Regions Of Complex Terrain Research Articles

A Large-Scale Emulation System for Realistic Three-Dimensional (3-D) Forest Simulation

The realistic reconstruction and radiometric simulation of a large-scale three-dimensional (3-D) forest scene have potential applications in remote sensing. Although many 3-D radiative transfer models concerning forest canopy have been developed, they mainly focused on homogeneous or relatively small heterogeneous scenes, which are not compatible with the coarse-resolution remote sensing observations. Due to the huge complexity of forests and the inefficiency of collecting precise 3-D data of large areas, realistic simulation over large-scale forest area remains challenging, especially in regions of complex terrain. In this study, a large-scale emulation system for realistic 3-D forest Simulation is proposed. The 3-D forest scene is constructed from a representative single tree database (SDB) and airborne laser scanning (ALS) data. ALS data are used to extract tree height, crown diameter and position, which are linked to the individual trees in SDB. To simulate the radiometric properties of the reconstructed scene, a radiative transfer model based on a parallelized ray-tracing code was developed. This model has been validated with an abstract and an actual 3-D scene from the radiation transfer model intercomparison website and it showed comparable results with other models. Finally, a 1 km $\times$ 1 km scene with more than 100 000 realistic individual trees was reconstructed and a Landsat-like reflectance image was simulated, which kept the same spatial pattern as the actual Landsat 8 image.

Assessing Agricultural Drought Vulnerability by a VSD Model: A Case Study in Yunnan Province, China

Drought vulnerability of agriculture is significant to economic development and sustainable food production. In this paper, we proposed a framework to evaluate the regional agricultural-eco environment in the face of drought caused by climate change. Based on a vulnerability scoping diagram (VSD) model, we built up a comprehensive system to evaluate the agricultural drought vulnerability of Yunnan Province in China. The model highlights the human-land relationship by considering both natural conditions and human activities. Twelve indicators were generated to construct three components of the model: exposure, sensitivity, and adaptive capacity. During the construction of the VSD model, the entropy and the analytic hierarchy process (AHP) comprehensive analysis method were adopted to generate the weights and to compute the composite index for each section. Furthermore, the factor analysis method was used to determine the dominant factors of different cities and the main indicators driving the system. The results indicated a spatial pattern that the vulnerability value was high on the eastern and western sides, but low in the middle of Yunnan Province. Most of the vulnerable regions were concentrated in remote areas. Indicators such as population density, irrigation level, annual average precipitation, cultivation land ratio, and difficulty of water supply were the main driving factors. This means that there is a deep connection between agricultural drought vulnerability and urbanization. The evaluation system developed during this research will provide guidance for drought mitigation in regions of complex terrain.

Downscaling wind and wavefields for 21st century coastal flood hazard projections in a region of complex terrain

AbstractWhile global climate models (GCMs) provide useful projections of near‐surface wind vectors into the 21st century, resolution is not sufficient enough for use in regional wave modeling. Statistically downscaled GCM projections from Multivariate Adaptive Constructed Analogues provide daily averaged near‐surface winds at an appropriate spatial resolution for wave modeling within the orographically complex region of San Francisco Bay, but greater resolution in time is needed to capture the peak of storm events. Short‐duration high wind speeds, on the order of hours, are usually excluded in statistically downscaled climate models and are of key importance in wave and subsequent coastal flood modeling. Here we present a temporal downscaling approach, similar to constructed analogues, for near‐surface winds suitable for use in local wave models and evaluate changes in wind and wave conditions for the 21st century. Reconstructed hindcast winds (1975–2004) recreate important extreme wind values within San Francisco Bay. A computationally efficient method for simulating wave heights over long time periods was used to screen for extreme events. Wave hindcasts show resultant maximum wave heights of 2.2 m possible within the Bay. Changes in extreme over‐water wind speeds suggest contrasting trends within the different regions of San Francisco Bay, but 21th century projections show little change in the overall magnitude of extreme winds and locally generated waves

GEFS Precipitation Forecasts and the Implications of Statistical Downscaling over the Western United States

Abstract Contemporary operational medium-range ensemble modeling systems produce quantitative precipitation forecasts (QPFs) that provide guidance for weather forecasters, yet lack sufficient resolution to adequately resolve orographic influences on precipitation. In this study, cool-season (October–March) Global Ensemble Forecast System (GEFS) QPFs are verified using daily (24 h) Snow Telemetry (SNOTEL) observations over the western United States, which tend to be located at upper elevations where the orographic enhancement of precipitation is pronounced. Results indicate widespread dry biases, which reflect the infrequent production of larger 24-h precipitation events (≳22.9 mm in Pacific ranges and ≳10.2 mm in the interior ranges) compared with observed. Performance metrics, such as equitable threat score (ETS), hit rate, and false alarm ratio, generally worsen from the coast toward the interior. Probabilistic QPFs exhibit low reliability, and the ensemble spread captures only ~30% of upper-quartile events at day 5. In an effort to improve QPFs without exacerbating computing demands, statistical downscaling is explored based on high-resolution climatological precipitation analyses from the Parameter-Elevation Regressions on Independent Slopes Model (PRISM), an approach frequently used by operational forecasters. Such downscaling improves model biases, ETSs, and hit rates. However, 47% of downscaled QPFs for upper-quartile events are false alarms at day 1, and the ensemble spread captures only 56% of the upper-quartile events at day 5. These results should help forecasters and hydrologists understand the capabilities and limitations of GEFS forecasts and statistical downscaling over the western United States and other regions of complex terrain.

Forecasting Atmospheric Rivers during CalWater 2015

Abstract Atmospheric rivers (ARs) are long and narrow corridors of enhanced vertically integrated water vapor (IWV) and IWV transport (IVT) within the warm sector of extra tropical cyclones that can produce heavy precipitation and flooding in regions of complex terrain, especially along the U.S. West Coast. Several field campaigns have investigated ARs under the CalWater program of field studies. The first field phase of CalWater during 2009–11 increased the number of observations of precipitation and aerosols, among other parameters, across California and sampled ARs in the coastal and near-coastal environment, whereas the second field phase of CalWater during 2014–15 observed the structure and intensity of ARs and aerosols in the coastal and offshore environment over the northeast Pacific. This manuscript highlights the forecasts that were prepared for the CalWater field campaign in 2015, and the development and use of an “AR portal” that was used to inform these forecasts. The AR portal contains archived and real-time deterministic and probabilistic gridded forecast tools related to ARs that emphasize water vapor concentrations and water vapor flux distributions over the eastern North Pacific, among other parameters, in a variety of formats derived from the National Centers for Environmental Prediction (NCEP) Global Forecast System and Global Ensemble Forecast System. The tools created for the CalWater 2015 field campaign provided valuable guidance for flight planning and field activity purposes, and they may prove useful in forecasting ARs and better anticipating hydrometeorological extremes along the U.S. West Coast.

Multi-year atmospheric forcing datasets for hydrologic modeling in regions of complex terrain – Methodology and evaluation over the Integrated Precipitation and Hydrology Experiment 2014 domain

A framework to derive high-resolution long-term meteorological forcing for hydrologic models from mesoscale atmospheric reanalysis products is presented, including topographic and cloud corrections, and a new physical parameterization of near-surface wind fields. The methodology is applied to downscale 3-hourly North American Regional Reanalysis (NARR) fields originally at 32km spacing to 1km and hourly resolution for a seven-year period (2007–2013) over the Integrated Precipitation and Hydrology Experiment 2014 (IPHEx2014) domain with the focus on the Southern Appalachian Mountains (SAM) in the SE US. Evaluation of the adjusted downscaled products was conducted against flux tower observations in the IPHEx domain. At high elevations, the Root Mean Squared Errors (RMSEs) of atmospheric pressure decreased from 44.71 to 2.78hPa, and the RMSEs of near-surface temperature improved by 1K (up to 5K in winter). In addition, RMSEs decreased by as much as 100% for near-surface winds (10m above ground) at all tower locations and by 25–30W/m2 for shortwave radiation at low elevations. Using the uncalibrated Duke Coupled surface-groundwater Hydrology Model (DCHM), the value and utility of the downscaled products for hydrologic offline simulations are demonstrated through comparative analysis of the sensitivity of water and energy budgets in mountain watersheds for four water-years (2007/10–2011/09) including a severe drought and several flood events. Cloud and topographic corrections applied to incoming solar radiation result in hourly net radiation changes ranging from 200 to 500Wm−2 at mid-day for clear-sky and cloudy conditions, respectively. Improvements in shortwave radiation and near-surface wind speed estimates have the highest impact on evapotranspiration and soil surface temperature. Wind speed differences of 2–10m/s translate into basin-averaged differences mid-day surface fluxes up to 300Wm−2 and 100Wm−2 in the inner SAM, for sensible and latent heat respectively.

Uncertainties in the Estimation of Global Observational Network Datasets of Precipitation over West Africa

This study assessed the uncertainty in estimating long-term (1971-2010) mean precipitation, its inter-annual variability, and linear trend of three network observation datasets over West Africa. A reference data, defined as a multi-dataset ensemble of precipitation observations of the Climate Research Unit (CRU) of the University of East Anglia, the Global Precipitation Climatology Centre (GPCC) and the University of Delaware (UDEL), all at horizontal resolutions of 0.5° by 0.5° were obtained and used in this study. Uncertainties in these climatological parameters of precipitation at both annual and seasonal time scales were examined in terms of inter-dataset variability using signalto- noise ratio (SNR), correlation, root-mean-square errors and the normalised standard deviation. Results showed that the mean, inter-annual variability and trends climatology varied for different datasets. The three datasets had good agreement (SNR>5) in terms of the annual mean precipitation and its inter-annual variability in most parts of West Africa. However, the agreement between the datasets was poor in the very dry Sahel parts of northern Niger, Mali, and Mauritania (SNR ≤ 1) due to very little precipitation and possibility of relatively low station density in these regions of complex terrain. In terms of correlation (0.89 ≤ r ≤ 0.98), and normalised standard deviation, NSD (0.8 ≤ NSD ≤ 1.7), the uncertainties in the spatial variations in linear trend were larger than mean precipitation and their inter-annual variability for both annual and seasonal scales. The long-term annual precipitation trend in the region is highly uncertain except in a few small areas.

The use of a numerical weather prediction model to simulate the release of a dense gas with an application to the Lake Nyos disaster of 1986

ABSTRACTThe spread of a dense gas in the atmosphere is a phenomenon that occurs widely with natural (and anthropogenic) causes and is often associated with high impact and hazardous events. In this study a method of simulating the spread of dense gases in a numerical weather prediction model is presented. This approach has the advantage that dense gases can be simulated in regions of complex terrain using realistic forcings (in terms of both the driving meteorological fields and the representation of surface characteristics). The model formulation is tested against semi‐idealized gravity‐current‐type experiments and similar modelling studies. As an example application, the Lake Nyos disaster of 1986, where a dense CO2 cloud spread through a mountainous region of Cameroon, is simulated. The predicted spread of CO2 agrees (qualitatively) very well with the observations. The method provides a means of determining a potential ‘safe height’ above which simulated concentrations are not hazardous, and thus the height above which refuge should be taken during similar future events. The simulation demonstrates a novel application which can be rapidly applied to other scenarios.

High-resolution dust modelling over complex terrains in West Asia

The present work demonstrates the impact of model resolution in dust propagation in a complex terrain region such as West Asia. For this purpose, two simulations using the NMMB/BSC-Dust model are performed and analysed, one with a high horizontal resolution (at 0.03° × 0.03°) and one with a lower horizontal resolution (at 0.33° × 0.33°). Both model experiments cover two intense dust storms that occurred on 17–20 March 2012 as a consequence of strong northwesterly Shamal winds that spanned over thousands of kilometres in West Asia. The comparison with ground-based (surface weather stations and sunphotometers) and satellite aerosol observations (Aqua/MODIS and MSG/SEVIRI) shows that despite differences in the magnitude of the simulated dust concentrations, the model is able to reproduce these two dust outbreaks. Differences between both simulations on the dust spread rise on regional dust transport areas in south-western Saudi Arabia, Yemen and Oman. The complex orography in south-western Saudi Arabia, Yemen and Oman (with peaks higher than 3000 m) has an impact on the transported dust concentration fields over mountain regions. Differences between both model configurations are mainly associated to the channelization of the dust flow through valleys and the differences in the modelled altitude of the mountains that alters the meteorology and blocks the dust fronts limiting the dust transport. These results demonstrate how the dust prediction in the vicinity of complex terrains improves using high-horizontal resolution simulations.

Projected Changes in Heat Extremes and Associated Synoptic- and Mesoscale Conditions over the Northwest United States

Abstract A number of studies have suggested that heat waves will increase in frequency, intensity, and duration under anthropogenic global warming. However, changes to heat extremes and temperature distributions in general are less understood in regions of complex terrain and substantial land–water contrasts. Such surface variations are important in the northwest United States, where synoptic- and mesoscale circulations interact with local topography and land–water interfaces to produce heat waves that have substantial impacts on fire weather, air quality, wind energy, and the population in general. Thus it is crucial to identify how the synoptic- and mesoscale circulations that drive such local extremes will change in a warming world. This paper analyzes changes to the conditions associated with heat extremes over the northwest United States by utilizing global and regional climate models. A maximum in 700-hPa warming is projected over the northwest United States and southwest Canada, with low-level warming attenuated near the coast. Soil moisture declines are projected over the region, which further enhances future extremes. It is found that low-level zonal wind distributions over the northwest United States become narrower, leading to fewer days with strong offshore flow. This is important since extreme warming events are associated with the strongest offshore/downslope flow. Historical and future regional temperature distributions are described and it is shown that although CMIP5 models predict increases in heat extremes for west Oregon and Washington, these increases are less than for inland areas.

A study of local turbulence and anisotropy during the afternoon and evening transition with an unmanned aerial system and mesoscale simulation

Abstract. Observations of turbulence are analysed for the afternoon and evening transition (AET) during the Boundary-Layer Late Afternoon and Sunset Turbulence (BLLAST) experimental field campaign that took place in Lannemezan (foothills of the Pyrenees) in summer 2011. The case of 2 July is further studied because the turbulence properties of the lower atmosphere (up to 300 m above ground level) were sampled with the Meteorological Mini Aerial Vehicle (M2AV) from turbulently mixed to stably stratified atmospheric conditions. Additionally, data from radiosoundings, 60 m tower and UHF wind profiler were taken together with the model results from a high-resolution mesoscale simulation of this case. Weak large-scale winds and clear-sky conditions were present on the studied AET case favouring the development of slope winds and mountain–plain circulations. It is found that during the AET the anisotropy of the turbulent eddies increases as the vertical motions are damped due to the stably stratified conditions. This effect is enhanced by the formation of a low-level jet after sunset. Finally, the comparison of the anisotropy ratio computed from the different sources of observations allow us to determine the most relevant scales of the motion during the AET in such a complex terrain region.

Interaction between two adjacent grounded sources in frequency domain semi-airborne electromagnetic survey.

Multi-source and multi-frequency emission method can make full use of the valuable and short flight time in frequency domain semi-airborne electromagnetic (FSAEM) exploration, which has potential to investigate the deep earth structure in complex terrain region. Because several sources are adjacent in multi-source emission method, the interaction of different sources should be considered carefully. An equivalent circuit model of dual-source is established in this paper to assess the interaction between two individual sources, where the parameters are given with the typical values based on the practical instrument system and its application. By simulating the output current of two sources in different cases, the influence from the adjacent source is observed clearly. The current waveforms show that the mutual resistance causes the fluctuation and drift in another source and that the mutual inductance causes transient peaks. A field test with dual-source was conducted to certify the existence of interaction between adjacent sources. The simulation of output current also shows that current errors at low frequency are mainly caused by the mutual resistance while those at high frequency are mainly due to the mutual inductance. Increasing the distance between neighboring sources is a proposed measure to reduce the emission signal errors with designed ones. The feasible distance is discussed in the end. This study gives a useful guidance to lay multi sources to meet the requirement of measurement accuracy in FSAEM survey.

Optimized use of real‐time vertical‐profile wind data and fast modelling for prediction of airflow over complex terrain

ABSTRACTA novel system for real‐time prediction of wind speed and direction in a critical region of complex terrain is developed by combining measurements and analytically based fast computation of the flow field. The new system is applied to the aircraft approach flight paths of Hong Kong International Airport (HKIA), where orographically generated turbulence downwind of a mountain ridge in high‐wind conditions causes disruptions to aircraft movements regularly. By using wind profiler and radiosonde measurements to drive the analytically based ‘FLOWSTAR’ model, good agreement is demonstrated between modelled and observed wind flow data from a network of ground‐based monitors and LIDAR scans in the vicinity of the airport for a historical wind event. The methodology forms the basis of a system that can be used to forecast extreme wind events.

Variable thrust directional control technique for plateau unmanned aerial vehicles

In order to increase the lift force of the unmanned aerial vehicles (UAV) in plateau areas, the UAV is commonly equipped with high span chord ratio wings. However, it may decrease the maneuverability of the aircraft, and thus increasing the risk of flight in complex terrain regions. Thrust vector control is a direct force flight control technique, which enhances the maneuverability and introduces the residual of the flight control system. In this paper, we develop a novel variable thrust direction mechanism, which provides the normal propeller UAV with the capability of directional force control. We propose a combinational flight control strategy for the newly developed UAV. Simulations and real flight test demonstrate the performance of the proposed technique in increasing the maneuverability of the conventional propeller UAV.

Evaluation of High-Resolution Satellite-Based Real-Time and Post-Real-Time Precipitation Estimates during 2010 Extreme Flood Event in Swat River Basin, Hindukush Region

Satellite-based real-time and post-real-time precipitation estimates of Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA-3B42) were evaluated during an extreme heavy precipitation event (on 28–30 July 2010) over Swat River Basin and adjacent areas in Hindukush Region. Observations of 15 rain gauging stations were used for the evaluation of TMPA products. Results showed that the spatial pattern of precipitation in the event was generally captured by post-real-time product (3B42V7) but misplaced by real-time product (3B42RT), witnessed by a high spatial correlation coefficient for 3B42V7 (CC = 0.87) and low spatial correlation coefficient for 3B42RT (CC = 0.20). The temporal variation of the storm precipitation was not well captured by both TMPA products. 3B42V7 product underestimated the storm accumulated precipitation by 32.15%, while underestimation by 3B42RT was 66.73%. Based on the findings of this study, we suggest that the latest TMPA-based precipitation products, 3B42RT and 3B42V7, might not be able to perform well during extreme precipitation events, particularly in complex terrain regions like Hindukush Mountains. Therefore, cautions should be considered while using 3B42RT and 3B42V7 as input data source for the modelling, forecasting, and monitoring of floods and potential landslides in Hindukush Region.

Simulation of atmospheric dispersion of NOX over complex terrain region of Ranchi with FLEXPART-WRF by incorporation of improved turbulence intensity relationships

Abstract Accurate representation of air pollutant dispersion is essential for environmental management and planning purposes. In this study, semi-empirical relationships of turbulence intensity (σ u /u * , σ v /u * and σ w /u * ) as a function of surface layer scaling and local stability are developed following boundary layer similarity concepts at Ranchi, a complex terrain in Jharkhand, Eastern India for various seasons. The impact of the new turbulence parameterization for air pollution dispersion simulation is studied by incorporating the same in the Hanna scheme of FLEXPART-WRF Lagrangian Particle dispersion model over study region. The model is used to estimate the ground level concentrations of nitrogen oxides (NO x ) due to industrial and vehicular sources in study region. The meteorological parameters needed in air-quality simulation are simulated using the Advanced Research WRF (ARW) mesoscale model at high resolution (3 km). Three turbulence schemes (YSU, MYNN2 and ACM2) in ARW are alternatively tested in dispersion simulation and comparisons are made with available air quality data for eight days in different seasons (winter, pre-monsoon, monsoon and post-monsoon). Simulations with FLEXPART revealed distinct seasonal variation of dispersion patterns. It has been found that the new turbulence intensity relationships in FLEXPART improved the NO x concentration estimates by reducing the negative bias seen with default Hanna scheme. Further, the ARW simulated meteorological parameters using ACM2 and MYNN2 significantly reduced the bias in modeled pollutant concentrations. The study demonstrates the utility of high quality seasonal turbulence measurements in pollution dispersion model for better diffusion parameterization needed in air quality modeling.

An Immersed Boundary Geometric Preprocessor for Arbitrarily Complex Terrain and Geometry

AbstractThere is a growing interest to apply the immersed boundary method to compute wind fields over arbitrarily complex terrain. The computer implementation of an immersed boundary module into an existing flow solver can be accomplished with minor modifications to the rest of the computer program. However, a versatile preprocessor is needed at the first place to extract the essential geometric information pertinent to the immersion of an arbitrarily complex terrain inside a 3D Cartesian mesh. Errors in the geometric information can negatively impact the correct implementation of the immersed boundary method as part of the solution algorithm. Additionally, the distance field from the terrain is needed to implement various subgrid-scale turbulence models and to initialize wind fields over complex terrain. Despite the popularity of the immersed boundary method, procedures used in the geometric preprocessing stage have received less attention. The present study found that concave and convex regions of complex terrain are particularly challenging to process with existing procedures discussed in the literature. To address this issue, a geometric preprocessor with a distance field solver was presented, and the solver demonstrated its versatility for arbitrarily complex geometry, terrain, and urban environments. The distance field solver uses the initial distance field at the immersed boundaries and propagates it to the rest of the domain by solving the Eikonal equation with the fast sweeping method.

A Methodology for Wind Energy Evaluation in Complex Terrain Regions of Sarawak

Wind power is the safest, cleanest resource and has emerged as the speediest growing renewable energy in terms of annual installed capacity. Before a wind-drive system is set up, thorough wind resource assessment (WRA) must be conducted. In this paper, a methodology based on ground-station and topographical neural network modeled data is proposed to study the wind energy potential, in the monitored location and areas not covered by directly measurement instrumentation at Kuching. A new topographical feed forward neural network (T-FFNN) back propagation trained with Levenberg-Marquardt (LM), which consists of three layers was used to model the wind speed profile. The daily 10 m height, average hourly measured wind speed data for a period of ten years (2003-2012) for eight stations operated by Malaysia Meteorological Department (MMD) were used for the training, testing and validation. The geographical, meteorological and synthesized topographical parameters were used as input data, whereas the monthly wind speeds as the objective function. The optimum topology with maximum mean absolute percentage error of 6.4 % and correlation value of 0.9946 between the reference measured and predicted was obtained. The predicted monthly wind speed varied from 1.3-1.98 m/s with an average annual wind speed of 1.62 m/s. The characteristics of ground -based station was analyzed and presented. It was found in all the areas examined that the wind power falls within a low power density class (PD ≤ 100w/m2 ). Results from the micro-sizing showed an annual energy output (AEO) in the range of 4-12 MWh/year.

Spatial variation in inversion-focused vs 24-h integrated samples of PM2.5 and black carbon across Pittsburgh, PA.

A growing literature explores intra-urban variation in pollution concentrations. Few studies, however, have examined spatial variation during “peak” hours of the day (e.g., rush hours, inversion conditions), which may have strong bearing for source identification and epidemiological analyses. We aimed to capture “peak” spatial variation across a region of complex terrain, legacy industry, and frequent atmospheric inversions. We hypothesized stronger spatial contrast in concentrations during hours prone to atmospheric inversions and heavy traffic, and designed a 2-year monitoring campaign to capture spatial variation in fine particles (PM2.5) and black carbon (BC). Inversion-focused integrated monitoring (0600–1100 hours) was performed during year 1 (2011–2012) and compared with 1-week 24-h integrated results from year 2 (2012–2013). To allocate sampling sites, we explored spatial distributions in key sources (i.e., traffic, industry) and potential modifiers (i.e., elevation) in geographic information systems (GIS), and allocated 37 sites for spatial and source variability across the metropolitan domain (~388 km2). Land use regression (LUR) models were developed and compared by pollutant, season, and sampling method. As expected, we found stronger spatial contrasts in PM2.5 and BC using inversion-focused sampling, suggesting greater differences in peak exposures across urban areas than is captured by most integrated saturation campaigns. Temporal variability, commercial and industrial land use, PM2.5 emissions, and elevation were significant predictors, but did not more strongly predict concentrations during peak hours.

Mesoscale atmospheric flow-field simulations for air quality modeling over complex terrain region of Ranchi in eastern India using WRF

In the present study mesoscale meteorological flow and planetary boundary layer (PBL) parameters over the complex topographic region of Jharkhand state of tropical India are simulated using high resolution Advanced Research WRF (ARW) mesoscale model to study their role in the air pollution dispersion characteristics using a Lagrangian Particle Dispersion Model (FLEXPART). Eight fair weather days in different seasons (winter, pre-monsoon, monsoon, and post-monsoon) are chosen. Sensitivity experiments are conducted with two non-local [Yonsei University (YSU), Asymmetric Convective Model version 2 (ACM2)] and three local turbulence kinetic energy (TKE) closure [Mellor- Yamada Nakanishi and Niino Level 2.5 PBL (MYNN2), Mellor-Yamada-Janjic (MYJ), and quasi-normal scale elimination (QNSE)] PBL parameterisations to study the evolution of PBL parameters and thermodynamic structure. Simulated parameters are validated with available in situ meteorological observations at three stations in the study region. Results indicate that the low-level flow field is highly influenced by the topography and widely varies in different seasons. Simulated vertical PBL structure varied across seasons with shallow boundary layers (1–1.7 km) during winter, monsoon and post-monsoon seasons, deep mixed layers (2–2.7 km) in pre-monsoon season. Simulations in various seasons revealed that ACM2 followed by MYNN2 and YSU reproduced various PBL features such as topographic flows, surface layer fluxes, meteorological variables and the thermo-dynamical structure reasonably well indicating the suitability of the above PBL schemes for air quality simulations over the region. This is corroborated with the error statistics as well. Simulations with FLEXPART using ARW derived meteorology revealed higher dilution potential of the atmosphere in monsoon and pre-monsoon compared to post monsoon and winter seasons over the region. Results also indicate the ACM2, MYNN2 and YSU produce relatively larger dispersion than the QNSE and MYJ.