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Article ; Online: The influence of solar-modulated regional circulations and galactic cosmic rays on global cloud distribution.

Kumar, Vinay / Dhaka, Surendra K / Hitchman, Matthew H / Yoden, Shigeo

2023 Volume 13, Issue 1, Page(s) 3707

Abstract: The influence of solar forcing and Galactic Cosmic Rays (GCR) ionization on the global distribution of clouds is investigated using 42 years ERA-5 data (1979-2020). In the mid-latitudes over Eurasia, GCR and cloudiness are negatively correlated, which ... ...

Abstract	The influence of solar forcing and Galactic Cosmic Rays (GCR) ionization on the global distribution of clouds is investigated using 42 years ERA-5 data (1979-2020). In the mid-latitudes over Eurasia, GCR and cloudiness are negatively correlated, which argues against the ionization theory of enhanced cloud droplet nucleation due to increased GCR during minima in the solar cycle. In the tropics, the solar cycle and cloudiness are positively correlated in regional Walker circulations below 2 km altitude. The phase relationship between amplification of regional tropical circulations and the solar cycle is consistent with total solar forcing, rather than modulation of GCR. However, in the intertropical convergence zone, changes in the cloud distribution are consistent with a positive coupling with GCR in the free atmosphere (2-6 km). This study opens some future challenges and research directions, and clarifies how atmospheric circulation at the regional scale can help in understanding solar-induced climate variability.
Language	English
Publishing date	2023-03-06
Publishing country	England
Document type	Journal Article
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-023-30447-9
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Nitrogen oxides concentration and emission change detection during COVID-19 restrictions in North India.

Misra, Prakhar / Takigawa, Masayuki / Khatri, Pradeep / Dhaka, Surendra K / Dimri, A P / Yamaji, Kazuyo / Kajino, Mizuo / Takeuchi, Wataru / Imasu, Ryoichi / Nitta, Kaho / Patra, Prabir K / Hayashida, Sachiko

Scientific reports

2021 Volume 11, Issue 1, Page(s) 9800

Abstract: COVID-19 related restrictions lowered particulate matter and trace gas concentrations across cities around the world, providing a natural opportunity to study effects of anthropogenic activities on emissions of air pollutants. In this paper, the impact ... ...

Abstract	COVID-19 related restrictions lowered particulate matter and trace gas concentrations across cities around the world, providing a natural opportunity to study effects of anthropogenic activities on emissions of air pollutants. In this paper, the impact of sudden suspension of human activities on air pollution was analyzed by studying the change in satellite retrieved NO
MeSH term(s)	Air Pollutants/analysis ; Air Pollution/analysis ; COVID-19/epidemiology ; COVID-19/prevention & control ; Cities ; Communicable Disease Control ; Environmental Monitoring ; Humans ; India/epidemiology ; Nitrogen Dioxide/analysis ; Nitrogen Oxides/analysis ; SARS-CoV-2/isolation & purification
Chemical Substances	Air Pollutants ; Nitrogen Oxides ; Nitrogen Dioxide (S7G510RUBH)
Language	English
Publishing date	2021-05-07
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-021-87673-2
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Very high particulate pollution over northwest India captured by a high-density in situ sensor network.

Singh, Tanbir / Matsumi, Yutaka / Nakayama, Tomoki / Hayashida, Sachiko / Patra, Prabir K / Yasutomi, Natsuko / Kajino, Mizuo / Yamaji, Kazuyo / Khatri, Pradeep / Takigawa, Masayuki / Araki, Hikaru / Kurogi, Yuki / Kuji, Makoto / Muramatsu, Kanako / Imasu, Ryoichi / Ananda, Anamika / Arbain, Ardhi A / Ravindra, Khaiwal / Bhardwaj, Sanjeev /

Kumar, Sahil / Mor, Sahil / Dhaka, Surendra K / Dimri, A P / Sharma, Aka / Singh, Narendra / Bhatti, Manpreet S / Yadav, Rekha / Vatta, Kamal / Mor, Suman

Scientific reports

2023 Volume 13, Issue 1, Page(s) 13201

Abstract: Exposure to particulate matter less than 2.5 µm in diameter ( ... ...

Abstract	Exposure to particulate matter less than 2.5 µm in diameter (PM
Language	English
Publishing date	2023-08-14
Publishing country	England
Document type	Journal Article
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-023-39471-1
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: PM

Dhaka, Surendra K / Chetna / Kumar, Vinay / Panwar, Vivek / Dimri, A P / Singh, Narendra / Patra, Prabir K / Matsumi, Yutaka / Takigawa, Masayuki / Nakayama, Tomoki / Yamaji, Kazuyo / Kajino, Mizuo / Misra, Prakhar / Hayashida, Sachiko

Scientific reports

2020 Volume 10, Issue 1, Page(s) 13442

Abstract: Delhi, a tropical Indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April 2020 ... ...

Abstract	Delhi, a tropical Indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April 2020 resulted in a dramatic near-zeroing of various activities (e.g. traffic, industries, constructions), except the "essential services". Here, we analysed variations in the fine particulate matter (PM
MeSH term(s)	Aerosols/analysis ; Air Pollutants/analysis ; Air Pollution/analysis ; Betacoronavirus ; COVID-19 ; Cities/epidemiology ; Coronavirus Infections/epidemiology ; Coronavirus Infections/prevention & control ; Coronavirus Infections/virology ; Environmental Monitoring/methods ; Humans ; India/epidemiology ; Ozone/analysis ; Pandemics/prevention & control ; Particulate Matter/analysis ; Pneumonia, Viral/epidemiology ; Pneumonia, Viral/prevention & control ; Pneumonia, Viral/virology ; Quarantine/methods ; SARS-CoV-2 ; Temperature ; Weather
Chemical Substances	Aerosols ; Air Pollutants ; Particulate Matter ; Ozone (66H7ZZK23N)
Keywords	covid19
Language	English
Publishing date	2020-08-10
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-020-70179-8
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Nitrogen oxides concentration and emission change detection during COVID-19 restrictions in North India

Prakhar Misra / Masayuki Takigawa / Pradeep Khatri / Surendra K. Dhaka / A. P. Dimri / Kazuyo Yamaji / Mizuo Kajino / Wataru Takeuchi / Ryoichi Imasu / Kaho Nitta / Prabir K. Patra / Sachiko Hayashida

Scientific Reports, Vol 11, Iss 1, Pp 1-

2021 Volume 11

Abstract: Abstract COVID-19 related restrictions lowered particulate matter and trace gas concentrations across cities around the world, providing a natural opportunity to study effects of anthropogenic activities on emissions of air pollutants. In this paper, the ...

Abstract	Abstract COVID-19 related restrictions lowered particulate matter and trace gas concentrations across cities around the world, providing a natural opportunity to study effects of anthropogenic activities on emissions of air pollutants. In this paper, the impact of sudden suspension of human activities on air pollution was analyzed by studying the change in satellite retrieved NO2 concentrations and top-down NOx emission over the urban and rural areas around Delhi. NO2 was chosen for being the most indicative of emission intensity due to its short lifetime of the order of a few hours in the planetary boundary layer. We present a robust temporal comparison of Ozone Monitoring Instrument (OMI) retrieved NO2 column density during the lockdown with the counterfactual baseline concentrations, extrapolated from the long-term trend and seasonal cycle components of NO2 using observations during 2015 to 2019. NO2 concentration in the urban area of Delhi experienced an anomalous relative change ranging from 60.0% decline during the Phase 1 of lockdown (March 25–April 13, 2020) to 3.4% during the post-lockdown Phase 5. In contrast, we find no substantial reduction in NO2 concentrations over the rural areas. To segregate the impact of the lockdown from the meteorology, weekly top-down NOx emissions were estimated from high-resolution TROPOspheric Monitoring Instrument (TROPOMI) retrieved NO2 by accounting for horizontal advection derived from the steady state continuity equation. NOx emissions from urban Delhi and power plants exhibited a mean decline of 72.2% and 53.4% respectively in Phase 1 compared to the pre-lockdown business-as-usual phase. Emission estimates over urban areas and power-plants showed a good correlation with activity reports, suggesting the applicability of this approach for studying emission changes. A higher anomaly in emission estimates suggests that comparison of only concentration change, without accounting for the dynamical and photochemical conditions, may mislead evaluation of lockdown impact. ...
Keywords	Medicine ; R ; Science ; Q
Subject code	333
Language	English
Publishing date	2021-05-01T00:00:00Z
Publisher	Nature Portfolio
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: PM2.5 diminution and haze events over Delhi during the COVID-19 lockdown period

Surendra K. Dhaka / Chetna / Vinay Kumar / Vivek Panwar / A. P. Dimri / Narendra Singh / Prabir K. Patra / Yutaka Matsumi / Masayuki Takigawa / Tomoki Nakayama / Kazuyo Yamaji / Mizuo Kajino / Prakhar Misra / Sachiko Hayashida

Scientific Reports, Vol 10, Iss 1, Pp 1-

an interplay between the baseline pollution and meteorology

2020 Volume 8

Abstract: Abstract Delhi, a tropical Indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April ...

Abstract	Abstract Delhi, a tropical Indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April 2020 resulted in a dramatic near-zeroing of various activities (e.g. traffic, industries, constructions), except the “essential services”. Here, we analysed variations in the fine particulate matter (PM2.5) over the Delhi-National Capital Region. Measurements revealed large reductions (by 40–70%) in PM2.5 during the first week of lockdown (25–31 March 2020) as compared to the pre-lockdown conditions. However, O3 pollution remained high during the lockdown due to non-linear chemistry and dynamics under low aerosol loading. Notably, events of enhanced PM2.5 levels (300–400 µg m−3) were observed during night and early morning hours in the first week of April after air temperatures fell close to the dew-point (~ 15–17 °C). A haze formation mechanism is suggested through uplifting of fine particles, which is reinforced by condensation of moisture following the sunrise. The study highlights a highly complex interplay between the baseline pollution and meteorology leading to counter intuitive enhancements in pollution, besides an overall improvement in air quality during the COVID-19 lockdown in this part of the world.
Keywords	Medicine ; R ; Science ; Q ; covid19
Subject code	333
Language	English
Publishing date	2020-08-01T00:00:00Z
Publisher	Nature Portfolio
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: PM2.5 diminution and haze events over Delhi during the COVID-19 lockdown period

Dhaka, Surendra K. / Chetna / Kumar, Vinay / Panwar, Vivek / Dimri, A. P. / Singh, Narendra / Patra, Prabir K. / Matsumi, Yutaka / Takigawa, Masayuki / Nakayama, Tomoki / Yamaji, Kazuyo / Kajino, Mizuo / Misra, Prakhar / Hayashida, Sachiko

Scientific Reports

an interplay between the baseline pollution and meteorology

2020 Volume 10, Issue 1

Keywords	Multidisciplinary ; covid19
Language	English
Publisher	Springer Science and Business Media LLC
Publishing country	us
Document type	Article ; Online
ZDB-ID	2615211-3
ISSN	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-020-70179-8
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Boundary layer evolution over the central Himalayas from radio wind profiler and model simulations

Singh, Narendra / Solanki, Raman / Ojha, Narendra / Janssen, Ruud H. H. / Pozzer, Andrea / Dhaka, Surendra K.

eISSN: 1680-7324

2016

Abstract: We investigate the time evolution of the Local Boundary Layer (LBL) for the first time over a mountain ridge at Nainital (79.5° E, 29.4° N, 1958 m a.m.s.l.) in the central Himalayan region, using a radar wind profiler (RWP) during November 2011 to March ... ...

Abstract	We investigate the time evolution of the Local Boundary Layer (LBL) for the first time over a mountain ridge at Nainital (79.5° E, 29.4° N, 1958 m a.m.s.l.) in the central Himalayan region, using a radar wind profiler (RWP) during November 2011 to March 2012, as a part of the Ganges Valley Aerosol Experiment (GVAX). We restrict our analysis to clear–sunny days, resulting in a total of 78 days of observations. The standard criterion of the peak in the signal-to-noise ratio ( S ∕ N ) profile was found to be inadequate in the characterization of mixed layer (ML) top at this site. Therefore, we implemented a criterion of S ∕ N > 6 dB for the characterization of the ML and the resulting estimations are shown to be in agreement with radiosonde measurements over this site. The daytime average (05:00–10:00 UTC) observed boundary layer height ranges from 440 ± 197 m in November (late autumn) to 766 ± 317 m above ground level (a.g.l.) in March (early spring). The observations revealed a pronounced impact of mountain topography on the LBL dynamics during March, when strong winds (> 5.6 m s −1 ) lead to LBL heights of 650 m during nighttime. The measurements are further utilized to evaluate simulations from the Weather Research and Forecasting (WRF) model. WRF simulations captured the day-to-day variations up to an extent ( r 2 = 0.5), as well as the mean diurnal variations (within 1 σ variability). The mean biases in the daytime average LBL height vary from −7 % (January) to +30 % (February) between model and observations, except during March (+76 %). Sensitivity simulations using a mixed layer model (MXL/MESSy) indicated that the springtime overestimation of LBL would lead to a minor uncertainty in simulated surface ozone concentrations. However, it would lead to a significant overestimation of the dilution of black carbon aerosols at this site. Our work fills a gap in observations of local boundary layer over this complex terrain in the Himalayas, and highlights the need for year-long simultaneous measurements of boundary layer dynamics and air quality to better understand the role of lower tropospheric dynamics in pollution transport.
Subject code	551
Language	English
Publishing date	2016-08-24
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Impact of quasi-biennial oscillation on the inter-annual variability of the tropopause height and temperature in the tropics: A study using COSMIC/FORMOSAT-3 observations

Kumar, V / A. Gupta / K.K. Reddy / M. Takahashi / Narendra Singh / S.B. Surendra Prasad / S.K. Dhaka / Shu-Peng Ho / V. Panwar

Atmospheric research. 2014 Mar. 15, v. 139

2014

Abstract: The effect of quasi-biennial oscillation (QBO) on the temperature of cold point tropopause (T-CPT) and its height (H-CPT) is being investigated using radio occultation measurements by COSMIC/FORMOSAT-3. Observations comprising of 935,863 numbers of ... ...

Abstract	The effect of quasi-biennial oscillation (QBO) on the temperature of cold point tropopause (T-CPT) and its height (H-CPT) is being investigated using radio occultation measurements by COSMIC/FORMOSAT-3. Observations comprising of 935,863 numbers of occultations have been used to study the zonal mean seasonal variability in T-CPT and H-CPT from January 2007 to December 2011. Results are shown over 30Â°Nâ30Â°S geographic latitudes. In general, T-CPT is found to be the coldest in February and the warmest in August. H-CPT attains maximum height during DecemberâFebruary and minimum during JulyâAugust. Interestingly, H-CPT shows maxima at off-equator region (around 20Â°N or 20Â°S) during all the seasons in both hemispheres. H-CPT at off-equatorial region, in reference to the equatorial region, is slightly higher (~1.0km) during winter as compared to monsoon season (~0.5km) in Northern Hemisphere (NH). Inter-annual variation in T-CPT and H-CPT found to be clearly influenced by the QBO. Westerly (easterly) phase generates warm (cold) T-CPT, which consequently results a decrease (increase) in H-CPT. It is concluded that QBO induces the changes in T-CPT by as much as 2Â°C and in H-CPT by 0.5km.
Keywords	cold ; latitude ; monsoon season ; radio ; seasonal variation ; temperature ; tropics ; tropopause ; winter
Language	English
Dates of publication	2014-0315
Size	p. 62-70.
Publishing place	Elsevier B.V.
Document type	Article
ISSN	0169-8095
DOI	10.1016/j.atmosres.2013.12.014
Database	NAL-Catalogue (AGRICOLA)

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