Long-term Variability of Precipitation in Republic of Macedonia NIKOLA SLAVOV, TANIA MARINOVA, PECE RISTEVSKI*

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Long-term Variability of Precipitation in
Republic of MacedoniaNIKOLA SLAVOV, TANIA
MARINOVA, PECE RISTEVSKI
BULGARIAN ACADEMY OF SCIENCES National Institute
of Meteorology and Hydrology
1. Introduction2. Material and investigation
methods3. Analysis of the results4. Conclusions
Hydrometeorological Service Skopje, FY
Republic of Macedonia
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Material and investigation methods
The rainfall regime in Republic of Macedonia is
investigated on the basis of monthly sums of
precipitation in 5 meteorological stations with
the longest period of observations during the
last century Skopje (1925 2000), Bitola
(19252000), Prilep (19242000), Stip
(19262000), Demir Kapija (19332000).

• Mean monthly precipitation sums are used to
  evaluate the anomalies of rainfall conditions
  during the different parts of the year as
  follows
• Mean seasonal precipitation
• Winter XII, I, II
• Spring III, IV, V
• Summer VI, VII, VIII
• Autumn IX, X, XI
• Mean half-year precipitation
• Cold half-year ?, ??, ???, ?, ??, ???
• Warm half-year ?V, V, V?, V??, V???, ??
• Mean annual precipitation
• I XII

Fig.1. Locations of the meteorological stations
within the limits of agricultural production
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• In order to assess the tendencies of change in
  annual precipitation and in precipitation during
  the different parts of the year for the last
  century, the corresponding linear trends are
  obtained.
• The analysis of periodicities and their duration
  is completed on the basis of 5-years running
  average.
• Variability of rainfall regime in the last
  century is evaluated by means of the deviations
  from the mean long-term precipitation amounts
  during the different periods of the century.

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Fig.2. Mean annual precipitation variations
in Macedonia
The mean long-term annual precipitation sum is
539.5 mm The maximum negative deviation from the
mean long-term annual precipitation sum is
214.9 mm in the year 2000s during the driest
period at the end of the last century.
Rainfall periods Maximum annual R 1933
1942 1937 (787.4 mm) 1954 1964
1962 (721.8 mm) 1972 1983
1981 (725.5 mm)
Dry periods Minimum annual R 1924
1932 1932 (358.1 mm) 1943 1953
1953 (409.2 mm) 1965 1971 1965
(414.2 mm) 1984 2000 2000 (324.6 mm)
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Fig.4. Mean precipitation variations in winter in
Macedonia
The mean long-term precipitation in winter
is 138.1 mm. The maximum negative deviation of
winter precipitation amounts is 103.2 mm in
1948s.
The winter period of 1934s is characterized with
the highest precipitation amount of 317.9 mm.
The driest winter period is in 1948s with 34.9
mm.
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Fig.6. Mean precipitation variations in spring in
Macedonia
The mean long-term precipitation in spring
is 142.2 mm. The maximum positive deviation of
spring precipitation amount is 95.3 mm (1958)
and the maximum negative deviation is 98.7 mm
(1945)
The wettest spring is in 1958s (237.5 mm) and the
driest one in 1945s (43.5 mm).
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Fig.8. Mean precipitation variations in summer in
Macedonia
The mean long-term precipitation in summer
is 106.8 mm. The maximum positive deviation of
summer precipitation is 146.8 mm (1983) and the
maximum negative one is 79.1 mm (1978).
The wettest summer is in 1983s (254.5 mm) the
driest summer in 1978s (27.7 mm).
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Fig.10. Mean precipitation variations in autumn
in Macedonia
The mean long-term precipitation in autumn
is 152.4 mm. The maximum positive deviation of
autumn precipitation is 121.7 mm (1962) and the
maximum negative one is 130.3 mm(1969)
The wettest autumn is in 1962s (274.1 mm) and the
driest one in 1969s (22.1 mm).
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Fig.12. Mean precipitation variations in the cold
half-year in Macedonia
The mean long-term precipitation in the cold
half-year is 295.9 mm The maximum positive
deviation of cold half-year precipitation is
259.5 mm (1961) and the maximum negative one is
150.5 mm (1976).
The wettest cold half-year is in 1961s with 555.4
mm and the driest one in 1976s with 145.4 mm.
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Fig.14. Mean precipitation variations in the warm
half-year in Macedonia
The mean long-term precipitation in the warm
half-year is 243.7 mm. The maximum positive
deviation is 170.0 mm (1983) and the maximum
negative one is 134.7 mm (1993).
The wettest warm half-year is in 1983s (413.7 mm)
and the driest one in 1993s (109.0 mm).
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Conclusions

• The results obtained in the present study on the
  long-term variations in precipitation during the
  period 19242000 in Republic of Macedonia can be
  summarized as follows
• 1. It is found out that the trend in annual
  precipitation variations is towards drought.
• 2. Similar tendency is peculiar to both cold
  and warm half-year precipitation amounts
  especially after the year 1983s of the last
  century.
• 3. The regions where the annual precipitation
  decreases more and more often below 300 mm are
  most vulnerable as degradation processes of plant
  ecosystems begin.