El efecto Ghost ("Global Hidden Ozone Structures from TOMS"): posibles implicaciones dinámicas

Ponencia presentada en: IV Simposio Nacional de Predicción del Instituto Nacional de Meteorología, celebrado en 1999 en MadridEl efecto GHOST consiste en la visua2ización del contorno de los continentes y otras estructuras geográficas más pequeñas a partir de las imágenes diarias o medias mensuales de ozono total con cobertura mundial proporcionados por el instrumento TOMS (Total Ozone Mapping Spectrometer) de la NASA. Este instrumento vuela a bordo de los satélites Nimbus-7 (NASA-Estados Unidos) y Meteor-3 (Rusia). Este hecho, que fue en principio atribuido a un “artifact” del instrumento TOMS, parece que puede ser debido a dos procesos/causas naturales: destrucción del ozono por radiación retrodifundida en el visible (explicación radiativa) y por elevación de la tropopausa sobre los continentes (explicación dinámica)

Evolución histórica de las lámparas de fotopolimerización

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Long-path averaged mixing ratios of O3 and NO2 in the free troposphere from mountain MAX-DOAS

A new approximation is proposed to estimate O3 and NO2 mixing ratios in the northern subtropical free troposphere (FT). The proposed method uses O4 slant column densities (SCDs) at horizontal and near-zenith geometries to estimate a station-level differential path. The modified geometrical approach (MGA) is a simple method that takes advantage of a very long horizontal path to retrieve mixing ratios in the range of a few pptv. The methodology is presented, and the possible limitations are discussed. Multi-axis differential optical absorption spectroscopy (MAX-DOAS) high-mountain measurements recorded at the Izaña observatory (28° 18' N, 16° 29' W) are used in this study. The results show that under low aerosol loading, O3 and NO2 mixing ratios can be retrieved even at very low concentrations. The obtained mixing ratios are compared with those provided by in situ instrumentation at the observatory. The MGA reproduces the O3 mixing ratio measured by the in situ instrumentation with a difference of 28%. The different air masses scanned by each instrument are identified as a cause of the discrepancy between the O3 observed by MAX-DOAS and the in situ measurements. The NO2 is in the range of 20–40 ppt, which is below the detection limit of the in situ instrumentation, but it is in agreement with measurements from previous studies for similar conditions.We acknowledge the support of AMISOC (Atmospheric Minor Species relevant to the Ozone Chemistry at both sides of the Subtropical jet, contract number CGL2011-24891), and NORS (Demonstration Network of Ground-Based Remote Sensing Observations in support of the GMES Atmospheric Service) integrated project under the 7th Framework Programme (contract number FP7-SPACE-2011-284421)

Intercomparison of the NO2 vertical column densities measured over Izaña with two ground-based remote sensing techniques: DOAS and FTIR

Ponencia presentada en: XV Congreso de la Asociación Española de Teledetección celebrado en Torrejón de Ardoz (Madrid), del 22 al 24 de octubre de 2013.[ES]En el marco del proyecto NORS se ha realizado una intercomparación de medidas de NO2 con dos técnicas de detección remota desde superficie: DOAS y FTIR. Las columnas verticales de NO2 medidas en Izaña por dos espectrómetros de alta calidad como son el RASAS basado en la técnica DOAS y el instrumento comercial BRUKER-120 basado en la técnica FTIR, han sido comparadas. Debido a la fuerte variación fotoquímica del NO2, las medidas realizadas con el FTIR han sido corregidas con un Box-model fotoquímico para referenciarlas a la hora de medida del RASAS. Los resultados de ambos instrumentos se comparan bien, dando unas diferencias medias de 7±18%.[EN]In the frame of the NORS Project, an intercomparison exercise of two ground-based remote sensing techniques is presented: DOAS and FTIR. Results form two high quality spectrometers located at the Izaña Atmospheric Observatory are shown and compared. DOAS based instruments are two RASAS, developed at INTA, working in the UV-VIS part of the spectrum. FTIR based instrument is a Bruker-120 that measures in the IR. To account for the NO2 strong photochemical variation a Box-model has been used to refer the FTIR data to the DOAS measurement time. Results show a good agreement in the NO2 concentrations. Mean differences are of 7±18%.The work described in this paper is partially supported by the NORS project under the funding of the European Community's Seventh Framework Programme ([FP7/2007-2013]) under grant agreement n°284421 and by the AMISOC project (CGL2011-24891) under the funding of the Spanish Ministry of Economy and Competitiveness (MINECO)

Saharan and arabian dust aerosols: a comparative case study of lidar ratio

El volumen 119 de 2016 de la revista EPJ Web of Conferences recoge las ponencias del 27th International Laser Radar Conference (ILRC 27)This work presents a first comparative study of the Lidar Ratio (LR) values obtained for dust particles in two singular dust-influenced regions: the Canary Islands (Spain, close to the African coast in the North Atlantic Ocean), frequently affected by Saharan dust intrusions, and the Kuwait area (Arabian Peninsula) as usually influenced by Arabian dust storms. Synergetic lidar and sun-photometry measurements are carried out in two stations located in these particular regions for that purpose. Several dusty cases were observed during 2014 in both stations and, just for illustration, two specific dusty case studies have been selected and analyzed to be shown in this work. In general, mean LR values of 54 sr and 40 sr were obtained in these studies cases for Saharan and Arabian dust particles, respectively. Indeed, these results are in agreement with other studies performed for dust particles arriving from similar desert areas. In particular, the disparity found in Saharan and Arabian dust LR values can be based on the singular composition of the suspended dust aerosols over each station. These results can be useful for CALIPSO extinction retrievals, where a single LR value (40 sr) is assumed for pure dust particles independently on the dust source region.This work has been supported by both the Spanish Ministerio de Economía y Competitividad (MINECO) under grant CGL2011-24891 (AMISOC project) and the Kuwait Foundation for the Advancement of Sciences under project 2011- 1401-01

Total ozone measurements from the NDACC Izaña Subtropical Station: visible spectroscopy versus Brewer and satellite instruments

Póster presentado en: Quadrennial Ozone Symposium 2012 celebrado del 27 al 31 de agosto de 2012 en Toronto, CanadáThis work has been partially funded by NORS, UE FP7 Project under grant agreement n° 284421 and AMISOC, CGL2011‐24891, from the Spanish Plan for Research, Development and Innovation

Intercomparison of stratospheric nitrogen dioxide columns retrieved from ground-based DOAS and FTIR and satellite DOAS instruments over the subtropical Izana station

The comparison of observations performed by different techniques and satellite instruments is important. An intercomparison of the stratospheric NO2 derived from ground-based and satellite instruments has been carried out over the Izaña subtropical site. The importance of the use of the effective solar zenith angle when comparing noon measurements with twilight measurements of photochemically active species is highlighted. All instruments show positive trends in NO2 stratospheric column.This publication has been funded by the AVATAR project of the Spanish national funding Agency (MINECO: CGL2014-55230-R ). This work has been carried out in the frame of the NORS (Demonstration Network of Ground-Based Remote Sensing Observations in support of the Copernicus Atmospheric Service) project (funded by the European Community’s Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 284421; http://nors.aeronomie.be/) and has been partially supported by AMISOC project funded by the Spanish national funding Agency (CGL2011-24891)

NO2 VCD Stratospheric trends Hemispheric and latitudinal dependence

Presentación realizada para el 7th International DOAS Workshop celebrado en Bruselas los días 6-8 de julio de 2015Twenty years of stratospheric NO2 VCD data from ground-based zenith DOAS instruments have been used for trend analysis. Spectrometers either NDACC qualified or under evaluation cover Subtropical latitudes in Northern Hemisphere (Izaña, 28ºN), and Southern Antarctic (Marambio, 64ºS) and SubAntarctic (Ushuaia, 55ºS) regions. The multiple linear regression method includes annual, semiannual, quarterly, solar activity cycle, stratospheric aerosols, QBO and NAO proxies. The instruments settings follow the NDACC recommendations for NO2 measurements and the same AMF code. Results show a mean am/pm positive trend of + 7.9% at the 99% confidence level in the Northern Hemisphere station whereas the trends are negative in the Southern Hemisphere ones (-9.8% Ushuaia, -14.9% Marambio). From comparison with FTIR data, it is estimated that the changes are restricted to the lower stratosphere (15-30km) suggesting a dynamic origin of the trend. MIPAS NOy on a global scale shows a similar feature with a redistribution of the nitrogen family within the lower stratosphere

Lidar ratio derived for pure dust aerosols: multi-year micro pulse lidar observations in a Saharan dust-influenced region

El volumen 119 de 2016 de la revista EPJ Web of Conferences recoge las ponencias del 27th International Laser Radar Conference (ILRC 27)A seasonal distribution of the Lidar Ratio (LR, extinction-to-backscattering coefficient ratio) for pure Saharan dust particles has been achieved. Simultaneous MPLNET/Micro Pulse lidar measurements in synergy with AERONET sun-photometer data were collected in the Tenerife area, a Saharan dust-influenced region, from June 2007 to November 2009. Dusty cases were mostly observed in summertime (71.4 % of total dusty cases). No differences were found among the LR values derived for spring, summertime and autumn times (a rather consistent seasonally averaged LR value of 57 sr is found). In wintertime, however, a higher mean LR is derived (65 sr), associated likely with a potential contamination from fine biomass burning particles coming from Sahel area during wintertime deforestation fires period. Results, obtained from a free-tropospheric pristine station (AEMET/Izaña Observatory) under Saharan dust intrusion occurrence, provide a more realistic perspective about LR values to be used in elastic lidar-derived AOD inversion for Saharan pure dust particles, and hence in improving CALIPSO AOD retrievals.This work has been supported by the Spanish Ministerio de Economía y Competitividad (MINECO) under grant CGL2011-24891 (AMISOC project)

Comparison between computed tomography and silicone-casting methods to determine gunshot cavities in ballistic soap

Current methods used in terminal ballistics to determine the volume of temporary cavities created by projectiles in soft tissue simulants (such as ballistic soap) usually involve silicone-casting to obtain the cavity moulds. However, these methods have important drawbacks including their little sensitivity and precision, besides the fact that they are destructive. Imaging techniques such as computed tomography (CT) might not only overcome those limitations but also offer useful tools for digitally reporting the scientific results. This work accomplished the 3D digital reconstruction of the cavities created by different projectiles in ballistic soap blocks. This way, the total volume of the cavities, the projectile penetration depths, and other measurements were determined, rendering better capabilities when compared to the current silicone method. All these features were achieved through the CT analysis and 3D Slicer imaging software. In addition, it is worth mentioning that the method can preserve the evidence by digitally obtaining, signing, and storing the infographic videos displaying the 3D-reconstructed cavities