Thermodynamic Processes Driving Thermal Circulations on Slopes: Modeling Anabatic and Katabatic Flows on Reunion Island

Journal of Geophysical Research Atmospheres, Год журнала: 2024, Номер 129(17)

Опубликована: Сен. 4, 2024

Abstract This study investigates thermal circulations on Reunion Island (21°07’S 55°32’E), focusing the complex terrain of region. Observations from BIO‐MAÏDO campaign, along with 2 days high‐resolution simulation using MesoNH model, were analyzed to understand thermally‐driven mechanisms. was conducted a horizontal resolution 100 m and employed vertically stretched grid, achieving 1 at lowest levels. Two distinct wind regimes identified, characterized by katabatic flows prevailing within 30 thick layer during nighttime, an anabatic flow manifesting spanning 150 200 daytime. The confirmed through validation surface measurements, thus enabling detailed breeze circulations. Results reveal that intensity trade winds significantly influences development Complex layered structures in atmosphere also identified. At 7 s −1 , impede atop slope, result emergence convergence zone between local regional analysis establishment period indicates stabilizes 35 min, quicker than flow, which takes 110 min. Momentum heat budget provide insights into primary drivers circulations: buoyancy acceleration, influenced heating onset, cooling onset.

Язык: Английский

Measurement report: Insights into the chemical composition and origin of molecular clusters and potential precursor molecules present in the free troposphere over the southern Indian Ocean: observations from the Maïdo Observatory (2150 m a.s.l., Réunion)

Atmospheric chemistry and physics, Год журнала: 2024, Номер 24(6), С. 3785 - 3812

Опубликована: Март 27, 2024

Abstract. New particle formation (NPF) in the free troposphere (FT) is thought to be a significant source of particles over oceans. The entrainment initially formed marine FT further suspected major contributor cloud condensation nuclei (CCN) number concentrations boundary layer (BL). Yet, little known about process and, more broadly, composition FT, which remains poorly explored due access difficulties. Here we report measurements performed April 2018 at Maïdo Observatory with nitrate-based chemical ionization atmospheric pressure interface time-of-flight mass spectrometer, have allowed first molecular-level characterization remote composition. A molecules and clusters were identified classified into nine groups according their composition; among species, containing methanesulfonic acid (MSA) C2 amines show signals that are on average significantly higher when site under conditions representative (compared BL). correlation analysis revealed apparent connections between compounds several variables concurrently measured (under conditions) or related air history, suggesting oxalic acid, malonic observed could terrestrial origin, with, addition, possible for amines, while iodic sulfur maleic dominant origin. Identification was based standard deviation wind direction; this parameter, can easily derived from continuous site, shown part study relevant tracer compared predictions Meso-NH model. Similar other high-altitude sites, mainly encountered night Maïdo; therefore, link NPF not established, research needed assess precursors nanoparticle FT.

Язык: Английский

Molecular composition of clouds: a comparison between samples collected at tropical (Réunion Island, France) and mid-north (Puy de Dôme, France) latitudes

Atmospheric chemistry and physics, Год журнала: 2024, Номер 24(9), С. 5567 - 5584

Опубликована: Май 15, 2024

Abstract. The composition of dissolved organic matter cloud water has been investigated through non-targeted high-resolution mass spectrometry on only a few samples that were mostly collected in the Northern Hemisphere USA, Europe and China. There remains, therefore, lack measurements for clouds located Southern Hemisphere, under tropical conditions influenced by forest emissions. As fact, comparison different locations is challenging since methodology analysis data treatment not standardized. In this work, chemical three at Réunion Island (REU) during BIO-MAÏDO field campaign, Indian Ocean, with influences from marine, anthropogenic biogenic (tropical) emissions, compared to Puy de Dôme (PUY) observatory France. same was employed, producing unique dataset investigation molecular water. Besides elemental composition, we carbon oxidation state (OSC) matter, finding overall PUY are more oxidized than those REU. Molecular formulas also classified based stoichiometric ratios, showing high frequency abundance reduced compounds, as lipids (LipidC), matrix, which led search terpene products samples. To better discriminate between REU, statistical (principal component agglomerative hierarchical clustering) performed ensemble their intensities. Samples REU have PUY, mainly linked primary sources, processing influence emissions two locations.

Язык: Английский