scholarly journals On the association between aerosol optical depths and surface meteorological conditions in a tropical coastal environment

MAUSAM ◽  
2022 ◽  
Vol 46 (4) ◽  
pp. 427-434
Author(s):  
PRABRA R. NAIR ◽  
K. KRISHNA MOORTHY
Keyword(s):  
Seasonal Variations ◽  
Monsoon Season ◽  
Surface Wind ◽  
Winter Season ◽  
Surface Wind Speed ◽  
Coastal Environment ◽  
Meteorological Conditions ◽  
Coastal Station ◽  
Depth Data ◽  
Multi Wavelength

 Columnar aerosol spectral optical depth data, estimated using a ground based passive multi-wavelength solar radiometer at the tropical coastal station of Thumba, Thiruvananthapuram (Trivandrum) (8.55°N, 77°E) during the period November 1985 to May 1991, are examined to study the association of the seasonal variations in the optical depths and their association with the prevailing meteorological conditions. A systematic seasonal variation has been observed, with the optical depths maximising in the summer/pre-monsoon season and reaching a minimum in the winter season. Significant association has been observed between the seasonal variations of aerosol spectral optical depths with those of the (on-shore) surface wind speed and the rainfall. The implications of the findings are discussed.  

Contrasting Aerosol Optical Characteristics and Source Regions During Summer and Winter Pollution Episodes in Nanjing, China

2020 ◽  
Author(s):  
Jing Wang ◽  
Gerrit de Leeuw
Keyword(s):  
Extreme Values ◽  
Source Region ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Meteorological Conditions ◽  
Asymmetry Factor ◽  
Anthropogenic Aerosols ◽  
Source Regions ◽  
Fine Mode ◽  
Aerosol Properties

<p>Two episodes with heavy air pollution in Nanjing, China, one in the summer and another one in the winter of 2017, were selected to study aerosol properties using sun photometer and ground-based measurements, together with source region analysis. The aerosol properties, the meteorological conditions, and the source regions during these two episodes were very different. The episodes were selected based on the air quality index (AQI), which reached a maximum value of 193 during the summer episode (26 May–3 June) and 304 during the winter episode (21–31 December). The particulate matter (PM) concentrations during the winter episode reached maximum values for PM<sub>2.5/10</sub> of 254 μg m<sup>−3</sup> and 345 μg m<sup>−3</sup>, much higher than those during the summer (73 and 185 μg m<sup>−3</sup>). In contrast, the value of aerosol optical depth (AOD) at 500 nm was higher during the summer episode (2.52 ± 0.19) than during that in the winter (1.38 ± 0.18). A high AOD value does not necessarily correspond to a high PM concentration but is also affected by factors, such as wind, Planetary Boundary Layer Height (PBLH), and relative humidity. The mean value of the Ångström Exponent (AE) varied from 0.91–1.42, suggesting that the aerosol is a mixture of invaded dust and black carbon. The absorption was stronger during the summer than during the winter, with a minimum value of the single scattering albedo (SSA) at 440 nm of 0.86 on 28 May. Low values of asymmetry factor (ASY) (0.65 at 440 nm and 0.58 at 1020 nm) suggest a large number of anthropogenic aerosols, which are absorbing fine-mode particles. The Imaginary part of the Refractive Index (IRI) was higher during the summer than during the winter, indicating there was absorbing aerosol during the summer. These differences in aerosol properties during the summer and winter episodes are discussed in terms of meteorological conditions and transport. The extreme values of PM and AOD were reached during both episodes in conditions with stable atmospheric stratification and low surface wind speed, which are conducive for the accumulation of pollutants. Potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analysis show that fine mode absorbing aerosols dominate during the summer season, mainly due to emissions of local and near-by sources. In the winter, part of the air masses was arriving from arid/semi-arid regions (Shaanxi, Ningxia, Gansu, and Inner Mongolia provinces) covering long distances and transporting coarse particles to the study area, which increased the scattering characteristics of aerosols.</p>

scholarly journals Assessment of MERRA-2 Surface PM2.5 over the Yangtze River Basin: Ground-based Verification, Spatiotemporal Distribution and Meteorological Dependence

2019 ◽  
Vol 11 (4) ◽  
pp. 460 ◽  
Author(s):  
Lijie He ◽  
Aiwen Lin ◽  
Xinxin Chen ◽  
Hao Zhou ◽  
Zhigao Zhou ◽  
...  
Keyword(s):  
Wind Speed ◽  
River Basin ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Meteorological Conditions ◽  
The Yangtze River ◽  
The Yangtze River Basin ◽  
Mlr Model

A good understanding of how meteorological conditions exacerbate or mitigate air pollution is critical for developing robust emission reduction policies. Thus, based on a multiple linear regression (MLR) model in this study, the quantified impacts of six meteorological variables on PM2.5 (i.e., particle matter with diameter of 2.5 µm or less) and its major components were estimated over the Yangtze River Basin (YRB). The 38-year (1980–2017) daily PM2.5 and meteorological data were derived from the newly-released Modern-Era Retrospective Analysis and Research and Application, version 2 (MERRA-2) products. The MERRA-2 PM2.5 was underestimated compared with ground measurements, partly due to the bias in the MERRA-2 Aerosol Optical Depth (AOD) assimilation. An over-increasing trend in each PM2.5 component occurred for the whole study period; however, this has been curbed since 2007. The MLR model suggested that meteorological variability could explain up to 67% of the PM2.5 changes. PM2.5 was robustly anti-correlated with surface wind speed, precipitation and boundary layer height (BLH), but was positively correlated with temperature throughout the YRB. The relationship of relative humidity (RH) and total cloud cover with PM2.5 showed regional dependencies, with negative correlation in the Yangtze River Delta (YRD) and positive correlation in the other areas. In particular, PM2.5 was most sensitive to surface wind speed, and the sensitivity was approximately −2.42 µg m−3 m−1 s. This study highlighted the impact of meteorological conditions on PM2.5 growth, although it was much smaller than the anthropogenic emissions impact.

scholarly journals Contrasting Aerosol Optical Characteristics and Source Regions During Summer and Winter Pollution Episodes in Nanjing, China

2019 ◽  
Vol 11 (14) ◽  
pp. 1696 ◽  
Author(s):  
Wang ◽  
de Leeuw ◽  
Niu ◽  
Kang
Keyword(s):  
Extreme Values ◽  
Source Region ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Meteorological Conditions ◽  
Asymmetry Factor ◽  
Anthropogenic Aerosols ◽  
Source Regions ◽  
Fine Mode ◽  
Aerosol Properties

Two episodes with heavy air pollution in Nanjing, China, one in the summer and another one in the winter of 2017, were selected to study aerosol properties using sun photometer and ground-based measurements, together with source region analysis. The aerosol properties, the meteorological conditions, and the source regions during these two episodes were very different. The episodes were selected based on the air quality index (AQI), which reached a maximum value of 193 during the summer episode (26 May–3 June) and 304 during the winter episode (21–31 December). The particulate matter (PM) concentrations during the winter episode reached maximum values for PM2.5/10 of 254 g m−3 and 345 g m−3, much higher than those during the summer (73 and 185 g m−3). In contrast, the value of aerosol optical depth (AOD) at 500 nm was higher during the summer episode (2.52 0.19) than during that in the winter (1.38 0.18). A high AOD value does not necessarily correspond to a high PM concentration but is also affected by factors, such as wind, Planetary Boundary Layer Height (PBLH), and relative humidity. The mean value of the Ångström Exponent (AE) varied from 0.91–1.42, suggesting that the aerosol is a mixture of invaded dust and black carbon. The absorption was stronger during the summer than during the winter, with a minimum value of the single scattering albedo (SSA) at 440 nm of 0.86 on 28 May. Low values of asymmetry factor (ASY) (0.65 at 440 nm and 0.58 at 1020 nm) suggest a large number of anthropogenic aerosols, which are absorbing fine-mode particles. The Imaginary part of the Refractive Index (IRI) was higher during the summer than during the winter, indicating there was absorbing aerosol during the summer. These differences in aerosol properties during the summer and winter episodes are discussed in terms of meteorological conditions and transport. The extreme values of PM and AOD were reached during both episodes in conditions with stable atmospheric stratification and low surface wind speed, which are conducive for the accumulation of pollutants. Potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analysis show that fine mode absorbing aerosols dominate during the summer season, mainly due to emissions of local and near-by sources. In the winter, part of the air masses was arriving from arid/semi-arid regions (Shaanxi, Ningxia, Gansu, and Inner Mongolia provinces) covering long distances and transporting coarse particles to the study area, which increased the scattering characteristics of aerosols.

scholarly journals Improvement of the detection of desert dust over the Sahel using METEOSAT IR imagery

2006 ◽  
Vol 24 (8) ◽  
pp. 2065-2073 ◽  
Author(s):  
G. Vergé-Dépré ◽  
M. Legrand ◽  
C. Moulin ◽  
A. Alias ◽  
P. François
Keyword(s):  
Radiative Transfer ◽  
Arid Regions ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Meteorological Conditions ◽  
Dust Layer ◽  
Desert Dust ◽  
Solar Elevation ◽  
The Arid Regions ◽  
Aerosol Properties

Abstract. Desert dust over the arid regions of Africa is detected using the Infrared Difference Dust Index (IDDI) derived from the thermal infrared (TIR) channel of METEOSAT. However, the comparison with photometric aerosol optical thickness (AOT) of this dust index reveals some discrepancies. Using an instrumented site in Sahel where aerosol properties and meteorological conditions were monitored daily during the dry season, we performed radiative transfer computations with the MODTRAN 4.1 code to develop a method to improve the IDDI usefulness. We found that discrepancies between AOT and IDDI variations mostly come from changes in the surface temperature (Ts), which is an important parameter for radiative transfer computations in the TIR. We show that this temperature varies from day to day with the surface wind speed and during the course of the season with the solar elevation, and that it is possible, for the site considered, to correct Ts from these combined effect using a simple parameterization. We also observe that the dust layer itself has an impact on Ts by reducing the amount of solar radiation at the surface, and that this phenomenon can also be accounted for by adding an AOT-dependence to the above parameterization of Ts. We show that this parameterization allows improving the agreement between the IDDI and the photometric AOT.

The seasonal variations in the significant wave height and sea surface wind speed of the China’s seas

2015 ◽  
Vol 34 (9) ◽  
pp. 58-64 ◽  
Author(s):  
Chongwei Zheng ◽  
Jing Pan ◽  
Yanke Tan ◽  
Zhansheng Gao ◽  
Zhenfeng Rui ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
Seasonal Variations ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Sea Surface ◽  
Significant Wave ◽  
Sea Surface Wind Speed ◽  
Sea Surface Wind

scholarly journals Seasonal variations in proximate composition and metallic elements of three cyprinids from a Central Himalayan river Alaknanda in Garhwal Himalaya, India

2020 ◽  
Vol 12 (4) ◽  
pp. 661-669
Author(s):  
Sharali Sharma ◽  
Sumit Kumar ◽  
Deepak Singh
Keyword(s):  
Seasonal Variations ◽  
Monsoon Season ◽  
Winter Season ◽  
Garhwal Himalaya ◽  
Human Consumption ◽  
Balanced Diet ◽  
Fish Samples ◽  
Aquatic Food ◽  
Pattern Of Variation ◽  
Himalayan River

Fish is an irreplaceable, highly nutritious aquatic food in a balanced diet. On the contrary, fish can also be a source of metal contamination when ingested in excess through food and water. The aim of the present study was to determine the seasonal variations in the proximate body composition and levels of Na, K, Ca, Fe, Zn, Cu, and Pb in the muscle tissue of three fish species namely, Schizothorax plagiostomus, Schizothorax progastus and Barilius bendelisis dwelling in Central Himalayan river Alaknanda at Srinagar (Garhwal)  in Garhwal Himalaya. The protein (21.01-21.74%) and carbohydrates (2.31-2.69%) were found maximum in summer season in all the studied fishes while lipid was found to be highest during monsoon season in S. plagiostomus (2.73%) and S. progastus (2.70%) and lowest (1.62-1.68%) in the winter season. B. bendelisis showed a different pattern of variation in lipid content being highest (6.32%) during summer and lowest (3.34%) in monsoon season. Significantly (F=5.69, p<0.04) high content of lipid was found in B. bendelisis as compared to S. plagiostomus and S. progastus during the three seasons. Na, Ca, K, and Fe were detected highest during monsoon, Pb, and Cu during summer and Zn during the winter season. However, Pb was not detected in all the fish samples during monsoon season. B. bendelisis was significantly (p<0.001)rich in Na and Ca, S. plagiostomus in K (p<0.01), and S. progastus in Fe (p<0.001) content during all three seasons. Ca was rich among macroelements while Fe among microelements in all the studied fishes. The amount of Zn (1.48-4.55 mg/100g), Cu (0.429-0.869 mg/100g), and Pb (0.117-0.447 mg/100g) were within the permissible limits of International food safety guidelines. The seasonal variations in the parameters are attributed to food availability, temperature changes, fish metabolism, and prevailing environmental conditions. Thus, these cyprinid species were regarded as safe and useful for human consumption.

PREVALENCE OF PSEUDOINVERTA ORAIENSIS IN FRESH WATER FISH, CLARIAS BATRACHUS

2019 ◽  
Vol 25 (1) ◽  
Author(s):  
ADITYA NARAYAN
Keyword(s):  
Fresh Water ◽  
Monsoon Season ◽  
Winter Season ◽  
Uttar Pradesh ◽  
Summer Season ◽  
Clarias Batrachus ◽  
Fresh Water Fish ◽  
Water Fish

The present investigation deals with the prevalence of infection of cestode, Pseudoinverta oraiensis19 parasitizing Clarias batrachus from Bundelkhand Region (U.P.) India. The studies were recorded from different sampling stations of Bundelkhand region of Uttar Pradesh. For this study 360 fresh water fish, Clarias batrachus were examined. The incidence of infection, monsoon season (17.50%) followed by winter season (20.00%) whereas high in summer season (30.00%).

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