THIRD NATIONAL COMMUNICATION TO THE UNFCCC ANALYSIS OF EXTREME TEMPERATURES HEAT AND COLD WAVES H YDROMETEOROLOGICAL S ERVICE Introduction The negative effects of climate changes are a major topic of concern for all international organizations within the United Nations system. Climate changes brought about by anthropogenic influences, above all by the combustion of fossil fuels, cause dangerous alterations in the structure of the atmosphere. Since the pre-industrial period, increased emissions of greenhouse gases have caused a rise in global mean air temperature from 0.3°C to 0.6°C (IPCC, 2001). Increases in air temperature cause ice to melt in polar areas, resulting in a rise in sea levels. On land, increased surface air temperature causes changes in the precipitation regime and increased aridity. Global climate changes lead to extreme climate events, including prolonged periods of high temperatures and droughts, followed by high air temperatures, intensive short periods of precipitation and the appearance of cold waves and negative temperatures, snowfall and precipitation periods. Extreme climate events have negative effects on the health of humans and animals, on agriculture and water resources, and an imbalance in heat and energy. It is of the utmost importance, therefore, to record and investigate extreme climate events. The following text and the Annex thus present an analysis of extreme air temperature conditions recorded in the territory of the Republic of Macedonia, including the occurrence of heat waves and cold waves, tropical and summer days, frost and ice days. Daily maximum and minimum air temperatures are given based on statistics from 11 main meteorological stations in the period 1961–2012. 2 1. HEAT WAVES AND WARM WEATHER Analysis of heat waves and warm weather in the period 1961–2012 is given for the 11 meteorological stations of Skopje, Bitola, Prilep, Stip, Demir Kapija, Gevgelija, Strumica, Kriva Palanka, Berovo, Ohrid and Lazaropole. This analysis is based on the following climate parameters: The Heat Wave Duration Index (HWDI): maximum duration of heat waves, interval of at least 6 successive days with Tx>Txavg+ 5°С. The number of heat waves. The monthly and annual frequency of heat waves. The frequency of heat wave occurrences in the warm and cold parts of the year. Summer days: days with a maximum air temperature of Тx >25 °C Tropical nights: days with minimum air temperature of Тn >20 °C These analyses has been made for the sites of Skopje, Stip and Bitola as the most representative stations for the main climate regions, and for the sites of Strumica, Demir Kapija and Gevgelija as representative stations for the southeast region, the region most vulnerable to climate changes. Absolute maximum air temperature values for the period 1961–1990 are given in a separate table for all stations, thus representing the extreme heat climate conditions in the territory of the Republic of Macedonia. In accordance with the recommendations of the World Meteorological Organization (WMO) Working Group for Climate Change Detection and Indices (CCI/CLIVAR), the Heat Wave Duration Index (HWDI) has been used for the analysis of heat waves. This index determines a heat wave as a period of at least 6 successive days with a maximum air temperature (Tx) of 5°С higher than the average maximum temperature (Txavg) for the period 1961–1990. On the basis of maximum daily air temperature values, it can be concluded that the frequency of heat waves decreases in correlation to the length of their duration, with the most frequently occurring heatwaves being those of the shortest duration—i.e., no more than 6 days in succession. Graph 1.1 shows the number of heatwaves with determined duration for the meteorological stations of Skopje, Stip, Bitola, Strumica, Demir Kapija and Gevgelija. For the period 1961–2012, the following number of heat waves of 6-day duration were recorded in the respective cities: 22 in Strumica, 25 in Skopje, 28 in Gevgelija, 34 in Bitola, 36 in Stip and 38 in Demir Kapija. Single occurrences of heatwaves of longer duration were recorded in the following cities in this period: 16 days in Skopje, 17 days in Demir Kapija, 18 days in Stip, 19 days in Bitola, 20 days in Strumica and 22 days in Gevgelija. 3 Graphs 1.1 Number of heat wave occurrences in the period 1961–2012 in Skopje, Stip, Bitola, Strumica, Demir Kapija and Gevgelija 4 Analysing the annual frequency of heat waves, it can be remarked that the total number of recorded waves were not evenly distributed throughout the years. As can be seen in Graphs 1.2, the annual frequency of heat waves increases in the second half of the analyzed period, that is, the frequency of occurrences increases from 1987 onwards. And in contrast to the first half of the period, a heat wave is recorded almost every year from 1987. It can also be noted that the greatest frequency of heat waves occurred in the last ten years, with maximum occurrences at the greatest number of stations in 2012 and 2007. During 2012, 10 heat waves were recorded in Kriva Palanka, 8 in Skopje, Stip, Lazaropole and Demir Kapija, 7 in Gevgelija and Berovo, 6 in Bitola, 5 in Strumica and Prilep and 3 in Ohrid. 5 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 1961 1961 1961 1964 1964 1964 Graphs 1.2 Annual frequency of heat waves in the the 1961 period of Graphsfrequency heat 1.2Annual in waves Annual wavesof heat Annual frequency 1967 1967 1967 wavesof heat Annual frequency Annual wavesof heat Annual frequency 1970 1970 1970 1973 1973 1973 1976 1976 1976 1979 1979 1979 MS Skopje MS MS Stip 1982 1982 MS Stip 1982 1985 1985 1985 1988 1988 1988 1991 1991 1991 1994 1994 1994 1997 1997 1997 2000 2000 2000 2003 2003 2003 2006 2006 2006 2009 2009 2009 2012 2012 2012 0 1 2 3 4 5 6 7 8 9 8 9 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 8 9 1961 1961 1961 1964 1964 1964 1967 wavesof heat Annual frequency Annual wavesof heat Annual frequency 1967 1967 wavesof heat Annual frequency 1970 1970 1970 1973 1973 1973 1976 MS MS Gevgelija 1976 1976 1979 1979 1979 MS MS Stip 1982 1982 1982 MS Stip 1985 1985 1985 1988 1988 1988 1991 1991 1991 1994 1994 1994 – 1997 1997 1997 2012 2000 2000 2000 2003 2003 2003 2006 2006 2006 2009 2009 2009 2012 2012 2012 6 2012 is a specific year with heat waves with most heat waves in the summer period for the analysed period. Graphs 1.3 show the occurrences of heat waves in the measuring sites of Skopje, Stip, Bitola, Strumica, Demir Kapija and Gevgelija. Graphs 1.3 Heat waves in 2012 (Skopje, Stip, Bitola, Strumica, Demir Kapija and Gevgelija) Heat waves Skopje 2012 7,0 март апри мај јун јул авгус септемвр октомври 6,0 5,0 4,0 C ° 3,0 5 average 2,0 1990 - 1,0 Tx>Tavg+ 1961 0,0 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 4 9 14 19 24 29 3 8 13 18 23 28 2 7 12 17 22 27 2 7 12 17 22 27 months ODepartures in maximum temperature from the inmaximum ODepartures Heat waves Stip 2012 7,0 March April May Jun July August September October 6,0 5,0 C 4,0 ° 5 average 3,0 1990 - 2,0 Tx>Tavg+ 1961 1,0 0,0 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 4 9 14 19 24 29 3 8 13 18 23 28 2 7 12 17 22 27 2 7 12 17 22 27 Departures in maximum thefrom inmaximum temperature Departures months Heat waves Stip 2012 7,0 March April May Jun July August September October 6,0 5,0 C 4,0 ° 5 average 3,0 1990 - 2,0 Tx>Tavg+ 1961 1,0 0,0 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 4 9 14 19 24 29 3 8 13 18 23 28 2 7 12 17 22 27 2 7 12 17 22 27 Departures in maximum thefrom inmaximum temperature Departures months 7 Heat waves Strumica 2012 8 March April May June July August September October 7 6 5 C 4 ° 5 average 3 1990 - 2 Tx>Tavg+ 1961 1 0 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 4 9 14 19 24 29 3 8 13 18 23 28 2 7 12 17 22 27 2 7 12 17 22 27 Departures in maximum thefrom inmaximum temperature Departures months Heat waves Demir Kapija 2012 8 March April May Jun July August September October 7 6 5 C 4 ° 5 average 3 1990 - 2 Tx>Tavg+ 1961 1 0 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 4 9 14 19 24 29 3 8 13 18 23 28 2 7 12 17 22 27 2 7 12 17 22 27 Departures in maximum in the temperature from Departures months Heat waves 2012 Gevgelija 8 March April May Jun July August September October 7 6 5 4 C ° 5 average 3 1990 - 2 Tx>Tavg+ 1961 1 0 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 4 9 14 19 24 29 3 8 13 18 23 28 2 7 12 17 22 27 2 7 12 17 22 27 months Departures in maximum in the temperature from Departures Heat waves did not occur with regular frequency during the year by months.