scholarly journals Size-selected black carbon mass distributions and mixing state in polluted and clean environments of northern India

2017 ◽  
Vol 17 (1) ◽  
pp. 371-383 ◽  
Author(s):  
Tomi Raatikainen ◽  
David Brus ◽  
Rakesh K. Hooda ◽  
Antti-Pekka Hyvärinen ◽  
Eija Asmi ◽  
...  
Keyword(s):  
Black Carbon ◽  
Detailed Examination ◽  
Mixing State ◽  
Gangetic Plain ◽  
Particle Properties ◽  
Mass Distributions ◽  
Northern India ◽  
Source Regions ◽  
Himalayan Foothills ◽  
Carbon Mass

Abstract. We have measured black carbon properties by using a size-selected single-particle soot photometer (SP2). The measurements were conducted in northern India at two sites: Gual Pahari is located at the Indo-Gangetic Plain (IGP) and Mukteshwar at the Himalayan foothills. Northern India is known as one of the absorbing aerosol hot spots, but detailed information about absorbing aerosol mixing state is still largely missing. Previous equivalent black carbon (eBC) mass concentration measurements are available for this region, and these are consistent with our observations showing that refractory black carbon (rBC) concentrations are about 10 times higher in Gual Pahari than those at Mukteshwar. Also, the number fraction of rBC-containing particles is higher in Gual Pahari, but individual rBC-containing particles and their size distributions are fairly similar. These findings indicate that particles at both sites have similar local and regional emission sources, but aerosols are also transported from the main source regions (IGP) to the less polluted regions (Himalayan foothills). Detailed examination of the rBC-containing particle properties revealed that they are most likely irregular particles such as fractal aggregates, but the exact structure remains unknown.

scholarly journals Size-selected black carbon mass distributions and mixing state in polluted and clean environments of northern India

2016 ◽  
Author(s):  
Tomi Raatikainen ◽  
David Brus ◽  
Rakesh K. Hooda ◽  
Antti-Pekka Hyvärinen ◽  
Eija Asmi ◽  
...  
Keyword(s):  
Black Carbon ◽  
Detailed Examination ◽  
Mixing State ◽  
Particle Properties ◽  
Mass Distributions ◽  
Northern India ◽  
Source Regions ◽  
Himalayan Foothills ◽  
Carbon Mass ◽  
Aerosol Mixing State

Abstract. We have measured black carbon properties by using a size-selected Single Particle Soot Photometer (SP2). The measurements were conducted in northern India at two sites: Gual Pahari is located at the Indo-Gangetic plains (IGP) and Mukteshwar at the Himalayan foothills. Northern India is known as one of the absorbing aerosol hot spots, but detailed information about absorbing aerosol mixing state is still largely missing. Previous black carbon mass concentration measurements are available for this region and these are consistent with our observations showing that refractory black carbon (rBC) concentrations are about ten times higher in Gual Pahari than those at Mukteshwar. Also the number fraction of absorbing particles is higher in Gual Pahari, but individual absorbing particles including their size distributions are fairly similar. These findings indicate that particles at both sites have similar local and regional emission sources, but aerosols are also transported from the main source regions (IGP) to the less polluted regions (Himalayan foothills). Detailed examination of the absorbing particle properties revealed that they are most likely fractal aggregates, but the exact structure remains unknown.

scholarly journals Black Carbon physical and optical properties across northern India during pre-monsoon and monsoon seasons

2019 ◽  
Author(s):  
James Brooks ◽  
Dantong Liu ◽  
James D. Allan ◽  
Paul I. Williams ◽  
Jim Haywood ◽  
...  
Keyword(s):  
Physical Properties ◽  
Black Carbon ◽  
Mixing State ◽  
Atmospheric Measurements ◽  
Core Diameter ◽  
Gangetic Plain ◽  
North West ◽  
North East ◽  
Northern India ◽  
Indo Gangetic Plain

Abstract. Black carbon (BC) is known to have major impacts on both climate and human health, so is therefore of global importance, particularly so in regions close to large populations that have strong sources. The physical properties and mixing state of black carbon containing particles are important determinants in these effects but information is often lacking, particularly in some of the most important regions of the globe. Detailed analysis into the vertical and horizontal BC optical and physical properties across northern India has been carried out using airborne in-situ measurements. The size-resolved mixing state of BC-containing particles was characterised using a single particle soot photometer (SP2). The study focusses on the Indo-Gangetic Plain during the pre-monsoon and monsoon seasons. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights during the pre-monsoon (11th and 12th June) and monsoon (30th June to 11th July) seasons of 2016. Over the Indo-Gangetic Plain, BC mass concentrations were greater (1.95 µg/m3) compared to north-west India (1.50 µg/m3) and north-east India (0.70 µg/m3) during the pre-monsoon. Across northern India, two distinct BC modes were recorded; a mode of small BC particles (core diameter 

scholarly journals Black carbon concentrations and mixing state in the Finnish Arctic

2015 ◽  
Vol 15 (17) ◽  
pp. 10057-10070 ◽  
Author(s):  
T. Raatikainen ◽  
D. Brus ◽  
A.-P. Hyvärinen ◽  
J. Svensson ◽  
E. Asmi ◽  
...  
Keyword(s):  
Black Carbon ◽  
Particle Diameter ◽  
The Arctic ◽  
Mixing State ◽  
Core Mass ◽  
Source Regions ◽  
Mean Diameter ◽  
Absorbing Material ◽  
Optically Detected ◽  
Core Volume

Abstract. Atmospheric aerosol composition was measured using a Single Particle Soot Photometer (SP2) in the Finnish Arctic during winter 2011–2012. The Sammaltunturi measurement site at the Pallas GAW (Global Atmosphere Watch) station receives air masses from different source regions including the Arctic Ocean and continental Europe. The SP2 provides detailed information about mass distributions and mixing state of refractory black carbon (rBC). The measurements showed widely varying rBC mass concentrations (0–120 ng m−3), which were related to varying contributions of different source regions and aerosol removal processes. The rBC mass was log-normally distributed showing a relatively constant rBC core mass mean diameter with an average of 194 nm (75–655 nm sizing range). On average, the number fraction of particles containing rBC was 0.24 (integrated over 350–450 nm particle diameter range) and the average particle diameter to rBC core volume equivalent diameter ratio was 2.0 (averaged over particles with 150–200 nm rBC core volume equivalent diameters). These average numbers mean that the observed rBC core mass mean diameter is similar to those of aged particles, but the observed particles seem to have unusually high particle to rBC core diameter ratios. Comparison of the measured rBC mass concentration with that of the optically detected equivalent black carbon (eBC) using an Aethalometer and a MAAP showed that eBC was larger by a factor of five. The difference could not be fully explained without assuming that only a part of the optically detected light absorbing material is refractory and absorbs light at the wavelength used by the SP2. Finally, climate implications of five different black carbon mixing state representations were compared using the Mie approximation and simple direct radiative forcing efficiency calculations. These calculations showed that the observed mixing state means significantly lower warming effect or even a net cooling effect when compared with that of a homogenous aerosol containing the same amounts of black carbon and non-absorbing material.

scholarly journals An overview of airborne measurement in Nepal – Part 1: Vertical profile of aerosol size, number, spectral absorption, and meteorology

2019 ◽  
Vol 19 (1) ◽  
pp. 245-258 ◽  
Author(s):  
Ashish Singh ◽  
Khadak S. Mahata ◽  
Maheswar Rupakheti ◽  
Wolfgang Junkermann ◽  
Arnico K. Panday ◽  
...  
Keyword(s):  
Black Carbon ◽  
Vertical Profiles ◽  
Gangetic Plain ◽  
Regional Transport ◽  
Near Surface ◽  
Airborne Measurements ◽  
Airborne Measurement ◽  
Himalayan Foothills ◽  
Test Flight ◽  
Pokhara Valley

Abstract. The paper provides an overview of an airborne measurement campaign with a microlight aircraft over the Pokhara Valley region, Nepal, a metropolitan region in the central Himalayan foothills. This is the first aerial measurement in the central Himalayan foothill region, one of the polluted but relatively poorly sampled regions of the world. Conducted in two phases (in May 2016 and December 2016–January 2017), the goal of the overall campaign was to quantify the vertical distribution of aerosols over a polluted mountain valley in the Himalayan foothills, as well as to investigate the extent of regional transport of emissions into the Himalayas. This paper summarizes results from the first phase where test flights were conducted in May 2016 (pre-monsoon), with the objective of demonstrating the potential of airborne measurements in the region using a portable instrument package (size with housing case: 0.45 m × 0.25 m × 0.25 m, 15 kg) onboard an ultralight aircraft (IKARUS-C42). A total of five sampling test flights were conducted (each lasting for 1–1.5 h) in the Pokhara Valley to characterize vertical profiles of aerosol properties such as aerosol number and size distribution (0.3–2 µm), total particle concentration (>14 nm), aerosol absorption (370–950 nm), black carbon (BC), and meteorological variables. Although some interesting observations were made during the test flight, the study is limited to a few days (and only a few hours of flight in total) and thus the analysis presented may not represent the entire pollution–meteorology interaction found in the Pokhara Valley. The vertical profiles of aerosol species showed decreasing concentrations with altitude (815 to 4500 m a.s.l.); a steep concentration gradient below 2000 m a.s.l. in the morning; and mixed profiles (up to ca. 4000 m a.s.l.) in the afternoon. The near-surface (<1000 m a.s.l.) BC concentrations observed in the Pokhara Valley were much lower than pre-monsoon BC concentrations in the Kathmandu Valley, and similar in range to Indo-Gangetic Plain (IGP) sites such as Kanpur in India. The sampling test flight also detected an elevated polluted aerosol layer (around 3000 m a.s.l.) over the Pokhara Valley, which could be associated with the regional transport. The total aerosol and black carbon concentration in the polluted layer was comparable with the near-surface values. The elevated polluted layer was also characterized by a high aerosol extinction coefficient (at 550 nm) and was identified as smoke and a polluted dust layer. The observed shift in the westerlies (at 20–30∘ N) entering Nepal during the test flight period could be an important factor for the presence of elevated polluted layers in the Pokhara Valley.

scholarly journals Black carbon concentrations and mixing state in the Finnish Arctic

2015 ◽  
Vol 15 (11) ◽  
pp. 15621-15654 ◽  
Author(s):  
T. Raatikainen ◽  
D. Brus ◽  
A.-P. Hyvärinen ◽  
J. Svensson ◽  
E. Asmi ◽  
...  
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
The Arctic ◽  
Core Size ◽  
Mixing State ◽  
Aerosol Composition ◽  
Total Size ◽  
Core Diameter ◽  
Source Regions ◽  
Absorbing Material

Abstract. Atmospheric aerosol composition was measured using a Single Particle Soot Photometer (SP2) in the Finnish Arctic during winter 2011–2012. The Sammaltunturi measurement site at the Pallas GAW (Global Atmosphere Watch) station receives air masses from different source regions including the Arctic Ocean and continental Europe. SP2 is a unique instrument that can give detailed information about mass distributions and mixing state of refractory black carbon (rBC). As expected, the measurements showed widely varying rBC mass concentrations (0–120 ng m−3), which were related to varying contributions of different source regions and aerosol removal processes. The log-normally distributed rBC core size was relatively constant with an average geometric mass mean diameter of 194 nm. On the average, the number fraction of particles containing rBC was 0.24 and the average rBC core size in these particles was half of the total size (coated to core diameter ratio was 2.0). These numbers mean that the core was larger and had a significantly thicker coating than in typical particles closer to their source regions. Comparison of the measured rBC mass concentration with that of the optically detected equivalent black carbon (eBC) showed a factor of five difference, which could not be fully explained without assuming that a part of the absorbing material is non-refractory. Finally, climate implications of five different rBC mixing state representations were quantified using the Mie approximation and simple direct radiative forcing efficiency calculations. These calculations showed that the observed mixing state (separate non-absorbing and coated rBC particles) means significantly lower warming effect or even a net cooling effect when compared with that of an homogenous aerosol containing the same amounts of rBC and non-absorbing material.

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