scholarly journals An investigation of methods for injecting emissions from boreal wildfires using WRF-Chem during ARCTAS

2011 ◽  
Vol 11 (12) ◽  
pp. 5719-5744 ◽  
Author(s):  
W. R. Sessions ◽  
H. E. Fuelberg ◽  
R. A. Kahn ◽  
D. M. Winker
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Atmospheric Stability ◽  
Vertical Wind Shear ◽  
Ground Level ◽  
Naval Research ◽  
Plume Rise ◽  
Hotspot Detection ◽  
Transport Pathways ◽  
Thermal Buoyancy

Abstract. The Weather Research and Forecasting Model (WRF) is considered a "next generation" mesoscale meteorology model. The inclusion of a chemistry module (WRF-Chem) allows transport simulations of chemical and aerosol species such as those observed during NASA's Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) in 2008. The ARCTAS summer deployment phase during June and July coincided with large boreal wildfires in Saskatchewan and Eastern Russia. One of the most important aspects of simulating wildfire plume transport is the height at which emissions are injected. WRF-Chem contains an integrated one-dimensional plume rise model to determine the appropriate injection layer. The plume rise model accounts for thermal buoyancy associated with fires and local atmospheric stability. This paper describes a case study of a 10 day period during the Spring phase of ARCTAS. It compares results from the plume model against those of two more traditional injection methods: Injecting within the planetary boundary layer, and in a layer 3–5 km above ground level. Fire locations are satellite derived from the GOES Wildfire Automated Biomass Burning Algorithm (WF_ABBA) and the MODIS thermal hotspot detection. Two methods for preprocessing these fire data are compared: The prep_chem_sources method included with WRF-Chem, and the Naval Research Laboratory's Fire Locating and Monitoring of Burning Emissions (FLAMBE). Results from the simulations are compared with satellite-derived products from the AIRS, MISR and CALIOP sensors. When FLAMBE provides input to the 1-D plume rise model, the resulting injection heights exhibit the best agreement with satellite-observed injection heights. The FLAMBE-derived heights are more realistic than those utilizing prep_chem_sources. Conversely, when the planetary boundary layer or the 3–5 km a.g.l. layer were filled with emissions, the resulting injection heights exhibit less agreement with observed plume heights. Results indicate that differences in injection heights produce different transport pathways. These differences are especially pronounced in area of strong vertical wind shear and when the integration period is long.

scholarly journals An investigation of methods for injecting emissions from boreal wildfires using WRF-Chem during ARCTAS

2010 ◽  
Vol 10 (11) ◽  
pp. 26551-26606 ◽  
Author(s):  
W. R. Sessions ◽  
H. E. Fuelberg ◽  
R. A. Kahn ◽  
D. M. Winker
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Atmospheric Stability ◽  
Vertical Wind Shear ◽  
Ground Level ◽  
Naval Research ◽  
Plume Rise ◽  
Hotspot Detection ◽  
Transport Pathways ◽  
Thermal Buoyancy

Abstract. The Weather Research and Forecasting Model (WRF) is considered a "next generation" mesoscale meteorology model. The inclusion of a chemistry module (WRF-Chem) allows transport simulations of chemical and aerosol species such as those observed during NASA's Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) in 2008. The ARCTAS summer deployment phase during June and July coincided with large boreal wildfires in Saskatchewan and Eastern Russia. One of the most important aspects of simulating wildfire plume transport is the height at which emissions are injected. WRF-Chem contains an integrated one-dimensional plume rise model to determine the appropriate injection layer. The plume rise model accounts for thermal buoyancy associated with fires and the local atmospheric stability. This study compares results from the plume model against those of two more traditional injection methods: Injecting within the planetary boundary layer, and in a layer 3–5 km above ground level. Fire locations are satellite derived from the GOES Wildfire Automated Biomass Burning Algorithm (WF_ABBA) and the MODIS thermal hotspot detection. Two methods for preprocessing these fire data are compared: The prep_chem_sources method included with WRF-Chem, and the Naval Research Laboratory's Fire Locating and Monitoring of Burning Emissions (FLAMBE). Results from the simulations are compared with satellite-derived products from the AIRS, MISR and CALIOP sensors. Results show that the FLAMBE pre-processor produces more realistic injection heights than does prep_chem_sources. The plume rise model using FLAMBE provides the best agreement with satellite-observed injection heights. Conversely, when the planetary boundary layer or the 3–5 km AGL layer were filled with emissions, the resulting injection heights exhibit less agreement with observed plume heights. Results indicate that differences in injection heights produce different transport pathways. These differences are especially pronounced in areas of strong vertical wind shear and when the integration period is long.

scholarly journals Vertical and horizontal variation of aerosol number size distribution in the boreal environment

2016 ◽  
Author(s):  
Riikka Väänänen ◽  
Radovan Krejci ◽  
Hanna E. Manninen ◽  
Antti Manninen ◽  
Janne Lampilahti ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Size Distribution ◽  
Planetary Boundary Layer ◽  
Particle Number ◽  
Ground Level ◽  
Number Concentration ◽  
Field Station ◽  
Airborne Measurements ◽  
Number Size Distribution ◽  
Particle Number Size Distribution

Abstract. This study explores the vertical and horizontal variability of the particle number size distribution from two flight measurements campaigns over a boreal forest in Hyytiälä, Finland during May–June 2013 and March–April 2014, respectively. Our other aims were to study the spatial extent of new particle formation events and to compare the airborne observation with the ground measurements from the SMEAR II (Station for Measuring Ecosystem-Atmosphere Relations) field station located in Hyytiälä. The airborne measurements extended vertically 3.8 km and horizontally 30 km from the station. A Cessna 172 aircraft was used as a measurement platform. The measured parameters included the particle number concentration (> 3 nm) and particle number size distribution (10–400 nm). The airborne data used in this study were equal to 111 flight hours. The measurements showed that despite local fluctuations there was a good agreement between the on-ground and airborne measurements inside the planetary boundary layer. On median, the airborne total number concentration was found to be 10 % larger than at the ground level. The seasonal and meteorological differences between the campaigns were reflected in aerosol properties. NPF days showed areas of intensified NPF on a scale from kilometres up to couple of tens of kilometres in the planetary boundary layer. NPF was also observed frequently in the free troposphere.

scholarly journals Current challenges in modelling far-range air pollution induced by the 2014–2015 Bárðarbunga fissure eruption (Iceland)

2016 ◽  
Vol 16 (17) ◽  
pp. 10831-10845 ◽  
Author(s):  
Marie Boichu ◽  
Isabelle Chiapello ◽  
Colette Brogniez ◽  
Jean-Christophe Péré ◽  
Francois Thieuleux ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Vertical Distribution ◽  
Planetary Boundary Layer ◽  
Large Scale ◽  
Temporal Dynamics ◽  
Ground Level ◽  
Optical Absorption Spectroscopy ◽  
Sulfate Aerosols ◽  
Volcanic Cloud

Abstract. The 2014–2015 Holuhraun lava-flood eruption of Bárðarbunga volcano (Iceland) emitted prodigious amounts of sulfur dioxide into the atmosphere. This eruption caused a large-scale episode of air pollution throughout Western Europe in September 2014, the first event of this magnitude recorded in the modern era. We gathered chemistry-transport simulations and a wealth of complementary observations from satellite sensors (OMI, IASI), ground-based remote sensing (lidar, sunphotometry, differential optical absorption spectroscopy) and ground-level air quality monitoring networks to characterize both the spatial-temporal distributions of volcanic SO2 and sulfate aerosols as well as the dynamics of the planetary boundary layer. Time variations of dynamical and microphysical properties of sulfate aerosols in the aged low-tropospheric volcanic cloud, including loading, vertical distribution, size distribution and single scattering albedo, are provided. Retrospective chemistry-transport simulations at low horizontal resolution (25 km  ×  25 km) capture the correct temporal dynamics of this far-range air pollution event but fail to reproduce the correct magnitude of SO2 concentration at ground-level. Simulations at higher spatial resolution, relying on two nested domains with finest resolution of 7.3 km  ×  7.3 km, improve substantially the far-range vertical distribution of the volcanic cloud and subsequently the description of ground-level SO2 concentrations. However, remaining discrepancies between model and observations are shown to result from an inaccurate representation of the planetary boundary layer (PBL) dynamics. Comparison with lidar observations points out a systematic under-estimation of the PBL height by the model, whichever the PBL parameterization scheme. Such a shortcoming impedes the capture of the overlying Bárðarbunga cloud into the PBL at the right time and in sufficient quantities. This study therefore demonstrates the key role played by the PBL dynamics in accurately modelling large-scale volcanogenic air pollution.

scholarly journals How well do tall-tower measurements characterize the CO<sub>2</sub> mole fraction distribution in the planetary boundary layer?

2015 ◽  
Vol 8 (4) ◽  
pp. 1657-1671 ◽  
Author(s):  
L. Haszpra ◽  
Z. Barcza ◽  
T. Haszpra ◽  
Zs. Pátkai ◽  
K. J. Davis
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Planetary Boundary Layer ◽  
Mole Fraction ◽  
Lower Troposphere ◽  
Co2 Flux ◽  
Ground Level ◽  
Rural Site ◽  
Mole Fraction Profile ◽  
Tall Tower

Abstract. Planetary boundary layer (PBL) CO2 mole fraction data are needed by transport models and carbon budget models as both input and reference for validation. The height of in situ CO2 mole fraction measurements is usually different from that of the model levels where the data are needed; data from short towers, in particular, are difficult to utilize in atmospheric models that do not simulate the surface layer well. Tall-tower CO2 mole fraction measurements observed at heights ranging from 10 to 115 m above ground level at a rural site in Hungary and regular airborne vertical mole fraction profile measurements (136 vertical profiles) above the tower allowed us to estimate how well a tower of a given height could estimate the CO2 mole fraction above the tower in the PBL. The statistical evaluation of the height-dependent bias between the real PBL CO2 mole fraction profile (measured by the aircraft) and the measurement at a given elevation above the ground was performed separately for the summer and winter half years to take into account the different dynamics of the lower troposphere and the different surface CO2 flux in the different seasons. The paper presents (1) how accurately the vertical distribution of CO2 in the PBL can be estimated from the measurements on the top of a tower of height H; (2) how tall of a tower would be needed for the satisfaction of different requirements on the accuracy of the estimation of the CO2 vertical distribution; (3) how accurate of a CO2 vertical distribution estimation can be expected from the existing towers; and (4) how much improvement can be achieved in the accuracy of the estimation of CO2 vertical distribution by applying the virtual tall-tower concept.

scholarly journals Vertical distribution of ozone and VOCs in the low boundary layer of Mexico City

2008 ◽  
Vol 8 (12) ◽  
pp. 3061-3079 ◽  
Author(s):  
E. Velasco ◽  
C. Márquez ◽  
E. Bueno ◽  
R. M. Bernabé ◽  
A. Sánchez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Mexico City ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Residual Layer ◽  
Background Concentration ◽  
Complex Interactions ◽  
Unstable Layer

Abstract. The evolution of ozone (O3) and 13 volatile organic compounds (VOCs) in the boundary layer of Mexico City was investigated during 2000–2004 to improve our understanding of the complex interactions between those trace gases and meteorological variables, and their influence on the air quality of a polluted megacity. A tethered balloon, fitted with electrochemical and meteorological sondes, was used to obtain detailed vertical profiles of O3 and meteorological parameters up to 1000 m above ground during part of the diurnal cycle (02:00–18:00 h). VOCs samples were collected up to 200 m by pumping air to canisters with a Teflon tube attached to the tether line. Overall, features of these profiles were found to be consistent with the formation of an upper residual layer during nighttime carrying over a fraction of the O3 from the previous day that contributes to the background concentration in surrounding regions. At the same time the release of heat stored in the urban surface forms a shallow unstable layer close to the ground, where the nocturnal emissions are trapped. After sunrise an O3 balance is determined by photochemical production, entrainment from the upper residual layer and destruction by titration with nitric oxide, delaying the ground-level O3 rise by 2 h. The subsequent evolution of the conductive boundary layer and vertical distribution of pollutants are discussed in terms of the energy balance, the presence of turbulence and the atmospheric stability.

scholarly journals Reasons for the Extremely High-Ranging Planetary Boundary Layer over the Western Tibetan Plateau in Winter

2016 ◽  
Vol 73 (5) ◽  
pp. 2021-2038 ◽  
Author(s):  
Xuelong Chen ◽  
Bojan Škerlak ◽  
Mathias W. Rotach ◽  
Juan A. Añel ◽  
Zhonbgo Su ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Tibetan Plateau ◽  
Sea Level ◽  
Planetary Boundary Layer ◽  
Weather Prediction ◽  
Atmospheric Stability ◽  
Small Scale ◽  
The Tibetan Plateau ◽  
Single Column ◽  
Upper Level

Abstract The planetary boundary layer (PBL) over the Tibetan Plateau (with a mean elevation about 4 km above sea level) reaches an unmatched height of 9515 m above sea level. The proximity of this height to the tropopause facilitates an exchange between the stratosphere and the boundary layer. However, the underlying mechanisms responsible for this unique PBL have remained uncertain. Here, the authors explore these mechanisms and their relative importance using measurements of the PBL, the associated surface fluxes, and single-column and regional numerical simulations, as well as global reanalysis data. Results indicate that the dry conditions of both ground soil and atmosphere in late winter cannot explain the special PBL alone. Rather, the results from a single-column model demonstrate the key influence of the stability of the free atmosphere upon the growth of extremely deep PBLs over the Tibetan Plateau. Simulations with the numerical weather prediction model Consortium for Small-Scale Modelling (COSMO) exhibit good correspondence with the observed mean PBL structure and realistic turbulent kinetic energy distributions throughout the PBL. Using ERA-Interim, the authors furthermore find that weak atmospheric stability and the resultant deep PBLs are associated with higher upper-level potential vorticity (PV) values, which in turn correspond to a more southerly jet position and higher wind speeds. Upper-level PV structures and jet position thus influence the PBL development over the Tibetan Plateau.

scholarly journals Diurnal cycle of coastal anthropogenic pollutant transport over southern West Africa during the DACCIWA campaign

2019 ◽  
Vol 19 (1) ◽  
pp. 473-497 ◽  
Author(s):  
Adrien Deroubaix ◽  
Laurent Menut ◽  
Cyrille Flamant ◽  
Joel Brito ◽  
Cyrielle Denjean ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
West Africa ◽  
Biomass Burning ◽  
Diurnal Cycle ◽  
Ground Level ◽  
Transport Pathways ◽  
Anthropogenic Pollutants ◽  
Coastal Cities ◽  
Anthropogenic Pollutant

Abstract. During the monsoon season, pollutants emitted by large coastal cities and biomass burning plumes originating from central Africa have complex transport pathways over southern West Africa (SWA). The Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa (DACCIWA) field campaign has provided numerous dynamical and chemical measurements in and around the super-site of Savè in Benin (≈185 km away from the coast), which allows quantification of the relative contribution of advected pollutants. Through the combination of in situ ground measurements with aircraft, radio-sounding, satellite, and high-resolution chemistry-transport modeling with the CHIMERE model, the source attribution and transport pathways of pollutants inland (here, NOx and CO) are carefully analyzed for the 1–7 July 2016 period. The relative contributions of different sources (i.e., emissions from several large coastal cities) to the air quality in Savè are characterized. It is shown that a systematic diurnal cycle exists with high surface concentrations of pollutants from 18:00 to 22:00 UTC. This evening peak is attributed to pollution transport from the coastal city of Cotonou (Benin). Numerical model experiments indicate that the anthropogenic pollutants are accumulated during the day close to the coast and transported northward as soon as the daytime convection in the atmospheric boundary layer ceases after 16:00 UTC, reaching 8∘ N at 21:00 UTC. When significant biomass burning pollutants are transported into continental SWA, they are mixed with anthropogenic pollutants along the coast during the day, and this mixture is then transported northward. At night, most of the coastal anthropogenic plumes are transported within the planetary boundary layer (below about 500 m above ground level), whereas the biomass burning pollutants are mostly transported above it, thus generally not impacting ground level air quality.

scholarly journals Optimization of the lidar optical design for measurement of the aerosol extinction vertical profile

2019 ◽  
Vol 197 ◽  
pp. 02006 ◽  
Author(s):  
Alessia Sannino ◽  
Antonella Boselli ◽  
Gaetano Sasso ◽  
Nicola Spinelli ◽  
Xuan Wang
Keyword(s):  
Boundary Layer ◽  
Ray Tracing ◽  
Planetary Boundary Layer ◽  
Vertical Profile ◽  
Optical Design ◽  
Ground Level ◽  
Aerosol Extinction ◽  
Quality Signals ◽  
Aerosol Monitoring ◽  
Difficult Challenge

A lidar for aerosol monitoring with conventional optical design can provide good quality signals from several hundred meters up to tens of kilometres above the ground, but the aerosol load is mainly contained (up to 80%) in the planetary boundary layer that can have a height of only hundreds of meters above the ground level. Therefore, the measurement of the complete aerosol extinction profile is generally a very difficult challenge. In this paper, we proposed an optical design of lidar systems able of producing signals starting from a few tens of meters above the ground. The overlap profiles obtained from an optimized lidar was compared with ray tracing simulations and further conventional lidar apparatuses.

scholarly journals Phenomenology of summer ozone episodes over the Madrid Metropolitan Area, central Spain

2018 ◽  
Vol 18 (9) ◽  
pp. 6511-6533 ◽  
Author(s):  
Xavier Querol ◽  
Andrés Alastuey ◽  
Gotzon Gangoiti ◽  
Noemí Perez ◽  
Hong K. Lee ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Altitude ◽  
Planetary Boundary Layer ◽  
Metropolitan Area ◽  
Ultrafine Particles ◽  
Ground Level ◽  
Atmospheric Dynamics ◽  
Mountain Range ◽  
Regional Production ◽  
Ozone Episodes

Abstract. Various studies have reported that the photochemical nucleation of new ultrafine particles (UFPs) in urban environments within high insolation regions occurs simultaneously with high ground ozone (O3) levels. In this work, we evaluate the atmospheric dynamics leading to summer O3 episodes in the Madrid air basin (central Iberia) by means of measuring a 3-D distribution of concentrations for both pollutants. To this end, we obtained vertical profiles (up to 1200 m above ground level) using tethered balloons and miniaturised instrumentation at a suburban site located to the SW of the Madrid Metropolitan Area (MMA), the Majadahonda site (MJDH), in July 2016. Simultaneously, measurements of an extensive number of air quality and meteorological parameters were carried out at three supersites across the MMA. Furthermore, data from O3 soundings and daily radio soundings were also used to interpret atmospheric dynamics. The results demonstrate the concatenation of venting and accumulation episodes, with relative lows (venting) and peaks (accumulation) in O3 surface levels. Regardless of the episode type, the fumigation of high-altitude O3 (arising from a variety of origins) contributes the major proportion of surface O3 concentrations. Accumulation episodes are characterised by a relatively thinner planetary boundary layer (< 1500 m at midday, lower in altitude than the orographic features), light synoptic winds, and the development of mountain breezes along the slopes of the Guadarrama Mountain Range (located W and NW of the MMA, with a maximum elevation of > 2400 m a.s.l.). This orographic–meteorological setting causes the vertical recirculation of air masses and enrichment of O3 in the lower tropospheric layers. When the highly polluted urban plume from Madrid is affected by these dynamics, the highest Ox (O3+ NO2) concentrations are recorded in the MMA. Vertical O3 profiles during venting episodes, with strong synoptic winds and a deepening of the planetary boundary layer reaching > 2000 m a.s.l., were characterised by an upward gradient in O3 levels, whereas a reverse situation with O3 concentration maxima at lower levels was found during the accumulation episodes due to local and/or regional production. The two contributions to O3 surface levels (fumigation from high-altitude strata, a high O3 background, and/or regional production) require very different approaches for policy actions. In contrast to O3 vertical top-down transfer, UFPs are formed in the planetary boundary layer (PBL) and are transferred upwards progressively with the increase in PBL growth.

scholarly journals Vertical distribution of ozone and VOCs in the low boundary layer of Mexico City

2007 ◽  
Vol 7 (4) ◽  
pp. 12751-12779 ◽  
Author(s):  
E. Velasco ◽  
C. Márquez ◽  
E. Bueno ◽  
R. M. Bernabé ◽  
A. Sánchez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Mexico City ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Residual Layer ◽  
Ground Level Ozone ◽  
Complex Interactions ◽  
Unstable Layer

Abstract. The evolution of ozone and 13 volatile organic compounds (VOCs) in the boundary layer of Mexico City was investigated during 2000–2004 to improve our understanding of the complex interactions between those trace gases and meteorological variables, and their influence on the air quality of a polluted megacity. A tethered balloon, fitted with electrochemical and meteorological sondes, was used to obtain detailed vertical profiles of ozone and meteorological parameters up to 1000 m above ground during part of the diurnal cycle (02:00–18:00 h). VOCs samples were collected up to 200 m by pumping air to canisters with a Teflon tube attached to the tether line. Overall, features of these profiles were found to be consistent with a simple picture of nighttime trapping of ozone in an upper residual layer and of VOCs in a shallow unstable layer above the ground. After sunrise an ozone balance is determined by photochemical production, entrainment from the upper residual layer and destruction by titration with NO, delaying the ground-level ozone rise by 2 h. The subsequent evolution of the conductive boundary layer and vertical distribution of pollutants are discussed in terms of the energy balance, the presence of turbulence and the atmospheric stability.

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