Hasan Tatli

Downscaling standardized precipitation index via model output statistics

This study investigates the possible impacts of future climate change on meteorological drought events in Turkey by using a new statistical downscaling technique based on polytomous logistic regression, denoted as the model output statistics (MOS) technique. It is designed to downscale the drought classes of the 12-month Standardized Precipitation Index (SPI). The main goal of a downscaling procedure is to determine the influences of large-scale climatic variability and the projected changes on the local scale-regional variables. The large-scale predictors used in this study were obtained from the output of the Second Generation Canadian Coupled General Circulation Model (CGCM2) simulations, run from 1940 to 2100 for three socioeconomic scenarios, namely control , with the constraint of the 20th century atmospheric concentration of greenhouse gases, and the SRES A2 and B2 scenarios. Observations from 96 meteorological stations were used to estimate 12-month SPI values for the period 1940-2010, leaving the last 10 years for validation against the results simulated by the CGCM2. The MOS results derived from the control climate simulation agree with the observed patterns for present climate. The MOS results derived from future climate scenarios lead to conclude that there is a decreased probability of very wet and extremely wet conditions. In addition, the probabilities of near-normal conditions will decrease in the Black Sea coast and will increase towards the Marmara Transition and continental eastern Anatolia regions.

Simulation of Agricultural Meteorological Factors Affecting Evapotranspiration by Fuzzy Inference

Abstract In agricultural meteorological studies, the major difficulty is the determination of evapotranspiration (latent heat flux). There are numerous methods for estimating its value. However, these approaches yield accurate and successful results proportionally with the complexity. The main purpose of this paper is to determine the effects of atmospheric, soil, and field measured plant quantities on the latent heat flux by using the fuzzy inference systems techniques. The necessary measurements are recorded during two different periods in the faba bean plant growth at an agricultural meteorology station by considering a Bowen Ratio Energy Balance System.