Climate Conditions in the Biosphere Reserve Srebarna Region

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Climate Conditions in the Biosphere Reserve
Srebarna Region

• Julia Ivancheva, Anna Tzenkova, Ekaterina Koleva,
  Luchian Krastev
• National Institute of Meteorology Hydrology
• Sofia, BULGARIA

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General climate conditions
Winter tlt5 oC 110 120 days 26 November 12
March mean January t oC 1.5 oC to 2.5 oC
minimum t from 20 to 25 oC microclimate
variability 5 6 oC precipitation total is
105 mm. The snow cover onset is 13 November up to
the mid-December 48 days.
Spring 5 oC lttlt15 oC 12 March up to 2 May
Spring frosts are mostly in the end of March and
in the beginning of April 1 2 days with t lt 5
oC, in 4 5 days of the month the tmin is under
2 oC Precipitation total of the astronomic
spring is about 122 128 mm, but for the
biological only about 70 mm.
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Summer t gt 15 oC,about 2 May up to 2 October
Mean July temperature is 23 oC with maximum up to
39 40 oC 80 85 of the days (June August
) t max gt 25 oC, 40 45 - with t max gt 30 oC.
The precipitation total is 159 mm. All in summer
and autumn there are 4 5 rainless periods with
average lasting about 16 20 days
Autumn 5 oC lt t lt 15 oC form about 2 October up
to 26 November Precipitation total of climatic
autumn is 113 mm and of the biological 66 mm t
lt 10 oC about 15 20 November The first autumn
frosts set in still in the end of October or in
the beginning of November
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The yearly course of De Marton drought index
The annual value of I is about 22, which
determine the region as moderate dry by the
classification of Kirov and Kjuchukova (1955).
The values of I less then 20 determine the
climate in a given region as semi arid. Such
values are observed from during the four months -
July October for the period 1961-1990 and
during May-August for the second period.1991-2004
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The long-term variability of Peds index
For assessment of the aridity of the examined
region Peds index is used. The values of Peds
index have an increasing tendency. In the end of
the last century the years 1992, 1994, 2000 are
extremely dry. The same refer for 2001. For these
years Peds index is above 2.
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Summer
Winter
Long term variability of air temperature
Annual
It can be seen that the increasing trend of
temperature during the considered period is well
expressed.
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Summer
Winter
In precipitation a slightly decreasing tendency
is observed, but it is not significant.The last
years in the region were warmer than the normal
for the period of so-called current climate
(1961-1990). Annual precipitation was about the
normal. During the last decade 1992, 1993, 1994,
1999 and 2002 winters were especially dry. Winter
air temperature in this period was about 1.5o
higher than the current climatic. Summer
precipitation during the period 1991-2004 was
about 88 of the normal and air temperature was
with 1.2o above the normal
Long term variability of precipitation
Annual
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Conclusions
The detected climate change tendencies may not be
negative, but they may influence the reserve
biota.   For example the decrease of the water
area and its depth has as a consequence changes
in the thermal regime of these water area. This
leads to increasing of the temperature in the
warm half-year, which will have as consequence
increasing of the evaporation and in the cold -
it is a cause for a lower temperature, which in
some more shallow area can lead to lake freezing.
 
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This problem can be resolved by carrying out of
measures for cleaning up the lake bad as well as
the vegetation of the koch if this is not
harmful for the birds colonies.  The reserve is
situated in the sphere of influence of industrial
zones of Silistra, Calarash and even Ruse so the
monitoring should not include only the basic
meteorological elements but also of atmospheric
pollution
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SOME REAL AIMS CAN BE OUTLINED

• Carrying out of research expedition during
  representative periods (central for the seasons
  months, vegetation periods or another piece of
  time, important for animal and plant species
• Evaluation of the air quality during the field
  investigations
•  Model simulation of the air pollution and
  deposition of pollutants emitted from the
  industrial objects in Silistra, Rruse and
  Kalarash