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
Graphs 1.2 Annual frequency of heat waves in the period 1961–2012
Annual frequency of heat waves Annual frequency of heat waves MS Skopje MS Stip
9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Annual frequency of heat waves Annual frequency of heat waves MS Stip MS Stip
9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1
0 0
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Annual frequency of heat waves Annual frequency of heat waves MS Stip MS Gevgelija
9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1
0 0
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
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 temperaturethefrom 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 the in 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 the in temperature from Departures Heat waves did not occur with regular frequency during the year by months. March stands out as the month with the greatest number of cases of heat waves at all stations. The frequency of heat waves ranges from 13 cases (in Ohrid) to 22 cases (in Skopje and Strumica). It can be concluded that the least frequency of heat waves at the greatest number of stations is recorded in April (Graphs 1.4).
8
Graphs 1.4 Frequency of heat waves by month in the period 1961–2012
Frequency of heat waves Frequency of heat waves ( period 1961-2012) ( period 1961-2012) MS Skopje MS Stip
25 22 25 20 20 18
15 15 12 9 10 10 10 10 10 6 5 7 7 9 7 8 9 5 5 4 7 3 5 8 4 7 0 4 0 1 I II I II III IV III IV V VI V VI VII VIII VII VIII IX X IX X XI XII XI XII
Frequency of heat waves Frequency of heat waves ( period 1961-2012) ( period 1961-2012) MS Strumica MS Bitola
25 25 22 21 20 20 15 15 15 11 8 10 10 10 8 12 5 6 4 7 5 6 5 8 8 3 5 4 5 4 0 2 4 0 3 2 I II I II III IV III IV V VI V VI VII VIII VII VIII IX X IX X XI XII XI XII
Frequency of heat waves Frequency of heat waves ( period 1961-2012) ( period 1961-2012) MS Gevgelija MS DEmir Kapija
25 25 21 20 20 20 15 15 12 10 10 11 10 10 10 7 10 10 5 10 7 5 5 4 7 5 8 7 9 2 5 0 0 3 3 I II I II 1 III IV III IV V VI V VI VII VIII VII VIII IX X IX X XI XII XI XII
Referring to the pattern of heat waves in the warm and cold part of the year, analysis shows (Graphs 1.5) that the percentage of recorded heat waves cases at almost all stations is greater in the cold part of the year (November–April) than in the warm part of the year (May- October).
9
Graphs 1.5 Frequency of heat waves in the warm and cold parts of the year In the period 1961–2012
Frequency of heat waves Frequency of heat waves (period 1961-2012) (period 1961-2012) MS Skopje MS Stip
May- May- October November- October November 48% April 49% -April 52% 51%
Frequency of heat waves Frequency of heat waves (period 1961-2012) (period 1961-2012) MS Bitola MS Strumica
May- May- October October 37% 39% November- November April -April 63% 61%
Frequency of heat waves Frequency of heat waves (period 1961-2012) (period 1961-2012) MS Demir Kapija MS Gevgelija
May- October November- May- November- 50% April October April 50% 52% 48%
The maximum durations of heat waves have been determined on the basis of analysis of the Heat Wave Duration Index (HWDI). Data for each station for warm parts of the year (May– October) and cold parts of the year (November–April) are given in Tables 1.1 (in Annex).
Of all recorded cases of heat waves, the most characteristic ones occurred in the warm part of the year in May 2003, July 2007, July and October 2012.
10
One of the heat waves of longest duration to have occurred, especially in the warm part of the year, was the heat wave distributed over the whole territory of the Republic of Macedonia in the period from 29 April 2003 to 15 May 2003. The maximum duration of heat waved ranged from 10 days in Stip to 17 days in Bitola, Strumica and Ohrid.
Although of shorter duration (from 8 to 15 days), the heat wave in the period from 16 to 25 July 2007 is also notable. In that period the highest values of maximum air temperature were recorded at most stations in the Republic of Macedonia. On 24 July 2007, an absolute maximum air temperature of 45.7°С was measured at the meteorological station of Demir Kapija, which is in general the highest measured air temperature recorded to date on the whole territory of the Republic of Macedonia (Table 1.6).
Table 1.2 Heat wave occurrences in the period from 29 April 2003 to 15 May 2003
Duration Met.station (days) First -last day Berovo 16 29.04.2003-14.05.2003 Bitola 17 29.04.2003-15.05.2003 Demir Kapija 16 29.04.2003-14.05.2003 Gevgelija 16 30.04.2003-15.05.2003 Kriva Palanka 16 29.04.2003-14.05.2003 Lazaropole 16 29.04.2003-14.05.2003 Ohrid 17 29.04.2003-15.05.2003 Skopje 16 29.04.2003-14.05.2003 Prilep 16 29.04.2003-14.05.2003 Stip 10 05.05.2003-14.05.2003 Strumica 17 29.04.2003-15.05.2003 Table 1.3 Heat wave occurrences in the period from 16 July 2007 to 25 July 2007
Duration Met.station (days) First -last day Berovo 10 16.07.2007-25.07.2007 Bitola 8 18.07.2007-25.07.2007 Demir Kapija 10 16.07.2007-25.07.2007 Gevgelija 9 17.07.2007-25.07.2007 Kriva Palanka 15 16.07.2007-30.07.2007 Lazaropole 10 16.07.2007-25.07.2007 Ohrid 8 18.07.2007-25.07.2007 Skopje 8 17.07.2007-24.07.2007 Prilep 9 17.07.2007-25.07.2007 Stip 8 17.07.2007-24.07.2007 Strumica 8 18.07.2007-25.07.2007
11
Tables 1.4 and 1.5 show the duration of two heat waves in the period from 30 June 2012 to 12 July 2012 and in the period from 24 September to 7 October 2012. The year 2012 was one of the most characteristic years in terms of the frequency and pattern of heat waves, mainly in the warmer part of the year.
Table 1.4 Heat wave occurrences in the period from 30 June 2012 to 12 July 2012
Duration Met.station (days) First -last day Bitola 8 05.07.2012-12.07.2012 Demir Kapija 11 05.07.2012-15.07.2012 Gevgelija 11 05.07.2012-15.07.2012 Kriva Palanka 16 30.06.2012-15.07.2012 Lazaropole 11 05.07.2012-15.07.2012 Ohrid 8 05.07.2012-12.07.2012 Skopje 9 04.07.2012-12.07.2012 Prilep 8 05.07.2012-12.07.2012 Stip 9 04.07.2012-12.07.2012 Strumica 8 05.07.2012-12.07.2012 Table 1.5 Heat wave occurrences in the period from 24 September 2007 to 7 October 2012
Duration Met.station (days) First -last day Berovo 8 25.09.2012-02.10.2012 Bitola 8 26.09.2012-03.10.2012 Demir Kapija 13 25.09.2012-07.10.2012 Gevgelija 13 25.09.2012-07.10.2012 Kriva Palanka 14 24.09.2012-07.10.2012 Lazaropole 7 27.09.2012-03.10.2012 Skopje 9 24.09.2012-02.10.2012 Prilep 9 24.09.2012-02.10.2012 Stip 9 24.09.2012-02.10.2012 Strumica 11 25.09.2012-05.10.2012
One characteristic of heat waves is a number of days with a maximum air temperature of Тx >25 °C (summer days), as shown in Figure 1.1, which was developed with GIS-technology for the period 1971–2000. It can be seen that the greatest number of summer days occurred in the lower region of the River Vardar and the region of Gevgelija-Valandovo.
12
Figure 1.1 Average annual number of summer days (days with a maximum air temperature of Тx >25 °C) in the period 1971–2000
Graphs 1.6 and 1.7 show the number of summer days by years recorded at the five main meteorological stations of Skopje, Stip, Bitola, Strumica, Demir Kapija and Gevgelija for the period 1961 to 2012, illustrating the changes in the number of summer days and tropical nights per year in this period. The Annex also gives graphs from other measuring stations in this period in the Republic of Macedonia.
Graphs 1.6 and 1.7 show that the number of summer days and tropical nights has significantly increased in recent years as compared to the number at the beginning of the analysed period.
Graphs 1.6 Summer days (days with a maximum air temperature of Тx >25 °C) in the period 1961–2012
Summer days (days with maximum air Summer days (days with maximum air temperaure Тx >25 °C) temperaure Тx >25 °C) МС Скопје MS Stip
180 180 y = 0,2578x + 112,65 y = 0,3452x + 108,45 160 R² = 0,1118 160 R² = 0,1697 140 140 120 120 100 100 80 80 60 60 40 40 20 20
0 0
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
13
Summer days (days with maximum air Summer days (days with maximum air temperaure Тx >25 °C) temperaure Тx >25 °C) MS Bitola MS Strumica
180 y = 0,4274x + 88,405 160 R² = 0,2321 180 y = 0,2927x + 119,59 160 140 R² = 0,1569 120 140 120 100 100 80 80 60 60 40 40 20 20
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Summer days (days with maximum air Summer days (days with maximum air temperaure Тx >25 °C) temperaure Тx >25 °C) MS Demir Kapija MS Gevgelija
180 180 y = 0,3104x + 122,99 y = 0,4364x + 128,01 160 R² = 0,1733 160 R² = 0,2622 140 140 120 120 100 100 80 80 60 60 40 40 20 20
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Graphs 1.7 Tropical nights (days with a minimum air temperature of Тn >20 °C) in the period 1961–2012
Tropic nights (days with minimum air Tropic nights (days with minimum air temperaure Тn >20 °C) temperaure Тn >20 °C) MS Skopje MS Stip
50 50 45 45 40 y = 0,068x + 0,3122 40 y = 0,1888x + 1,2466 R² = 0,2795 35 R² = 0,1476 35 30 30 25 25 20 20 15 15 10 10 5 5
0 0
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
14
Tropic nights (days with minimum air Tropic nights (days with minimum air temperaure temperaure Тn >20 °C) Тn >20 °C) MS Bitola MS Strumica
50 50 40 y = 0,0067x + 0,129 45 y = 0,0409x + 0,0882 R² = 0,0353 40 R² = 0,1263 35 30 30 25 20 20 15 10 10 5
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Tropic nights (days with minimum air temperaure Tropic nights (days with minimum air Тn >20 °C) temperaure Тn >20 °C) MS Demir Kapija MS Gevgelija
50 50 45 45 y = 0,517x + 1,4344 y = 0,0826x + 5,81 40 40 R² = 0,4554 R² = 0,0692 35 35 30 30 25 25 20 20 15 15 10 10 5 5
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
15
2. COLD WAVES AND COLD WEATHER
Analysis of cold waves and cold weather is made on the basis of the following climate parameters:
The Cold Wave Duration Index (CWDI): (maximum length of cold wave with an interval of at least 6 successive days with Tn < Tnavg - 5°С)
Number of heat wave occurrences
Monthly and annual frequency of cold wave occurrences
Frost days: days with a minimum air temperature of Тn <0 °C
Ice days: days with a maximum air temperature of Тх <0 °C
The analysis is based on statistical processing of daily minimum air temperature values for the period 1961–2012 from the eleven meteorological stations of Skopje, Prilep, Stip, Bitola, Strumica, Demir Kapija, Kriva Palanka, Berovo, Ohrid, Lazaropole and Gevgelija.
A separate table gives the values from all stations for absolute minimum air temperatures in the period 1961–2012, as being characteristic of extreme cold climate conditions on the territory of Republic of Macedonia.
On the basis of statistical processing of daily minimum air temperature values for eleven meteorological stations, it can be concluded that the most frequently occurring cold waves are those of the shortest duration, i.e. of six days. For example, 7 cold waves of six-day duration were recorded in Skopje, 12 in Stip, and 18 in Bitola. Cold waves of longer duration occurred with less frequency in the period analysed.
Cold waves occur much less frequently than heat waves. For example, a total number of 27 cold waves were recorded in Skopje in the period 1961–2012, while 38 were recorded in Stip and 49 in Bitola, compared to a total number of 87 heat waves recorded in the same period in Skopje, 105 heat waves in Stip and 113 in Bitola.
1991 and 1967 are years as characteristic years, with the greatest annual number (4 cases) of cold waves.
As can be noted from Graphs 2.1, the cold waves did not occur with equal frequency in each month; rather, they occurred with highest frequency in the cold part of the year, especially in January and February, and with lowest frequency in the warm part of the year. The highest number of cold wave occurrences (49) for the whole period 1961–2012 was recorded in Bitola, as well as the greatest number of occurrences (14) in January.
16
Graphs 2.1 Frequency of cold waves by months in the period 1961–2012
Frequency of cold waves Frequency of cold waves (period 1961-2012) (period 1961-2012) MS Skopje MS Stip
15 15
9 10 8 8 10 8
8 5 5 8 2 2 2 4 0 4 0 1 1 I II I II III IV III IV V VI V VI VII VIII VII VIII IX X IX X XI XII XI XII
Frequency of cold waves Frequency of cold waves (period 1961-2012) (period 1961-2012) MS Bitola MS Strumica
14 15 15 11 9 10 10 11 6 8 5 5 3 2 6 1 0 0 1 3 2 1 I I II II III IV III IV V VI V VI VII VIII VII VIII IX X IX X XI XII XI XII
Frequency of cold waves Frequency of cold waves (period 1961-2012) (period 1961-2012) MS Demir Kapija MS Gevgelija
15 15
9 10 10 7
8 5 4 5 3 7 3 1 1 5 0 2 0 1 2 I II I II III IV III IV V VI V VI VII VIII VII VIII IX X IX X XI XII XI XII
The maximum durations of cold waves are determined on the basis of CWDI analysis. Data are given in Tables 2.1 (in the Annex) separately for each station.
The frequency of cold waves in the periods from 22 January to 2 February 1963 and 12-27 February 1985 have been presented separately as being the most characteristic of all recorded cases. Cold waves of the longest duration were recorded in these periods throughout the whole territory of the Republic of Macedonia. Cold waves of the longest duration with a maximum length of 22 days are recorded in Skopje (in the period from 17
17
December 2001 to 7 January 2002 and 21 days in Bitola in the period from 4 January 1993 to 24 January 1993.
Table 2.2 Cold wave occurrences in the period 22 January 1963 to 2 February 1963 Duration Met.station (days) First -last day Berovo 11 22.01.1963-01.02.1963 Bitola 11 22.01.1963-01.02.1963 Gevgelija 12 22.01.1963-02.02.1963 Kriva Palanka 11 22.01.1963-01.02.1963 Lazaropole 11 21.01.1963-31.01.1963 Ohrid 11 21.01.1963-31.01.1963 Skopje 11 22.01.1963-01.02.1963 Prilep 11 22.01.1963-01.02.1963 Stip 12 21.01.1963-01.02.1963 Strumica 12 22.01.1963-02.02.1963
Table 2.3 Cold wave occurrences in the period 12 February 1985 to 27 February 1985
Duration Met.station (days) First -last day Berovo 14 13.02.1985-26.02.1985 Bitola 15 13.02.1985-27.02.1985 Gevgelija 8 17.02.1985-24.02.1985 Kriva Palanka 14 12.02.1985-25.02.1985 Lazaropole 8 19.02.1985-26.02.1985 Ohrid 13 14.02.1985-26.02.1985 Skopje 15 12.02.1985-26.02.1985 Prilep 16 12.02.1985-27.02.1985 Stip 15 12.02.1985-26.02.1985 Strumica 15 12.02.1985-26.02.1985 The spatial arrangement of these extreme climate parameters of air temperatures (average number of frost and iced days) for the territory of the Republic of Macedonia is shown in the following map.
18
Figure 2.1 Average annual number of frost days (days with a minimum air temperature of Тn <0 °C) in the period 1971–2000.
The least average number of frost days on the territory of the Republic of Macedonia occurs along the river Vardar, while there are 20 to 60 frost days on the biggest territory of the republic of Macedonia.
The average number is 80 to 125 days on the highest mountain regions.
19
Graphs 2.2 Frost days (days with minimum air temperature Тn <0 °C (period 1961-2012)
Frost days (days with minimum air temperature Frost days (days with minimum air temperature Тn <0 °C) Тn <0 °C) MS Skopje MS Stip 160 160 y = 0,1227x + 81,229 140 R² = 0,0222 140 y = -0,1696x + 76,919 R² = 0,0407 120 120
100 100
80 80
60 60
40 40
20 20
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Frost days (days with minimum air temperature Frost days (days with minimum air temperature Тn <0 °C) Тn <0 °C) MS Bitola MS Strumica
160 160 y = -0,0092x + 88,475 y = 0,0256x + 76,649 140 140 R² = 0,0001 R² = 0,0008 120 120
100 100
80 80
60 60
40 40
20 20
0 0
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Frost days (days with minimum air temperature Frost days (days with minimum air temperature Тn <0 °C) Тn <0 °C) MS Demir Kapija MS Gevgelija
160 160 y = -0,2929x + 55,262 140 y = 0,1492x + 62,545 140 R² = 0,041 R² = 0,1405 120 120
100 100
80 80
60 60
40 40
20 20
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
20
Figure 2.2 Average annual number of cold days – (days with minimum air temperature Тx <0 °C (period 1971-2000)
The average number of cold days on the territory of the republic of Macedonia varies from 5 to 60 days, depending on height above sea level.
21
Graphs 2.3 Ice days – days with a maximum air temperature of Тх <0 °C in the period 1961– 2012
Ice days (days with maximum air temperature Ice days (days with maximum air temperature Тх <0 °C) Тх <0 °C) MS Skopje MS Stip
45 45 y = 0,0108x + 9,4842 y = -0,0787x + 11,624 40 R² = 0,001 40 R² = 0,0503 35 35 30 30 25 25 20 20 15 15 10 10 5 5
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Ice days (days with maximum air temperature Ice days (days with maximum air temperature Тх <0 °C) Тх <0 °C) MS Bitola MS Strumica
45 45 y = -0,0241x + 17,12 y = -0,0227x + 6,0045 40 40 R² = 0,0022 R² = 0,0056 35 35
30 30
25 25
20 20
15 15
10 10
5 5
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
Ice days (days with maximum air temperature Ice days (days with maximum air temperature Тх Тх <0 °C) <0 °C) MS Demir Kapija MS Gevgelija
45 45 40 y = -0,0356x + 2,5 y = -0,0605x + 8,8348 R² = 0,0509 40 R² = 0,0367 35 35 30 30 25 25 20 20
15 15
10 10
5 5
0 0
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 1961
22
As can be noted from the graphs above, there is general trend of decline in the number of ice days per year while there is no general change in the number of annual frost days.
Absolute minimum air temperatures
Table 2.2. shows the lowest air temperature values by months for the period 1961–2012 from 11 measuring sites on the territory of the Republic of Macedonia. The lowest air temperature was recorded on 7 January 1993, when the lowest air temperatures were recorded as follows: in Bitola -30.40C, in Demir Kapija -23.20C, in Berovo -27.4°С and in Strumica -27.30C.
Analysed by month, the lowest air temperature on the whole territory of the Republic of Macedonia was recorded on 6 February 2006, with extreme low air temperatures ranging from -19.20C in Stip, -25.40C in Berovo to -28.10C in Bitola.
Extreme low air temperatures were recorded In April 2003 on the greater part of the territory of the Republic of Macedonia, ranging from -11.50C in Prilep and -18.00C in Berovo, to -19.40C in Bitola (measured on 8 April 2003).
The period from 19 to 22 December 2001 saw negative air temperatures throughout the greater part of the territory of the Republic of Macedonia, with air temperatures ranging from -10.60C in Gevgelija, -22.0 0C in Stip, -24.60C in Berovo to -25.50C in Strumica.
23