Mediterranean Urban Area Research Articles

Partitioning of Black Carbon between ultrafine and fine particle modes in an urban airport vs. urban background environment

In this work, we characterize the Black Carbon (BC) aerosol in an urban airport vs. urban background environment with the objective to evaluate when and how the ultrafine BC dominates the bulk aerosol. Aerosol optical and microphysical properties were measured in a Mediterranean urban area (Rome) at sites impacted by BC sources including fossil fuels (FF), and biomass burning (BB). Experimental BC data were interpreted through measurement-constrained simulations of BC microphysics and optical properties. A “scheme” to separate the ultrafine BC was experimented on the basis of the relation found between changes in the BC partitioning between Aitken and accumulation mode particles, and relevant changes in particle size distribution and optical properties of the bulk aerosol. This separation scheme, applied to experimental data, proved useful to reveal the impact of airport and road traffic emissions. Findings may have important atmospheric implications. The experimented scheme can help separating different BC sources (FF, BB, “aged” BC) when BC size distributions may be very difficult to obtain (satellite, columnar observations, routine monitoring). Indeed, separating the ultrafine BC from the fine BC may provide significant benefits in addressing BC impact on air quality and climate.

Lichens as ecological indicators in urban areas: beyond the effects of pollutants

Summary In this work, we hypothesized that in urban areas with reduced pollution levels, local climatic conditions can be an important driver of lichen diversity. Thus, lichen functional groups could be used to study the effects of the urban heat island, characterized by higher temperature and lower humidity in urban than in peri‐urban areas. To test this hypothesis, we sampled functional groups of epiphytic lichens in 48 forest remnants of a Mediterranean urban area (Almada, Portugal). Of all tested functional groups (including those most closely associated with air pollution), groups related to water requirements showed the most significant correlations with surrounding artificial areas, roads and forest. These results suggest that the current major driver of lichen diversity is the climate within the urban area rather than air pollution, as frequently assumed. The analysis of local climate using meteorological data of temperature and humidity confirmed the existence of urban heat island in the study area. Synthesis and applications. The analysis of lichen functional groups gave an integrated response to the climatic modifications occurring in urban areas, namely to the urban heat island, suggesting that lichens can be used as a tool to evaluate the impact of urban areas on local climate and the effectiveness of mitigation and adaptation strategies if pollution levels are low.

Effects of road dust suppressants on PM levels in a Mediterranean urban area.

The abatement of road dust emissions is currently a major challenge for sustainable transportation, causing exceedances of limits on particulate matter (PM) and high population exposures to mineral dust and metals. Mitigation measures have been proposed such as improved street cleaning and the use of dust suppressants. This study evaluated, for the first time, the effectiveness of calcium-magnesium acetate (CMA) and MgCl2 in reducing road dust emissions in a Mediterranean city. During a two-month campaign, a typical urban road in the city of Barcelona was sprayed, and changes in PMx levels and components were monitored at four traffic sites and one background monitoring sites. The integrated results indicate no statistically significant effectiveness of dust suppressants on PM10 and PM2.5-10 levels. Episodic reductions of Al, K, Mg, Cr, Li, Cu, and Zn were observed during CMA applications, but they were not systematically statistically significant over different stations and spreading days. MgCl2 days showed lower PM10 mean concentrations, but these reductions were not statistically significant and were not supported by significant drops in mineral and brake-wear metals. Based on our literature review, it can be postulated that the higher the road dust loading, the higher the dust suppressant effectiveness.

Assessment of PM2.5 and PM1 chemical profile in a multiple-impacted Mediterranean urban area: Origin, sources and meteorological dependence

Airborne particulate matter in the PM2.5 and PM1 size ranges has been sampled at three sites within the Mediterranean urban area of the Athens Basin, representing background, roadside-industrialized and coastal background locations. With the principal aim to identify the sources and discriminate the contribution of the regional input versus the local one, simultaneous chemical characterization with respect to carbonaceous and ionic species was also carried out on the collected samples. In general, the average recorded values were within the Mediterranean concentration range. The constant prevalence of the ionic mass (52%–79%) over one of the carbonaceous, being combined with the occurrence of its maximum rates at the coastal background environment (74%–79% and 73%–77% for PM2.5 and PM1, respectively) leads to the hypothesis that the fine PM pollution in the basin, especially for the remote locations, is evidently governed by the external intrusion. Even at the polluted atmosphere of the roadside-industrialized environment, the PM mass was regionally originated, with the corresponding input reaching up to 87% (northward flow). Applying factor analysis on the PM2.5 database it came obvious that the sources which were responsible for the configured PM burden were not fully differentiated not only between the different types of environment but also between the exceedances and the clean air events. The contribution of the secondary, marine and combustion processes was constant at all the stations of the network, while a continuous input of crustal particles characterized both the roadside-industrialized and the coastal atmosphere. Finally, the episodic values show a general common signal of secondary mixed ΡΜ emissions, high influence of both regional and local pollution spikes, confirming the earlier findings for the significance of transportation.

Wind-forced circulation model and water exchanges through the channel in the Bay of Toulon

A hydrodynamic model of the Bay of Toulon has been developed for use as a post-accident radionuclide dispersion simulation tool. Located in a Mediterranean urban area, the Bay of Toulon is separated into two basins by a 1.4-km long seawall. The Little Bay is semi-enclosed and connected to the Large Bay by a fairway channel. This channel is the site of significant water mass exchange as a result of both wind-driven currents and bathymetry. It is therefore a focal point for marine contamination. As part of the model calibration and validation process, the first step consisted of studying the water mass exchange between the two basins. An Acoustic Doppler Current Profiler was moored in the channel for 1 year. The present study analyses in situ data to determine the current intensity and direction, and also to better understand the vertical current profile, which is highly correlated with meteorological forcing. Comparisons of model-generated and measured data are presented, and various atmospheric forcing datasets are used to enhance computed results. It appears that accurate meteorological forcing data is needed to enhance the accuracy of the hydrodynamic model. This channel is an important location for water mass renewal in the Bay of Toulon, and model results are used to quantify these exchanges. The mean calculated annual water exchange time is approximately 3.4 days. However, this duration is strongly wind dependent and shortens during windy winter months. It ranges from 1.5 days during strong wind periods to 7.5 days during calm weather. Residence time values calculated through tracer dispersion modelling after release at the back of the Little Bay are found to be comparable to the mean exchange time values, especially for windy conditions.

Do land cover changes shape sensitivity to forest fires in peri-urban areas?

The present study assesses the spatial distribution of selected land cover classes at two years (1975 and 2000) in a Mediterranean urban area (Athens, Greece) to test the hypothesis that land cover changes determine an increase in the sensitivity of landscape to forest fires on a regional scale. While urban and agricultural areas increased, although with different rates of growth, forests and semi-natural areas decreased in the study area. These changes are reflected in a significant increase of vegetation sensitivity to forest fires measured by the forest fire risk (FR) index developed in the framework of MEDALUS project. The cover classes which contributed the most to the increase of the FR index were crop mosaic, mixed agricultural-natural areas and discontinuous, low-density settlements. Results of the present study indicate that the transformation of the fringe landscape towards low-quality agricultural and pasture areas and fragmented forest patches is potentially detrimental for environmental quality and the ecological fragility of land.

PReS-FINAL-2309: Juvenile systemic lupus erythematosus: a case series depiction in an urban community and a comparison to an adult case series

Methods we detected all our jSLE patients from our database. We collected sociodemographic data and both clinical and serological variables from our jSLE patients’ charts at Hospital Sant Joan de Deu, Esplugues (Catalunya, Spain). We defined the following variables: cutaneous disease (as presence of discoid lupus, photosensitivity, and/or malar rash), joint disease (arthritis), hematological disease (anemia, leucopenia, and/or plaquetopenia), renal disease (>0.5 g/d proteinuria and, if available, histological WHO class), neurolupus (psychosis and/or convulsions). We collected the following data: age at onset, time disease evolution, and gender. In regarding to serological markers: DNAds positivity through follow-up was recorded. We also collected information from a well-recognised aSLE cohort of 124 patients in the same Mediterranean urban area. We analysed all data in order to depict the type of clinical and serological features for each group of patients. Results we assessed charts from 42 jSLE (n = 42), and compared to aSLE (n = 124). 90% of the jSLE patients were female, compared to a 95% of the aSLE cohort. Age at onset was 12.1 years in jSLE. In the jSLE group of patients: 81% had had cutaneous disease, 62% haematological disorder, 44% arthritis, 40% nephropathy (60% class IV, 20% class III, 10% class II and 10% class V), and 14% convulsions. In the aSLE cohort: 80% had cutaneous disease, 54% haematological disorder, 29% arthritis, 14% nephropathy and 3.2% neuro-lupus. DNAds positivity was 68% in jSLE and 54.8% in aSLE.

Particulate matter pollution over a Mediterranean urban area

The main purpose of this study is to investigate the aerosols' (PM10, PM2.5, and PM1) spatial and temporal distribution in different types of environment in a Mediterranean urban region, the Greater Athens Area based on data from a sampling campaign that took place during the cold and warm period of 2008. The influence of the atmospheric circulation patterns, the possible local transport mechanisms, as well as the differentiation of the PM behaviour from that of the inorganic pollutants (NOx, O3), are analysed and discussed. Furthermore, the Comprehensive Air Quality Model with extensions (CAMx) was applied for selected sampling dates and its results were evaluated against measurements in order to interpret qualitatively the configured picture of the air pollution above the GAA. Analysis of the measurement data show that local sources such as traffic and industry dominate over the prevailing PM loads, especially at the ‘hot spot’ areas. Moreover, the synoptic circulation patterns associated with calm conditions and southerly flows lead to high particulate pollution levels that also affect the urban background stations. Saharan dust outbreaks appeared to increase the particles' diameter as well as the number of E.U. limit value exceedances within the stations of our network. Without any dependence on the characteristics of the investigated atmosphere, PM1 always constituted the greatest part of the PM2.5 mass while PM10, especially during the Saharan dust episodes, was mainly constituted by the coarse fraction. The numerical modelling approach of the geographical distribution of PM10, PM2.5, NOx and O3 justified the design of the sampling campaign, indicating the need for the systematic and parallel monitoring and modelling of the pollutants' dispersion in order to understand the particulate pollution problem in the GAA and to aid to the formulation of pollution control strategies.

Feeding activity and space use of a naturalized population of Monk Parakeet, Myiopsitta monachus, in a Mediterranean urban area

We studied a naturalized population of monk parakeet breeding in an urban park in Rome, by collecting data on the diurnal and feeding activity, space use (e. g, roosting preferences, flight height) and behavioural traits (e. g., cluster size). Consideration on the potential ecological impact of the species is also made. The diurnal activity of parakeets did not differ between morning and afternoon. Most individuals were observed in flight 6-10 m from the ground, and when at roost, parakeets preferred perch es higher than 5 m. The clusters sighted on ground were significantly larger in size than those observed on roosts, while cluster size was not linked to flight height. For this species, the observed roost preference indicates that the availability of perches on high trees seems to be an important factor for habitat selection : standing on trees may increase the chances to identify trophic resources, reduce the risk of predation when at rest, and prevent overheating from high summer temperatures during the day. Regarding to feeding habits, at our study site the monk parakeet fed on different plant species both on the trees and at the ground level (e. g., Fabaceae, Ulmaceae, Poaceae, Rosaceae), showing a clear preference towards some plant species, irrespective to their abundance, and with Scolymus hispanicus (Asteraceae) as the most exploited species by far.

Environmental analysis of the logistics of agricultural products from roof top greenhouses in Mediterranean urban areas

As urban populations increase so does the amount of food transported to cities worldwide, and innovative agro-urban systems are being developed to integrate agricultural production into buildings; for example, by using roof top greenhouses (RTGs). This paper aims to quantify and compare, through a life cycle assessment, the environmental impact of the current linear supply system with a RTG system by using a case study for the production of tomatoes. The main results indicate that a change from the current linear system to the RTG system could result in a reduction, per kilogram of tomatoes (the functional unit), in the range of 44.4-75.5% for the different impact categories analysed, and savings of up to 73.5% in energy requirements. These savings are associated with re-utilisation of packaging systems (55.4-85.2%), minimisation of transport requirements (7.6-15.6%) and reduction of the loss of product during transportation and retail stages (7.3-37%). The RTG may become a strategic factor in the design of low-carbon cities in Mediterranean areas. Short-term implementation in the city of Barcelona could result in savings of 66.1 tonnes of CO₂ eq. ha(-1) when considering the global warming potential, and of 71.03 t ha(-1) when considering that the transformation from woodland to agricultural land is avoided.

Response of sowed, flowering herbaceous communities suitable for anthropic Mediterranean areas under different mowing regimes

Growing traditional ornamental plants in urban soil often fails, due to the low quality of the soil modified by anthropic activities. The aim of this research was to study the behavior of herbaceous plants suitable for sowing in mixes in order to revegetate soils in different urban environments.Three different mixes of herbaceous plants were studied: N (native) was composed of autochthonous species, US (urban short) and UT (urban tall) were composed of both autochthonous and allochthonous species. Plant height was lower than 60cm in N and US, and above 60cm in UT. Each mix was sown in three randomized plots and each plot was mown at three different times: 110, 140 and 170 days after sowing (early, mid and late season respectively). Number of plants per square meter, plant height and biomass were recorded at each mowing time. In order to assess how well the plants would establish themselves we calculated the Shannon diversity index, the evenness of species and Simpson's index of dominance.The N mix composed of autochthonous species resulted to be well-balanced with an equal number of annual and perennial species grown. The presence of annuals and perennials made the community richer and the individual plants more evenly distributed. The best mowing time to improve diversity in all the mixes was late-season. Our study suggests that native species from southern Europe are suitable for creating diverse herbaceous communities for ornamental purposes, thus enhancing the role of Mediterranean urban areas in the conservation of biodiversity.

Preliminary experiments and verification of controlled pulling tests for tree stability assessments in Mediterranean urban areas

Tree stability assessments are an indispensable tool for preserving the safety of people and property. National legislation identifies the tree custodians as those responsible for monitoring the risk factors with regard to civil and criminal liability for damage to persons or property. Currently evaluations to assess tree stability are usually made by means of visual methods and they do not always allow for an evaluation of the true health the plant. The controlled pulling test is considered to be particularly useful to evaluate the tendency of root-plate windthrow caused by thrust exerted by meteorological events such as wind and snow. This type of instrumental analysis is not yet widespread in Italy and it is sometimes applied improperly. As a result, this preliminary study focuses on these issues in order to develop a methodology with particular reference to the definition of the fundamental variables, as well investigating the possibility of its application to Mediterranean species. ► Falling trees or tree parts constitute a significant hazard to people and property. ► Visual analysis does not always permit a complete study of tree health and stability. ► Controlled pulling test represent a tool to visual analysis for evaluating root-plate rollover. ► Pulling tests estimate the critical wind speed that causes windthrow. ► These procedures improve stability tree assessment.

Assessing contextual descriptive features for plot-based classification of urban areas

A methodology for mapping urban land-use types integrating information from multiple data sources (high spatial resolution imagery, LiDAR data, and cadastral plots) is presented. A large set of complementary descriptive features that allow distinguishing different urban structures (historical, urban, residential, and industrial) is extracted and, after a selection process, a plot-based image classification approach applied, facilitating to directly relate the classification results and the urban descriptive parameters computed to the existent land-use/land-cover units in geospatial databases. The descriptive features are extracted by considering different hierarchical scale levels with semantic meaning in urban environments: buildings, plots, and urban blocks. Plots are characterised by means of image-based (spectral and textural), three-dimensional, and geometrical features. In addition, two groups of contextual features are defined: internal and external. Internal contextual features describe the main land cover types inside the plot (buildings and vegetation). External contextual features describe each object in terms of the properties of the urban block to which it belongs. After the evaluation in an heterogeneous Mediterranean urban area, the land-use classification accuracy values obtained show that the complementary descriptive features proposed improve the characterisation of urban typologies. A progressive introduction of the different groups of descriptive features in the classification tests show how the subsequent addition of internal and external contextual features have a positive effect by increasing the final accuracy of the urban classes considered in this study.

Land degradation in Mediterranean urban areas: an unexplored link with planning?

This paper examines the role of biophysical and anthropogenic factors as potential drivers of land degradation in a large Mediterranean urban region. The sensitivity of land to degradation is examined in relation to the territorial disparities observed within Rome's metropolitan area (Italy), and to the changes in its spatial organisation resulting from urban shrinkage. We derive a composite index of land sensitivity to degradation using the Environmentally Sensitive Areas Index (ESAI) at the municipal level. The observed regional disparities in ESAI scores are analysed diachronically for the period 1990–2008, based on elevation, distance from the coast and population density. The results indicate that spatial disparities in ESAI recorded in 1990 had decreased by 2008, although the degree of land sensitivity had increased throughout the urban region. We subsequently relate these changes to different models of urban organisation (i.e. ‘compact growth’ vs ‘sprawl’) observed in Rome since the 1990s. In 1990, the highest degree of land sensitivity was on the urban fringe of Rome, whereas by 2008 the greatest increase in land sensitivity was observed within suburban municipalities. This sensitivity progressively spread further away from the main urban centre during the study period. The results suggest the need to reconsider the polycentric spatial framework as an environmentally sustainable model for Rome and other urban regions in the Mediterranean.

The use of lichen functional groups as indicators of air quality in a Mediterranean urban environment

Functional groups of epiphytic lichens are proposed as indicators of air quality in a Mediterranean urban area in the south of Portugal. Local land use: traffic (for areas near roads), green (for park areas) and house (residential areas); and bark pH are applied as proxies of air quality. Epiphytic lichen diversity was evaluated using lichen diversity values (LDV) methodology. Global LDV value decreases on traffic areas, as well as absolute values of LDV for the examined functional groups, which are lower in traffic areas than green and house areas. However, the composition of lichen communities shows a different pattern, based on the relative values of functional groups. Some functional groups, such as oligotrophic, hygrophytic and acidophilous lichens, are sensitive to pollution caused by traffic, and their richness declines markedly close to roads. These groups are well represented in areas without traffic, especially in park and residential areas. Otherwise, eutrophic, xerophytic and basophilous lichens are more represented in traffic areas. Sensitive functional groups seemed to be more reliable than total diversity for evaluating the impact of atmospheric pollution on small urban areas.

Insights into the secondary fraction of the organic aerosol in a Mediterranean urban area: Marseille

Abstract. A comprehensive aerosol characterization was conducted at Marseille during summer, including organic (OC) and elemental carbon (EC), major ionic species, radiocarbon (14C), water-soluble OC and HULIS (HUmic LIke Substances), elemental composition and primary and secondary organic markers. This paper is the second paper of a two-part series that uses this dataset to investigate the sources of Organic Aerosol (OA). While the first paper investigates the primary sources (El Haddad et al., 2010), this second paper focuses on the secondary fraction of the organic aerosol. In the context of overall OC mass balance, primary OC (POC) contributes on average for only 22% and was dominated by vehicular emissions accounting on average for 17% of OC. As a result, 78% of OC mass cannot be attributed to the major primary sources and remains un-apportioned. Radiocarbon measurements suggest that more than 70% of this fraction is of non-fossil origin, assigned predominantly to biogenic secondary organic carbon (BSOC). Therefore, contributions from three traditional BSOC precursors, isoprene, α-pinene and β-caryophyllene, were considered. These were estimated using the ambient concentrations of Secondary Organic Aerosol (SOA) markers from each precursor and laboratory-derived marker mass fraction factors. Secondary organic markers derived from isoprene photo-oxidation (ie: 2-methylglyceric acid and 2-methyltetrols) do not exhibit the same temporal trends. This variability was assigned to the influence of NOx concentration on their formation pathways and to their potential decay by further processing in the atmosphere. The influence of changes in isoprene chemistry on assessment of isoprene SOC contribution was evaluated explicitly. The results suggest a 60-fold variation between the different estimates computed using different isoprene SOC markers, implying that the available profiles do not reflect the actual isoprene SOC composition observed in Marseille. Using the marker-based approach, the aggregate contribution from traditional BSOC was estimated at only 4.2% of total OC and was dominated by α-pinene SOC accounting on average for 3.4% of OC. As a result, these estimates underpredict the inexplicably high loadings of OC. This underestimation can be associated with (1) uncertainties underlying the marker-based approach, (2) presence of other SOC precursors and (3) further processing of fresh SOC, as indicated by organosulfates (RSO4H) and HUmic LIke Substances (HULIS) measurements.

Impact of the Mediterranean Urban Environment on Photosynthetic Efficiency of Quercus ilex Leaves

Environmental constrains and anthropogenic changes can contribute simultaneously to the limitation of plant performance in Mediterranean urban areas. Photosynthetic efficiency of Quercus ilex L. leaves from the urban area of Naples was evaluated by comparison with leaves from remote site (Vesuvius National Park). The photosynthetic performance of leaves with different age (current year [CY], 1- [1Y] and 2-year old [2Y]) was assessed by measurements of gas exchange, chlorophyll fluorescence and pigment contents. The photosynthetic activity at the urban site was higher than that at the remote site for the CY leaves, while the opposite was observed for the 1Y and 2Y leaves. The growth of Q. ilex trees was mainly sustained by the CY leaves at the urban site, whereas at the remote site the photosynthetic activity was not affected by leaf ageing. In the urban environment, Q. ilex leaves strongly decreased the photosynthetic performance with leaf ageing as highlighted by leaf gas exchanges, although the photochemistry did not show any significant change. The mature leaves of urban site drove the reductive power deriving from the photochemistry more in non-assimilative processes rather than in carbon assimilative ones, avoiding a strong decrease of PSII photochemical efficiency.

Value of an urban habitat for the native Mediterranean avifauna

Mediterranean landscapes resulted from complex land uses that produced a mosaic of extensive crops, grasslands, scrublands and scattered woodlands. During the twentieth century the decrease in traditional agriculture triggered a decrease in open habitats and an increase in forests. In the meantime urban centres grew dramatically. Both spread of forest and urban areas have been suspected to participate in the decline of typical Mediterranean bird species and, in general, to cause faunal loss. However, modern cities offer a variety of landscape types and, in the Mediterranean, their value for native bird species has been little assessed. We compared the bird communities from an urban landscape, including built up and natural or semi natural units within the limits of the city of Montpellier, to the bird communities from non-urban habitats (cropland, grassland and woodland) located nearby but away from direct urban influence. Fifty four percent of the bird species recorded in the non-urban habitats also occurred in the urban landscape. On average, estimated species richness in the urban landscape was similar to values obtained for non-urban habitats. Within the urban landscape species richness was lowest in the dense historical centre and highest in the residential areas. The residential areas and urban woods were suitable habitats for most generalist species but also for several more specialized species recorded in the non-urban habitats. Some species actually reached their highest observation frequency in the urban landscape. Urban landscape was least favourable to the same farmland and open-habitat specialists that have been negatively affected by agricultural abandonment in the region. Finally, five of the species common in the urban landscape had an unfavorable conservation status in 2004 in the EU. This study emphasizes that Mediterranean urban areas have the potential to host a diverse native bird community. Finding ways to improve their carrying capacity for the local avifauna might be a worthwhile objective for animal conservation.

Seasonal Differences in Atmospheric Nitrous Acid near Mediterranean Urban Areas

The major objective of this paper is to provide insights to sources and sinks of nitrous acid in urban areas, and their seasonal dependency on meteorology, photochemistry and long range transport. With this aim, nitrous acid (HONO) mixing ratios and other compounds were measured in Ashdod (south of Tel Aviv, Israel), a typical Mediterranean urban area. Statistical data analysis revealed the expected correlation between HONO and nitrogen oxides during the autumn campaign when HONO sources appeared to be traffic-, harbor-, and industry-related. Conversely, during summer HONO and NO2 were no longer correlated: NO2 at nighttime was probably deposited onto surfaces, soil and plants, whereas HONO at daytime was likely destroyed photolytically contributing to the OH concentration. Photolysis was expected to be the dominant HONO sink at daytime, especially during the summer period. Using modeled photolytical HONO lifetimes we estimate the magnitude of heterogeneous and/or organic electron transfer source reactions of HONO as 6–8 ppbv/h.

Time series analysis and identification of trends in a Mediterranean urban area

During the last decade there has been considerable interest in the stochastic analysis of temperature trends. This attention usually focuses upon global and hemispheric time series. Analyses of global temperatures are of obvious importance but it is equally of interest to analyse questions of warming at a more ‘micro’ level. The objective of the paper is to illustrate that the appropriate estimation of a local record trend component necessitates the use of flexible methods. A long time series of temperature data from a Mediterranean urban area is analysed. The data comprise a series on monthly mean surface temperatures for Valencia (Spain), a Mediterranean city in terms of its urban structure and climatology. Trends are extracted from the temperature data available from 1938, using both annual and seasonal averages. Attention is focused on applying non-parametric methods which allow the analysis of non stationary trends in comparison to other methods. A local polynomial regression fitting and wavelet thresholding indicate that there is an upward trend in the annual series. The bandwidth in the local regression model selected by cross-validation follows short-term cycles rather than tracing out the long-term component. Therefore to extract the long-term trend a higher smoothing parameter is selected. The trend visualization plots show that the increase in the mean temperature per year is non-stationary. A change-point detection test indicates a trend change in the series around the year 1968. There is compelling evidence of a trend increase after this year, which is probably due to increase urbanization. The analysis of monthly observations is also discussed. Seasonal differences in trend patterns are more clearly observed when the monthly data are averaged across seasons. There have been upward shifts in the trends of spring and summer temperatures.