Water vapor in cold and clean atmosphere: a 3-year data set in the boundary layer of Dome C, East Antarctic Plateau

The air at the surface of the high Antarctic Plateau is very cold, dry and clean. In such conditions the atmospheric moisture can significantly deviate from thermodynamic equilibrium conditions, and supersaturation with respect to ice can occur. Most conventional humidity sensors for meteorological applications cannot report supersaturation in this environment. A simple approach for measuring supersaturation using conventional instruments, one being operated in a heated airflow, is presented. Since 2018, this instrumental setup was deployed at 3 levels in the lower ~40 m above the surface at Dome C on the high Antarctic Plateau. The 3-year 2018–2020 record (Genthon et al. 2021) is presented and analyzed for features such as the frequency of supersaturation with respect to ice, diurnal and seasonal variability, and vertical distribution. As supercooled liquid water droplets are frequently observed in clouds at the temperatures met on the high Antarctic Plateau, the distribution of relative humidity with respect to liquid water at Dome C is also discussed. It is suggested that, while not strictly mimicking the conditions of the high troposphere, the surface atmosphere on the Antarctic Plateau is a convenient natural laboratory to test parametrizations of cold microphysics predominantly developed to handle the genesis of high tropospheric clouds. Data are distributed on the PANGAEA data repository at https://doi.pangaea.de/10.1594/PANGAEA.939425 (Genthon et al., 2021).

ONE-YEAR ANALYSIS OF MEASUREMENTS WITH SOLAR PHOTOMETER IN THENORTHWEST OF GREAT BUENOS AIRES AREA

This paper presents a first photometric study of the aerosol charge in the northwest of Great Buenos Aires area, spe-cifically on the campus of the National University of General Sarmiento (UNGS) in Los Polvorines. For this purpose,one year of manual measurements with a solar photometer has been used and the aerosol optical depth (AOD) calcu-lations were corroborated with the Lambert-Beer law. The results of the AOD histogram at 465 nm and the Ångstrom coefficient vs AOD are related to the study area characteristics, with a clean atmosphere and aerosols categorized in the“clean continental” and “average” groups.

A new balance formula to estimate new particle formation rate: reevaluating the effect of coagulation scavenging

A new balance formula to estimate new particle formation rate is proposed. It is derived from the aerosol general dynamic equation in the discrete form and then converted into an approximately continuous form for analyzing data from new particle formation (NPF) field campaigns. The new formula corrects the underestimation of the coagulation scavenging effect that occurred in the previously used formulae. It also clarifies the criteria for determining the upper size bound in measured aerosol size distributions for estimating new particle formation rate. An NPF field campaign was carried out from 7 March to 7 April 2016 in urban Beijing, and a diethylene glycol scanning mobility particle spectrometer equipped with a miniature cylindrical differential mobility analyzer was used to measure aerosol size distributions down to ∼ 1 nm. Eleven typical NPF events were observed during this period. Measured aerosol size distributions from 1 nm to 10 µm were used to test the new formula and the formulae widely used in the literature. The previously used formulae that perform well in a relatively clean atmosphere in which nucleation intensity is not strong were found to underestimate the comparatively high new particle formation rate in urban Beijing because of their underestimation or neglect of the coagulation scavenging effect. The coagulation sink term is the governing component of the estimated formation rate in the observed NPF events in Beijing, and coagulation among newly formed particles contributes a large fraction to the coagulation sink term. Previously reported formation rates in Beijing and in other locations with intense NPF events might be underestimated because the coagulation scavenging effect was not fully considered; e.g., estimated formation rates of 1.5 nm particles in this campaign using the new formula are 1.3–4.3 times those estimated using the formula neglecting coagulation among particles in the nucleation mode.

The Impact of Gas Flaring On Man and His Environment and the Way Out

The nature of flaring processes has created a severe impact on man and the environment. Massive environmental degradation as a result of flaring activities has led to fluctuations in climate as well as depletion of the vegetation cover through acid rain. Findings have been made on some harmful gases released into the atmosphere that have effects on the environment and also on man. In order to control these effects by ensuring a clean atmosphere and environment, a new flaring model (DanMat flaring model) has been suggested. The model uses smoldering mechanism to reduce the amount of heat released into the atmosphere during conventional flaring by 60%. It also uses scavengers to oxidize harmful gas produced during flaring activities into less harmful ones. With this model one can flare gas without polluting the environment since it reduces the emissions of harmful gases during flaring.

A new balance formula to estimate new particle formation rate: reevaluating the effect of coagulation scavenging

A new balance formula to estimate new particle formation rate is proposed. It was derived from aerosol general dynamic equation in the discrete form and then converted into an approximately continuous form for analysing data from new particle formation (NPF) field campaigns. The new formula corrects the underestimation of the coagulation scavenging effect occurred in previously used formulae. It also clarifies the criterions in determining upper size bound in measured aerosol size distributions for estimating new particle formation rate. A NPF field campaign was carried out from March 7th to Apr. 7th, 2016, in urban Beijing, and a diethylene glycol scanning mobility particle spectrometer equipped with a miniature cylindrical differential mobility analyser was used to measure aerosol size distributions down to ~1 nm. 11 typical NPF events were observed during this period. Measured aerosol size distributions from 1 nm to 10 μm was used to test the new formula and those widely used ones. Previously used formulae that perform well in relatively clean atmosphere where nucleation intensity is not strong were found to underestimate the comparatively high new particle formation rate in urban Beijing because of their underestimation or neglect of the coagulation scavenging effect. Coagulation sink term is the governing component of the estimated formation rate in the observed NPF events in Beijing, and coagulation among newly formed particles contributes a large fraction to the coagulation sink term. Previously reported formation rates in Beijing and in other locations with intense NPF events might be underestimated because the coagulation scavenging effect was not fully considered, e.g., formation rates of 1.5 nm particles in Beijing are underestimated by 58.9 % on average if neglecting coagulation among particles in nucleation mode.

The atmospheric oxidation of dimethyl, diethyl, and diisopropyl ethers. The role of the intramolecular hydrogen shift in peroxy radicals

Ethers can be auto-oxidized with no O3 formation in a ‘clean’ atmosphere.

Critical Success Factors for Franchised Restaurants Entering the Kenyan Market: Customers’ Perspective

This article seeks to determine the critical success factors for franchised restaurants entering the Kenyan market from the customers’ perspective. We used a quantitative methodology by taking a survey. The respondents were identified using convenience sampling. A sample of 389 franchised restaurant customers was drawn and a response rate of 98.7% was obtained. It is suggested that the critical success factors for franchised restaurants from customers’ perspective include good and consistent products and product range (menu mix), competent staff who were clean, warm, courteous and welcoming, a pleasant and clean atmosphere, reasonable and stable prices of products and a convenient location with efficient service. This paper has added value in theory by identifying the critical success factors for franchised restaurants entering the Kenyan market from customers’ perspective. The findings can be used by restaurant franchises that seek to establish successful businesses in the Kenyan market and other similar regional markets.