Mikdat Kadioğlu

Trends in surface air temperature data over Turkey

Eighteen stations are considered for the study of climatic records over Turkey in search for possible trends. Mean, unfiltered, seasonal and annual maximum and minimum temperatures are analysed using the Mann–Kendall rank statistic to demonstrate any existence of possible trends. The analyses indicate that the mean annual temperature records in Turkey have a warming trend over the 1939 to 1989 period, but a cooling trend from 1955 to 1989. These trends in mean annual temperatures, however, are not statistically significant. Comparatively greater warming effects have occurred in spring and winter minimum rather than the maximum temperature records. A regional increase in the mean minimum temperature around 1955 is attributed to the urban heat island effect. In general, general circulation models (GCM) predictions are consistent with the sign of the trends only in Turkish climate records during the entire 1939 to 1989 period

An application of the degree-hours method to estimate the residential heating energy requirement and fuel consumption in Istanbul

Cold season heating energy requirements in buildings can be estimated with the degree-hours method based on human comfort levels and available meteorological temperature records for a given area. Such estimations are especially significant for cities where fossil fuel consumption must be eliminated in favor of clean energy alternatives to reduce air pollution. This paper considers the city of Istanbul in Turkey and presents a detailed account for practical energy requirements and fuel consumption calculations.

Regional variability of seasonal precipitation over Turkey

Principal components (PCs) of the parametric spatial Pearson and non-parametric Spearman rank correlation matrices are used to depict the seasonal precipitation characteristics or features over Turkey. Eighty-five irregularly scattered meteorology stations over Turkey were chosen to study the monthly totals of precipitation observed from 1931 to 1990 inclusive. There are similarities among the rotated and unrotated first four components of the seasonal precipitation distributions. Meteorological processes, such as cyclonic storms during autumn and winter, are represented by the first PC over the whole study region. The influences of continentality towards the inland in Anatolia and the effect of mountains in the east of Turkey are shown by the second PC. The third PC explains the marine influence of the surrounding seas on the precipitation. Finally, it is shown that in this study, a non-parametric spatial correlation matrix produces quite similar fields with those of a parametric spatial correlation matrix. Copyright

Variations and Trends in Turkish Seasonal Heating and Cooling Degree-Days

The potential effect of climate change on energy demand is important especially for the developing and non-oil-producing countries. Cooling and heating degree-day (CDD and HDD) concepts are among the most significant meteorological variables related to residential energy consumption. This paper presents the spatial and temporal characteristics of Turkish seasonal CDD and HDD in the context of climate change. CDD and HDD are defined objectively by truncation of the temperature series at any constant base temperature level. This leads to surpluses and deficits as deviations. The surpluses are instances for cooling and the deficits for heating. Depending on temperature fluctuations, the degree-day statistics at any location show local and seasonal variations. In this study, regional variations of seasonal HDD and CDD are mapped for Turkey and their relations to local topography and climatic features are examined with conclusive interpretations. The sequential version of Mann–Kendall rank statisticis applied to demonstrate any existence of possible non-linear trends in accumulated HDD and CDD over the seasons. Spatially coherent and statistically significant trends of HDD and CDD appear in some regions of Turkey. In general, the sign of the trends is inconsistent with General Circulation Models (GCM) predictions.

Degree-Day Formulations and Application in Turkey

Abstract Degree-days are fundamental design parameters in many application fields such as power generation and consumption, agriculture, architecture, snow melt estimation, environmental energy planning, population siting, and military domains. Depending on temperature fluctuations, the degree-day statistics at any location show local and seasonal variations. Among these parameters the average degree-day durations for cooling and heating periods, degree-day sums, and their maximums play a significant role in practical applications. In the body of literature to date the average degree-day durations have been analytically studied most often for independent processes. In this paper, however, degree-day sums in addition to durations are considered as important design variables with analytical formulation for dependent processes on the basis of the first-order Markov process. The application of the methodologies developed are presented for five temperature measurement stations scattered throughout Turkey withi...

Variability of Turkish precipitation compared to El Niño events

Potential effects of the El Nino-Southern Oscillation (ENSO) warm extreme on the Turkish monthly precipitation totals between 1931 and 1990 were investigated using precipitation data from more than one hundred and eight Turkish meteorological stations. The data were normalized by using the annual total precipitation to minimize the probable topographical effects. A quiet standard annual variation was determined by month-by-month averaging for each annual month of the Neutral years. The anomalies in percent of the Turkish precipitation data were then calculated by subtracting El Nino-year monthly percent precipitation from the corresponding quiet standard value. The obtained anomalies were sorted after the El Nino high ENSO index month and analyzed by superposed epoch method. Distinct effects of high ENSO index months were found so that a large part of the month-to-month variability may be attributed to El Nino event. Spatially coherent and statistically significant precipitation responses to El Nino were shown in some regions of Turkey.

Monthly precipitation-runoff polygons and mean runoff coefficients

Abstract The runoff coefficient, the ratio of total streamflow volume to the total precipitation over a certain area and time, plays a fundamental role in the planning, design and operation of water resources in a catchment. Most often its long-term global value, especially on an annual basis, is presented either in a tabular form as a function of vegetation cover, degree of urbanization, climatological features and geological setting of the catchment area, or in the form of empirical formulations. However, in this paper, monthly runoff coefficient changes within an annual period are represented through a simple polygon diagram concept obtained from monthly precipitation and runoff data. This method provides not only variations in the monthly runoff coefficients but also, qualitatively, many useful interpretations concerning the rainfall-runoff transformation in a catchment. The application of the polygon method is presented for some catchments around the city of Istanbul, Turkey.

Trends of Growing Degree-Days in Turkey

Variations in the surface air temperatures show an associationwith the atmospheric CO2 under the hypothesis that warmertemperatures promote increases in plant growth in mid-northernlatitudes. Historical daily temperature records at seventy-fourweather stations (around 60-yr) in Turkey are used in orderto investigate this hypothesis. Separate calculations and analyses are undertaken for monthly and seasonal growing degree-days (GDD). The sequential version of Mann-Kendall rankstatistic is applied to demonstrate existence of any possible non-linear trends in accumulated GDDs above 5 °C over the months and seasons. Spatially coherent and statisticallysignificant trends of GDD are shown in some parts of Turkey. The statistically significant trends are negative mostly in summer and autumn seasons over the coastal areas of Turkey.These results strongly agree with the previous studies where weak cooling trends are observed in maximum temperatures overTurkey. They suggest the significant decreases in GDD may lead to long-term decreases in vegetation growth mostly overthe coastal regions of Turkey.

Heating energy requirements and fuel consumptions in the biggest city centers of Turkey

Seasonal energy requirements and fuel consumption for heating purposes in the buildings in a city can be estimated from the predetermined architectural design and material characteristics of the buildings, the regular meteorological temperature measurements and the population of the city. This paper considers the city centers of Istanbul, Ankara, Bursa, Adana and Konya in Turkey and presents a detailed account of the practical seasonal heating energy requirements in an apartment building and fuel consumption estimations in each city center by using the degree-hours method. Since 50.8% of the total city center population in Turkey is considered, the total amounts of these estimations may be interpreted as a good indicator to give an idea about the energy requirements and fuel consumption for heating purposes in the buildings in all the city centers of Turkey.

Monthly clearness index values of Turkey by harmonic analysis approach

The clearness index is among the most significant concepts in solar engineering. It gives more information about the atmospheric characteristics of solar stations in addition to the degree of solar energy potential of stations and their surrounding areas. Most often, the clearness index is related to sunshine duration measurements at a single station without spatial feature searches. In this study, harmonic analysis is used to model the monthly clearness index values recorded at nine stations of Turkey with distinct meteorological conditions. Consequently, the coefficients of harmonics, amplitude variances and phase angles of the harmonics are calculated, and then, maps of the total variances are evaluated for spatial interpolations. It is seen that up to the seventh harmonic, more than 90% of the total variance can be presented. It is shown that the western and eastern parts of Turkey have nearly similar characteristics. The contribution of each harmonic to total variance is calculated, and then, regional variance maps are evaluated.