Variations of Aerosol Optical Depth in Bhaktapur, Nepal

Sharma, Niranjan Prasad

doi:10.3126/jie.v13i1.20358

Cited by 4 publications

(3 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This means that the submicron aerosol particle is dominant in this vicinity than that of coarse mode aerosol. The dominance of shorter wavelength AOD was also reported in different literatures [7,33,34]. Minimum aerosols loading in the atmosphere was observed during the month of January, which may be due to the weak generation mechanisms as well as the colder ground surface.…”

Section: Diurnal Variation Of Mean Aodsupporting

confidence: 74%

Influence of COVID-19 Lockdown on Aerosol Optical Depth over Pokhara and Kyanjin Gompa in Nepal

Silwal

Gautam

Karki

et al. 2021

Preprint

View full text Add to dashboard Cite

The outbreak of the COVID-19 pandemic and the subsequent global economic shutdown provided an opportunity to conduct a real-time experiment assessing the influence of global emission reductions in the Aerosol Optical Depth (AOD) level, an indicator of air pollution over Nepal. Nepal's government imposed a lockdown on the country for approximately three months (from 24 March onwards) in 2020. The purpose of this study is to examine the temporal fluctuation in Aerosol Optical Depth (AOD) caused by the COVID-19 shutdown by comparing its value during the same time period of the past year over two sites: Pokhara and Kyanjin Gompa. We comparatively analyzed the variation of diurnal mean and monthly average AOD of two selected sites, from the month of January to May 2020 and January to May 2018. By examining the time-series graph of daily average AOD prior to and during the lockdown period, our study showed an apparent fluctuation in AOD throughout the studied areas. The major findings of the research revealed that after the lockdown, a significant variation in monthly averaged AOD was observed, ranging from 20–60% deviation over Pokhara and 25–50% deviation in Kyanjin Gompa at different wavelengths. This confirms previous studies on aerosols and other particulate matter during COVID-19 lockdown, as well as theoretical assumptions. In addition, we performed the heatmap correlation analysis among AOD, Total precipitable water (Tpw), Angstrom exponent (α), Turbidity coefficient (β), and Visibility (V) during the studied period with possible explanations. We believe this research work serves as a crucial reference for our government to implement appropriate policies for pollution control over the studied areas in the future.

show abstract

Section: Diurnal Variation Of Mean Aodsupporting

confidence: 74%

Influence of COVID-19 Lockdown on Aerosol Optical Depth over Pokhara and Kyanjin Gompa in Nepal

Silwal

Gautam

Karki

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…5 the other channels have a bandwidth of 10 nm (Sharma, 2018;Tiwari et al, 2018). The full field of view of the instrument is 2.5°.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Aerosols over the Foothills of the Eastern Himalayan Region during Post-monsoon and Winter Seasons

Dahal

Rupakheti

Sharma

et al. 2022

Aerosol Air Qual. Res.

View full text Add to dashboard Cite

In this study a Microtops II sunphotometer is used for the first time over Birtamode, a rapidly growing city located in the eastern Himalayan foothills of Nepal, to measure aerosol optical depth (AOD). The average AOD for the observation period (October 2018 -February 2019) was 0.68 ± 0.39 with the post-monsoon season having a higher value (0.74 ± 0.43) compared to the winter season (0.60 ± 0.32). The Angstrom exponent (α) for post-monsoon and winter are found to be 1.08 ± 0.10 and 1.11 ± 0.16 respectively. During the monitoring period, the majority of AOD values (47%) are above 0.60, indicating moderately polluted conditions in the region. Anthropogenic, biomass burning, and mixed aerosols are identified as the prevalent aerosol types in the study region. The observed aerosol classification is also explained in terms of CAMS near-real-time model datasets. The AOD values retrieved by MODIS, VIIRS, Himawari-8, and CAMS show a good correlation with the observed Microtops AOD with R 2 values ranging from 0.60 to 0.94. Moreover, different MODIS aerosol products (DB, DT, and combined DB-DT) are evaluated based on a comparison of Collection 6.1 AOD with the ground truth obtained from Microtops. The spatial distribution of AOD as observed by various satellites are compared and the vertical distribution of aerosol is also explained with the extinction coefficient provided by the CALIOP lidar onboard CALIPSO and aerosol types provided by CAMS.

show abstract

“…We used a hand-held Microtops II sunphotometer (manufactured by Solar Light Company Inc., USA) containing five different interference filters at 340-, 440-, 500-, 675-, and 870 nm wavelengths and provides columnar information about aerosols. The sunphotometer works on the principle of extinction of solar radiation intensity at a certain wavelength and has the bandwidth of 2 nm at a 340 nm channel and 10 nm for rest of channels [8] [9]. The instrument has five accurately aligned optical collimators with 2.5° as a full field of view.…”

Section: B Instrumentationmentioning

confidence: 99%

Festival Induced Air Quality Perturbation over an Urban Center in Eastern Nepal

Dahal

Bhattarai

Rupakheti

et al. 2022

J. Lumbini Eng. Coll.

View full text Add to dashboard Cite

An attempt has been made to investigate the changes in the characteristics of aerosol optical properties and a columnar load of carbon monoxide (CO) induced during the Dashain celebration 2018 over Birtamode, Nepal. Ground-based measurements of Aerosol Optical Depth (AOD) were carried out using a Microtops II sun-photometer during 13th to 25th Oct, 2018. AOD values on days before Dashain were in the range of 0.6 which increased above 1 attaining a maximum value of 1.6 on 19th. The AOD values started dropping below 1 on 24th, attaining a daily average of 0.64. The peak values on the respective days were also captured by Moderate Resolution Imaging Spectroradiometer (MODIS) AOD retrievals. A similar pattern was observed with the TROPOspheric Measuring Instrument (TROPOMI) CO column with peak value on the 19th. The air mass trajectories show that the increase in the AOD and CO values is of local origin and the CAMS GFAS wildfire flux of CO and PM2.5 show no change during the study period. However, the spatial analysis of AOD shows that the increased values are of regional nature. The results highlight the necessity of installation of low-cost air quality sensors in the region and utilization of aerosol and trace gaseous products derived from satellite remote sensing instruments at high temporal resolution and the application of chemical transport models.

show abstract

Variations of Aerosol Optical Depth in Bhaktapur, Nepal

Cited by 4 publications

References 9 publications

Influence of COVID-19 Lockdown on Aerosol Optical Depth over Pokhara and Kyanjin Gompa in Nepal

Influence of COVID-19 Lockdown on Aerosol Optical Depth over Pokhara and Kyanjin Gompa in Nepal

Aerosols over the Foothills of the Eastern Himalayan Region during Post-monsoon and Winter Seasons

Festival Induced Air Quality Perturbation over an Urban Center in Eastern Nepal

Contact Info

Product

Resources

About