Abdullah Kahraman

Severe Hail Climatology of Turkey

AbstractA climatology of severe hail (diameter equal to or exceeding approximately 1.5 cm) for Turkey is constructed from official severe weather reports from meteorological stations, newspaper archives, and Internet sources. The dataset consists of 1489 severe hail cases on 1107 severe hail days (days with at least one severe hail case) during 1925–2014. Severe hail was reported most often in the 1960s, followed by a decrease until the 2000s, and an ensuing increase in the past decade. Severe hail is most likely to occur in the afternoon and evening, and in spring and summer, particularly May and June. The geographical distribution implies that almost all of Turkey is prone to severe hailstorms. In 8.3% of the severe hail cases, very large hailstones (diameter equal to or exceeding approximately 4.5 cm) were observed.

Tornado Climatology of Turkey

AbstractA climatology of tornadoes in Turkey is presented using records from a wide variety of sources (e.g., the Turkish State Meteorological Service, European Severe Weather Database, newspaper archives, Internet searches, etc.). The climatology includes the annual, diurnal, geographical, and intensity distributions of both mesocyclonic and nonmesocyclonic tornadoes. From 1818 to 2013, 385 tornado cases were obtained. The tornadoes range from F0 to F3, with F1 being the most frequently reported or inferred intensity. Mesocyclonic tornadoes are most likely in May and June, and a secondary maximum in frequency is present in October and November. Nonmesocyclonic tornadoes (waterspouts) are most common in the winter along the (southern) Mediterranean coast and in the fall along the Black Sea (northern) coast. Tornadoes (both mesocyclonic and nonmesocyclonic) are most likely in the afternoon and early evening hours.

Severe Convective Storm Environments in Turkey

AbstractSevere convective storms occasionally result in loss of life and property in Turkey, a country not known for its severe convective weather. However, relatively little is known about the characteristics of Turkish severe weather environments. This paper documents these characteristics using European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data on tornado and severe hail days in Turkey from 1979 to 2013. Severe storm environments are characterized by larger convective available potential energy (CAPE) in Turkey compared to the rest of Europe, but the CAPE values are less than those in typical U.S. severe storm environments. Severe hail is associated with large CAPE and vertical wind shear. Nonmesocyclonic tornadoes are associated with less CAPE compared with the other forms of severe weather. Deep-layer vertical wind shear is slightly weaker in Turkish supercell environments than in U.S. supercell environments, and Turkish tornadic supercell environments are characterized by muc...

Improving WRF GHI Forecasts with Model Output Statistics

Solar energy applications need reliable forecasting of solar irradiance. In this study, we present an assessment of a short-term global horizontal irradiance forecasting system based on Advanced Research Weather Research and Forecasting (WRF-ARW) meteorological model and neural networks as a post-processing method to improve the skill of the system in a highly favorable location for the utilization of solar power in Turkey.

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.