-9947-1053]; Swart, D. [0000-0002-6128-337X]; Vlemmix, T. [0000-0003-2584-3402]; Wang, Y. [0000-0002-9828-9871]; Zhang, C. [0000-0003-2092-9135]
The second Cabauw Intercomparison of Nitrogen Dioxide measuring Instruments (CINDI-2) took place in Cabauw (the Netherlands) in September 2016 with the aim of assessing the consistency of multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of tropospheric species (NO2, HCHO, O3, HONO, CHOCHO and O4). This was achieved through the coordinated operation of 36 spectrometers operated by 24 groups from all over the world, together with a wide range of supporting reference observations (in situ analysers, balloon sondes, lidars, long-path DOAS, direct-sun DOAS, Sun photometer and meteorological instruments).
In the presented study, the retrieved CINDI-2 MAX-DOAS trace gas (NO2, HCHO) and aerosol vertical profiles of 15 participating groups using different inversion algorithms are compared and validated against the colocated supporting observations, with the focus on aerosol optical thicknesses (AOTs), trace gas vertical column densities (VCDs) and trace gas surface concentrations. The algorithms are based on three different techniques: six use the optimal estimation method, two use a parameterized approach and one algorithm relies on simplified radiative transport assumptions and analytical calculations. To assess the agreement among the inversion algorithms independent of inconsistencies in the trace gas slant column density acquisition, participants applied their inversion to a common set of slant columns. Further, important settings like the retrieval grid, profiles of O3, temperature and pressure as well as aerosol optical properties and a priori assumptions (for optimal estimation algorithms) have been prescribed to reduce possible sources of discrepancies.
The profiling results were found to be in good qualitative agreement: most participants obtained the same features in the retrieved vertical trace gas and aerosol distributions; however, these are sometimes at different altitudes and of different magnitudes. Under clear-sky conditions, the root-mean-square differences (RMSDs) among the results of individual participants are in the range of 0.01–0.1 for AOTs, (1.5–15) ×1014molec.cm−2 for trace gas (NO2, HCHO) VCDs and (0.3–8)×1010molec.cm−3 for trace gas surface concentrations. These values compare to approximate average optical thicknesses of 0.3, trace gas vertical columns of 90×1014molec.cm−2 and trace gas surface concentrations of 11×1010molec.cm−3 observed over the campaign period. The discrepancies originate from differences in the applied techniques, the exact implementation of the algorithms and the user-defined settings that were not prescribed.
For the comparison against supporting observations, the RMSDs increase to a range of 0.02–0.2 against AOTs from the Sun photometer, (11–55)×1014molec.cm−2 against trace gas VCDs from direct-sun DOAS observations and (0.8–9)×1010molec.cm−3 against surface concentrations from the long-path DOAS instrument. This increase in RMSDs is most likely caused by uncertainties in the supporting data, spatiotemporal mismatch among the observations and simplified assumptions particularly on aerosol optical properties made for the MAX-DOAS retrieval.
As a side investigation, the comparison was repeated with the participants retrieving profiles from their own differential slant column densities (dSCDs) acquired during the campaign. In this case, the consistency among the participants degrades by about 30 % for AOTs, by 180 % (40 %) for HCHO (NO2) VCDs and by 90 % (20 %) for HCHO (NO2) surface concentrations.
In former publications and also during this comparison study, it was found that MAX-DOAS vertically integrated aerosol extinction coefficient profiles systematically underestimate the AOT observed by the Sun photometer. For the first time, it is quantitatively shown that for optimal estimation algorithms this can be largely explained and compensated by considering biases arising from the reduced sensitivity of MAX-DOAS observations to higher altitudes and associated a priori assumptions.
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.
Aerosol radiative impact during the summer 2019 heatwave produced partly by an inter-continental Saharan dust outbreak – Part 1: Short-wave dust direct radiative effect
(European Geoscience Union (EGU), 2021-04-30) Córdoba Jabonero, C.; Sicard, M.; López Cayuela, M. A.; Ansmann, A.; Comerón, A.; Zorzano, María Paz; Rodríguez Gómez, A.; Muñóz Porcar, C.; Ministerio de Ciencia e Innovación (MICINN); Agencia Estatal de Investigación (AEI); European Research Council (ERC); Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO); Córdoba Jabonero, C. [0000-0003-4859-471X]; Sicard, M. [0000-0001-8287-9693]; López Cayuela, M. A. [0000-0002-8825-830X]; Comerón, A. [0000-0001-6886-3679]; Rodríguez Gómez, A. [0000-0002-9209-0685]; Unidad de Excelencia Científica María de Maeztu Grupo de investigación en Teledetección, Antenas, Microondas y Superconductividad UNIVERSITAT POLITECNICA DE CATALUNYA, MDM-2016-0600; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The short-wave (SW) direct radiative effect (DRE) during the summer 2019 heatwave produced partly by a moderate, long-lasting Saharan dust outbreak over Europe is analysed in this study. Two European sites (periods) are considered: Barcelona, Spain (23–30 June), and Leipzig, Germany (29 and 30 June), 1350 km apart from each other. Major data are obtained from AERONET and polarised Micro-Pulse Lidar (P-MPL) observations. Modelling is used to describe the different dust pathways, as observed at both sites. The coarse dust (Dc) and fine dust (Df) components (with total dust, DD = Dc + Df) are identified in the profiles of the total particle backscatter coefficient using the POLIPHON (POlarisation LIdar PHOtometer Networking) method in synergy with P-MPL measurements. This information is used to calculate the relative mass loading and the centre-of-mass height, as well as the contribution of each dust mode to the total dust DRE. Several aspects of the ageing of dust are put forward. The mean dust optical depth and its ratios are, respectively, 0.153 and 24 % in Barcelona and 0.039 and 38 % in Leipzig; this Df increase in Leipzig is attributed to a longer dust transport path in comparison to Barcelona. The dust produced a cooling effect on the surface with a mean daily DRE of −9.1 and −2.5 W m−2, respectively, in Barcelona and Leipzig, but the DRE ratio is larger for Leipzig (52 %) than for Barcelona (37 %). Cooling is also observed at the top of the atmosphere (TOA), although less intense than on the surface. However, the DRE ratio at the TOA is even higher (45 % and 60 %, respectively, in Barcelona and Leipzig) than on the surface. Despite the predominance of Dc particles under dusty conditions, the SW radiative impact of Df particles can be comparable to, even higher than, that induced by the Dc ones. In particular, the DRE ratio in Barcelona increases by +2.4 % d−1 (surface) and +2.9 % d−1 (TOA) during the dusty period. This study is completed by a second paper about the long-wave and net radiative effects. These results are especially relevant for the next ESA EarthCARE mission (planned in 2022) as it is devoted to aerosol–cloud–radiation interaction research.
Changes in black carbon emissions over Europe due to COVID-19 lockdowns
(European Geoscience Union (EGU), 2021-02-23) Evangeliou, N.; Platt, S. M.; Eckhardt, S.; Lund Myhre, C.; Laj, P.; Alados Arboledas, L.; Backman, J.; Brem, B. T.; Fiebig, M.; Flentje, H.; Marinoni, A.; Pandolfi, M.; Yus Dìez, J.; Prats, N.; Putaud, J. P.; Sellegri, K.; Sorribas, M.; Eleftheriadis, K.; Vratolis, S.; Wiedensohler, A.; Stohl, A.; Research Council of Norway; European Commission (EC); Evangeliou, N. [0000-0001-7196-1018]; Eckhardt, S. [0000-0001-6958-5375]; Lund Myhre, C. [0000-0003-3587-5926]; Alados Arboledas, L. [0000-0003-3576-7167]; Backman, J. [0000-0002-4444-8777]; Brem, B. T. [0000-0001-6211-2815]; Fiebig, M. [0000-0002-3380-3470]; Marinoni, A. [0000-0002-6580-7126]; Yus Díez, J. [0000-0002-8124-1492]; Sorribas, M. [0000-0003-2131-9021]; Eleftheriadis, K. [0000-0003-2265-4905]; Wiedensohler, A. [0000-0001-8298-491X]; Stohl, A. [0000-0002-2524-5755]
Following the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for COVID-19 in December 2019 in Wuhan (China) and its spread to the rest of the world, the World Health Organization declared a global pandemic in March 2020. Without effective treatment in the initial pandemic phase, social distancing and mandatory quarantines were introduced as the only available preventative measure. In contrast to the detrimental societal impacts, air quality improved in all countries in which strict lockdowns were applied, due to lower pollutant emissions. Here we investigate the effects of the COVID-19 lockdowns in Europe on ambient black carbon (BC), which affects climate and damages health, using in situ observations from 17 European stations in a Bayesian inversion framework. BC emissions declined by 23 kt in Europe (20 % in Italy, 40 % in Germany, 34 % in Spain, 22 % in France) during lockdowns compared to the same period in the previous 5 years, which is partially attributed to COVID-19 measures. BC temporal variation in the countries enduring the most drastic restrictions showed the most distinct lockdown impacts. Increased particle light absorption in the beginning of the lockdown, confirmed by assimilated satellite and remote sensing data, suggests residential combustion was the dominant BC source. Accordingly, in central and Eastern Europe, which experienced lower than average temperatures, BC was elevated compared to the previous 5 years. Nevertheless, an average decrease of 11 % was seen for the whole of Europe compared to the start of the lockdown period, with the highest peaks in France (42 %), Germany (21 %), UK (13 %), Spain (11 %) and Italy (8 %). Such a decrease was not seen in the previous years, which also confirms the impact of COVID-19 on the European emissions of BC.
