scholarly journals Performance Evaluation of the Boundary-Layer Height from Lidar and the Weather Research and Forecasting Model at an Urban Coastal Site in the North-East Iberian Peninsula

2015 ◽  
Vol 157 (2) ◽  
pp. 265-292 ◽  
Author(s):  
Robert F. Banks ◽  
Jordi Tiana-Alsina ◽  
Francesc Rocadenbosch ◽  
José M. Baldasano
Keyword(s):  
Boundary Layer ◽  
Performance Evaluation ◽  
Iberian Peninsula ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Coastal Site ◽  
Layer Height ◽  
Boundary Layer Height ◽  
North East ◽  
The North

scholarly journals Relationships between the planetary boundary layer height and surface pollutants derived from lidar observations over China

2018 ◽  
Author(s):  
Tianning Su ◽  
Zhanqing Li ◽  
Ralph Kahn
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Negative Correlation ◽  
North China Plain ◽  
North China ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
The North ◽  
The North China Plain

Abstract. The frequent occurrence of severe air pollution episodes in China has raised great concerns with the public and scientific communities. Planetary boundary layer height (PBLH) is a key factor in the vertical mixing and dilution of near-surface pollutants. However, the relationship between PBLH and surface pollutants, especially particulate matter (PM) concentration, across the whole of China, is not yet well understood. We investigate this issue at ~ 1500 surface stations using PBLH derived from space-borne and ground-based lidar, and discuss the influence of topography and meteorological variables on the PBLH-PM relationship. A generally negative correlation is observed between PM and the PBLH, albeit varying greatly in magnitude with location and season. Correlations are much weaker over the highlands than plains regions, which may be associated with lower pollution levels and mountain breezes. The influence of horizontal transport on surface PM is considered as well, manifested as a negative correlation between surface PM and wind speed over the whole nation. Strong wind with clean upwind sources plays a dominant role in removing pollutants, and leads to weak PBLH-PM correlation. A ventilation rate is introduced to jointly consider horizontal and vertical dispersion, which has the largest impact on surface pollutant accumulation over the North China Plain. Aerosol absorption feedbacks also appear to affect the PBLH-PM relationship, as revealed via comparing air pollution in Beijing and Hong Kong. Absorbing aerosols in high concentrations likely contribute to the significant PBLH-PM correlation over the North China Plain (e.g., during winter). As major precursor emissions for secondary aerosols, sulfur dioxide, nitrogen dioxide, and carbon monoxide have similar negative responses to increased PBLH, whereas ozone is positively correlated with PBLH over most regions, which may be caused by heterogeneous reactions and photolysis rates.

Comparison of indirect methods for the estimation of Boundary Layer height over flat-terrain in a coastal site

2009 ◽  
Vol 18 (3) ◽  
pp. 309-320 ◽  
Author(s):  
Daniele Contini ◽  
Danilea Cava ◽  
Paolo Martano ◽  
Antonio Donateo ◽  
Fabio M. Grasso
Keyword(s):  
Boundary Layer ◽  
Coastal Site ◽  
Indirect Methods ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Flat Terrain

Seasonal and episodic influence of local meteorology on fine particulate matter at a regional background site in North East India.

2021 ◽  
Author(s):  
Adnan Qadri ◽  
Shahadev Rabha ◽  
Binoy Saikia ◽  
Tarun Gupta
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Ambient Air ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Wind Speeds ◽  
Background Site ◽  
North East ◽  
Regional Background ◽  
Ventilation Coefficient

<p>Climatological parameters like wind speed, temperature, boundary layer height facilitate in dispersion and accumulation of aerosols. Stagnant condition of atmosphere promote accumulation while the pollutants are more likely to get dispersed when non stagnation conditions exist. Sparse studies exist to assess the seasonal and episodic impact of stagnant weather conditions on enhancing aerosol formation in the North-East region of India.PM<sub>2.5 </sub>sampling was carried from January to November 2019 at a regional background site in Jorhat,Assam. Meteorological variables like wind speed, surface ambient temperature and relative humidity were obtained at one-minute resolution from a collocated air weather sensor. Ventilation coefficient was calculated from wind speed and Boundary Layer Height (BLH) ( from ERA5 reanalysis dataset)</p><p>Episodic days were identified as those exceeding permissible values of PM<sub>2.5 </sub>(National Ambient Air Quality Standards) i.e, 60µg/m<sup>3</sup>. Average wind speed on polluted and non-polluted days was 0.58±0.08 and 0.77 ± 0.17 m/s respectively. The average BLH was lower for the polluted days (243±73) than the non-polluted days (316±79). Pearson corelation coefficient of PM<sub>2.5 </sub>and wind speeds on polluted days was low (-0.23) compared to the non-polluted days (-0.54).</p><p>Wind rose plots reveal a seasonality trend with winter and summer winds being mostly between North East and South South-West while in monsoon and autumn it lies predominantly between SSW and South South-East (from the Bay of Bengal).  The Pearson correlation coefficients between PM<sub>2.5 </sub>and wind speeds are -0.66, -0.54 and -0.52 (all p <0.01) in winter, summer and autumn, respectively.Low average BLH persists in Winter and autumn . The seasonal maxima of BLH during winter, summer, monsoon and autumn was 847±167m, 932 ± 271m, 871 ±275m and 814 ± 256m, respectively.  Low night-time BLH (≈ 50m) in winter and autumn contributes to higher aerosol loading. The ventilation coefficient reaches its maxima during daytime around noon with summer season having the maximum daytime VC. High VC (≈270m<sup>2</sup>/s) in summer and monsoon  signify the seasonal effect on the pollutant dispersion and consequent high PM<sub>2.5 </sub>loading. Statistically significant negative correlations were obtained between PM<sub>2.5 </sub>and VC in winter and autumn seasons (-0.75 and -0.43).</p><p>Wind speeds have a strong correlation with PM<sub>2.5 </sub>except for the monsoon season and play a major role in aerosol dispersion.During monsoon, weak dependence of PM<sub>2.5 </sub>with wind speed and ventilation coefficient suggest significance of precipitation  which cause sscavenging of aerosols. Low correlations exist in summer for PM<sub>2.5 </sub>and VC due to possible interference due to regional transport of aerosols. 5-day backward trajectory analysis suggest  transport of air masses across the Thar desert and Indo Gangetic Plains to the site during the March(summer) suggesting transport of dust across the region.</p>

scholarly journals Land-Use Improvements in the Weather Research and Forecasting Model over Complex Mountainous Terrain and Comparison of Different Grid Sizes

2021 ◽  
Author(s):  
Alessio Golzio ◽  
Silvia Ferrarese ◽  
Claudio Cassardo ◽  
Gugliemina Adele Diolaiuti ◽  
Manuela Pelfini
Keyword(s):  
Boundary Layer ◽  
Land Use ◽  
Land Cover ◽  
Mixing Layer ◽  
Local Area ◽  
Heat Fluxes ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Mountainous Terrain ◽  
Weather Research

AbstractWeather forecasts over mountainous terrain are challenging due to the complex topography that is necessarily smoothed by actual local-area models. As complex mountainous territories represent 20% of the Earth’s surface, accurate forecasts and the numerical resolution of the interaction between the surface and the atmospheric boundary layer are crucial. We present an assessment of the Weather Research and Forecasting model with two different grid spacings (1 km and 0.5 km), using two topography datasets (NASA Shuttle Radar Topography Mission and Global Multi-resolution Terrain Elevation Data 2010, digital elevation models) and four land-cover-description datasets (Corine Land Cover, U.S. Geological Survey land-use, MODIS30 and MODIS15, Moderate Resolution Imaging Spectroradiometer land-use). We investigate the Ortles Cevadale region in the Rhaetian Alps (central Italian Alps), focusing on the upper Forni Glacier proglacial area, where a micrometeorological station operated from 28 August to 11 September 2017. The simulation outputs are compared with observations at this micrometeorological station and four other weather stations distributed around the Forni Glacier with respect to the latent heat, sensible heat and ground heat fluxes, mixing-layer height, soil moisture, 2-m air temperature, and 10-m wind speed. The different model runs make it possible to isolate the contributions of land use, topography, grid spacing, and boundary-layer parametrizations. Among the considered factors, land use proves to have the most significant impact on results.

scholarly journals Technical note: Boundary layer height determination from Lidar for improving air pollution episode modelling: development of new algorithm and evaluation

2017 ◽  
Author(s):  
Ting Yang ◽  
Zifa Wang ◽  
Wei Zhang ◽  
Alex Gbaguidi ◽  
Nubuo Sugimoto ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
High Performance ◽  
Accurate Determination ◽  
Technical Note ◽  
Strong Increase ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Retrieval Algorithms ◽  
The Impact

Abstract. Predicting air pollution events in low atmosphere over megacities requires thorough understanding of the tropospheric dynamic and chemical processes, involving notably, continuous and accurate determination of the boundary layer height (BLH). Through intensive observations experimented over Beijing (China), and an exhaustive evaluation existing algorithms applied to the BLH determination, persistent critical limitations are noticed, in particular over polluted episodes. Basically, under weak thermal convection with high aerosol loading, none of the retrieval algorithms is able to fully capture the diurnal cycle of the BLH due to pollutant insufficient vertical mixing in the boundary layer associated with the impact of gravity waves on the tropospheric structure. Subsequently, a new approach based on gravity wave theory (the cubic root gradient method: CRGM), is developed to overcome such weakness and accurately reproduce the fluctuations of the BLH under various atmospheric pollution conditions. Comprehensive evaluation of CRGM highlights its high performance in determining BLH from Lidar. In comparison with the existing retrieval algorithms, the CRGM potentially reduces related computational uncertainties and errors from BLH determination (strong increase of correlation coefficient from 0.44 to 0.91 and significant decrease of the root mean square error from 643 m to 142 m). Such newly developed technique is undoubtedly expected to contribute to improve the accuracy of air quality modelling and forecasting systems.

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