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.

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 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.

scholarly journals Anthropogenic Decline of African Dust inferred from Insights From the Holocene Records and Beyond: are dust purely  natural?

2021 ◽  
Author(s):  
Tianle Yuan ◽  
Hongbin Yu ◽  
Mian Chin ◽  
Lorraine Remer ◽  
David McGee ◽  
...  
Keyword(s):  
Surface Wind ◽  
Dust Emission ◽  
Surface Wind Speed ◽  
Natural Phenomenon ◽  
Unified Framework ◽  
Dust Source ◽  
The Holocene ◽  
African Dust ◽  
Source Regions ◽  
The Relationship

<p>African dust exhibits strong variability on a range of time scales. Here we show that the interhemispheric contrast in Atlantic SST (ICAS) drives African dust variability at decadal to millennial timescales, and the strong anthropogenic increase of the ICAS in the future will decrease African dust loading to a level never seen during the Holocene. We provide a physical framework to understand the relationship between the ICAS and African dust activity: positive ICAS anomalies push the Intertropical Convergence Zone (ITCZ) northward and decrease surface wind speed over African dust source regions, which reduces dust emission and transport. It provides a unified framework for and is consistent with relationships in the literature. We find strong observational and proxy‐record support for the ICAS‐ITCZ‐dust relationship during the past 160 and 17,000 years. Model‐projected anthropogenic increase of the ICAS will reduce African dust by as much as 60%, which has broad consequences. We posit that dust cannot be thought of as a purely natural phenomenon.</p>

scholarly journals Marine aerosol properties over the Southern Ocean in relation to the wintertime meteorological conditions

2022 ◽  
Vol 22 (1) ◽  
pp. 119-137
Author(s):  
Manu Anna Thomas ◽  
Abhay Devasthale ◽  
Michael Kahnert
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Relative Humidity ◽  
Southern Ocean ◽  
Surface Wind ◽  
Ocean Surface ◽  
Meteorological Conditions ◽  
Sea Salt ◽  
Aerosol Backscatter ◽  
Aerosol Properties

Abstract. Given the vast expanse of oceans on our planet, marine aerosols (and sea salt in particular) play an important role in the climate system via multitude of direct and indirect effects. The efficacy of their net impact, however, depends strongly on the local meteorological conditions that influence their physical, optical and chemical properties. Understanding the coupling between aerosol properties and meteorological conditions is therefore important. It has been historically difficult to statistically quantify this coupling over larger oceanic areas due to the lack of suitable observations, leading to large uncertainties in the representation of aerosol processes in climate models. Perhaps no other region shows higher uncertainties in the representation of marine aerosols and their effects than the Southern Ocean. During winter the Southern Ocean boundary layer is dominated by sea salt emissions. Here, using 10 years of austral winter period (June, July and August, 2007–2016) space-based aerosol profiling by CALIOP-CALIPSO in combination with meteorological reanalysis data, we investigated the sensitivity of marine aerosol properties over the Southern Ocean (40–65∘ S) to various meteorological parameters, such as vertical relative humidity (RH), surface wind speed and sea surface temperature (SST) in terms of joint histograms. The sensitivity study is done for the climatological conditions and for the enhanced cyclonic and anticyclonic conditions in order to understand the impact of large-scale atmospheric circulation on the aerosol properties. We find a clear demarcation in the 532 nm aerosol backscatter and extinction at RH around 60 %, irrespective of the state of the atmosphere. The backscatter and extinction increase at higher relative humidity as a function of surface wind speed. This is mainly because of the water uptake by the wind-driven sea salt aerosols at high RH near the ocean surface resulting in an increase in size, which is confirmed by the decreased depolarization for the wet aerosols. An increase in aerosol backscatter and extinction is observed during the anticyclonic conditions compared to cyclonic conditions for the higher wind speeds and relative humidity, mainly due to aerosols being confined to the boundary layer, and their proximity to the ocean surface facilitates the growth of the particles. We further find a very weak dependency of aerosol backscatter on SSTs at lower wind speeds. However, when the winds are stronger than about 12 m s−1, the backscattering coefficient generally increases with SST. When aerosol properties are investigated in terms of aerosol verticality and in relation to meteorological parameters, it is seen that the aerosol backscatter values in the free troposphere (pressure <850 hPa) are much lower than in the boundary layer, irrespective of the RH and the three weather states. This indicates that the local emissions from the ocean surface make the dominant contribution to aerosol loads over the Southern Ocean. A clear separation of particulate depolarization is observed in the free and lower troposphere, more prominent in the climatological mean and the cyclonic states. For RH > 60 %, low depolarization values are noticeable in the lower troposphere, which is an indication of the dominance of water-coated and mostly spherical sea salt particles. For RH < 60 %, there are instances when the aerosol depolarization increases in the boundary layer; this is more prominent in the mean and anticyclonic cases, which can be associated with the presence of drier aerosol particles. Based on the joint histograms investigated here, we provide third-degree polynomials to obtain aerosol extinction and backscatter as a function of wind speed and relative humidity. Additionally, backscattering coefficient is also expressed jointly in terms of wind speed and sea surface temperature. Furthermore, depolarization is expressed as a function of relative humidity. These fitting functions would be useful to test and improve the parameterizations of sea salt aerosols in the climate models. We also note some limitations of our study. For example, interpreting the verticality of aerosol properties (especially depolarization) in relation to the meteorological conditions in the free and upper troposphere (pressure <850 hPa) was challenging. Furthermore, we do not see any direct evidence of sudden crystallization (efflorescence), deliquescence or hysteresis effects of the aerosols. Observing such effects will likely require a targeted investigation of individual cases considering tracer transport, rather than the statistical sensitivity study that entails temporally and geographically averaged large data sets.

scholarly journals Sea-spray aerosols and SARS-Cov-2: an analysis using AERONET data

2020 ◽  
Author(s):  
Jacques Piazzola ◽  
Christelle Desnues ◽  
Philippe Parent ◽  
Christophe Yohia ◽  
Elisa Canepa
Keyword(s):  
Atmospheric Transport ◽  
Meteorological Conditions ◽  
Sea Spray ◽  
Anthropogenic Aerosols ◽  
Virus Propagation ◽  
Air Masses ◽  
The People ◽  
The Social ◽  
Aerosol Properties

Abstract Even if the people density, habits and displacements probably represent the most important causes of the SARS-Cov-2 virus propagation, the role of the atmospheric aerosol needs to be investigated. Therefore, we aimed to study if the aerosol properties related to the different sources and meteorological conditions we can observe in urbanized areas can have an influence on in the atmospheric transport of the SARS-Cov-2 virus. This paper focuses on the lockdown period to reduce the differences in the social behavior. As an example, we investigated the contamination cases during March 2020 in two specific French areas located in both continental and coastal areas with regard to the meteorological conditions and the corresponding aerosol properties. To this end, we used both the optical depth (AOD) and the Angstrom exponent provided by the AERONET network. The results show that the analysis of aerosol ground-based data can be of interest to assess a virus survey. In particular, our data show that moderate to strong onshore winds occurring in coastal regions, which allow large sea-spray production episodes, deal with smaller COVID-19 contamination rates. This is probably due to the fact that the coagulation of SARS-Cov-2 particles with hygroscopic salty sea-spray aerosols would tend to inhibit its viral infectivity via possible reaction with NaCl, especially in high relative humidity environments. In contrast, out results confirm that the atmospheric transport of the SARS-Cov-2 can be favored by its coagulation with anthropogenic aerosols, which protects the virus particle from ambient humidity and preserves its infectivity.Capsule: Our results suggest that maritime air-masses limit the SARS-Cov-2 impact via the role of the sea-spray.

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 Marine aerosol properties over the Southern Ocean in relation to the wintertime meteorological conditions

2021 ◽  
Author(s):  
Manu Anna Thomas ◽  
Abhay Devasthale ◽  
Michael Kahnert
Keyword(s):  
Boundary Layer ◽  
Relative Humidity ◽  
Southern Ocean ◽  
Surface Wind ◽  
Lower Troposphere ◽  
Ocean Surface ◽  
Meteorological Conditions ◽  
Sea Salt ◽  
Aerosol Backscatter ◽  
Aerosol Properties

Abstract. Given the vast expanse of oceans on our planet, marine aerosols, and sea salt in particular, play an important role in the climate system via multitude of direct and indirect effects. The efficacy of their net impact however depends strongly on the local meteorological conditions that influence their physical, optical and chemical properties. Understanding the coupling between aerosol properties and meteorological conditions is therefore important. It has been historically difficult to statistically quantify this coupling over larger oceanic areas due to the lack of suitable observations, leading to large uncertainties in the representation of aerosol processes in climate models. Perhaps no other region shows higher uncertainties in the representation of marine aerosols and their effects than the Southern Ocean. During winter the Southern Ocean boundary layer is dominated by sea salt emissions. Here, using 10 years of austral winter period (June, July and August, 2007–2016) space based aerosol profiling by CALIOP-CALIPSO in combination with meteorological reanalysis data, we investigated the sensitivity of marine aerosol properties over the Southern Ocean (40S–65S) to various meteorological parameters, such as vertical relative humidity (RH), surface wind speed, and sea surface temperature (SST) in terms of joint histograms. The sensitivity study is done for the climatological conditions as well as for the enhanced cyclonic and anticyclonic conditions in order to understand the impact of large-scale atmospheric circulation on the aerosol properties. We find a clear demarcation in the 532 nm aerosol backscatter and extinction at RH around 60 %, irrespective of the state of the atmosphere. The backscatter and extinction increase at higher relative humidity as a function of surface wind speed. This is mainly because of the water uptake by the wind driven sea salt aerosols at high RH near the ocean surface resulting in an increase in size, which is confirmed by the decreased depolarization for the wet aerosols. An increase in aerosol backscatter and extinction is observed during the anticyclonic conditions compared to cyclonic conditions for the higher wind speeds and relative humidity, mainly due to aerosols being confined to the boundary layer and their proximity to the ocean surface facilitates the growth of the particles. We further find a very weak dependency of aerosol backscatter on SSTs at lower wind speeds. But when the winds are stronger than about 12 m/s, the backscattering coefficient generally increases with SST. When aerosol properties are investigated in terms of aerosol verticality and in relation to meteorological parameters, it is seen that the aerosol backscatter values in the free troposphere (pressure < 850 hPa) are much lower than in the boundary layer, irrespective of the RH and the three weather states. This indicates that the local emissions from the ocean surface make the dominant contribution to aerosol loads over the Southern Ocean. A clear separation of particulate depolarization is observed in the free and lower troposphere, more prominent in the climatological mean and the cyclonic states. For RH > 60 %, low depolarization values are noticeable in the lower troposphere, which is an indication of the dominance of water-coated, mostly spherical sea salt particles. For RH < 60 %, there are instances when the aerosol depolarization increases in the boundary layer, more prominently in the mean and anticyclonic cases which can be associated with the presence of drier aerosol particles. We also note some limitations of our study. For example, interpreting the verticality of aerosol properties (especially depolarization) in relation to the meteorological conditions in the free and upper troposphere (pressure < 850 hPa) was challenging. Furthermore, we do not see any direct evidence of sudden crystallization (efflorescence), deliquescence, or hysteresis effects of the aerosols. Observing such effects will likely require a targeted investigation of individual cases considering tracer transport, rather than the statistical sensitivity study that entails temporally and geographically averaged large data sets.

scholarly journals A Study of the Influence of Atmospheric Aerosol Sources on the COVID-19 Contamination Cases Using Meteorological and Extinction Data

2020 ◽  
Author(s):  
Jacques Piazzola ◽  
Christelle Desnues ◽  
Philippe Parent ◽  
Christophe Yohia ◽  
Elisa Canepa
Keyword(s):  
Atmospheric Aerosol ◽  
Atmospheric Transport ◽  
Meteorological Conditions ◽  
Sea Spray ◽  
Virus Infectivity ◽  
Anthropogenic Aerosols ◽  
Virus Propagation ◽  
The People ◽  
The Social ◽  
Aerosol Properties

Abstract Background: Even if the people density, habits and displacements probably represent the most important causes of the SARS-Cov-2 virus propagation, the role of the atmospheric aerosol needs to be investigated. Therefore, we aimed to study if the aerosol properties related to the different sources and meteorological conditions we can observe in urbanized areas can have an influence on in the atmospheric transport of the SARS-Cov-2 virus. This study focuses on the lockdown period to reduce the differences in the social behavior.Methods: We have investigated the contamination cases of four specific geographic areas, two in France and two in Italy, located in both continental and coastal areas with regard to the meteorological conditions and the corresponding air mass properties. To this end, we used a survey of meteorological conditions and aerosol properties via both the optical depth (AOD) and Angstrom exponent retrievals for these locations during March 2020. Results: The results show that the analysis of aerosol ground-based data can be of interest to assess a virus survey. In particular, our data show that moderate to strong onshore winds occurring in coastal regions, which allow large sea-spray production episodes deal with smaller COVID-19 contamination rates. One possible reason is the coagulation of SARS-Cov-2 particles with hygroscopic salty sea-spray aerosols that would tend to inhibit its viral infectivity in environments with high relative humidity via possible reaction with NaCl. Conclusions: In this paper, we hypothesize that marine atmosphere conditions tend to decrease virus infectivity. In contrast, the atmospheric transport of the SARS-Cov-2 can be favored by its coagulation with anthropogenic aerosols, which protects the virus particle from ambient humidity and preserves its infectivity.

scholarly journals Global Dust Optical Depth Climatology Derived from CALIOP and MODIS Aerosol Retrievals on Decadal Time Scales: Regional and Interannual Variability

2021 ◽  
Author(s):  
Qianqian Song ◽  
Zhibo Zhang ◽  
Hongbin Yu ◽  
Paul Ginoux ◽  
Jerry Shen
Keyword(s):  
Optical Depth ◽  
Surface Wind ◽  
Active Regions ◽  
Surface Wind Speed ◽  
Single Scattering ◽  
Northwestern Pacific ◽  
Gobi Desert ◽  
Shape Information ◽  
Fine Mode ◽  
Seasonal And Interannual Variations

Abstract. We present a satellite-derived global dust climatological record over the last two decades, including the monthly mean visible dust optical depth (DAOD) and vertical distribution of dust extinction coefficient at a 2º (latitude) × 5º (longitude) spatial resolution derived from CALIOP and MODIS. Dust is distinguished from non-dust aerosols based on particle shape information (e.g., lidar depolarization ratio) for CALIOP, and on dust size and absorption information (e.g., fine-mode fraction, Angstrom exponent, and single-scattering albedo) for MODIS, respectively. On multi-year average basis, the global (60° S–60° N) and annual mean DAOD is 0.029 and 0.063 derived from CALIOP and MODIS retrievals, respectively. In most dust active regions, CALIOP DAOD generally correlates well with the MODIS DAOD, with CALIOP DAOD being significantly smaller. CALIOP DAOD is 18 %, 34 %, 54 % and 31 % smaller than MODIS DAOD over Sahara Deserts, the tropical Atlantic Ocean, the Caribbean Sea, and the Arabian Sea, respectively. Over East Asia and the northwestern Pacific Ocean (NWP), however, the two datasets show weak correlation. Despite these discrepancies, CALIOP and MODIS show similar seasonal and interannual variations in regional DAOD. For dust aerosol over NWP, both CALIOP and MODIS show a declining trend of DAOD at a rate of about 2 % yr−1. This decreasing trend is consistent with the observed declining trend of DAOD in the southern Gobi Desert at a rate of −3 % yr−1 and −5 % yr−1 according to CALIOP and MODIS, respectively. The decreasing trend of DAOD in the southern Gobi Desert is in turn found to be significantly correlated with an increasing trend of vegetation and a decreasing trend of surface wind speed in the area.

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.  

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