Differences In Wind Direction Research Articles

Expertise effects in cutaneous wind perception.

We examined whether expertise effects are present in cutaneous wind perception. To this end, we presented wind stimuli consisting of different wind directions and speeds in a wind simulator. The wind simulator generated wind stimuli from 16 directions and with three speeds by means of eight automotive wind fans. Participants were asked to judge cutaneously perceived wind directions and speeds without having access to any visual or auditory information. Expert sailors (n = 6), trained to make the most effective use of wind characteristics, were compared to less-skilled sailors (n = 6) and to a group of nonsailors (n = 6). The results indicated that expert sailors outperformed nonsailors in perceiving wind direction (i.e., smaller mean signed errors) when presented with low wind speeds. This suggests that expert sailors are more sensitive in picking up differences in wind direction, particularly when confronted with low wind speeds that demand higher sensitivity.

벡터 형식의 GIS 자료와 CFD 모델을 이용한 도시 지역 상세 대기 흐름 연구

In this study, detailed air flow characteristics in an urban areas were analyzed using GIS data and a Computational Fluid Dynamics (CFD) model. For this, a building construction algorithm optimized for Geographic Information System (GIS) data with a vector format (Los Angeles region imagery acquisition consortium 2 geographic information system, LARIAC2 GIS) was used. In the LARIAC2 GIS data, building vertices were expressed as latitude and longitude. Using the model buildings constructed by the algorithm as the surface boundary data in the CFD model, we performed numerical simulations for two building-congested areas in Los Angeles using inflow information provided by California Air Resources Board. Comparing with the inflow, there was a marked difference in wind speed and direction within the target areas, which was mainly caused by the secondarily induced local circulations such as street-canyon vortices, horse-shoe vortices, and recirculation zones. In street canyons parallel to the inflow direction, wind speed increased due to a channeling effect and, in street canyons perpendicular to the inflow direction, vertically well developed vortices were induced. In front of a building, a horse-shoe vortex was developed near the surface and, behind a building, a recirculation zone was developed. Near the surface in the areas where the secondarily induced local circulations, wind speed remarkably increased. Overall, wind direction little (largely) changed at the areas where wind speed largely increased (decreased).

Impacts of inland water area changes on the local climate of Wuhan, China

A distinct feature of Wuhan is that almost a quarter of the total area of this city is covered with water, leading to its unique hot and humid climate characteristics in summer. However, according to records, water area in built-up zone of Wuhan has been reduced by 130.5 km2 from 1965 to 2008, while the annual average air temperature has been increased by more than 3℃. To investigate the quantitative connection between the water area reduction and air temperature increase, three scenarios were simulated in a summer; to evaluate the impact of water reduction on the local thermal environment in different water areas; and to study the impact of water reduction on the urban heat island (UHI) phenomenon. Meso-scale meteorological models of Weather Research and Forecasting model were applied in this study for quantitative assessment and prediction. With the predictions, this study reveals that the decreased water area could affect air temperature, wind velocity and wind flow direction, energy balance and the UHI intensity. The simulations show that areas with significant wind velocity, wind direction and air temperature differences are distributed among the downwind zones. Moreover, the areas with high UHI intensity are wider and farther from the boundary of urban areas because of the reduction of water areas.

Reconstructed Wind Fields from Multi-Satellite Observations

We present and validate a method of reconstructing high-resolution sea surface wind fields from multi-sensor satellite data over the Grand Banks of Newfoundland off Atlantic Canada. Six-hourly ocean wind fields from blended products (including multi-satellite measurements) with 0.25° spatial resolution and 226 RADARSAT-2 synthetic aperture radar (SAR) wind fields with 1-km spatial resolution have been used to reconstruct new six-hourly wind fields with a resolution of 10 km for the period from August 2008 to December 2010, except July 2009 to November 2009. The reconstruction process is based on the heapsort bucket method with topdown search and the modified Gauss–Markov theorem. The result shows that the mean difference between the reconstructed wind speed and buoy-estimated wind speed is smaller than 0.6 m/s, and the standard deviation is smaller than 2.5 m/s. The mean difference in wind direction between reconstructed and buoy estimates is 3.7°; the standard deviation is 40.2°. There is fair agreement between the reconstructed wind vectors and buoy-estimated ones.

Seasonal Variations and Sources of Heavy Metals in Free Fall Dust in an Industrial City of Western India

This study investigates seasonal variations in average concentrations of metals in free fall dust samples (350) collected at various sampling sites situated in five different zones of an industrial city Kota, India. Average concentrations of heavy metals (Cu, Cd, Zn and Pb) were higher in winter and lower in summer and reverse trend was observed for crustal metals (Fe, Ca and Mg). Overall, the order of average concentrations of heavy metals were Zn >Pb> Cu > Cd in both seasons.Seasonal differences in metal concentrationswere due to differences in wind direction, wind strength, temperature, relative humidity and anthropogenic activities at sampling sites. Enrichment factor and positive correlation between anthropogenic metal species such as Cu and Cd; Cu and Zn; Cu and Pb; Cd and Zn; Cd and Pb; Zn and Pb in both seasons indicate that their origin source iscommon i.e. coal combustion at thermal power station.

Turbine‐scale wind field measurements using dual‐Doppler lidar

AbstractSpatially resolved measurements of microscale winds are retrieved using scanning dual‐Doppler lidar and then compared with independent in situ wind measurements. Data for this study were obtained during a month‐long field campaign conducted at a site in north‐central Oklahoma in November of 2010. Observational platforms include one instrumented 60 m meteorological tower and two scanning coherent Doppler lidars. The lidars were configured to perform coordinated dual‐Doppler scans surrounding the 60 m tower, and the resulting radial velocity observations were processed to retrieve the three‐component velocity vector field on surfaces defined by the intersecting scan planes. The dual‐Doppler analysis method is described, and three‐dimensional visualizations of the retrieved fields are presented.The retrieved winds are compared with sonic anemometer (SA) measurements at the 60 m level on the tower. The Pearson correlation coefficient between the retrievals and the SA wind speeds was greater than 0.97, and the wind direction difference was very small (<0.1o), suggesting that the dual‐Doppler technique can be used to examine fine‐scale variations in the flow. However, the mean percent difference between the SA and dual‐Doppler wind speed was approximately 15%, with the SA consistently measuring larger wind speeds. To identify the source of the discrepancy, a multi‐instrument intercomparison study was performed involving lidar wind speeds derived from standard velocity‐azimuth display (VAD) analysis of plan position indicator scan data, a nearby 915 MHz radar wind profiler (RWP) and radiosondes. The lidar VAD, RWP and radiosondes wind speeds were found to agree to within 3%. By contrast, SA wind speeds were found to be approximately 14% larger than the lidar VAD wind speeds. These results suggest that the SA produced wind speeds that were too large. Copyright © 2013 John Wiley & Sons, Ltd.

Oceansat-2 and RAMA buoy winds: A comparison

Sea surface vector winds from scatterometers onboard satellites play an important role to make accurate Numerical Weather Prediction (NWP) model analysis over the data sparse oceanic region. Sea surface winds from Oceansat-2 scatterometer (OSCAT) over the Indian Ocean were validated against the Research Moored Array for African–Asian–Australian Monsoon Analysis and Prediction (RAMA) buoy winds to establish the accuracy of OSCAT winds. The comparison of OSCAT winds against RAMA buoy winds for a period of one year (2011) shows that the wind speeds and directions derived from OSCAT agree with RAMA buoy winds. The monthly mean wind speeds from both OSCAT and RAMA buoy show maximum value during the monsoon period as expected. In the complete annual cycle (2011), the monthly mean root mean square differences in the wind speed and wind direction were less than ∼2.5 ms−1 and ∼20°, respectively. The better match between the OSCAT and RAMA buoy wind is observed during Indian summer monsoon (June–September). During monsoon 2011, the root mean square differences in wind speed and wind direction were less than 1.9 ms−1 and 11°, respectively. Collocation of scatterometer winds against equatorial and off-equatorial buoys clearly brought out the monsoon circulation features. Collocation of Advanced Scatterometer (ASCAT) winds on-board European Space Agency (ESA) MeTop satellite with respect to RAMA buoy winds during monsoon 2011 also showed that the OSCAT wind statistics are comparable with that of ASCAT over the Indian Ocean, and indicates that the accuracy of both the scatterometers over the Indian Ocean are essentially the same.

NATURAL VENTILATION OF COMMERCIAL DAIRY COW HOUSES: SIMULATING THE EFFECT OF ROOF SHAPE USING CFD

In livestock buildings the ventilation rate influences both the pollutant emission rates and animal?s welfare. In the present study a 3D simulation model was used to simulate 7 commercial dairy cow houses with different roof types and side ventilators. The simulations have been carried out considering different wind speeds (1, 4 and 8 m/s), different wind directions (0, 45 and 90°) and different outside air temperatures (0, 10 and 20°C). The resistance of the cows to the air flow was calculated by simulating a virtual wind tunnel with cows. The ventilation rate was calculated by simulating the experimental tracer gas method (constant injection of a virtual gas having the same physical properties with air). The results show that both ventilation rate and uniformity of indoor climate were influenced by the roof shape. For the same dairy cow house type the ventilation rate was influenced by the wind speed, wind direction and air temperature differences. At low wind speeds the ventilation rate depends on both wind direction and air temperature differences; while at high wind speeds the most important factor seems to be the wind direction. For all the cases the ventilation rate at the cow level is different than the ventilation rate calculated for the overall house. These differences are varying even for the same house type, showing that the knowledge of overall ventilation rate does not provide enough information about the environmental conditions at cow level.

Assessment of the ASCAT wind error characteristics by global dropwindsonde observations

This research focuses on assessing the accuracy of the advanced scatterometer (ASCAT) wind vector around tropical cyclones by using data from dropwindsondes deployed by the surveillance and reconnaissance flights during 2007–2010. There are 987 matching samples for the comparisons, with wind speed up to 50 m s−1. The bias and root‐mean‐square differences of wind speed between ASCAT and dropwindsonde data are −1.7 and 5.3 m s−1, respectively. Further analyses also indicate that large wind direction differences occur in the low wind speed regime, while large wind speed differences occur in the high wind speed regime. The accuracy of wind vector in weak wind speed and high wind speed regimes are significantly reduced in saturated regions, implying that the rain contamination issue still affects the accuracy of ASCAT wind retrieval. The wind vector in the medium wind speed regime has much better quality, in good agreement with the satellite's designed specification. The ASCAT wind data obviously contain negative wind speed bias, which grows larger as wind speed increases. A regression fit between ASCAT and dropwindsonde wind speed is adopted to correct the bias of the ASCAT wind speed. The error characteristics are largely determined by the magnitude of wind speed and moisture saturation which are highly variable around the storm. Nevertheless, results from this study suggest that ASCAT wind data of velocities measuring between 12 and 18 m s−1 are more reliable and can be applied to determine the radius of 34 knot winds, a critical parameter in operational tropical cyclone analysis.

On the Ability of the WRF Model to Reproduce the Surface Wind Direction over Complex Terrain

AbstractThe ability of the Weather Research and Forecasting (WRF) model to reproduce the surface wind direction over complex terrain is examined. A simulation spanning a winter season at a high horizontal resolution of 2 km is compared with wind direction records from a surface observational network located in the northeastern Iberian Peninsula. A previous evaluation has shown the ability of WRF to reproduce the wind speed over the region once the effects of the subgrid-scale topography are parameterized. Hence, the current investigation complements the previous findings, providing information about the model's ability to reproduce the direction of the surface flow. The differences between the observations and the model are quantified in terms of scores explicitly designed to handle the circular nature of the wind direction. Results show that the differences depend on the wind speed. The larger the wind speed is, the smaller are the wind direction differences. Areas with more complex terrain show larger systematic differences between model and observations; in these areas, a statistical correction is shown to help. The importance of the grid point selected for the comparison with observations is also analyzed. A careful selection is relevant to reducing comparative problems over complex terrain.

Examining the Impact of Surface Currents on Satellite Scatterometer and Altimeter Ocean Winds

Abstract A 5-yr dataset collected over two surface current and meteorological moorings allows rigorous evaluation of questions surrounding wave–current interaction and the scatterometer. Results demonstrate that scatterometer winds represent winds relative to the moving sea surface, affirming previous observational efforts that inferred the phenomenon using climatological approaches over larger time and space scales in equatorial and western boundary currents. Comparisons of wind residuals between Ku-band Quick Scatterometer (QuikSCAT) and buoy measurements show nearly one-to-one correlations with ocean surface velocity for 5-, 12.5-, and 25-km resolution wind speed products, especially under conditions of moderate wind speed and near-neutral atmospheric stability. Scatterometer and buoy wind direction differences due to currents were observed to be negligible for the range of surface velocities encountered and the length scales observed by QuikSCAT. Similar analyses are applied to C-band Advanced Scatterometer (ASCAT) satellite wind measurements at the same sites, as well as to satellite altimeter winds, and overall confirm the results seen with QuikSCAT; differences are likely the combined result of sampling, satellite wind algorithms, and geophysical wind–wave coupling in the presence of currents. On the whole, this study affirms that at length scales of 10 km and longer the scatterometer wind can be considered to be current relative. Observed differences between earth-relative and current-relative winds of order 10%–20% of the wind velocity are not uncommon in this and other ocean regions and this study more fully validates that microwave remote sensing winds appear to respond to wind stress even in the presence of larger-scale currents.

Characteristics and recent trends of sulfur dioxide at urban, rural, and background sites in North China: Effectiveness of control measures

Abstract SO 2 measurements made in recent years at sites in Beijing and its surrounding areas are performed to study the variations and trends of surface SO 2 at different types of sites in Northern China. The overall average concentrations of SO 2 are (16.8 ± 13.1) ppb, (14.8 ± 9.4) ppb, and (7.5 ± 4.0) ppb at China Meteorological Administration (CMA, Beijing urban area), Gucheng (GCH, relatively polluted rural area, 110 km to the southwest of Beijing urban area), and Shangdianzi (SDZ, clean background area, 100 km to the northeast of Beijing urban area), respectively. The SO 2 levels in winter (heating season) are 4-6 folds higher than those in summer. There are highly significant correlations among the daily means of SO 2 at different sites, indicating regional characteristics of SO 2 pollution. Diurnal patterns of surface SO 2 at all sites have a common feature with a daytime peak, which is probably caused by the downward mixing and/or the advection transport of SO 2-richer air over the North China Plain. The concentrations of SO 2 at CMA and GCH show highly significant downward trends (−4.4 ppb/yr for CMA and −2.4 ppb/yr for GCH), while a less significant trend (−0.3 ppb/yr) is identified in the data from SDZ, reflecting the character of SDZ as a regional atmospheric background site in North China. The SO 2 concentrations of all three sites show a significant decrease from period before to after the control measures for the 2008 Olympic Games, suggesting that the SO 2 pollution control has long-term effectiveness and benefits. In the post-Olympics period, the mean concentrations of SO 2 at CMA, GCH, and SDZ are (14.3 ± 11.0) ppb, (12.1 ± 7.7) ppb, and (7.5 ± 4.0) ppb, respectively, with reductions of 26%, 36%, and 13%, respectively, compared to the levels before. Detailed analysis shows that the differences of temperature, relative humidity, wind speed, and wind direction were not the dominant factors for the significant differences of SO2 between the pre-Olympics and post-Olympics periods. By extracting the data being more representative of local or regional characteristics, a reduction of up to 40% for SO2 in polluted areas and a reduction of 20% for regional SO2 are obtained for the effect of control measures implemented for the Olympic Games.

풍력자원평가용 윈드큐브 라이다와 씬텍 소다의 비교.검증 - 잠실 원격탐사 캠페인

The only practical way to measure wind resource at high-altitude over 100 m above ground for a feasibility study on a high-rise building integrated wind turbine might be ground-based remote sensing. The remote-sensing campaign was performed at a 145 m-building roof in Jamsil where is a center of metropolitan city Seoul. The campaign aimed uncertainty assessment of Leosphere WindCube LIDAR and Scintec MPAS SODAR through a mutual comparison. Compared with LIDAR, the data availability of SODAR was about 2/3 at 550 m altitude while both showed over 90% under 400 m, and it is shown that the data availability decrease may bring a distortion of statistical analysis. The wind speed measurement of SODAR was fitted to a slope of 0.92 and <TEX>$R^2$</TEX> of 0.90 to the LIDAR measurement. The relative standard deviation of wind speed difference and standard deviation of wind direction difference were evaluated to be 30% and 20 degrees, respectively over the whole measurement heights.

Parameterizing Mesoscale Wind Uncertainty for Dispersion Modeling

Abstract A parameterization of numerical weather prediction uncertainty is presented for use by atmospheric transport and dispersion models. The theoretical development applies Taylor dispersion concepts to diagnose dispersion metrics from numerical wind field ensembles, where the ensemble variability approximates the wind field uncertainty. This analysis identifies persistent wind direction differences in the wind field ensemble as a leading source of enhanced “virtual” dispersion, and thus enhanced uncertainty for the ensemble-mean contaminant plume. This dispersion is characterized by the Lagrangian integral time scale for the grid-resolved, large-scale, “outer” flow that is imposed through the initial and boundary conditions and by the ensemble deviation-velocity variance. Excellent agreement is demonstrated between an explicit ensemble-mean contaminant plume generated from a Gaussian plume model applied to the individual wind field ensemble members and the modeled ensemble-mean plume formed from the one Gaussian plume simulation enhanced with the new ensemble dispersion metrics.

Efecto de la dispersión de polen en la producción de semilla de maíz, en Texcoco, México

Con la finalidad de conocer cómo se dispersa el polen de maíz en un lote de producción de semillas con problemas de aislamiento y sus implicaciones en la calidad genética, se condujo un experimento en un lote de 189 por 42,5 m en el ciclo primaveraverano de 1992 en Texcoco, México. Se establecieron tres poblaciones de maíz contrastantes en la composición del endospermo: dos de tipo normal y una de tipo dulce. Las variedades de tipo normal estuvieron colocadas en tres surcos rodeando a la variedad dulce. Se evaluó la altura de planta y mazorca, floración femenina y masculina; además, el porcentaje de grano con endospermo normal, como indicativo del cruzamiento ocurrido en la variedad de endospermo dulce. Las condiciones que facilitaron el cruzamiento con las variedades de endospermo normal fueron la inexistencia de aislamiento por distancia y coincidencia de las floraciones. La dispersión de polen y subsecuente contaminación dentro del lote siguió una distribución normal; existieron variaciones en los niveles y distancias de contaminación debidas a la dirección de los vientos y en el vigor de las plantas contaminantes. La menor contaminación fue 1% que se presentó en el centro del lote. La ecuación de superficie de respuesta obtenida estimó que con 25 surcos borderos es posible obtener una calidad de semilla sin contaminación.

Evaluating wind fields from a diagnostic model over complex terrain in the Phoenix region and implications to dispersion calculations for regional emergency response

AbstractThis paper compares the wind field from a diagnostic model (CALMET) over complex terrain in the Phoenix region in the USA with observations that are gridded by a state‐of‐the‐art Four‐Dimensional Data Assimilation (FDDA) system. The wind difference between the CALMET and FDDA wind fields is larger at night than in the day. The magnitude of the wind difference can be smaller than 5% of the mean wind speed at low levels in areas with dense observational stations, while it can be larger than 80% in areas without observational stations or at high altitudes. The vector‐mean wind direction difference over the domain is 15° on the surface level and 25° between 10 and 1500 m. To evaluate the effects of the wind difference on dispersion calculations, dispersion of a hypothetical passive tracer released from surface point sources is simulated by the second‐order closure integrated puff (SCIPUFF) model driven by the CALMET and FDDA wind fields, respectively. Differences in the two simulated tracer concentration fields increase with time due to accumulation of effects of the wind differences both near the surface and at higher altitudes. Even for release in the area with the densest distribution of surface stations, the relative difference in the peak surface concentration from CALMET‐SCIPUFF and from FDDA‐SCIPUFF is less than 10% only within 0.5 h after the release in the afternoon, and increases to 70% at 1.5 h; this is because of large differences in wind above the surface. For release in the area with few stations, the difference can be larger than 100% or even larger after 1.5 h from the release. To improve dispersion simulations driven by the CALMET wind in the region, observations at upper‐air stations are needed and the current surface observation network needs to be reorganized or more stations are needed to account for the influence of terrain. Copyright © 2009 Royal Meteorological Society

삼림파괴로 인한 미기후 환경변화에 관한 관측적 연구

We investigated the change of several meteorological variables due to deforestation. We established two sets of automatic weather observation system: one on a hill where forest was destructed by lumbering (Point 1) and the other in a neighboring district (Point 2) of fairly preserved forest. The observations were continued for one year (2006. 12-2007. 12). In this study, we analysed the data observed for one week from the nea day after summertime rainfall. The results showed that the air temperatures of Point 1 were about higher than those of Point 2 during the daytime. But there were small gaps between the two poults during the nighttime. The relative humidities also differed greatly between the two during the daytime. It was as high as about 10% at Point 2. The surface and underground (15 cm in depth) soil temperatures were also fealty different between the two points during the daytime. They were higher at Point 2 than those of Point 1. And the gaps reduced drastically during the nighttime. The averaged soil moistures were 7.1% at Point 1 and 19.5% at Point 2 during the observation period, respectively. The differences of wind direction were small, but the wind speeds differed between the two points. The observed wind speeds during the observation period were roughly estimated to be about 0.5m/s at Point 1 and 0.3m/s at Point 2. The heat budget analysis was also performed based on the observation data.

Three-Dimensional Wind Retrieval: Application of MUSCAT to Dual-Doppler Lidar

Abstract During the field campaign of the Terrain-induced Rotor Experiment (T-REX) in the spring of 2006, Doppler lidar measurements were taken in the complex terrain of the Californian Owens Valley for six weeks. While fast three-dimensional (3D) wind analysis from measured radial wind components is well established for dual weather radars, only the feasibility was shown for dual-Doppler lidars. A computationally inexpensive, variational analysis method developed for multiple-Doppler radar measurements over complex terrain was applied. The general flow pattern of the 19 derived 3D wind fields is slightly smoothed in time and space because of lidar scan duration and analysis algorithm. The comparison of extracted wind profiles to profiles from radiosondes and wind profiler reveals differences of wind speed and direction of less than 1.1 m s−1 and 3°, on average, with standard deviations not exceeding 2.7 m s−1 and 27°, respectively. Standard velocity–azimuth display (VAD) retrieval method provided higher vertical resolution than the dual-Doppler retrieval, but no horizontal structure of the flow field. The authors suggest a simple way to obtain a good first guess for a dual-lidar scan strategy geared toward 3D wind retrieval that minimizes scan duration and maximizes spatial coverage.

An Evaluation of a Diagnostic Wind Model (CALMET)

Abstract A U.S. Environmental Protection Agency (EPA)-approved diagnostic wind model [California Meteorological Model (CALMET)] was evaluated during a typical lake-breeze event under fair weather conditions in the Chicago region. The authors focused on the performance of CALMET in terms of simulating winds that were highly variable in space and time. The reference winds were generated by the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) assimilating system, with which CALMET results were compared. Statistical evaluations were conducted to quantify overall model differences in wind speed and direction over the domain. Below 850 m above the surface, relative differences in (layer averaged) wind speed were about 25%–40% during the simulation period; wind direction differences generally ranged from 6° to 20°. Above 850 m, the differences became larger because of the limited number of upper-air stations near the studied domain. Analyses implied that model differences were dependent on time because of time-dependent spatial variability in winds. Trajectory analyses were made to examine the likely spatial dependence of CALMET deviations from the reference winds within the domain. These analyses suggest that the quality of CALMET winds in local areas depended on their proximity to the lake-breeze front position. Large deviations usually occurred near the front area, where observations cannot resolve the spatial variability of wind, or in the fringe of the domain, where observations are lacking. Results simulated using different datasets and model options were also compared. Differences between CALMET and the reference winds tended to be reduced with data sampled from more stations or from more uniformly distributed stations. Suggestions are offered for further improving or interpreting CALMET results under complex wind conditions in the Chicago region, which may also apply to other regions.

Climatology and impact on air quality of sea breeze in an urban coastal environment

AbstractThe aims of this paper are to investigate the characteristics of the sea breeze that is developing in Volos area, a medium sized coastal city in central Greece, and to study the influence of sea breeze on concentration levels of ozone and PM10, during the period 2001–2005. The identification of sea breeze days is based on a set of strict, objective criteria, which include the wind direction and its diurnal reversal, the wind direction difference between the surface winds and the winds in the free atmosphere and the thermal contrast between the sea and the land surface. The statistical analysis reveals that sea breeze is developing in 85.6% of days from May until July, with maximum frequency of occurrence 89% in June. Its most frequent onset and cessation time periods are 09:00–11:00 and 20:00–22:00 LST respectively and its usual duration is approximately 10 h. The average maximum strength is 2.6 m/s, usually between 14:00 and 17:00 LST, while the maximum observed value equals 5.9 m/s. Studying the variation of ozone and PM10 levels during the cold and the warm period of the year (October–April and May–September respectively), it is concluded that sea breeze development is associated with an increase of the concentration of both pollutants. This increase is more pronounced during the cold period and is attributed to unfavourable meteorological conditions. Copyright © 2008 Royal Meteorological Society