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Disentangling the drivers of soil CO2 ventilation in a Mediterranean dryland using in situ and remote sensing techniques

2026-04-30T23:47:28Z

Título : Disentangling the drivers of soil CO2 ventilation in a Mediterranean dryland using in situ and remote sensing techniques Autor : Abril Gago, Jesús; Tovar, Irene; Echeverría, María Teresa; Andújar Maqueda, Juana; Ortiz Amezcua, Pablo; Cabrera Carrillo, Germán; Serrano Ortiz, Penélope; Domingo, Francisco; Alados Arboledas, Lucas; Kowalski, Andrew S.; Sánchez Cañete, Enrique P.; Guerrero-Rascado, Juan Luis Resumen : Subterranean CO2 concentrations are driven by complex interactions between biological and physical processes. In semiarid ecosystems, atmospheric processes can play a relevant role in modulating soil CO2 storage and release. In the current study, a multi-instrumental dataset, collected in a Mediterranean shrubland in southern Spain, was analyzed, and the main atmospheric drivers controlling soil CO2 and radon (Rn) dynamics were investigated. Based on a precise methodology, 10 significant ventilation events were detected, and the Spearman correlation coefficients between the soil CO2 and Rn concentrations and the different atmospheric variables were calculated. The results identified surface atmospheric pressure as the most consistent and independent driver across the events, exhibiting strong negative correlations with the subterranean CO2 and Rn concentrations. Surface-level friction velocity (u∗), boundary-layer turbulent kinetic energy dissipation rate (ϵ) and wind shear (sh) showed significant positive correlations. However, their independence was not consistent when compared with diluting ventilation events, when u∗ was more relevant, with enriching ventilation periods, that were more influenced by boundary-layer ϵ and sh. In contrast, at lower altitudes ϵ, sh, atmospheric boundary layer height and mixing layer height were less strongly correlated with soil CO2 and Rn concentration changes. These findings provide new insights into the mechanisms that promote soil-atmosphere transport in drylands, especially those regarding the carbon cycle, and highlight the need to incorporate such mechanisms into Earth system models to improve carbon cycle predictions under future climate scenarios.

Volcanic plume height during the 2021 Tajogaite eruption (La Palma) from two complementary monitoring methods – implications for satellite-based products

2026-04-30T23:47:31Z

Título : Volcanic plume height during the 2021 Tajogaite eruption (La Palma) from two complementary monitoring methods – implications for satellite-based products Autor : Barreto Velasco, África; Quirós, Francisco; García Rodríguez, Omaira Elena; Pereda de Pablo, Jorge; González-Fernández, Daniel; Bedoya Velásquez, Andrés Esteban; Sicard, Michaël; Córdoba-Jabonero, Carmen; Iarlori, Marco; Rizi, Vicenzo; Krotkov, Nickolay; Carn, Simon; Roininen, Reijo; Molina Arias, Antonio J.; Almansa Rodríguez, Antonio Fernando; Álvarez-Losada, Óscar; Aramo, Carla; Bustos Seguela, Juan José de; Ceolato, Romain; Comerón, Adolfo; Felpeto, Alicia; García Cabrera, Rosa Delia; González-Sicilia, Pablo; González Ramos, Yenny; Hedelt, Pascal; Hernández Martínez de la Peña, Miguel; López Cayuela, María Ángeles; Loyola, Diego; Meletlidis, Stavros; Muñoz Porcar, Constantino; Pietropaolo, Ermanno; Ramos López, Ramón; Rodríguez Gómez, Alejandro; Román, Roberto; Romero Campos, Pedro Miguel; Stuefer, Martin; Toledano, Carlos; Welton, Ellsworth J. Resumen : Volcanic emissions from the Tajogaite volcano, located on the Cumbre Vieja edifice on the island of La Palma (Canary Islands, Spain), caused significant public health and aviation disruptions throughout the eruption (19 September–13 December 2021, officially declared over on 25 December). Nonetheless, it is considered the most significant volcanic event in Europe over the past 75 years due to the substantial amount of SO2 released into the atmosphere. The Instituto Geográfico Nacional (IGN), the authority responsible for volcano surveillance in Spain, implemented extensive operational monitoring to track volcanic activity and to provide a robust estimation of the volcanic plume height using a video-surveillance network. In parallel, the State Meteorological Agency of Spain (AEMET), in partnership with other Spanish ACTRIS (Aerosol, Clouds, and Trace Gases Research Infrastructure) members and collaborating institutions, conducted an unprecedented instrumental deployment to evaluate the impacts of this volcanic event on atmospheric composition. This effort included a network of aerosol profilers surrounding the volcano. A total of four profiling instruments were installed on La Palma: one MPL-4B lidar and three ceilometers. Additionally, a pre-existing Raman lidar on the island contributed valuable data to this study. These efforts are undertaken due to the importance of monitoring volcanic plume height in terms of air quality (necessary for the implementation of effective civil protection policies), volcanic activity surveillance (for tracking and forecasting eruptive behaviour), and, from a scientific perspective, for improving our understanding of the climatic and radiative impacts of this type of aerosol.

Atmosphere Extinction at the ORM on La Palma: A 20 yr Statistical Database Gathered at the Carlsberg Meridian Telescope

2026-04-30T23:11:50Z

Título : Atmosphere Extinction at the ORM on La Palma: A 20 yr Statistical Database Gathered at the Carlsberg Meridian Telescope Autor : García Gil, Alejandro Manuel; Muñoz Tuñón, Casiana; Varela, Antonia María Resumen : The Observatorio del Roque de los Muchachos (ORM), in the Canary Islands (Spain), was one of the candidates to host the future European Extremely Large Telescope (E-ELT) and is the site of the Gran Telescopio Canarias (GTC), the largest optical infrared facility to date. Sky transparency is a key parameter as it defines the quality of the photometry to be acquired in the astronomical observations. We present a study of the atmosphere extinction at the ORM, carried out after analysis of a database spanning more than 20 yr,1to our knowledge, the longest and most complete and homogeneous in situ database available for any observatory. It is based on photometric measurements in the V band and r′ band (transformed to the V-band extinction coefficient kV) using the Carlsberg Meridian Telescope (CMT). Clear seasonal variations that repeat yearly are observed. The median value of kV is 0.13 mag airmass-1; the mean value has a maximum in the summer months (June-September), corresponding to the season with maximum frequency of nights affected by dust or cirrus (∼29% in summer, but only ∼13% during the rest of the year). Two volcanic eruptions took place during the database baseline, which has enabled the study of the impact of volcanoes on the global atmosphere extinction. For the 5 yr of available information, we have estimated the average monthly weather downtime from the CMT data log, obtaining a result (20.7%) in reasonable agreement with earlier studies. The main conclusion of our study is that there is no significant evidence from the CMT data for any secular changes in kV over the 20 yr database baseline.

Thirty Years of Atmospheric Extinction from Telescopes of the North Atlantic Canary Archipelago

2026-04-30T23:24:26Z

Título : Thirty Years of Atmospheric Extinction from Telescopes of the North Atlantic Canary Archipelago Autor : Laken, Benjamin A.; Parviainen, Hannu; García Gil, Alejandro Manuel; Muñoz Tuñón, Casiana; Varela, Antonia María; Fernández-Acosta, Sergio; Pallé, Pere Resumen : This study examines 30 years of atmospheric extinction, τ, obtained from both stellar and solar telescope measurements, at ~2.4 km MSL, from the North Atlantic Canary Archipelago—an island chain located at approximately 28°N, around 100 km from the west coast of Africa. Data from three AERONET monitors, located at varying heights on one of the main islands, were also used, although these are only available over a shorter (<10 yr) period. The Canary Archipelago is regularly affected by dust intrusions into the local atmosphere as they intersect one of the primary export pathways of mineral dust from the Sahara. The τ of “baseline” and “dust influenced” conditions were statistically distinguished by fitting normal-gamma mixture distributions to the observations using Markov chain Monte Carlo methods, and then the seasonal and long-term characteristics of these data were examined. The telescope data show that baseline conditions are usually stable at τ < 0.1 (except during periods influenced by volcanic aerosols) and indicate the existence of a low-amplitude () seasonal variation. During dust-influenced conditions, τ regularly reaches values of a factor of 2–6 times higher than normal. The majority of dust intrusions take place during the months of July and August, when they may occur 44 ± 15% of the time, predominantly at high altitudes (with ~94.3 ± 1.6% of intrusions occurring ≥ 2.4 km), whereas during the months of November–May, dust intrusions occur far less frequently (~19 ± 7%) and are more common at lower altitudes—with intrusions at <2.4 km comprising ~ 79.5 ± 3.2% of all outbreaks. Year-to-year variations in the frequency of dust-influenced conditions (of ~9%) were found but no long-term trend over the observed 30-yr period.