scholarly journals Direct radiative effect of the Russian wildfires and their impact on air temperature and atmospheric dynamics during August 2010

2013 ◽  
Vol 13 (6) ◽  
pp. 15829-15866
Author(s):  
J. C. Péré ◽  
B. Bessagnet ◽  
M. Mallet ◽  
F. Waquet ◽  
I. Chiapello ◽  
...  

Abstract. The present study aims at investigating the shortwave aerosol direct radiative forcing (ADRF) and its feedback on air temperature and atmospheric dynamics during a major fire event that occurred in Russia during August 2010. The methodology is based on an off-line coupling between the CHIMERE chemistry-transport and the Weather Research and Forecasting (WRF) models. First, simulations for the period 5–12 August 2010 have been evaluated by using AERONET and satellite measurements of the POLarization and Directionality of the Earth's Reflectance (POLDER) and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) sensors. During this period, elevated POLDER AOT are found over a large part of Eastern Europe with values above 2 (at 550 nm) in the aerosol plume. According to CALIOP observations, particles remain confined within the first five kilometres of the atmospheric layer. Comparisons with satellite measurements show the ability of CHIMERE to reproduce the regional and vertical distribution of aerosols during their transport from the source region. Over Moscow, AERONET measurements indicate an important increase of AOT (340 nm) from 0.7 on 5 August to 2–4 between 6 and 10 August when the aerosol plume is advected over the city. Particles are mainly observed in the fine size mode (radius in the range 0.2–0.4 μm) and are characterized by elevated SSA (0.95–0.96 between 440 and 1020 nm). Also, comparisons of simulations with AERONET measurements show that aerosol physical-optical properties (size distribution, AOT, SSA) have been well simulated over Moscow in term of intensity and/or spectral dependence. Secondly, modelled aerosol optical properties have been used as input in the radiative transfer code of WRF to evaluate their direct radiative impact. Simulations indicate a significant reduction of solar radiation at the ground (up to 80–150 W m−2 in diurnal-averaged) over a large part of Eastern Europe due to the presence of the aerosol plume. This ADRF causes an important reduction of the near-surface air temperature between 0.2 and 2.6°C at a regional scale. Moscow has been also affected by the aerosol plume, especially between 6 and 10 August. During this period, aerosol causes a significant reduction of surface shortwave radiation (up to 70–84 W m−2 in diurnal-averaged) with a moderate part (20–30%) due to solar absorption within the aerosol layer. The resulting feedbacks lead to a cooling of the air up to 1.6°C at the surface and 0.1°C at an altitude of 1500–2000 m (in diurnal-averaged), that contribute to stabilize the atmospheric boundary layer (ABL). Indeed, a reduction of the ABL height of 13 to 65% have been simulated during daytime in presence of aerosols. This decrease is the result of a lower air entrainment as the vertical wind speed in the ABL is shown to be reduced by 5 to 80% (at midday) when the feedback of the ADRF is taken into account. In turn, CHIMERE simulations driven by the WRF meteorological fields including this ADRF feedback result in a large increase in the modeled near-surface PM10 concentrations (up to 99%) due to their lower vertical dilution in the ABL, which tend to reduce model biases with the ground PM10 values observed over Moscow during this specific period.

2014 ◽  
Vol 14 (4) ◽  
pp. 1999-2013 ◽  
Author(s):  
J. C. Péré ◽  
B. Bessagnet ◽  
M. Mallet ◽  
F. Waquet ◽  
I. Chiapello ◽  
...  

Abstract. In this study, we investigate the shortwave aerosol direct radiative forcing (ADRF) and its feedback on air temperature and atmospheric dynamics during a major fire event that occurred in Russia during August 2010. The methodology is based on an offline coupling between the CHIMERE chemistry-transport and the Weather Research and Forecasting (WRF) models. First, simulations for the period 5–12 August 2010 have been evaluated by using AERONET (AErosol RObotic NETwork) and satellite measurements of the POLarization and Directionality of the Earth's Reflectance (POLDER) and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) sensors. During this period, elevated POLDER aerosol optical thickness (AOT) is found over a large part of eastern Europe, with values above 2 (at 550 nm) in the aerosol plume. According to CALIOP observations, particles remain confined to the first five kilometres of the atmospheric layer. Comparisons with satellite measurements show the ability of CHIMERE to reproduce the regional and vertical distribution of aerosols during their transport from the source region. Over Moscow, AERONET measurements indicate an important increase of AOT (340 nm) from 0.7 on 5 August to 2–4 between 6 and 10 August when the aerosol plume was advected over the city. Particles are mainly observed in the fine size mode (radius in the range 0.2–0.4 μm) and are characterized by elevated single-scattering albedo (SSA) (0.95–0.96 between 440 and 1020 nm). Comparisons of simulations with AERONET measurements show that aerosol physical–optical properties (size distribution, AOT, SSA) have been well simulated over Moscow in terms of intensity and/or spectral dependence. Secondly, modelled aerosol optical properties have been used as input in the radiative transfer code of WRF to evaluate their direct radiative impact. Simulations indicate a significant reduction of solar radiation at the ground (up to 80–150 W m−2 in diurnal averages over a large part of eastern Europe due to the presence of the aerosol plume. This ADRF causes an important reduction of the near-surface air temperature between 0.2 and 2.6° on a regional scale. Moscow has been affected by the aerosol plume, especially between 6 and 10 August. During this period, aerosol causes a significant reduction of surface shortwave radiation (up to 70–84 W m−2 in diurnal averages) with a moderate part (20–30%) due to solar absorption within the aerosol layer. The resulting feedbacks lead to a cooling of the air up to 1.6° at the surface and 0.1° at an altitude of 1500–2000 m (in diurnal averages), that contribute to stabilize the atmospheric boundary layer (ABL). Indeed, a reduction of the ABL height of 13 to 65% has been simulated during daytime in presence of aerosols. This decrease is the result of a lower air entrainment as the vertical wind speed in the ABL is shown to be reduced by 5 to 80% (at midday) when the feedback of the ADRF is taken into account. However, the ADRF is shown to have a lower impact on the horizontal wind speed, suggesting that the dilution of particles would be mainly affected by the weakening of the ABL development and associated vertical entrainment. Indeed, CHIMERE simulations driven by the WRF meteorological fields including this ADRF feedback result in a large increase in the modelled near-surface PM10 concentrations (up to 99%). This is due to their lower vertical dilution in the ABL, which tend to reduce model biases with the ground PM10 values observed over Moscow during this specific period.


2018 ◽  
Author(s):  
Konrad Deetz ◽  
Heike Vogel ◽  
Peter Knippertz ◽  
Bianca Adler ◽  
Jonathan Taylor ◽  
...  

Abstract. Southern West Africa (SWA) undergoes rapid and significant socioeconomic changes associated with a massive increase in air pollution. Still, the impact of atmospheric pollutants, in particular that of aerosol particles, on weather and climate in this region is virtually unexplored. In this study, the regional-scale model framework COSMO-ART is applied to SWA for a summer monsoon process study on 2–3 July 2016 to assess the aerosol direct and indirect effect on clouds and the atmospheric dynamics. The modeling study is supported by observational data obtained during the extensive field campaign of the project DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) in June–July 2016. As indicated in previous studies, a coastal front is observed that develops during daytime and propagates inland in the evening (Atlantic Inflow). Increasing the aerosol amount in COSMO-ART leads to reduced propagation velocities with frontal displacements of 10–30 km and a weakening of the nocturnal low-level jet. This is related to a subtle balance of processes related to the decrease in near-surface heating: (1) flow deceleration due to reduced land-sea temperature contrast and thus local pressure gradient, (2) reduced turbulence favoring frontal advance inland and (3) delayed stratus-to-cumulus transition of 1–2 h via a later onset of the convective boundary layer. The spatial shift of the Atlantic Inflow and the temporal shift of the stratus-to-cumulus transition are synergized in a new conceptual model. We hypothesize a negative feedback of the stratus-to-cumulus transition on the Atlantic Inflow with increased aerosol. The results exhibit radiation as the key player governing the aerosol affects on SWA atmospheric dynamics via the aerosol direct effect and the Twomey effect, whereas impacts on precipitation are small.


2018 ◽  
Vol 18 (13) ◽  
pp. 9767-9788 ◽  
Author(s):  
Konrad Deetz ◽  
Heike Vogel ◽  
Peter Knippertz ◽  
Bianca Adler ◽  
Jonathan Taylor ◽  
...  

Abstract. Southern West Africa (SWA) is undergoing rapid and significant socioeconomic changes associated with a massive increase in air pollution. Still, the impact of atmospheric pollutants, in particular that of aerosol particles, on weather and climate in this region is virtually unexplored. In this study, the regional-scale model framework COSMO-ART is applied to SWA for a summer monsoon process study on 2–3 July 2016 to assess the aerosol direct and indirect effect on clouds and atmospheric dynamics. The modeling study is supported by observational data obtained during the extensive field campaign of the project DACCIWA (Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa) in June–July 2016. As indicated in previous studies, a coastal front is observed that develops during daytime and propagates inland in the evening (Atlantic inflow). Increasing the aerosol amount in COSMO-ART leads to reduced propagation velocities with frontal displacements of 10–30 km and a weakening of the nocturnal low-level jet. This is related to a subtle balance of processes related to the decrease in near-surface heating: (1) flow deceleration due to reduced land–sea temperature contrast and thus local pressure gradient, (2) reduced turbulence favoring frontal advance inland and (3) delayed stratus-to-cumulus transition of 1–2 h via a later onset of the convective boundary layer. The spatial shift of the Atlantic inflow and the temporal shift of the stratus-to-cumulus transition are synergized in a new conceptual model. We hypothesize a negative feedback of the stratus-to-cumulus transition on the Atlantic inflow with increased aerosol. The results exhibit radiation as the key player governing the aerosol affects on SWA atmospheric dynamics via the aerosol direct effect and the Twomey effect, whereas impacts on precipitation are small.


2020 ◽  
Vol 20 (16) ◽  
pp. 10073-10090
Author(s):  
Allison B. Marquardt Collow ◽  
Mark A. Miller ◽  
Lynne C. Trabachino ◽  
Michael P. Jensen ◽  
Meng Wang

Abstract. Marine boundary layer clouds, including the transition from stratocumulus to cumulus, are poorly represented in numerical weather prediction and general circulation models. Further uncertainties in the cloud structure arise in the presence of biomass burning carbonaceous aerosol, as is the case over the southeast Atlantic Ocean, where biomass burning aerosol is transported from the African continent. As the aerosol plume progresses across the southeast Atlantic Ocean, radiative heating within the aerosol layer has the potential to alter the thermodynamic environment and therefore the cloud structure; however, limited work has been done to quantify this along the trajectory of the aerosol plume in the region. The deployment of the first Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF1) in support of the Layered Atlantic Smoke Interactions with Clouds field campaign provided a unique opportunity to collect observations of cloud and aerosol properties during two consecutive biomass burning seasons during July through October of 2016 and 2017 over Ascension Island (7.96∘ S, 14.35∘ W). Using observed profiles of temperature, humidity, and clouds from the field campaign alongside aerosol optical properties from Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), as input for the Rapid Radiation Transfer Model (RRTM), profiles of the radiative heating rate due to aerosols and clouds were computed. Radiative heating is also assessed across the southeast Atlantic Ocean using an ensemble of back trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Idealized experiments using the RRTM with and without aerosols and a range of values for the single-scattering albedo (SSA) demonstrate that shortwave (SW) heating within the aerosol layer above Ascension Island can locally range between 2 and 8 K d−1 depending on the aerosol optical properties, though impacts of the aerosol can be felt elsewhere in the atmospheric column. When considered under clear conditions, the aerosol has a cooling effect at the TOA, and based on the observed cloud properties at Ascension Island, the cloud albedo is not large enough to overcome this. Shortwave radiative heating due to biomass burning aerosol is not balanced by additional longwave (LW) cooling, and the net radiative impact results in a stabilization of the lower troposphere. However, these results are extremely sensitive to the single-scattering albedo assumptions in models.


Author(s):  
E. Galytska ◽  
V. Danylevsky ◽  
S. Snizhko

Introduction. Aerosols in the Earth's atmosphere are not only air pollutants but also a factor that affects the climate. The study of the dynamics of aerosol layer properties and aerosol particles properties, and revealing sources of the atmosphere pollution by aerosols is one of the urgent problems of modern environmental sciences. Monitoring of the air pollution caused by aerosols contributes to the determination of its effects on the climate and to the reduction of its negative impacts on the health of the population. The purpose of this paper is to present the analysis of the dynamics of aerosols in the atmosphere over Eastern Europe. Thus, latest technologies and approaches are used: remote ground-based measurements of the optical properties of aerosol particles with the international sun photometers network AERONET; analysis of fires distribution during summer 2010 with the data application from satellite instrument MODIS; atmospheric dynamics research with the analysis of synoptic situation and modeling of transport of particles with the application of HYSPLIT model. Results. The peculiarities of changes of aerosol optical depth at 500 nm spectral channel and Angstrom parameter 440-870 nm for 10 AERONET stations in Eastern Europe are discussed in the article. The authors provide complex analysis of aerosols distribution together with natural processes as forest fires and overview these processes considering weather conditions that were conducive for aerosols accumulation during that time. HYSPLIT back trajectories for mentioned stations in the altitude 0.5, 1.5, 3, 4 and 5 km are used as the improvement of results of synoptic analysis. Clear advantage of modelling of transport processes give the ability to receive detailed transport paths, which makes easier to distinguish the origin of aerosols. Conclusion. Detailed research of aerosols with the application of up-to-date technologies makes the analysis of the optical properties of aerosols over large area quite efficient. The obvious effect of forest fires in European territory of Russia (UTR) on air quality of observational stations of Ukraine, Russia, Moldova, Romania, Poland, Belarus and Estonia is detected and analysed. The further application of satellite measurements of optical properties of aerosols are attempted to be implemented to the further research.


Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 831
Author(s):  
Anatoliy R. Galamay ◽  
Krzysztof Bukowski ◽  
Igor M. Zinczuk ◽  
Fanwei Meng

Currently, fluid inclusions in halite have been frequently studied for the purpose of paleoclimate reconstruction. For example, to determine the air temperature in the Middle Miocene (Badenian), we examine single-phase primary fluid inclusions of the bottom halites (chevron and full-faceted) and near-surface (cumulate) halites collected from the salt-bearing deposits of the Carpathian region. Our analyses showed that the temperatures of near-bottom brines varied in ranges from 19.5 to 22.0 °C and 24.0 to 26.0 °C, while the temperatures of the surface brines ranged from 34.0 to 36.0 °C. Based on these data, such as an earlier study of lithology and sedimentary structures of the Badenian rock salts, the crystallization of bottom halite developed in the basin from concentrated and cooled near-surface brines of about 30 m depth. Our results comply with the data on the temperature distribution in the modern Dead Sea.


2007 ◽  
Vol 46 (10) ◽  
pp. 1587-1605 ◽  
Author(s):  
J-F. Miao ◽  
D. Chen ◽  
K. Borne

Abstract In this study, the performance of two advanced land surface models (LSMs; Noah LSM and Pleim–Xiu LSM) coupled with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5), version 3.7.2, in simulating the near-surface air temperature in the greater Göteborg area in Sweden is evaluated and compared using the GÖTE2001 field campaign data. Further, the effects of different planetary boundary layer schemes [Eta and Medium-Range Forecast (MRF) PBLs] for Noah LSM and soil moisture initialization approaches for Pleim–Xiu LSM are investigated. The investigation focuses on the evaluation and comparison of diurnal cycle intensity and maximum and minimum temperatures, as well as the urban heat island during the daytime and nighttime under the clear-sky and cloudy/rainy weather conditions for different experimental schemes. The results indicate that 1) there is an evident difference between Noah LSM and Pleim–Xiu LSM in simulating the near-surface air temperature, especially in the modeled urban heat island; 2) there is no evident difference in the model performance between the Eta PBL and MRF PBL coupled with the Noah LSM; and 3) soil moisture initialization is of crucial importance for model performance in the Pleim–Xiu LSM. In addition, owing to the recent release of MM5, version 3.7.3, some experiments done with version 3.7.2 were repeated to reveal the effects of the modifications in the Noah LSM and Pleim–Xiu LSM. The modification to longwave radiation parameterizations in Noah LSM significantly improves model performance while the adjustment of emissivity, one of the vegetation properties, affects Pleim–Xiu LSM performance to a larger extent. The study suggests that improvements both in Noah LSM physics and in Pleim–Xiu LSM initialization of soil moisture and parameterization of vegetation properties are important.


2015 ◽  
Vol 15 (19) ◽  
pp. 10983-10998 ◽  
Author(s):  
J. C. Péré ◽  
B. Bessagnet ◽  
V. Pont ◽  
M. Mallet ◽  
F. Minvielle

Abstract. In this work, impact of aerosol solar extinction on the photochemistry over eastern Europe during the 2010 wildfires episode is discussed for the period from 5 to 12 August 2010, which coincides to the peak of fire activity. The methodology is based on an online coupling between the chemistry-transport model CHIMERE (extended by an aerosol optical module) and the radiative transfer code TUV. Results of simulations indicate an important influence of the aerosol solar extinction, in terms of intensity and spatial extent, with a reduction of the photolysis rates of NO2 and O3 up to 50 % (in daytime average) along the aerosol plume transport. At a regional scale, these changes in photolysis rates lead to a 3–15 % increase in the NO2 daytime concentration and to an ozone reduction near the surface of 1–12 %. The ozone reduction is shown to occur over the entire boundary layer, where aerosols are located. Also, the total aerosol mass concentration (PM10) is shown to be decreased by 1–2 %, on average during the studied period, caused by a reduced formation of secondary aerosols such as sulfates and secondary organics (4–10 %) when aerosol impact on photolysis rates is included. In terms of model performance, comparisons of simulations with air quality measurements at Moscow indicate that an explicit representation of aerosols interaction with photolysis rates tend to improve the estimation of the near-surface concentration of ozone and nitrogen dioxide as well as the formation of inorganic aerosol species such as ammonium, nitrates and sulfates.


2015 ◽  
Vol 15 (10) ◽  
pp. 5429-5442 ◽  
Author(s):  
E. Giannakaki ◽  
A. Pfüller ◽  
K. Korhonen ◽  
T. Mielonen ◽  
L. Laakso ◽  
...  

Abstract. Raman lidar data obtained over a 1 year period has been analysed in relation to aerosol layers in the free troposphere over the Highveld in South Africa. In total, 375 layers were observed above the boundary layer during the period 30 January 2010 to 31 January 2011. The seasonal behaviour of aerosol layer geometrical characteristics, as well as intensive and extensive optical properties were studied. The highest centre heights of free-tropospheric layers were observed during the South African spring (2520 ± 970 m a.g.l., also elsewhere). The geometrical layer depth was found to be maximum during spring, while it did not show any significant difference for the rest of the seasons. The variability of the analysed intensive and extensive optical properties was high during all seasons. Layers were observed at a mean centre height of 2100 ± 1000 m with an average lidar ratio of 67 ± 25 sr (mean value with 1 standard deviation) at 355 nm and a mean extinction-related Ångström exponent of 1.9 ± 0.8 between 355 and 532 nm during the period under study. Except for the intensive biomass burning period from August to October, the lidar ratios and Ångström exponents are within the range of previous observations for urban/industrial aerosols. During Southern Hemispheric spring, the biomass burning activity is clearly reflected in the optical properties of the observed free-tropospheric layers. Specifically, lidar ratios at 355 nm were 89 ± 21, 57 ± 20, 59 ± 22 and 65 ± 23 sr during spring (September–November), summer (December–February), autumn (March–May) and winter (June–August), respectively. The extinction-related Ångström exponents between 355 and 532 nm measured during spring, summer, autumn and winter were 1.8 ± 0.6, 2.4 ± 0.9, 1.8 ± 0.9 and 1.8 ± 0.6, respectively. The mean columnar aerosol optical depth (AOD) obtained from lidar measurements was found to be 0.46 ± 0.35 at 355 nm and 0.25 ± 0.2 at 532 nm. The contribution of free-tropospheric aerosols on the AOD had a wide range of values with a mean contribution of 46%.


Sign in / Sign up

Export Citation Format

Share Document