The Largest Ten Heat Waves Over Ankara Between 1965-2006 and Their Simulations by WRF-ARW
Abstract
Global climate change is one of the greatest environmental, economical and social threats. Ecosystems and various sectors of human activities are very sensitive to extreme events such as floods, droughts, heat waves and cold spells. Even relatively small changes in means and variations of climate variables can induce considerable changes in the severity of extreme events. The purpose of this study is to determine the heat waves affecting the capital city of Turkey, Ankara, from observational records and to simulate the selected cases by using meso-scale atmospheric model of WRF-ARW. Here, we used maximum temperatures and 2:00 pm relative humidity data to calculate the daily apparent temperatures (heat index) for the 1965-2006-summer period following Steadman heat index formula (Steadman, 1984). Then, the heat waves were identified by using the apparent temperatures and defined as the period in which the apparent temperatures exceed the 90th percentile for at least three consecutive days. We have found that there were 49 heat waves in summer months between 1965 and 2006 in Ankara. Statistical analyses show that both the frequency of heat waves and the number of days within the heat waves have been increased from 1965 to 2006. Among 49 cases, ten extreme heat waves were selected for simulation. WRF-ARW model are used in three nested domain forms with the highest resolution of 3km. It is initialized and forced from the lateral boundaries by NNRP data set. The simulations show that during heat wave events, Arabian low and extended Azores high through the central Mediterranean play crucial role on the transport of warm and humid air towards Ankara region. Also, Arabian low deepens and extends towards eastern part of Turkey. It is found that the soil moisture around the region and precipitation regime of the previous seasons (spring and winter) also control the number of the days in which the apparent temperatures exceeding the 90th percentile value. Our findings suggest that the dry winters and springs cause the soil moisture deficits and strengthen the heat advection through the region and result in heat waves.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.A11J..01A
- Keywords:
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- 1610 GLOBAL CHANGE / Atmosphere;
- 4313 NATURAL HAZARDS / Extreme events;
- 4314 NATURAL HAZARDS / Mathematical and computer modeling