Reliable secular time series of essential climatic variables are a fundamental element for the assessment of vulnerability, impact and adaptation to climate change. Here, we implement a readily portable procedure for building an upgradable long-term homogeneous climate dataset using monthly and daily observations of temperature and precipitation over a given area of interest, exemplified here with Abruzzo, a region in Central Italy characterized by complex orography. We process the dataset according to a preliminary ranking of stations based on data quantity and quality, and we exploit the Climatol algorithm for inhomogeneity correction. The corrected time series show trends in broad agreement with external databases (CRU, Berkeley Earth, E-OBS), and highlight the importance of relying on a local network for a better representation of gradients and variability over the territory. We estimate that maximum (TX) and minimum temperature (TN) increased by~1.6 and~2.2 C/century, respectively, over the period 1930-2019, while in the recent decades 1980-2019 we found an accelerated trend of~5.7 and~3.9 C/century. Precipitation (RR) decreased by~10%/century in 1930-2019, while it has been increasing at a rate of~26%/century in 1980-2019. The Köppen-Geiger climate classification is sensitive to the increase of precipitation in the recent decades, which is attributable to decreased summer precipitation overcompensated by more rain in late spring and early autumn. The cold climate types are retreating upwards along the slopes of the mountain ranges. Over the period 1980-2019, extreme values are also displaying significant trends. Every 2 years, there is one less frost day (TN <0 C) and one more summer day (TX >25 C) in the Apennines area, while there is one more tropical night (TN >20 C) in the Adriatic coastal area. Precipitation extremes are increasing, especially along the coast, with rain accumulated in the rainiest days increasing at a rate of 1-2%/year.

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&lt;p&gt;Organic aerosol (OA) from natural or anthropogenic origin can be directly emitted into the atmosphere (primary organic aerosols, POA) or formed by secondary processes via the oxidation of volatile organic compounds (VOC). However, the formation pathways and their chemical composition of these secondary organic aerosols (SOA), which may contribute up to 90% of the OA mass, are not well understood to date, which is problematic due to the relevance of SOA on climate. To address this issue, this study uses a tracer-based approach to identify and quantify the contribution of different anthropogenic/biogenic VOCs precursors to the SOA formation. To do so, we combine experiments in a large scale atmospheric simulations chamber, CESAM (which means Multiphase Atmospheric Experimental Simulation Chamber), and field measurements during the ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) campaign conducted in the Paris area in summer 2022. This approach provides both a mechanistic study of the oxidation of targeted VOCs in simulated and controlled rural/urban atmospheres and the identification of targeted tracers in the real atmosphere, to quantify their concentrations in ambient air.&lt;/p&gt; &lt;p&gt;The ACROSS dataset consists in atmospheric samples of submicron aerosols collected twice a day (day and night) in the urban area of Paris and the Rambouillet forest on the south-west of Paris, as well as samples collected onboard the Safire ATR-42 research aircraft on low-level flights targeting the &amp;#160;evolution and dilution of the Paris urban plume. The CESAM chamber dataset consists in samples of SOA generated by the OH oxidation of toluene/ m-xylene in various conditions.&lt;/p&gt; &lt;p&gt;Filters are analyzed to provide with the chemical composition at the molecular scale by SFE-GC-MS (Supercritical Fluid Extraction Gas Chromatography- Mass Spectrometry) and UPLC-QTOF-MS (Ultra Performance Liquid Chromatography Time of Flight Mass Spectrometry). The organic mass and chemical speciation are obtained by aerosol mass spectrometry and the organic carbon (OC) concentrations by thermal-optical analysis.&lt;/p&gt; &lt;p&gt;The first results of the ambient samples of Paris revealed that the OC concentration varied between 0.69 &amp;#177; 0.07 and 9.48 &amp;#177; 0.51 &amp;#181;gC/m&lt;sup&gt;3&lt;/sup&gt;, which correspond to the 28% and 53% of the total mass of the submicron aerosols, for background and polluted (fire) conditions, respectively. These diverse conditions are favorable to trace the compounds identified during the simulation chamber experiments, such as benzoic acid, succinic acid, and 2-methyl-4-nitrophenol. These attempts will be presented and discussed in order to determine the contribution of specific precursors to SOA formation.&lt;/p&gt;