Heat waves trend in Slovak Carpathian region

for 1961 -2010 periodPavol Nejedlík1, Milan Lapin2, Pavel Šťastný1, Peter Kajaba1, Oliver Bochníček1, Katarína Mikulová1

1 Slovak Hydrometeorological Institute, 2 Comenius University, Bratislava

BackgroundWith the current concern for global warming it is reasonable to suppose that heat waves may increase in frequency, severity, duration, or areal extent in the future. The period from May to August 2003 gives the example, when heat waves affected large areas of Europe. There was evidence that this period of high temperature had large impact on mortality. Such waves cause serious problems in the health sector also in Slovak territory. Some expected changes in the regime of heat waves regime in Slovak Carpathian region are analyzed in the paper. The data used in this analysis are the output of harmonized daily datasets in the frame of the CARPATCLIM project. The number of 22 climatological stations from the period of 1961 - 2010 was selected from Slovak territory; regularly represent all altitude and terrain scales. The MASH software was used for data quality control, missing data completion and homogenization of daily data series.

References:Szentimrey, T., Bihari, Z., Lakatos, M. (2010): Quality control procedures in MISH-MASH systems, European Conference on Applied Climatology (ECAC), 13-17 September 2010, Zürich, Switzerland Rothfusz, L. P. (1990): The heat index equation (or, more than you ever wanted to know about heat index). NWS South. Reg. Techn. Attachm., SR/SSD 90-23, Fort Worth, TX.

Acknowledgement: The authors thank to the Join Research Centre of the EC for supporting the project “CLIMATE OF THE CARPATHIAN REGION”.

MethodsCombined temperature - humidity ap proach was used to analyse the defined impacts of heath waves. The first method was originated on thermal influence only - the number of days with mean temperature more than 20°C and number of summer and tropical days were taken into account like a thermal stress indices. The second method was based on the muggy day definition. The muggy day was considered in the case, when meteorological condition for muggy feeling was reached. The occurrence of water vapour pressure 18.8 hPa and more at any observ ing term during the day was taken into the consideration. The third method used the heat index (HWI) criteria (Rothfusz, 1990). The heat index is a combination of ambient temperature (T) and relative humidity (U) that approximates the environmental aspect of the thermal regime of a human body. The day with HWI ≥ 80 °F was taken into account for this analyse.

ResultsTwo stations with reliable meteorological data were used to show different temperature conditions in southern and northern part of Slovakia. Hurbanovo station (115 m a.s.l.) represents the warmest region of Slovakia in lowland position. The Poprad station (694 m a.s.l.) in the northern part of the country lies in the basin position of moderately cool region at the foot of the High Tatras mountains. Presented results show significant increase in number of summer days, tropical days and days with high daily means (more than 20 °C) in changed climate (Fig. 1 and 2). Only thermal approach is not sufficient for the heat stress assessment. The analyse of muggy days and days with HWI≥ 80 °F showed significant increase of the number of both heat stress indices. The example of both heat stress indices courses is showed for Hurbanovo station (lowland condition) (Fig. 3). Spatial analyse of heat stress indices showed highest mean number of muggy and HWI≥ 80 °F days in lowland conditions especially in the eastern part of Slovakia (Fig. 4 and 5). The occurrence of heat stress is rare in position more than 700 m a.s.l. in our region.

Fig.1: Annual number of summer (SU), tropical (TR) and warm (>20°C) days in Hurbanovo

Fig.2: Annual number of summer (SU), tropical (TR) and warm (>20°C) days in Poprad

Fig.3: Number (N) of muggy days (D) and days with HWI-80 indices (left) and mean T in WHY (right)

Fig.4: Mean annual number of muggy days (with water vapor pressure 18.8 hPa and more) for 1961 – 2010 period

Fig.5: Mean annual number of days with heath wave index HWI ≥ 80 °F for 1961 – 2010 period