ALBERT

Description: The Pan-Third Pole (PTP) owns complex geography and demographic features where aerosol roles and their impact cannot be neglected as it jeopardizes both the environment and human health. Therefore, we analyzed spatio-temporal aerosol concentration, the influence of meteorological conditions, and underlying aerosol transport mechanisms over the PTP by leveraging observation, satellite dataset, and model outputs. The observation and model simulation result showed that aerosol concentrations exceeded the world health organization (WHO) and China guideline values in most of the locations. This study revealed distinctive seasonality with the highest and lowest aerosol concentrations during the winter and summer seasons, respectively, which could be favored by meteorological conditions and emissions from biomass burning. In response to higher aerosol concentrations, the maximum aerosol optical depth (AOD) values were observed over the major hotspot regions however, interestingly summer high (AOD 〉 0.8) was observed over the Indo Gangetic Plain (IGP) in South Asia. The columnar aerosol profile indicated that the higher aerosol concentrations were limited within 1–2 km elevation over the densely populated regions over South Asia and Eastern China. However, the significant aerosols concentrations found to be extended as high as 10 km could potentially be driven by the deep convection process and summer monsoon activities. Regionally, the integrated aerosol transport (IAT) for black carbon (BC) and organic carbon (OC) was found to be maximum over SA. Noticeable OC IAT anomaly (~5 times 〉 annual mean) found during spring that was linked with the biomass burning events. Yet, the dust transportation was found to be originated from the arid land and deserts that prolonged especially during summer followed by spring seasons. This study highlights the driver mechanism in aerosol seasonality, transport mechanism, and further motivates the additional assessment into potential dynamic relation between aerosol species, aerosol atmospheric river, and its societal impact.

Description: The location of Central Asia, almost at the center of the global dust belt region, makes it susceptible for dust events. The studies on atmospheric impact of dust over the region are very limited despite the large area occupied by the region and its proximity to the mountain regions (Tianshan, Hindu Kush-Karakoram-Himalayas, and Tibetan Plateau). In this study, we analyse and explain the modification in aerosols’ physical, optical and radiative properties during various levels of aerosol loading observed over Central Asia utilizing the data collected during 2010–2018 at the AERONET station in Dushanbe, Tajikistan. Aerosol episodes were classified as strong anthropogenic, strong dust and extreme dust. The mean aerosol optical depth (AOD) during these three types of events was observed a factor of ~3, 3.5 and 6.6, respectively, higher than the mean AOD for the period 2010–2018. The corresponding mean fine-mode fraction was 0.94, 0.20 and 0.16, respectively, clearly indicating the dominance of fine-mode anthropogenic aerosol during the first type of events, whereas coarse-mode dust aerosol dominated during the other two types of events. This was corroborated by the relationships among various aerosol parameters (AOD vs. AE, and EAE vs. AAE, SSA and RRI). The mean aerosol radiative forcing (ARF) at the top of the atmosphere (ARFTOA), the bottom of the atmosphere (ARFBOA), and in the atmosphere (ARFATM) were −35 ± 7, −73 ± 16, and 38 ± 17 Wm−2 during strong anthropogenic events, −48 ± 12, −85 ± 24, and 37 ± 15 Wm−2 during strong dust event, and −68 ± 19, −117 ± 38, and 49 ± 21 Wm−2 during extreme dust events. Increase in aerosol loading enhanced the aerosol-induced atmospheric heating rate to 0.5–1.6 K day−1 (strong anthropogenic events), 0.4–1.9 K day−1 (strong dust events) and 0.8–2.7 K day−1 (extreme dust events). The source regions of air masses to Dushanbe during the onset of such events are also identified. Our study contributes to the understanding of dust and anthropogenic aerosols, in particular the extreme events and their disproportionally high radiative impacts over Central Asia.

Description: The Tibetan Plateau is a global hotspot of stratospheric intrusion, and elevated surface ozone was observed at ground monitoring sites. Still, links between the variability of surface ozone and stratospheric intrusion at the regional scale remain unclear. This study synthesized ground measurements of surface ozone over the Tibetan Plateau and analyzed their seasonal variations. The monthly mean surface ozone concentrations over the Tibetan Plateau peaked earlier in the south in April and May and later in the north in June and July. The migration of monthly surface ozone peaks was coupled with the synchronous movement of tropopause folds and the westerly jet that created conditions conducive to stratospheric ozone intrusion. Stratospheric ozone intrusion significantly contributed to surface ozone across the Tibetan Plateau, especially in the areas with high surface ozone concentrations during their peak-value month. We demonstrated that monthly variation of surface ozone over the Tibetan Plateau is mainly controlled by stratospheric intrusion, which warrants proper consideration in understanding the atmospheric chemistry and the impacts of ozone over this highland region and beyond.

Description: Urban agriculture, including peri-urban farming, can nourish around one billion city dwellers and provide multiple social, economic, and environmental benefits. However, these benefits depend on various factors and are debated. Therefore, we used machine learning to semi-automate a systematic review of the existing literature on urban agriculture. It started with around 76,000 records for initial screening based on a broad keyword search strategy. We applied the topic modeling approach to systematically understand various aspects of urban agriculture based on the full text of around 1450 relevant publications. Urban agriculture literature covers 14 topics, clustered into 11 themes related to urban agriculture forms, their multi-functionalities, and their underlying challenges. These forms are small-scale ground-based and building-integrated systems. The multifunctionalities include food, livelihoods, health benefits, social space, green infrastructure, biodiversity, and ecosystem services. Therefore, promoting urban agriculture requires accounting for its multi-functionalities, besides food provisioning,and encouraging efficient and sustainable practices.