Hüseyin Toros

URBANIZATION EFFECTS ON REGIONAL CLIMATE CHANGE IN THE CASE OF FOUR LARGE CITIES OF TURKEY

The growing interest in urbanization problems is stimulating detailed studies of their effects on local climate change in the developed world. The absence of such studies in developing countries is restricting many decisions to be made and applied by policymakers. In one developing country, Turkey, results of the study of four urban stations and their neighboring rural sites for the 1951-1990 time period reveal that there is a shift towards the warmer side in the frequency distributions of daily minimum and 21.00 hr temperature difference series. This shift is an indication of urban heat island. The maximum urban heat island intensity trend that is obtained from the temperature differences database agrees well with Okes (1973) formula for European cities. Seasonal analysis of individual 21.00 hr temperature series suggests that the regional warming is strongest in spring and weakest in autumn and winter. Urban warming is detected to be more or less equally distributed over the year wi th a slight increase in the autumn months. The Mann-Kendall trend test is applied to the temperature difference series, and the urban heat island effect is found to be significant in all urban sites. On the other hand, almost no significant urban effect on precipitation can be detected.

Solar energy potential for heating and cooling systems in big cities of Turkey

In this study, the solar energy gain on vertical surfaces for heating and cooling systems in big cities, such as Istanbul, Ankara and Izmir of Turkey, has been estimated for different orientations using hourly solar radiation measurements. During summer, the monthly mean solar energy potential on vertical surfaces comes from the east and west directions more than other orientations in all the cities. However, during winter, it comes from the south, and the highest solar energy is received in Izmir, where the average annual global radiation attains its maximum. Additionally, north oriented surfaces produce between 65% and 75% lower total solar energy than other orientations in all the cities.

Temporal variability of the precipitation chemistry in the forest area of Istanbul, Turkey

The chemical compositions of precipitation show temporal and spatial variability. It is important to determine the temporal variation of the chemical composition of rainwater for estimating the impacts of pollutants on the forest. In this study, the 34 rainwater samples are collected using, for the first time, the specially designed collectors between November 1997 and March 1998 in Istanbul University, Faculty of Forestry at Bahcekoy, Istanbul in Belgrad Forest. The sequentially collected samples are analysed for major ions concentrations and pH estimations. The pH values for all samples vary from 5.1-7.6. In general, the concentration of all rainwater samples decrease with time. Furthermore, it is estimated that the average Ca2+) (1943.0 µeql-1) and SO42- (887.3 µeql-1) concentrations are extremely high during the first ten minutes of the precipitation event.

Case study of PM pollution in playgrounds in Istanbul

In a world where at least 50% of the population is living in urban environments, air pollution and specifically particulate matter (PM) have become one of the most critical issues for human health. Children are more susceptible than adults to air pollution and its adverse effects because they inhale and retain larger amounts of air pollutants per unit of body weight. In this study, PM pollution, particularly PM10 and PM2.5, at selected playgrounds were investigated in Istanbul city. Istanbul is a megacity of over 15 million inhabitants, and on-road traffic is increasing rapidly (over 3 million vehicles on the road). To estimate the effect of traffic emissions on children, the location of the playgrounds were selected according to traffic density. Measurements were carried out at five different playgrounds throughout the city in 2009. Field results show that the values of PM10 and PM2.5 have reached critical limits at the playgrounds close to the main roads, especially at P-1. Thus, we focused on this location and investigated a source other than traffic emissions. One of the episode days has been observed on 5–7 March 2009. Evaluations of meteorological events are very important to determine air pollution sources and their long-range transport. Therefore, the Weather Research and Forecasting model (WRF) was used to simulate and forecast meteorological parameters and the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) applied to investigate long-range transport. According to the WRF model outputs, there was a low-pressure system over Geneva gulf on the 500-hPa level, and its core had been located over Britain on 5 March 2009 00UTC. The system had been sweeping dust from the Sahara Desert and carrying the air particles over Istanbul. Similarly, backward HYSPLIT analysis showed that air particles had moved through Istanbul from Northern Africa.

Analysis of long-term changes in extreme climatic indices: a case study of the Mediterranean climate, Marmara Region, Turkey

This study aimed to analyze extreme temperature and precipitation indices at seven stations in the Marmara Region of Turkey for the period 1961–2016. The trend of temperature indices showed that the warm-spell duration and the numbers of summer days, tropical nights, warm nights, and warm days have increased, while the cold-spell duration and number of ice days, cool nights, and cool days have decreased across the Marmara Region. Additionally, the diurnal temperature range has slightly increased at most of the stations. A majority of stations have shown significant warming trends for warm days and warm nights throughout the study area, whereas warm extremes and night-time based temperature indices have shown stronger trends compared to cold extremes and day-time indices. The analysis of precipitation indices has mostly shown increasing trends in consecutive dry days and increasing trends in annual rainfall, rainfall intensity for inland and urban stations, especially for stations in Sariyer and Edirne, which are affected by a fast rate of urbanization. Overall, a large proportion of study stations have experienced an increase in annual precipitation and heavy precipitation events, although there was a low percentage of results that was significant. Therefore, it is expected that the rainfall events will tend to become shorter and more intense, the occurrence of temperature extremes will become more pronounced in favor of hotter events, and there will be an increase in the atmospheric moisture content over the Marmara Region. This provides regional evidence for the importance of ongoing research on climate change.

Analysis of HIRLAM NWP Model During an Air Pollution Episode in Istanbul in 2009

Meteorological forecasts have been analyzed in detail during an episode involving substantially high concentrations of PM10 that occurred in Istanbul on 18–20 November 2009. The episode addressed here is associated with areas of high pressure over the Northwest of Turkey. These conditions caused poor air quality, especially in the Istanbul Metropolitan Area. Simulations were executed with version 7.2.1 of the HIRLAM model. The simulations were able to predict the temperatures, wind speeds and relative humidity at near surface.

Hava Kirlilik Modellerinde Kullanılacak Emisyon Envanteri Oluşturulması için Yaklaşımlar ve İstanbul Hava Kirliliği Dağılımı Örneği

Sanayilesme ve sehirlesme hava kirliligi sorunlarina yol acmaktadir. Insan sagligi ve ekosistem icin en ciddi tehditlerden biri nufusun artmasi dolayisiyla uretimin artmasi ile hava kalitesinin bozulmasidir. Bu dongu, sanayilesme ve sehirlesme yogunlugunun yuksek oldugu alanlarda daha yogunlasmaktadir. Dogrudan olcum ile mekânsal hava kalitesinin belirlenmesi zor ve pahalidir, bu yuzden alternatif yontemler kullanilir, arastirilir ve gelistirilir. Bir yerin hava kalitesinin iyilestirilmesi oncelikle emisyon kaynaklarinin ve miktarlarinin belirlenmesi, daha sonra kirleticilerin dagiliminin arastirilmasi, sayisal modeller vasitasiyla dagitilmasi ve son olarak alinacak politikalarin belirlenmesiyle yapilabilir. Emisyon envanteri hava kirliligi modellemesinde cok onemli bir adimdir ve karmasik bir surectir. Şehirlerde ve sehirler arasinda arac emisyonu onemli bir hava kirliligi kaynagidir ve mekânsal emisyon dagilimini belirlemek icin kullanilabilir. Yol yogunlugu insan etkinliginin ve sehirlesmenin dolayli bir gostergesi olabilir, dolayisiyla insan kaynakli hava kirliligi motorlu araclarin yogunlugu, sayisi ve turu ile dolayli olarak nitelendirilebilir. Bu calisma, yol haritalariyla diger verilerin kullanilarak emisyon envanterinin olusturulmasina bir ornektir. Uretilen verilerin yeni nesil hava kirliligi modellerinde kullanilmasi, modelin basariminin arttirilmasina katki saglayacaktir. Calisma sonuclari hava kalitesinin dolayli olarak insan ve diger canli yasaminin iyilestirilmesi uzerine olumlu etki yapacagi dusunulmektedir.

Long-Term Variations of Temperature and Precipitation in the Megacity of Istanbul for the Development of Adaptation Strategies to Climate Change

Istanbul, as one of the four anchor megacities of Europe, has shown a rise of 0.94°C in average annual temperature over the long period of 1912–2016 under impacts of anthropogenic climate change. A notable increase in temperatures has started after the 1940s, which is in parallel with the beginning of industrialization era in Istanbul. This warming is associated with an extensive population growth and accompanied the decrease in vegetation cover. Increasing in minimum series of temperature is more evident than maximum values and the rising rate of temperature values has been more pronounced during recent decades. The first significant upward trend in precipitation series has periodically started in 1920s, while there has been a stable trend from 2001 till today. The daily average of rainfall amount increased with a mean value of 58 mm during the total study period. Rising rate of daily maximum precipitation has been more evident in the last 3 decades, which is shown by the increased frequency of heavy rainfall. In this regard, both of the temperature and precipitation series had higher mean values (13.9°C and 878 mm) for the final period (1965–2016) compared to the mean values (13.6°C and 799 mm) belonging to the first period (1912–1964).

Meteorological Modeling of the PM10 Episode in the Creek Valley of Golden Horn Harbour, Istanbul Under Very Stable Conditions for November 6–9, 2010 Episode

This paper presents verification results of numerical simulations of meteorological conditions leading to an air pollution episode on 6–9 November 2010 in Istanbul. WRF-ARW ver 3.3 is run with GFS and ECMWF input. For verification, horizontal wind components and temperature data of nine meteorological stations are used for both simulations. Results indicate that the model is successful in simulating the meteorological conditions with both two different input data, especially with the GFS input, although ECMWF runs had a finer horizontal resolution of 1 km.