The First IBCS Meeting, 1-5 July 2013, Geneva
OPERATIONAL CLIMATE SERVICES:A DIALOGUE ON PRACTICAL ACTION

Climate Change Projection over Iran using the PRECIS Regional Modeling SystemIman Babaeian, Maryam karimian, Rahele Modirian
ibabaeian@yahoo.com
Climatological Research Institute /I. R. of Iran National Centre for Climatology (http://www.cri.ac.ir)
Mashad, I.R. of Iran, P.O. Box: 91735-676, Tel: 0511-3822203, Fax: 0511-3822311

Abstract
Monthly precipitation of Iran has been modeled using PRECIS model driven byHadAM3P boundary conditions data with A2 and B2. Model run in 0.44 × 0.44 degree inlatitude and longitude (approximately 50 km × 50 km) horizontal resolutions. We found that
overall precipitation error of modeling is 5.3%. Monthly maximum precipitation errors occurredin September as the transition month from summer to autumn. Minimum monthly precipitation
has happened in May. As a main result, PRECIS can model well the total precipitation of Iran,but its skill in modeling regional precipitation, especially over the regions with high amount ofconvective and local precipitation, is relatively low. Mean annual precipitation over Southeast ofCaspian Sea, South Zagros mountain chain, Northwest and Southeast provinces will be decreased
by 0.1-0.2mm/day both in A2 and B2 scenarios during 2071-2100. Average temperature of Iranwill increase by 5-6 oC relative to the base period of 1961-1990 in A2 scenario. Mean futuretemperature of Iran in B2 scenario is 1.5-2oC less than A2 scenario. Results from A2 and B2scenarios indicate an 85% increase in annual runoff by the end of 21st century in central andwestern part of Caspian Sea and south Zagross mountain chains, but in the other regions of thecountries the runoff rate change is negligible.

The formula use for computing percentage error of the modeled precipitation is as bellow:

Where RE(%) is relative percentage error of modeling, Pmod is amount of modeled precipitation
and Pobs is observed precipitation (Wang, et. al; 2010).
Modeling bias of meteorological variables is computed using bellow formula.

Results
Results showed that, Minimum errors are occurred during rainy season starting fromOctober to May while maximum errors are seen in summer when there are convective and local
rainfalls because of surface instability due to high temperature gradient in the surface and nearsurface layers. Two important regions of convective and local rainfalls are in the northern(Caspian Sea or Khazari region) and southeastern region (Baluchi and Hormozi region) of Iran(Fig. 2).
250

Simple relative error
Weighted relative error

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Kordi
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esan
tKi
hora
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KhorasC
anen
tralNorthKh
uziHormoziAzari
BaluchiKhaz
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th0entralsThe climate of Iran has experienced a gradual warming of approximately 0.5oC from 1961
(Rahimzadeh and Asgari, 2004). Frequency of extreme precipitation events also is investigated toincrease over majority of Iran due to greenhouse gases (Asgari et al, 2007). In the recent years,
Iran has experienced many extreme weather and climatic events such as heavy flooded weather
systems and tropical cyclones. Southeastern and Southern coasts of Iran have experienced twounusual and major tropical cyclones of Gonu and Phet in June 2007 and 2010.
The Intergovernmental Panel on Climate Change (IPCC) confirmed that there are strong
evidences that most of warming observed over last 50 years is attributed to human activities(IPCC, 2007). Many studies have confirmed that global mean temperature is projected toincrease by 1.4 to 5.8oC during 21st century (Kwon et al. 2005). PRECIS (Providing REgional
Climate for Impact Studies) model was used to obtain fine resolution climate change responses
for the South Asia region in 2080s under A2 scenario. The simulated spatial patterns show anincrease of precipitation over the monsoon belt and over some central parts of India. The rise oftemperature in Pakistan varies from 6°C in summer and 4 to 5°C in winter (Khan and Chaudhry,2007). A regional climate model can be used to resolve detailed climatic and geographicalcharacteristics of the surface (Babaeian et al, 2009). In this regard, PRECIS regional climate
modeling system is issued to simulate detailed climate change projection over Iran. In this paper,skill of PRECIS model in simulation of precipitation and temperature of Iran as well as futureclimate of Iran during 2071-2100 under SRES A2 and B2 scenarios has been studied. Thefindings of this research can be used for long term planning climate change mitigation andadaptation in the field of agriculture and water resource management which is in line with GFCS
goals.

150

CIntroduction

Relative error (%)

200

Figure 2. Simple and weighted regional errors in different precipitation regimes of Iran in thebase period of 1961-1990.

In 2071-2100 the maximum increasing in annual precipitation will be occurred in Southcentral and maximum decreasing will be occurred in Caspian Sea (Khazari) region (Fig.1). InA2 scenario, maximum annual temperature increase has been occurred in East and central partof Iran by more than 7oC. South of Eastern Alborz Mountain, Southwest and Southeast of Iranwill experience the minimum annual rising temperature less than 5oC. Annual pattern oftemperature change in B2 run is almost same to A2 scenarios. maximum runoff change has beenoccurred in mountainous area of Alborz in the north and Zagross in the west. Also in the HezarMasjed Mountain in the northeastern part of Iran, the runoff is increased as well. On the otherremaining parts of Iran there is no significant change in runoff comparing to the base period of
1961-1990. A2 scenario shows greater amount of runoff relative to B2.

Data and Methodology
Area of study is Iran, which consist from two mountain chain of Alborz in the North,Zagros in the West, Caspian Sea in the North, Persian Gulf and Oman Sea in the South and two
great deserts of Lut and Kevir in the Central-east. Simulations has been done for two period of
1961-1990 and 2071-2100. Two kinds of data are used in this research: 1-observed precipitationof 12 precipitation regimes of Iran (Fig.1) and 2-HadAM3p boundary condition data to feed thePRECIS model.
Figure 3. Annual amount of precipitation change in 2071-2100 comparing to the base period of
1961-1990 in A2 scenario (left) and B2 scenario (right).

SummaryResults show that PRECIS capability in modeling regional precipitation is relatively low,
especially over convective precipitation regions which are located in south and southwest of Iran,but its overall capability is highly accepted, with percentage error of 5.3%. Maximum annualtemperature increase in A2 scenario has mainly occurred in east and central part of Iran.
Southwest, Persian Gulf, Oman sea beaches and north central part of Iran will experience theminimum annual rising temperature of 0.5-3oC. Mean temperature increase in B2 scenario is 1.52oC less than A2 scenario. Because of rising in mean temperature of Iran, amount of runoff will
be increased considerably during 2071-2100. Maximum runoff increase of 15.8mm and 14.3mm
is modeled over mountainous area of Alborz in the north using A2 and B2 scenarios, alternatively.

Acknowledgement
We thank to Hadley Center of UK Met. Office for providing PRECIS code and boundary
condition data.

References

Figure 1. Precipitation regime of Iran. 1: Central South, 2: Farsi, 3: Kordi, 4: Sistani, 5: West
Khorasan, 6: East Khorasan, 7: Central North, 8: Khuzi, 9: Hormozi, 10: Azari, 11: Baluchi and
12: Khazari (Masoudian, 2008).

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