This work investigates the meteorological mechanisms forming a classical frontal system on 26 August 2020 in the northeast and eastern parts of Afghanistan. The weather system caused heavy rainfall and led to severe flash floods. Flooding, affected by torrential rain showers, struck mostly the city of Charikar in Parvan province early in the morning day, while most people were asleep. This caused 150 deaths, and nearly 500 houses were destroyed. This research explores atmospheric processes by examining the National Centers for Environmental Prediction dataset and MERRA Model database. The calculation of the convective available potential energy (CAPE) and Showalter index extracted from the Skew-T log-pressure diagram shows a high value of the CAPE at around 2,632 J/kg and −6.6 for the Showalter index, respectively. This presents a very extreme instability in the study area during the time of the flood. The study reveals that the triggering of this system was mostly by thermodynamical aspects, low-level deep convergence, and local topographical aspects rather than the PV streamer. However, the anomaly climate analysis for different atmospheric elements with a comparison of the climate normal values shows the importance of climate change in the weather system into a stronger frontal activity associated with stronger baroclinicity over the study area.

Most major field campaigns, such as the Southern Africa Fire Atmosphere Research Initiative (SAFARI-92 and SAFARI-2000) and AErosol, RadiatiOn and CLOuds in southern Africa (AEROCLO-sA), have focused on the west coast of southern Africa, leaving the east coast underexplored. To address this, the Biomass Burning Aerosol Campaign (BiBAC) was initiated by the IRP ARSAIO (International Research Project – Atmospheric Research in Southern Africa and Indian Ocean) during the 2022 biomass burning season to study aerosol optical properties over southern Africa and the southwestern Indian Ocean (SWIO). This study analyzes aerosol properties during the intensive observation period (IOP) of BiBAC at Skukuza in Kruger National Park during two events: 18–23 September (Event 1) and 9–17 October (Event 2). Sun-photometer data, consistent with CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization), revealed a predominance of biomass burning aerosols. Transport analyses show southeastward movement of carbon monoxide (CO) and aerosols, reaching up to 6 km during Event 1 and 10 km during Event 2. Synoptic conditions, including frontal systems and baroclinic waves, drove regional and intercontinental pollutant transport, impacting the Mozambique Channel and surrounding areas. A “river of smoke” observed in Event 1 suggests novel synoptic conditions compared to previous studies. This study is the first to highlight two distinct transport mechanisms of aerosol plumes and CO from southern Africa and South America toward the SWIO basin, underscoring the significance of east-coast observations in understanding regional and global atmospheric dynamics.

Introduction: Poor air quality in the heavily polluted cities like Tehran is often the main city problem that influences people health and comfort. The main goals of this study are summarized as: 1) Seasonal pollutants mean variations during 2005, meteorological conditions effects on pollutant concentration; 2) Meteorological conditions case study and pollution spatial distribution for three determining synoptic patterns (MET1, MET4, MET5); 3) Further analysis of the episode from 30th November to 13th December 2005 (MET4); 4) Episode analysis from 30th November to 13th December 2005 (MET4) and 5) Episode analysis from 12th-22th of September 2005 (MET5). These are systematic weather patterns that usually affect the air pollution levels in Tehran. Materials and methods: Concentration changes of CO, PM10, SO2 and O3, as the relationship between the air pollution extreme events and atmospheric conditions in Tehran have been investigated. The hourly air pollution data from 11 representative monitoring sites were used. To understand the relationship between local meteorological synoptic patterns and air pollution, the principal component analysis (PCA) method has been applied to meteorological data. Then for minimizing the data complication the varimax rotations (VR) was used and five synoptic perspectives weather patterns have resulted for highly polluted periods. Results: Pollutants correlation investigation of the five patterns showed that air quality was highly dependent on middle tropospheric high geopotential ridge development, local southerly wind with strong static stability. Conclusion: The most polluted periods were associated with a weak pressure gradient, a weak wind, severe air descent, and radiation inversion.