At present, our discussion page lacks any statistical data about the thread, a feature that is pretty common in most of social networks or forums. These platforms typically display a total count of replies, boosts, likes, and participants.

Take Discourse as an example, a platform with a great UX for productive conversations. Discourse displays the list of links shared in a post and provides a statistical box that details thread engagement. This includes also an approximation of the time required to read through the entire thread, if significant.

What are some meaningful statistics we must/should incorporate for the Bonfire 1.0 release? We are seeking to find statistics that can effectively foster engagement in discussions without solely promoting addictive behaviors. Any thoughts or suggestions ? #bonifre_feedback

No doubt Discourse's stats are awesome!
I would say it would be nice to have those avatars at the bottom of people who have engaged in the conversation - showing first the people you follow or you mostly engage with and an option to expand to get the whole list of people who interacted with the post. Maybe -this could be controversial- an AI-derived icon next to people's avatars in the list indicating if they agree or disagree with the original post.

I am using Firefox and after posting and trying to close the Compose prompt, there is a message indicating the content will be lost.

Atmospheric Measurement Techniques
Importance of size representation and morphology in modelling optical properties of black carbon: comparison between laboratory measurements and model simulations
Baseerat Romshoo, Mira P枚hlker, Alfred Wiedensohler, Sascha Pfeifer, Jorge Saturno, Andreas Nowak, Krzysztof Ciupek, Paul Quincey, Konstantina Vasilatou, Michaela N. Ess, Maria Gini, Konstantinos Eleftheriadis, Chris Robins, Fran莽ois Gaie-Levrel, Thomas M眉ller
December 6, 2022

Abstract. Black carbon (BC) from incomplete combustion of biomass or fossil fuels is the strongest absorbing aerosol component in the atmosphere. Optical properties of BC are essential in climate models for quantification of their impact on radiative forcing. The global climate models, however, consider BC to be spherical particles, which causes uncertainties in their optical properties. Based on this, an increasing number of model-based studies provide databases and parameterization schemes for the optical properties of BC, using more realistic fractal aggregate morphologies. In this study, the reliability of the different modelling techniques of BC was investigated by comparing them to laboratory measurements. The modelling techniques were examined for bare BC particles in the first step and for BC particles with organic material in the second step. A total of six morphological representations of BC particles were compared, three each for spherical and fractal aggregate morphologies. In general, the aggregate representation performed well for modelling the particle light absorption coefficient abs, single-scattering albedo SSA, and mass absorption cross-section MACBC for laboratory-generated BC particles with volume mean mobility diameters dp,V larger than 100鈥塶m. However, for modelling 脜ngstr枚m absorption exponent AAE, it was difficult to suggest a method due to size dependence, although the spherical assumption was in better agreement in some cases. The BC fractal aggregates are usually modelled using monodispersed particles, since their optical simulations are computationally expensive. In such studies, the modelled optical properties showed a 25鈥% uncertainty in using the monodisperse size method. It is shown that using the polydisperse size distribution in combination with fractal aggregate morphology reduces the uncertainty in measured abs to 10鈥% for particles with dp,V between 60鈥160鈥塶m.

Furthermore, the sensitivities of the BC optical properties to the various model input parameters such as the real and imaginary parts of the refractive index (mre and mim), the fractal dimension (Df), and the primary particle radius (app) of an aggregate were investigated. When the BC particle is small and rather fresh, the change in the Df had relatively little effect on the optical properties. There was, however, a significant relationship between app and the particle light scattering, which increased by a factor of up to 6 with increasing total particle size. The modelled optical properties of BC are well aligned with laboratory-measured values when the following assumptions are used in the fractal aggregate representation: mre between 1.6 and 2, mim between 0.50 and 1, Df from 1.7 to 1.9, and app between 10 and 14鈥塶m. Overall, this study provides experimental support for emphasizing the importance of an appropriate size representation (polydisperse size method) and an appropriate morphological representation for optical modelling and parameterization scheme development of BC.

Atmospheric Chemistry and Physics
Occurrence and growth of sub-50 nm aerosol particles in the Amazonian boundary layer
Marco A. Franco, Florian Ditas, Leslie A. Kremper, Luiz A. T. Machado, Meinrat O. Andreae, Alessandro Ara煤jo, Henrique M. J. Barbosa, Joel F. de Brito, Samara Carbone, Bruna A. Holanda, Fernando G. Morais, Jana铆na P. Nascimento, Mira L. P枚hlker, Luciana V. Rizzo, Marta S谩, Jorge Saturno, David Walter, Stefan Wolff, Ulrich P枚schl, Paulo Artaxo, Christopher P枚hlker
March 16, 2022

Abstract. New particle formation (NPF), referring to the nucleation of molecular clusters and their subsequent growth into the cloud condensation nuclei (CCN) size range, is a globally significant and climate-relevant source of atmospheric aerosols. Classical NPF exhibiting continuous growth from a few nanometers to the Aitken mode around 60鈥70鈥塶m is widely observed in the planetary boundary layer (PBL) around the world but not in central Amazonia. Here, classical NPF events are rarely observed within the PBL, but instead, NPF begins in the upper troposphere (UT), followed by downdraft injection of sub-50鈥塶m (CN<50) particles into the PBL and their subsequent growth. Central aspects of our understanding of these processes in the Amazon have remained enigmatic, however. Based on more than 6 years of aerosol and meteorological data from the Amazon Tall Tower Observatory (ATTO; February 2014 to September 2020), we analyzed the diurnal and seasonal patterns as well as meteorological conditions during 254 of such Amazonian growth events on 217 event days, which show a sudden occurrence of particles between 10 and 50鈥塶m in the PBL, followed by their growth to CCN sizes. The occurrence of events was significantly higher during the wet season, with 88鈥% of all events from January to June, than during the dry season, with 12鈥% from July to December, probably due to differences in the condensation sink (CS), atmospheric aerosol load, and meteorological conditions. Across all events, a median growth rate (GR) of 5.2鈥塶m鈥塰鈭1 and a median CS of 1.1鈥鈥10鈭3鈥塻鈭1 were observed. The growth events were more frequent during the daytime (74鈥%) and showed higher GR (5.9鈥塶m鈥塰鈭1) compared to nighttime events (4.0鈥塶m鈥塰鈭1), emphasizing the role of photochemistry and PBL evolution in particle growth. About 70鈥% of the events showed a negative anomaly of the equivalent potential temperature (e) 鈥 as a marker for downdrafts 鈥 and a low satellite brightness temperature (Tir) 鈥 as a marker for deep convective clouds 鈥 in good agreement with particle injection from the UT in the course of strong convective activity. About 30鈥% of the events, however, occurred in the absence of deep convection, partly under clear-sky conditions, and with a positive e anomaly. Therefore, these events do not appear to be related to downdraft transport and suggest the existence of other currently unknown sources of sub-50鈥塶m particles.

Summary report on the current state-of-the-art of Exhaust Flow Meter (EFM) calibration procedures, including (i) its associated uncertainty for relevant carrier gases and (ii) its relation to on-road emission tests
Menne Schakel, Wouter Stiphout, Mitra Zabihigivi, Rasmus Pettinen, Jorge Saturno
June 8, 2022
Deliverable 6 of the聽19ENV09 EMPIR project MetroPEMS "Summary report on the current state-of-the-art of Exhaust Flow Meter (EFM) calibration procedures, including (i) its associated uncertainty for relevant carrier gases and (ii) its relation to on-road emission tests"
MesSBAR鈥擬ulticopter and Instrumentation for Air Quality Research
Lutz Bretschneider, Andreas Schlerf, Anja Baum, Henning Bohlius, Marcel Buchholz, Sebastian D眉sing, Volker Ebert, Hassnae Erraji, Paul Frost, Ralf K盲thner, Thomas Kr眉ger, Anne Caroline Lange, Marcel Langner, Andreas Nowak, Falk P盲tzold, Julian R眉diger, Jorge Saturno, Hendrik Scholz, Tobias Schuldt, Rickmar Seldschopf, Andre Sobotta, Ralf Tillmann, Birgit Wehner, Christian Wesolek, Katharina Wolf, Astrid Lampert
Air quality measurements usually consist of ground-based instrumentation at fixed locations. However, vertical profiles of pollutants are of interest for understanding processes, distribution, dilution and concentration. Therefore, a multicopter system has been developed to investigate the vertical distribution of the concentration of aerosol particles, black carbon, ozone, nitrogen oxides (NOx) and carbon monoxide and the meteorological parameters of temperature and humidity. This article presents the requirements by different users, the setup of the quadrocopter system, the instrumentation and the results of first applications. The vertical distribution of particulate matter next to a highway was strongly related to atmospheric stratification, with different concentrations below and above the temperature inversion present in the morning. After the qualification phase described in this article, two identically equipped multicopters will be used upwind and downwind of line or diffuse sources such as highways or urban areas to quantify the influence of their emissions on the local air quality.
Atmospheric Chemistry and Physics
Optical properties of coated black carbon aggregates: numerical simulations, radiative forcing estimates, and size-resolved parameterization scheme
Baseerat Romshoo, Thomas M眉ller, Sascha Pfeifer, Jorge Saturno, Andreas Nowak, Krzysztof Ciupek, Paul Quincey, Alfred Wiedensohler
September 2, 2021

Abstract. The formation of black carbon fractal aggregates (BCFAs) from combustion and subsequent ageing involves several stages resulting in modifications of particle size, morphology, and composition over time. To understand and quantify how each of these modifications influences the BC radiative forcing, the optical properties of BCFAs are modelled. Owing to the high computational time involved in numerical modelling, there are some gaps in terms of data coverage and knowledge regarding how optical properties of coated BCFAs vary over the range of different factors (size, shape, and composition). This investigation bridged those gaps by following a state-of-the-art description scheme of BCFAs based on morphology, composition, and wavelength. The BCFA optical properties were investigated as a function of the radius of the primary particle (ao), fractal dimension (Df), fraction of organics (forganics), wavelength (), and mobility diameter (Dmob). The optical properties are calculated using the multiple-sphere T-matrix (MSTM) method. For the first time, the modelled optical properties of BC are expressed in terms of mobility diameter (Dmob), making the results more relevant and relatable for ambient and laboratory BC studies. Amongst size, morphology, and composition, all the optical properties showed the highest variability with changing size. The cross sections varied from 0.0001 to 0.1鈥m2 for BCFA Dmob ranging from 24 to 810鈥塶m. It has been shown that MACBC and single-scattering albedo (SSA) are sensitive to morphology, especially for larger particles with Dmob>鈥100鈥塶m. Therefore, while using the simplified core鈥搒hell representation of BC in global models, the influence of morphology on radiative forcing estimations might not be adequately considered. The 脜ngstr枚m absorption exponent (AAE) varied from 1.06 up to 3.6 and increased with the fraction of organics (forganics). Measurement results of AAE鈥鈥1 are often misinterpreted as biomass burning aerosol, it was observed that the AAE of purely black carbon particles can be 鈥1 in the case of larger BC particles. The values of the absorption enhancement factor (E) via coating were found to be between 1.01 and 3.28 in the visible spectrum. The E was derived from Mie calculations for coated volume equivalent spheres and from MSTM for coated BCFAs. Mie-calculated enhancement factors were found to be larger by a factor of 1.1 to 1.5 than their corresponding values calculated from the MSTM method. It is shown that radiative forcings are highly sensitive to modifications in morphology and composition. The black carbon radiative forcing FTOA (W鈥塵鈭2) decreases up to 61鈥% as the BCFA becomes more compact, indicating that global model calculations should account for changes in morphology. A decrease of more than 50鈥% in FTOA was observed as the organic content of the particle increased up to 90鈥%. The changes in the ageing factors (composition and morphology) in tandem result in an overall decrease in the FTOA. A parameterization scheme for optical properties of BC fractal aggregates was developed, which is applicable for modelling, ambient, and laboratory-based BC studies. The parameterization scheme for the cross sections (extinction, absorption, and scattering), single-scattering albedo (SSA), and asymmetry parameter (g) of pure and coated BCFAs as a function of Dmob were derived from tabulated results of the MSTM method. Spanning an extensive parameter space, the developed parameterization scheme showed promisingly high accuracy up to 98鈥% for the cross sections, 97鈥% for single-scattering albedos (SSAs), and 82鈥% for the asymmetry parameter (g).

Publishable Summary of 19ENV09 MetroPEMS - Improved vehicle exhaust quantification by portable emission measurement systems metrology
Jorge Saturno
December 1, 2020
Publishable Summary 19ENV09 MetroPEMS - Improved vehicle exhaust quantification by portable emission measurement systems metrology