Aerosol Observations at High Altitude Stations

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Aerosols".

Deadline for manuscript submissions: closed (31 July 2021) | Viewed by 7635

Special Issue Editors


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Guest Editor
Finnish Meteorological Institute, 00560 Helsinki, Finland
Interests: atmospheric aerosol observations, boundary layer dynamics and linkages with climate change and human health; aerosol-cloud interactions, and their impact on precipitation and hydrological cycle; model-observation studies of aerosols, their source apportionment and climate effects

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Guest Editor
Atmospheric Science Division, Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital 263001, India
Interests: atmospheric aerosol observation; black carbon; radiative and climate impact; in situ and remote sensing aerosols; radiation; aerosol–cloud interactions; carbonaceous aerosols; source apportionment; secondary aerosol formations; air pollution; specific phenomena like dust storms and biomass burning; solar energy
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Special Issue Information

Dear Colleagues,

Atmospheric aerosol observations at high-altitude stations provide an opportunity to collect information on background aerosol properties in a larger area, trends in aerosol concentrations and properties, and data for validating models. Moreover, these stations are important for studying the climatology of aerosols’ radiative properties and the influence of regional sources and processes. However, it is well-known that the high-altitude stations designed to measure the free troposphere are, to some extent, influenced by the transport of boundary layer air masses. The atmospheric structure becomes much more complicated over mountainous terrain, and even a universal definition of convective boundary layer (CBL) height over mountains remains an ambiguous issue. While station altitude may not be the main parameter explaining the CBL influence, topographical features around the station are nevertheless involved in the CBL development, and in the formation of thermally induced winds leading to CBL air lifting. The diurnal evolution of CBL exhibits significant variability between different environments, which makes measuring and modeling aerosol processes a very demanding task. The processes occur with temporal scales ranging from hours to one day, and with spatial scales ranging from hundreds of meters to kilometers vertically and up to 100 km horizontally, and their study is inevitable.

This Special Issue of Atmosphere (ISSN 2073-4433) brings together scientists using in-situ and ex-situ methods to monitor and investigate aerosol properties, processes, and modeling, and the structures and processes of boundary layer dynamics in mountainous environments.

Prof. Dr. Rakesh Hooda
Dr. Umesh Chandra Dumka
Guest Editors

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Keywords

  • high altitude
  • aerosol
  • climatology
  • meteorology
  • phenomenon and processes
  • black carbon
  • boundary layer
  • himalayan mountain
  • arctic
  • elevated aerosols

Published Papers (2 papers)

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Research

18 pages, 9891 KiB  
Article
Impacts of Aerosol Loading in the Hindu Kush Himalayan Region Based on MERRA-2 Reanalysis Data
by Shantikumar S. Ningombam, Umesh Chandra Dumka, Sivasamy Kalamani Mugil, Jagdish Chandra Kuniyal, Rakesh K. Hooda, Alok Sagar Gautam and Suresh Tiwari
Atmosphere 2021, 12(10), 1290; https://doi.org/10.3390/atmos12101290 - 03 Oct 2021
Cited by 3 | Viewed by 2395
Abstract
The impacts of climate change have severely affected geosphere, biosphere and cryosphere ecosystems in the Hindu Kush Himalayan (HKH) region. The impact has been accelerating further during the last few decades due to rapid increase in anthropogenic activities such as modernization, industrialization and [...] Read more.
The impacts of climate change have severely affected geosphere, biosphere and cryosphere ecosystems in the Hindu Kush Himalayan (HKH) region. The impact has been accelerating further during the last few decades due to rapid increase in anthropogenic activities such as modernization, industrialization and urbanization, along with energy demands. In view of this, the present work attempts to examine aerosol optical depth (AOD) over the HKH region using the long-term homogeneous MERRA-2 reanalysis data from January, 1980 to December, 2020. The AOD trends are examined statistically with student’s t-test (t). Due to a vast landmass, fragile topography and harsh climatic conditions, we categorized the HKH region into three sub-regions, namely, the northwestern and Karakoram (HKH1), the Central (HKH2) and the southeastern Himalaya and Tibetan Plateau (HKH3). Among the sub-regions, the significant enhancement of AOD is observed at several potential sites in the HKH2 region, namely, Pokhara, Nainital, Shimla and Dehradun by 55.75 × 104 ± 3.76 × 104, 53.15 × 104 ± 3.94 × 104, 51.53 × 104 ± 4.99 × 104 and 39.16 × 104 ± 4.08 × 104 AOD year1 (550 nm), respectively, with correlation coefficients (Rs) of 0.86 to 0.93. However, at a sub-regional scale, HKH1, HKH2 and HKH3 exhibit 23.33 × 104 ± 2.28 × 104, 32.20 × 104 ± 2.58 × 104 and 9.48 × 104 ± 1.21 × 104 AOD year1, respectively. The estimated trends are statistically significant (t > 7.0) with R from 0.81 to 0.91. Seasonally, the present study also shows strong positive AOD trends at several potential sites located in the HKH2 region, such as Pokhara, Nainital, Shimla and Dehradun, with minimum 19.81 × 104 ± 3.38 × 104 to maximum 72.95 × 104 ± 4.89 × 104 AOD year1 with statistical significance. In addition, there are also increasing AOD trends at all the high-altitude background sites in all seasons. Full article
(This article belongs to the Special Issue Aerosol Observations at High Altitude Stations)
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20 pages, 4640 KiB  
Article
Chemical Composition and Source Apportionment of Total Suspended Particulate in the Central Himalayan Region
by Rahul Sheoran, Umesh Chandra Dumka, Dimitris G. Kaskaoutis, Georgios Grivas, Kirpa Ram, Jai Prakash, Rakesh K. Hooda, Rakesh K. Tiwari and Nikos Mihalopoulos
Atmosphere 2021, 12(9), 1228; https://doi.org/10.3390/atmos12091228 - 19 Sep 2021
Cited by 14 | Viewed by 3953
Abstract
The present study analyzes data from total suspended particulate (TSP) samples collected during 3 years (2005–2008) at Nainital, central Himalayas, India and analyzed for carbonaceous aerosols (organic carbon (OC) and elemental carbon (EC)) and inorganic species, focusing on the assessment of primary and [...] Read more.
The present study analyzes data from total suspended particulate (TSP) samples collected during 3 years (2005–2008) at Nainital, central Himalayas, India and analyzed for carbonaceous aerosols (organic carbon (OC) and elemental carbon (EC)) and inorganic species, focusing on the assessment of primary and secondary organic carbon contributions (POC, SOC, respectively) and on source apportionment by positive matrix factorization (PMF). An average TSP concentration of 69.6 ± 51.8 µg m−3 was found, exhibiting a pre-monsoon (March–May) maximum (92.9 ± 48.5 µg m−3) due to dust transport and forest fires and a monsoon (June–August) minimum due to atmospheric washout, while carbonaceous aerosols and inorganic species expressed a similar seasonality. The mean OC/EC ratio (8.0 ± 3.3) and the good correlations between OC, EC, and nss-K+ suggested that biomass burning (BB) was one of the major contributing factors to aerosols in Nainital. Using the EC tracer method, along with several approaches for the determination of the (OC/EC)pri ratio, the estimated SOC component accounted for ~25% (19.3–29.7%). Furthermore, TSP source apportionment via PMF allowed for a better understanding of the aerosol sources in the Central Himalayan region. The key aerosol sources over Nainital were BB (27%), secondary sulfate (20%), secondary nitrate (9%), mineral dust (34%), and long-range transported mixed marine aerosol (10%). The potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analyses were also used to identify the probable regional source areas of resolved aerosol sources. The main source regions for aerosols in Nainital were the plains in northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area. The outcomes of the present study are expected to elucidate the atmospheric chemistry, emission source origins, and transport pathways of aerosols over the central Himalayan region. Full article
(This article belongs to the Special Issue Aerosol Observations at High Altitude Stations)
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