It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the
west, Iran to the south, and Turkmenistan to the southeast. It is 1200 Km long, 200 Km to 480
Km wide and has a surface area of 370000
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2
and is 28 m below sea level. (Cullen, 1999)
The natural resources of the Caspian Sea are of high economic value. There are many
species
of fish, aquatic birds and the Caspian seals in this area, which are sensetive to any changes in
temperature.
CORDEX is a WCRP-sponsored program to organize an international coordinated framework to
produce an improved generation of regional climate change projections world-wide for input
into impact and adaptation studies within the AR5 timeline and beyond. CORDEX
will produce
an ensemble of multiple dynamical and statistical downscaling models considering multiple
forcing GCMs from the CMIP5 archive. (www.meteo.unican.es)
CORDEX focuses on the GCM experiments using emission scenarios known as RCP4.5 and
RCP8.5 which represent a mid and a high-level emission scenario.Ideally CORDEX simulations
will span 1951 to 2100. (Evans, 2011)
In order to evaluate the impact of climate change on the variation of air temperature over the
Caspian Sea, the CORDEX model results for the period of 2080-2100 with 6-hourly temporal
resolution and spatial resolutions of 0.44 degrees longitude and 0.44 degrees latitude in
Central Asia domain were used.
In order to to know about present air temperature
in the mentioned region, local air
temperature was obtained from the European Centre for Medium-Range Weather Forecasts
(ECMWF), with 0.5 degree and 6-hourly spatial and temporal resolutions, respectively, for the
period of 1980 to 2000.
Results
ECMWF and CORDEX air temperature data over the Caspian Sea, during the period of (1980 -
2000) were compared to assess CORDEX data accuracy. As it is shown in figure 1, seasonal
average air temperature of CORDEX data is almost matching ECMWF data, in both northern
and southern part of Caspian Sea.
The ECMWF and CORDEX temperature data over the Caspian Sea during the periods of (1980-
2000) and (2080-2100) were also compared, in order to assess the effect of climate change on
air temperature of this area.The future data have been downloaded for the RCP 4.5 scenario,
which represents a mid-level emission scenario.
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Summer
Autumn
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data(1980-2000)
CORDEX
data(1980-2000)
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Summer
Autumn
Winter
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CORDEX
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ECMWF data
(1980-2000)
CORDEX data
(2080-2100)
(a)
(b)
Figure 1: Seasonal average air temperature comparison in (a) Northern part (b) Sothern part of Caspian Sea
Figure 2 shows the monthly average of ECMWF and CORDEX air temperature
data for the
periods of (1980-2000) and (2080-2100), respectively.
The graphs show the increment of air temperature in future in comparison to the present, in
all months.The lowest increase in air temperature in northern part of the Caspian Sea, will
occur during May-September, with the range of 0.2-1.5°C. In July the minimum change is
observed with the value of 0.2°C .The maximum variation is observed
in February with the
value of 6.4°C.
According to graph b, in southern part of the Caspian Sea in most months of the year except
February, July, September, October and December the
temperature increment is not
noticeable (0.1-0.7°C).The highest variation will occur in February with value of 2.98°C.
(a)
(b)
Figure 2: Monthly average air temperature comparison in (a) Northern part (b) Sothern part of Caspian Sea
68
DIscussion
Air temperature from CORDEX Project, which has downscaled CMIP5 future climate data, are
used to determine the impact of climate change on air temperature over the Caspian Sea,
comparing with ECMWF data for (1980-2000).Sasonal and monthly average air temperature
were compared for the mentioned periods.The comparison of seasonal average air
temperature in period of (1980-2000) for two sets of mentioned data, showed high accordance
between CORDEX data and ECMWF data.
Results showed that air temperature in future, will have an increasing trend over the Caspian
Sea. August has the highest temperature in current and future climate. In addition, the
maximum value of increment in northern and southern part of Caspian Sea will occur in
February with the value of 6.4°C and 2.98 °C; respectively.The minimum
variation in northern
and southern area will be in July and June with the value of 0.2 °C and 0.15°C; respectively.The
air temperature in northern part of the area will increase more then the southern part.
This increase in air temperature in future can affect the air-sea heat exchange and will result in
water temperature changes. It may also affect the wind field, wind wave field, sea level and
dynamics of currents in the Caspian Sea.These side effects can be studied in future researches.
References
[1]
Cullen, R., 1999. The rise and fall of the Caspian Sea.
National Geographic,
195(5)
[2]
Dahm, R.J., Singh, U.K., Lal, M., Marchand, M., Sperna-Weiland, F.C., Singh, S.K. and Singh, M.P.,
2016. Downscaling GCM data for climate change impact assessments on rainfall: a practical application
for the Brahmani-Baitarani river basin.
Hydrol. Earth Syst. Sci. Discuss.
[3]
Evans, J.P., 2011, December. CORDEX–An international climate downscaling initiative. In
19th
International Congress on Modelling and Simulation, Perth, Australia (pp. 12-16)
[4]
Giorgi, F., Jones, C. and Asrar, G.R., 2009. Addressing climate information needs at the regional level:
the CORDEX framework.
World Meteorological Organization (WMO) Bulletin,
58(3), p.175.
[
5] Gunduz, M. and Özsoy, E., 2014. Modelling seasonal circulation and thermohaline structure of the
Caspian Sea. Ocean Science, 10(3), pp.459-471.
[6] Jouni, R., 2017. Future Climate Change in the Baltic Sea Region and Environmental Impacts, Oxford
Research Encyclopedias.
[7] National Research Council, America’s Climate Choices: Panel on Advancing the Science of Climate
Change, 2010.
Adapting to the impacts of climate change.
[8] Ozturk, T., Altinsoy, H., Türkeş, M. and Kurnaz, M.L., 2012. Simulation of temperature and
precipitation climatology for the Central Asia CORDEX domain using RegCM 4.0. Climate Research, 52,
pp.63-76.
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