Storms and meteorological parameters affecting the aviation

Storms and meteorological parameters affecting the aviation (such as wind gust, thunderstorms, runway visual range, volcanic ash) are the atmospheric events which affect human lives negatively. Understanding these meteorological events' formation mechanisms and predicting the weather before happening of these atmospheric events and taking the proper precautions are particularly important for aviation. Within the scope of this thesis, storms and the meteorological parameters affecting the aviation, respectively, severe thunderstorm for Esenboğa International Airport, thunderstorm and fog for Atatürk International Airport and Volcanic ash for Turkish FIR areas were examined. This thesis study is based on 3 SCI & SCI-E articles and 1 national article. Thunderstorms are produced when clouds develop vertically and some may exceed the tropopause and spread out widely. That is why thunderstorms are very important for the aviation industry because of their dynamical mechanism and air safety. The main purpose of this study is to unveil the thunderstorm activity at Istanbul Ataturk International Airport (LTBA) and its relationship to convective available potential energy (CAPE) values handled from soundings statistically. In this study, thunderstorms at LTBA are analysed by periods and using METAR (Aviation Routine Weather Report) and SPECI (Aviation Selected Special Weather Report) reports in the period 2008–2013. Also CAPE and CIN (Convective Inhibition) values are estimated statistically and classified according to moderate and deep convection thresholds. During the 5 years study period, there were 127 thunderstorm (TS) days and chance of a TS was 6.95%. Although the highest CAPE values were observed in summer, TS frequency was highest during. Maximum frequency of thunderstorms is observed during September (22 days) and June (19 days). It is observed that 42.16% of thunderstorms occurred between 1700 and 2400 UTC (Coordinated Universal Time) and 17.48% are between 0900 and 1300 UTC. The longest-lasting thunderstorm was detected on September 8 and 9, 2009 and June 23, 2010, lasting 7 hours 30 minutes (Özdemir et al., in press, a). In this study, a severe thunderstorm that occurred at Esenboğa International Airport (ICAO code: LTAC) on the 15th of July, 2013, was investigated. A heavy thunderstorm with hail and rain showers occurred at 14:32 UTC. The maximum wind speed of 61 knots was measured at 14:34 UTC. During a 14-minute time interval, 16.2 mm of precipitation occurred. The aircraft parking area was under water, and rainwater leaked from the terminal roof, which affected passengers. For LTAC and its surroundings, 57 dBZ maximum reflectivity values at radar echo intensity were measured (Özdemir&Deniz, 2016). The aims of this study were to classify the fog that occurs at Istanbul Ataturk International Airport according to its formation mechanism, identify the instrument landing system category (ILS-CAT) operations required to land aircraft in the fog, and determine the CAT operations of the foggy hours at the airport. METAR and SPECI observations were used to investigate fog events occurring at the airport for the years of 2006 to 2015. Of the flights that required an Instrument Landing System to land, 97.63% were under the CAT IIIA operation, 100% of flights were under the CAT IIIB operation and 100% flights were under the CAT IIIC operation (Özdemir et al., in press, b). Volcanic ash clouds could be drifted to hundreds, thousands of miles away and even intercontinental depending on meteorological conditions. They can have an effect over a very large air space. Ash clouds can drift over multiple countries, FIR (Flight Information Regions) and control areas and may cause danger. Volcanic ash clouds, which are effective in a very large area, have vital importance for aviation. Existence of volcanic ash clouds, or locating the dangerous areas may cause route changes, delays or even flight cancellations. In this study, the effect of volcanic eruptions between 2010-2015 in Turkish FIR areas were examined. The 5 year period of VAG (Volcanic Ash Graphic), which is designed by London Volcanic Ash Advisory Centre (VAAC) and works in coordination with Toulouse VAAC located in France, was used. In order to investigate the effects on Turkish FIR areas of Ankara FIR (LTAA) and Istanbul FIR (LTBB) areas, the SIGMET (Significant Meteorological Information) messages, which were generated by Esenboğa and Atatürk International Airport Meteorological Offices respectively, were examined. As the result of SIGMET messages generated by Atatürk International Airport Meteorological Office, flights between 10.000 and 30.000 feet altitude were cancelled in 18th April 2010 for northern Thrace and south west Black Sea region as well as in 19th of April 2010 for south west Black Sea region (Özdemir&Deniz, 2015).