Wind Circulation Research Articles

An Approach to Link Climate Model Tropical Cyclogenesis Bias to Large‐Scale Wind Circulation Modes

AbstractAttributing sources of tropical cyclogenesis (TCG) bias to large‐scale circulation in global circulation models is challenging. Here, we propose the use of empirical orthogonal functions as an approach to understand model bias of TCG. Two leading modes of large‐scale wind circulations in the West Pacific can explain the TCG frequency and location in both climate reanalysis and the MetUM model. In the reanalysis, the two modes distinguish the summer monsoon trough position and the strength of the north Pacific subtropical high. However, in the model, the wind circulations are biased toward the positive phase of simulated modes thus overestimating TCG in the entire Main Development Region. This bias is further related to the north‐eastward shifted monsoon trough and a weakened subtropical high, and overly strong tropics‐subtropics connections. This approach could be deployed more widely to other basins and models to diagnose the causes of TCG bias.

Diurnal Variation Characteristics of Clouds and Precipitation during the Summer Season in Two Typical Climate Regions of the Tibetan Plateau

Mêdog and Nagqu are two typical climate regions of the Tibetan Plateau, with different atmospheric conditions and local orography. This may lead to different diurnal variation patterns of clouds and precipitation. This paper investigates the diurnal variations of clouds and precipitation in Mêdog and Nagqu, using ground-based measurements from Ka-band cloud radar and a Particle Size and Velocity (PARSIVEL) disdrometer. High frequencies of cloud cover and precipitation occur from 23:00 local solar time (LST) to 05:00 LST in Mêdog, while low frequencies appear from 11:00 LST to 17:00 LST. The occurrence frequencies in Nagqu maintain high values from 13:00 LST to 21:00 LST. In terms of mean rain rate, heavier rainfall appears in the evening and at night in Mêdog, with peaks at 00:00 LST and 18:00 LST, respectively. In Nagqu, the heaviest rainfall occurs at 12:00 LST. In addition, the afternoon convective rainfall in Nagqu is characterized by a much higher concentration of large drops, which can be classified as continental-like. The morning rainfall has the lowest concentration of large drops and can be classified as maritime-like. Finally, the mechanisms of diurnal variations in the two regions are discussed. The diurnal cycle of clouds and precipitation in Mêdog may be associated with the nocturnal convergence of moisture flux and mountain–valley wind circulation. Diurnal variations in Nagqu have a high correlation with the diurnal cycle of solar radiation. The high nocturnal frequency of clouds and precipitation in the two regions at night is closely related to the convergence of moisture flux.

Investigating the effect of the physical layout of the architecture of high-rise buildings, residential complexes, and urban heat islands

Improper development of land uses in the city leads to climate changes, resulting in an increase in GW and the formation of UHIs. These changes have adverse effects on people's level of comfort. This research is supposed to extract the optimal model by proving the relationship between the physical arrangement of the architecture of high-rise buildings in residential complexes and reducing the adverse effects of this. Therefore, in this research, four models of solitary, environmental, combined, and rowly block arrangement were investigated based on numerical calculation methods and CFD simulation. These simulations were done by ENVI-meto software based on air temperature, relative humidity, wind speed, and thermal comfort in the open space. The results showed that the type of physical arrangement of buildings can increase air temperature for GW by up to 3 °C and UHIs by 0.5 °C. The combined pattern is the most optimal in this section due to its more compact structure than the solitary pattern. Regarding the effect of relative humidity on climate changes, the solitary pattern has the lowest percentage of relative humidity compared to other patterns due to more air circulation in its physical structure. Also, the type of physical arrangement of buildings can improve the wind speed for GW by up to 0.2 m/s and for UHIs by up to 0.7 m/s. Based on this, the most optimal model is the environmental pattern, because the physical structures of the buildings are an obstacle in wind circulation. The fluctuation range of the PMV index for the intensity of GW effects on thermal comfort, is 0.7°, and the fluctuation range of this index for the power of UHIs is about 0.2°. The solitary pattern is the most optimal pattern to reduce the severity of adverse effects of GW and UHIs; this is due to the scattered distribution of blocks in this pattern. In general, according to the research findings, it can be concluded that the most optimal pattern to reduce the severity of the adverse effects of GW is solitary and environmental patterns, and to reduce the severity of the negative impact of UHIs, the solitary pattern is used.

The Effects of Orientation and Width of Space Between Buildings on Ventilation of High-Rise Areas

Excessive heat in the high-rise urban fabric has contributed to pedestrian and occupants' discomfort. Establishing wind circulation in space with an environmentally compatible and optimal configuration is necessary to improve comfort in this region. The study benefits from field measurements and experimental validation of CFD simulation to investigate the effective parameters that affect wind speed. The master plan has proposed decentralized and limited high-rise construction to prevent the horizontal growth of Babolsar city. Meanwhile, the demand for high-rise buildings is high in the city. Therefore, altitude density (height factor) is considered as a constant factor. The buildings' orientation and enclosure based on the passages' width have opposite reactions in the direction of the prevailing wind. The correlation between the orientation and the enclosure with the wind speed are the values of 0.504 and 0.2226 respectively, which have the highest correlation among other parameters. The changes have been made in the building orientation factor in the dominant wind direction by creating permeability as well as creating low enclosure in the paths and empty spaces perpendicular to the dominant wind (W’= 3W, E’ = 0.33E). These strategies have finally improved wind velocity and created wind circulation in urban block spaces. Finally, according to the data analysis for Climate compatible in humid areas and the optimal behavior of wind flow for proper urban ventilation, an improved layout for future developments will be presented.

ქ. რუსთავის და მიმდებარე ტერიტორიის ატმოსფეროში PM2.5-ის გავრცელების გამოკვლევა

The distribution of PM2.5 in the atmosphere of the city of Rustavi and its environs was studied under eastern background light air, gentle and fresh breeze. It has been established that the maximum concentrations of PM2.5 in the atmosphere of Rustavi are almost always higher than the corresponding maximum allowable concentrations. The trend of hourly changes in concentrations showed that during the day the concentration of microparticles reaches its maximum in the various period of the day. Numerical modeling of the local distribution of microparticles carried out in the city of Rustavi during background easterly light air, gentle and fresh breeze showed us that the change in the daily regime of relief and temperature with eastern light air in Rustavi for 12 hours leads to a complex and significant change in the wind speed directed to land. It forms on the territory of Kvemo Kartli the opposite current of the background wind, which corresponds to the horizontal circular wind circulation. The value of circulation gradually decreases with increasing height and in the boundary layer of the atmosphere (600 m above the earth's surface) has the form of a wave disturbance. the picture obtained with an average background east wind is qualitatively similar to the field obtained with a background light air, and with a fresh breeze, in contrast to the case of a light air and gentle breeze, the pollution zone covers most of the simulation zone.

Turbulent characteristics in complex coastal areas assessed using BSWO observations and WRF-LES simulation results

Studies exploring the turbulent structure of the planetary boundary layer (PBL) over complex topographies are very limited, especially at night, because of the lack of available observations and difficulty of highly resolved simulation. In this study, micro-meteorological and turbulent characteristics over complex coastal areas were investigated based on high spatial-temporal resolution by using the Weather Research and Forecasting–Large Eddy Simulation (WRF-LES) model. Then, the simulations were compared to comprehensive observations obtained at the Boseong Standard Weather Observatory (BSWO), which is equipped with various observation facilities, such as a meteorological observation tower with a height of 307 m, and aiding ground-based remote sensing measurements used for PBL research. The comparison between the WRF-LES model results and the measurements by the wind lidar system at the BSWO showed that the LES approach in this study reproduced the spatial/vertical wind field structure and land-sea wind circulation distinctly better than the conventional PBL schemes. High turbulent kinetic energy (TKE) was observed near the surface level at night due to the increased nocturnal shear production following the evolution of land and mountain breezes. The calculated TKE from WRF-LES model was applied to identify the mixing intensity based on the mixing length and eddy diffusion coefficient within the boundary layer, and then those were evaluated with the observed extinction coefficient from the aerosol Micro-Pulse Lidar system (MPL). In addition, the planetary boundary layer height (PBLH) at night was explored by using the TKE threshold method combined with the bulk Richardson number threshold method for the daytime PBLH. Compared with the observed value from a ceilometer at the BSWO, we found that the TKE threshold method proposed in this study could yield highly accurate PBLH values, especially at night. It is also expected that the enhanced application of WRF-LES like to this study can lead to understanding and prediction with the high confidence for much detail and accurate spatiotemporal turbulent structure over complex coastal areas, which will contribute to more comprehensive air quality modeling studies.

HEALTH RESORT DAN SPA DENGAN PENDEKATAN ARSITEKTUR TROPIS

Changes in lifestyle with increasingly crowded routines make humans pay less attention to physical conditions that can cause stress. So that from this potential, the idea of planning a design that prioritizes "health” in tourism and "health" can also be found in beautiful views around the area. The location is located in Singkawang City, which is in the waterfront area (Palm Beach) Jl. Pasir Panjang Beach, Sedau Village, Singkawang Selatan District which is a tourism area, and the soil type is soft soil. The selection of the structure used applies a concrete pile foundation. Health resorts and spas located in the tropics use a design approach using tropical architecture to provide visitors with comfort. This effort is made by implementing placement and orientation facing the main view and spreading so that each building gets wind circulation and is supported by mass compositions and the use of local materials, the use of natural ventilation, skylights, and sun shading. Visitors consist of individuals, couples, families, and other general groups who do not stay overnight by providing lodging facilities that are not only for resting but have health service facilities (health resort) like resort standards, resort suite, and resort family suite, treatment facility (health spa), restaurants, and wedding venues. The design method consists of the stages of an idea, information, analysis, synthesis, evaluation, and optimization.

Untangling the importance of dynamic and thermodynamic drivers for wet and dry spells across the Tropical Andes

Andean vegetation and agriculture depend on the patterns of rainfall during the South American monsoon. However, our understanding on the importance of dynamic (upper-level wind circulation) as compared to thermodynamic (Amazon basin moisture) drivers for Andes rainfall remains limited. This study examines the effect of these drivers on 3–7 day wet and dry spells across the Tropical Andes and assesses resulting impacts on vegetation. Using reanalysis and remote sensing data from 1985–2018, we find that both dynamic and thermodynamic drivers play a role in determining the rainfall patterns. Notably, we show that the upper-level wind is an important driver of rainfall across the entire Tropical Andes mountain range, but not in the Amazon lowlands, suggesting a crucial role of topography in this relationship. From thermodynamic perspective, we find wet spell conditions to be associated with increased moisture along the Andes’ eastern foothills accompanied by a strengthened South American low-level jet, with moisture lifted into the Andes via topography and convection for all considered regions. Our results suggest that while changes in Amazon basin moisture dominate rainfall changes on daily time scales associated with three day spells, upper-level dynamics play a more important role on the synoptic time scale of 5–7 day spells. Considering impacts on the ground, we find that only 5–7 day spells in the semi-arid Andes have a prolonged effect on vegetation. Our study emphasizes the need to consider both dynamic and thermodynamic drivers when estimating rainfall changes in the Tropical Andes, including in the context of future climate projections.

A new strategy for risk assessment of PM2.5-bound elements by considering the influence of wind regimes

For regulatory purposes, air pollution has been reduced to management of air quality control regions (AQCR), by inventorying pollution sources and identifying the receptors significantly affected. However, beyond being source-dependent, particulate matter can be physically and chemically altered by factors and elements of climate during transport, as they act as local environmental constraints, indirectly modulating the adverse effects of particles on the environment and human health. This case study, at an industrial site in a Brazilian coastal city – Joinville, combines different methodologies to integrate atmospheric dynamics in a strategic risk assessment approach whereby the influence of different wind regimes on environmental and health risks of exposure to PM2.5-bound elements, are analysed. Although Joinville AQCR has been prone to stagnation/recirculation events, distinctly different horizontal wind circulation patterns indicate two airsheds within the region. The two sampling sites mirrored these two conditions and as a result we report different PM2.5 mass concentrations, chemical profiles, geo-accumulation, and ecological and human health risks. In addition, feedback mechanisms between the airsheds seem to aggravate the air quality and its effects even under good ventilation conditions. Recognizably, the risks associated with Co, Pb, Cu, Ni, Mn, and Zn loadings were extremely high for the environment as well as being the main contributors to elevated non-carcinogenic risks. Meanwhile, higher carcinogenic risks occurred during stagnation/recirculation conditions, with Cr as the major threat. These results highlight the importance of integrating local airshed characteristics into the risk assessment of PM2.5-bound elements since they can aggravate air pollution leading to different risks at a granular scale. This new approach to risk assessment can be employed in any city's longer-term development plan since it provides public authorities with a strategic perspective on incorporating environmental constraints into urban growth planning and development zoning regulations.

Diurnal and interannual variations of canopy urban heat island (CUHI) effects over a mountain–valley city with a semi-arid climate

Taking Lanzhou (a typical mountain–valley city in Northwest China) as an example, the diurnal and interannual variation characteristics of the canopy urban heat island (CUHI) and its relationship with heat waves (HWs), local climate zones (LCZs), mountain–valley wind circulation and aerosol pollution were explored. Results showed that the peak CUHI intensity (CUHII) in Lanzhou occurred at nighttime, while the minimum appeared in the daytime. The interannual variation of the CUHI fluctuated greatly, showing an upward trend. The average CUHII in HW periods was 103.6% higher than that in non-heat wave (NHW) periods. Longer-lasting HWs amplified the CUHII, in turn stronger CUHII led to more frequent HWs. The spatial variation of CUHIIs mainly varied with LCZ types. In addition, relative to NHW periods, the mountain–valley wind circulation was strengthened during HW periods, favoring an increase in CUHII. On the one hand, the increased urban wind speed contributed to the enhancement of vertical turbulent heat transfer during HW periods. On the other hand, the ventilation conditions were improved, resulting in the reduced aerosol concentration, the urban canopy received more shortwave radiation, and the heat storage increased during HW periods. Both of these situations were conducive to enhanced CUHII.

Enhanced Effect of Mining Dust Diffusion on Melting of the Adjacent Glacier: A Case Study in Xinjiang, China

Given the typical disturbances in the aqueous environment in the alpine area because of mining activities in Northwest China, a case study highlighting the enhanced effect of mining dust diffusion on the melting of the adjacent glacier is presented here. Initially, a three-dimensional numerical model of the local airflow field was established by considering the effects of both mines and glaciers using the FLUENT software. Then, the diffusion path and size range of dust particles from the mines were simulated by feeding the mining dust parameters into the above numerical model. Finally, a physical simulation experiment was performed to evaluate the influence of mining dust coverage on the glaciers. The major conclusions of this study were as follows: (1) The local airflow field in the target alpine area is controlled by the ‘heat and cold double-island effects’ formed by the mine and the glacier, and the wind circulation always takes place in a clockwise direction between the mining pit on the left and the glacier on the right. (2) In a given airflow field, there is a spread of mining dust from the mine to the glacier along the upper airflow. The arrival rates of the dust are 16.9% and 13.3% in winter and summer, respectively, and the horizontal distance of dust diffusion is inversely proportional to its particle size. (3) For an ice sample with a sectional area of 225 cm2 and a volume of 1000 mL, the melting rate increased by 4.5 mL/h with an increase of dust coverage by 10%. Furthermore, when compared with a control group without dust cover, the effect of a 28% increase in dust coverage is approximately equivalent to the effect of a 1 °C increase in temperature on the ablation speed of the glacier. The study results can provide a useful reference for the selection of mining sites and the control of mining dust diffusion in alpine regions with glaciers, thereby facilitating environmentally friendly mining in alpine regions.

Kajian Sirkulasi Ruang Luar Terhadap Aliran Angin Pada Permukiman Padat Taman Sari Kota Bandung

Unplanned dense settlements in the development pay little attention to the technical aspects of the building and the environment, one of which is high humidity conditions and circulation pathways. Circulation in settlements can also function as wind circulation, which can affect natural ventilation, comfort, and the health of residents. This study uses a quantitative method with a descriptive approach to describe the relationship between the circulation width variable and the wind speed variable. The results of periodic field observations and measurements are then interpreted descriptively to determine the effect of circulation width on wind flow in densely populated settlements in Taman Sari, Bandung. The results showed that outdoor circulation close to open spaces had better wind speeds compared to areas far from open spaces.

Machine learning and dynamics based error‐index method for the detection of monsoon onset vortex over the Arabian Sea: Climatology and composite structures

AbstractMonsoon onset vortex (MOV) forms over the Arabian Sea near the northern flank of the low‐level jet during the monsoon onset over Kerala (MOK). The study concerns the development and evaluation of an algorithm for detecting and tracking MOVs in regional/global analyses. The first step involves preparing the first‐guess database of MOV locations based on geopotential height, surface and 850 hPa wind magnitude and circulation from ERA5 reanalysis for 1982–2020. Three different approaches: (a) error‐index of MOV, (b) machine‐learning (ML), and (c) combination of error‐index and ML models, are employed to detect MOV. The error‐index method, in which the detected vortex is compared with the idealized vortex, achieves an accuracy of 0.6 with a 0.95 true‐positive‐rate and 0.55 false‐positive‐rate. The best ML models can identify the MOVs in the training samples with maximum accuracy of 0.99. However, their accuracy is limited in tracking the MOVs continuously in the global analyses as they are not trained with wind circulation. The combined error‐index and ML models could detect all the 27 observed MOVs in the ERA5 reanalysis with 5 false‐positives. This approach is tested on IMDAA reanalysis, and the success rate is 0.79 with 6 false‐positives. Temporal analyses show that ∼95% of the MOVs occur during −10 to +20 days from MOK. Composite structures indicate that the MOVs exhibit higher sea‐surface temperatures (>0.3 °C) in the forward sector with 85% cloud cover in the left‐rear sector. Rainfall of 4–5 mm·hr−1 is seen in the left sector. Upper‐level (700–200 hPa) warm core (>3.5°C) and lower‐level (1000–700 hPa) cold‐core (<1°C) is evident. The composite structures of MOVs are almost similar to that of monsoon depressions with higher asymmetry in the forward‐rear sectors. This study may help explore future projections of MOV activity from climate models and its relationship with monsoon rainfall activity.

Atmospheric impacts of local sea surface temperatures versus remote drivers during strong South China Sea winter cold tongue events

AbstractSea surface temperatures (SSTs) in the western part of the South China Sea (SCS) are cooler than in the eastern part in boreal winter, owing to a winter climatological cold tongue (CT). In this study, using a regional atmospheric model configured for the Maritime Continent, we assess the atmospheric impacts of local (or SCS) SSTs versus those from remote drivers (e.g., western tropical Pacific SSTs) during strong CT events with anomalously cool SSTs. In the local run, more rainfall is observed over the eastern SCS, but no significant atmospheric impacts are found over the CT region when SSTs associated with strong CT events are imposed within the SCS while climatological conditions are imposed elsewhere. SCS SST anomalies during strong CT events do not significantly modify the regional wind circulation. The lack of atmospheric response to SSTs over the CT region may be explained by the wintertime mean SSTs (i.e., <27–28°C) over the CT region that are inadequate to trigger deep atmospheric convection, while eastern SCS SSTs are high enough. The increase of anomalous positive moist static energy (MSE) near the sea level over the eastern SCS indicates underlying warm eastern SCS SST anomalies could be influencing positive rainfall anomalies. In the remote run, imposing climatological SCS SSTs but remote SSTs and lateral boundary conditions linked to strong CT events results in cyclonic wind and positive rainfall anomalies over the eastern SCS and Philippines, which are a Matsuno–Gill response to the diabatic heating anomalies over the warm western tropical Pacific SST anomalies. Positive rainfall and cloud cover anomalies associated with the cyclonic wind anomalies are due to the anomalous positive MSE import into the eastern SCS by horizontal advection.

An eolian dust origin for clastic fines of Devono-Mississippian mudrocks of the greater North American midcontinent

ABSTRACT Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiquitously fine-grained and silt-rich, comprising both so-called shale as well as argillaceous limestone (or calcareous siltstone) that accumulated in the Laurentian epeiric sea. Although long recognized as recording marine deposition, the origin and transport of the fine-grained siliciclastic material in these units remains enigmatic because they do not connect to any proximal deltaic feeder systems. Here, we present new data on grain size, whole-rock geochemistry, mineralogy, and U-Pb detrital-zircon geochronology from units across Oklahoma; we then integrate these data with models of surface wind circulation, refined paleogeographic reconstructions, and correlations from the greater midcontinent to test the hypothesis that wind transported the siliciclastic fraction to the marine system. The exclusively very fine silt to very fine sand grain size, clear detrital origin, widespread distribution over large regions of the epeiric sea, Appalachian sources, and paleogeographic setting in the subtropical arid belt far-removed from contemporaneous deltaic feeder systems are most consistent with eolian transport of dust lofted from subaerial delta plains of the greater Appalachian orogen and incorporated into subaqueous depositional systems. Delivery of dust that was minimally chemically weathered to Devono-Mississippian epeiric seas likely provided essential nutrients that stimulated organic productivity in these commonly organic-rich units.

Wave disturbances of the atmosphere in a spatially inhomogeneous flow

Analysis of measurements by the Dynamics Explorer 2 satellite indicates a close connection between atmospheric wave disturbances and wind circulation in the polar thermosphere. According to satellite observations, large-amplitude acoustic-gravity waves are systematically observed in the regions of formation of powerful wind systems. At the same time, the azimuths of AGW propagation are spatially consistent with the directions of wind circulation. Waves propagate mainly against the wind, and their amplitude is approximately proportional to the wind speed. In order to explain the experimental data, the paper theoretically investigated the changes in the amplitudes of AGW in a horizontally inhomogeneous wind flow. The dispersion equation of the AGW in the reference frame of the medium, which moves with a non-uniform speed, was obtained. When obtaining it, inertial forces were taken into account, as well as the change in the background density of the atmosphere in an inhomogeneous flow. It is shown that under the slow change in wind speed, the real part of this equation coincides with the dispersion equation of AGW for a stationary medium. An expression for the change in the amplitude of waves in a moving medium was obtained, according to which, in an oncoming inhomogeneous wind, the amplitude of the wave increases approximately according to a linear law, which is consistent with the data of satellite observations.

Spatio-temporal analysis of rainfall in relation to monsoon teleconnections and agriculture at Regional Scale in Haryana, India.

This study examined the long-term (1980-2019) spatio-temporal trends, variability and teleconnections of Indian summer monsoon rainfall (ISMR) of all districts of Haryana, India and their impact on agricultural productivity. The gridded datasets of India Meteorological Department (IMD) were used to statistically analyse the rainfall distribution, trend, coefficient of variation and intensity of rainfall. The gridded datasets of European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis V5 (ERA5) were examined for lower and upper tropospheric wind circulation (850hPa and 200hpa), vertically integrated moisture transport (VIMT) and surface moisture flux (SMF). The datasets of National Oceanic and Atmospheric Administration (NOAA) were correlated with ISMR and composite deviation of rainfall and rainfall intensity during El Niño and La Niña from neutral years was examined at district level. Our analysis revealed that districts lying in eastern agroclimatic zone (EAZ) of Haryana received more ISMR during each month of monsoon season as compared to the ones situated in western agroclimatic zone (WAZ). Trend-free pre-whitening Mann-Kendall (TFPW-MK) test revealed that Kurukshetra, Panipat, Ambala, Rohtak, Faridabad, Jhajjar, Sonipat, Fatehabad and Palwal have shown a decreasing trend while Mahendragarh and Panchkula have shown an increasing trend of rainfall. During the El Niño years, most of the locations in the state received deficient to large deficient category, whereas during the La Niña episodes, most of the locations received excess to large excess category of ISMR, which is indicative of the influence of El Niño-Southern Oscillation (ENSO) on the regional scale. The influence of ISMR on bajra productivity for the districts lying in WAZ and rice productivity for the districts lying in EAZ was undertaken. This study is beneficial for understanding the impacts of climate change and climate variability on ISMR dynamics in Haryana which may further guide the policy-makers and beneficiaries for optimising the use of hydrological resources.

Isotopes-based characterization of precipitation compositions and atmospheric water vapor sources over typical Eurasian steppes in south mongolian Plateau

An inland river grassland basin is a fragile ecosystem, and precipitation is of great significance to its resilience. However, the knowledge of where precipitation-forming water vapor originated is not well understood, limiting the predictability of future precipitation provided climate change. The objective of this study was to characterize the hydrogen (δD) and oxygen (δ18O) isotopes and hydro-chemical compositions of precipitation as well as decipher atmospheric water vapor sources in a typical Eurasian steppe river basin. In this regard, this study collected 59 water samples from 44 storm events in 2019 and 2020. The samples were analyzed in our laboratory for ions, δD, and δ18O, which in turn were used to examine the stable isotopic features, hydro-chemical characteristics, and water vapor transport at different temporal scales by a backward trajectory model and correlation and redundancy analyses. The results showed negative δD and δ18O during the wet season with a trend of positive deuterium excess, indicating that precipitation effect was significant. In comparison with a linear model of global meteoric water levels, the local meteoric water lines had smaller slopes and intercepts, with a maximum slope in August and a minimum slope in July. In addition, HCO3− and Ca2+ were the primary hydro-chemical ions in precipitation. Ca2+ and Mg2+ were significantly correlated with HCO3− and Na+, indicating that they shared terrestrial and marine sources. NH4+ originated mainly from human activities and chemical reactions, whereas K+ originated primarily from continental and marine processes. Further, the atmospheric water vapor was mainly transported from the northeast, northwest, and southeast directions into the study basin, as affected by the westerly wind circulation, the East Asian summer monsoon, northeast anticyclone circulation, and local evapotranspiration. Moreover, the water vapor was from both onsite and offsite sources: over 40% from Eurasia, 10 to 25% from the Arctic Ocean, and 35 to 45% from the Pacific Ocean.

Impacts of regional wind circulations on aerosol pollution and planetary boundary layer structure in Metro Manila, Philippines

Fine particulate matter (PM2.5) concentrations in Metro Manila, Philippines have consistently exceeded the guideline values set by the World Health Organization (WHO). Although there has been much progress in understanding the components and sources of PM2.5, limited research has been done on the influence of meteorological factors. In particular, the influence of the planetary boundary layer height (PBLH) on PM2.5 concentration has not been studied due to inadequate observations. From January 2019–June 2020, measurements from a High Spectral Resolution Lidar (HSRL) filled this gap and allowed for PBLH estimation and aerosol typing. This paper investigates the roles of PBLH and regional and local wind circulations on the temporal evolution of aerosol pollution. Results show that daytime and nighttime PBLH variability is associated with solar heating and radiative cooling, respectively. Cloud-free conditions during the dry season yield a higher PBL growth rate than during the wet season when lower daytime and elevated nighttime PBLH are observed. Lower PM2.5 levels are generally observed during daytime when PBLH is at its maximum. However, the PBLH has a significant inverse correlation with PM2.5 only in the months of December-January-February. We find that horizontal directional wind shear between synoptic and mesoscale circulations confounds the PM2.5 - PBLH relationship by creating stagnant conditions conducive to aerosol accumulation. The lower 20% of PM2.5 concentrations occur during the prevalence of strong monsoon winds. On the other hand, the upper 80% are found during the occurrence of compound mesoscale winds (i.e., sea/land/lake/valley/mountain breezes and channeling monsoon winds). In addition, mountain breeze is found to be associated with lifting of aerosols, resulting in multi-layering within the PBL. The findings in the present study emphasize the role of complex topography and mesoscale scale winds arising from the landscape on aerosol pollution variability.

Urban Wind Field Mapping Technique for Municipal Environmental Planning: A Case Study of Cheongju-Si, Korea

The integrated management of land and environmental plans (EPs) has been a key direction of sustainable policy in Korea. Although local EPs should be established based on spatial data, much of the pertinent environmental information has not been mapped. Accordingly, we develop a wind field mapping technique for establishing local EPs. This method was developed via a numerical weather prediction model (Weather Research and Forecast—WRF), and a diagnostic meteorological model (California Meteorological model—CALMET), based on weather observation data, as well as terrain and land cover data. The developed method was applied to a case study in Cheongju-si, Korea, for verifying its effectiveness. The created wind field maps of Cheongju-si provided an intuitive visual representation of the spatial distribution of seasonal and daytime/nighttime wind patterns. Such data helped understand the directionality and patterns of winds blowing into a city, or identify stagnant areas of wind circulation. Overlaying the wind field map with maps of air pollutant emissions revealed that pollutants from industrial areas could flow along the prevailing winds into residential areas downtown. These maps also implied that open spaces, such as parks and grasslands, were recommendable for stagnant areas, instead of creating industrial complexes or residential areas.