Oman is vulnerable to the impacts of climate change, the most significant of which are increased temperature, less and more erratic precipitation, see level rise (SLR) and desertification. The objective of this research is to investigate the potential variation of precipitation and temperature in Muscat, the capital city of Sultanate of Oman in future. We used the MIROC general circulation model (GCM) output (maximum and minimum temperatures and precipitation) from the Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0 and 8.5 scenarios of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) for assessing changes in climate in the period of 2080-2099 compared to the baseline period of 1986-2005. The spatial mismatch between GCM grid scale and local scale was resolved by applying the LARS stochastic Weather Generator (WG) model. The results obtained for 4 scenarios indicate a significant warming in future, which ranges from 0.93ᴼC (minimum temperature by 1.1ᴼC and maximum temperature by 0.86ᴼC) for the lowest scenario, RCP 2.6, to 3.1ᴼC (minimum temperature by 3.2ᴼC and maximum temperature by 3.0ᴼC) for the highest one, RCP 8.5, relative to baseline level. The differences in the precipitation projections between the scenarios are much greater compared to consistent warming depicted in temperatures. The results reveal  -36.4% and -36.0% decreases in precipitation for the RCP 2.6 and RCP 4.5 scenarios, respectively, while, RCP 6.0 and RCP 8.5 scenarios predict increase in precipitation in a range from 9.6% to 12.5%, respectively during 2080-2099 compared to 1986-2005 period. These results need to be further improved by adopting more GCMs, which will provide potential changes in a consistent

Ghafri, Abdulaziz Al-

Gunawardhana, Luminda

Rawas, Ghazi Al-

English

Gyandhara International Academic Publication (GIAP): Journals

 International Journal of Students Research in Technology & Management 
 Vol 2 (03), May 2014,  ISSN 2321-2543, pg. 109-112 
http://www.giapjournals.org/ijsrtm.html   109 
An Assessment of Temperature and Precipitation 
Change Projections in Muscat, Oman from Recent 
Global Climate Model Simulations 
Abdulaziz Al-Ghafri
 #1
, Luminda Gunawardhana
 #2
, Ghazi Al-Rawas
 #3
 
# 
Department of Civil and Architectural Engineering, Sultan Qaboos University 
P.O. Box 33, Postal code 123, Al-Khoud, Sultanate of Oman 
1 
u088532@student.squ.edu.om  
2 
luminda@squ.edu.om 
3 
ghazi@squ.edu.om 
 
Abstract— Oman is vulnerable to the impacts of climate 
change, the most significant of which are increased temperature, 
less and more erratic precipitation, see level rise (SLR) and 
desertification. The objective of this research is to investigate the 
potential variation of precipitation and temperature in Muscat, 
the capital city of Sultanate of Oman in future. We used the 
MIROC general circulation model (GCM) output (maximum 
and minimum temperatures and precipitation) from the 
Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0 and 
8.5 scenarios of the Fifth Assessment Report (AR5) of the 
Intergovernmental Panel on Climate Change (IPCC) for 
assessing changes in climate in the period of 2080-2099 compared 
to the baseline period of 1986-2005. The spatial mismatch 
between GCM grid scale and local scale was resolved by applying 
the LARS stochastic Weather Generator (WG) model. The 
results obtained for 4 scenarios indicate a significant warming in 
future, which ranges from 0.93ᴼC (minimum temperature by 
1.1ᴼC and maximum temperature by 0.86ᴼC) for the lowest 
scenario, RCP 2.6, to 3.1ᴼC (minimum temperature by 3.2ᴼC and 
maximum temperature by 3.0ᴼC) for the highest one, RCP 8.5, 
relative to baseline level. The differences in the precipitation 
projections between the scenarios are much greater compared to 
consistent warming depicted in temperatures. The results reveal 
-36.4% and -36.0% decreases in precipitation for the RCP 2.6 
and RCP 4.5 scenarios, respectively, while, RCP 6.0 and RCP 8.5 
scenarios predict increase in precipitation in a range from 9.6% 
to 12.5%, respectively during 2080-2099 compared to 1986-2005 
period. These results need to be further improved by adopting 
more GCMs, which will provide potential changes in a consistent 
range. 
I. INTRODUCTION 
Observed and projected increases in temperature and 
precipitation variability are perhaps the most influential 
climate driven changes to impact water systems (Parry et al., 
2007). Located in an arid region, the climate of Oman is 
vulnerable to the potential impacts of climate change, the most 
significant of which are increased average temperatures, less 
and more erratic precipitation, sea level rise (SLR) and 
desertification. Oman is primarily concerned due to its chronic 
water stress and lack of resilience (institutional, infrastructure 
and social) against climate change. 
Groundwater represents about 78% of the water supply in 
Oman. Owing to a lack of data and the very slow reaction of 
groundwater systems to changing recharge conditions, 
impacts of climate change on groundwater are poorly 
understood. Groundwater resources are related to climate 
change through hydrologic processes, such as precipitation 
and evapotranspiration, and through interaction with surface 
water. With increased evapotranspiration as a result of higher 
air temperature and decreased precipitation, the impact of 
climate change will result in declining groundwater recharge 
(Eckhardt and Ulbrich, 2003; Brouyere et al., 2004) and alter 
the associate temperature distribution in the subsurface. For 
example, in the Ogallala Aquifer region, projected natural 
groundwater recharge decreases more than 20% in all 
simulations with warming of 2.5°C or greater (Rosenberg et 
al., 1999).  
Integrating climate change mitigation and adaptation in 
development strategies and policies is a must for Oman which 
is at the early stage of economic and industrial development. 
Thus far in Oman, the scientific knowledge about the climate 
change and its impacts on the hydro-meteorological extremes 
has not been fully studied thereby making it difficult to assess 
future risks. Therefore, the main objective of this research is 
to investigate the potential variation of precipitation and 
temperature in Muscat, the capital city of Sultanate of Oman 
in future.  
II. STUDY AREA 
Oman located in south-Eastern corner of the Arabian 
Peninsula, encompasses a diverse range of topography, 
including mountain ranges, low land, coastal areas and arid 
deserts. The coastal line of Oman extends over 3165 km and 
experiences very severe tropical cyclones. The supper 
cyclonic storm, hurricane Gonu in 2007 led to the worst 
natural disaster on record in Oman, with total rainfall reached 
610 mm near the cost. The cyclone and flash flood caused 
about $4 billion in damage (2007 USD) and 49 deaths (Rafy 
and Hafez, 2008). The climate of the country is mainly arid or 
semiarid, which receives less than 100 mm in annual rainfall 
on average compared to annual global average of 1123 mm. 
 International Journal of Students Research in Technology & Management 
 Vol 2 (03), May 2014,  ISSN 2321-2543, pg. 109-112 
http://www.giapjournals.org/ijsrtm.html   110 
Muscat, the capital city of Oman is a coastal city (Fig.1), 
which accommodates 29.5% of the total population in Oman 
in 2010. The average precipitation of Muscat is 81 mm over 
the period 1977-2011 and it shows statistically weak 
increasing trend at an average rate of 6 mm/10 yr. The rainfall 
pattern proved to be irregular, averaging rain on only around 7 
days per year. Consequently, number of consecutive days of 
no rainfall is relatively high, which was estimated to be about 
225 days per year over the period 1977-2011. The daily 
maximum temperature in Muscat fluctuates between 17 and 
49C, and the daily minimum temperature is between 10 and 
40C over the period 1986-2011.   
 
 
Fig. 1. Study area in Oman 
 
III. METHODOLOGY 
Observed precipitation and temperature data in the Muscat 
airport meteorological station for the period of 1986-2005 
were obtained. For the future climates, we used the MIROC 
general circulation model (GCM) output (maximum and 
minimum temperatures and precipitation) from the 
Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0 
and 8.5 scenarios in the periods of 1986-2005 and 2080-2099. 
The four RCPs are based on multi-gas emission scenarios. 
They are being used to drive climate model simulations 
planned as part of the World Climate Research Programme’s 
Fifth Coupled Model Intercomparison Project (CMIP5) 
(Taylor et al. 2009). 
The spatial mismatch between GCM grid scale and local 
scale was resolved by applying statistical downscaling method. 
A stochastic weather generator (LARS-WG) used in this study 
serve as a computationally inexpensive tool to produce 
multiple-year climate change scenarios at the daily time scale 
which incorporate changes in both mean climate and in 
climate variability (Semenov & Barrow, 1997). LARS-WG 
can be used for the simulation of weather data at a single site 
under both current and future climate conditions. These data 
are in the form of daily time-series for a suite of climate 
variables, namely, precipitation (mm), maximum and 
minimum temperature (°C) and solar radiation (MJm
-2
day
-1
). 
The simulation of precipitation occurrence is based on 
distributions of the length of continuous sequences, or series, 
of wet and dry days. To developed future scenarios, the mean 
of the empirical distributions for wet and dry spell length from 
the baseline (1986-2005) and future time period (2080-2099) 
were calculated for each month. The relative change in length 
of wet (or dry) series was calculated as follows. 
 
Relative change in length = length2080-2099 / length1986-
2005    (1) 
 
Similarly, the relative change in standard deviation 
(St.dev.) of minimum and maximum temperatures and the 
mean change in precipitation amount were calculated as 
follows. 
 
Relative change in St.dev  = St.dev.2080-2099 / 
St.dev.1986-2005  (2) 
Relative change in Precipitation = pre.2080-2099 
/pre.1986-2005     (3) 
 
For monthly mean changes in maximum and minimum 
temperatures, the monthly mean changes in these values 
between the future and baseline periods were considered. 
IV. RESULTS AND DISCUSSIONS 
We used the MIROC model output of maximum and 
minimum temperatures and precipitation from the RCPs 2.6, 
4.5, 6.0 and 8.5 scenarios for assessing changes in climate in 
the period of 2080-2099 compared to the baseline period of 
1986-2005. An example of the scenario file developed for the 
RCP4.6 is shown in Fig. 2. 
The scenario files developed for each scenario were used 
with the observations during 1986-2005 to produce time series 
of weather variable for the period of 2080-2099. Table 1 
shows a summary of weather variables and their relative 
change in future compared to baseline time period. Figure 3 
depicts accumulative probability distributions of three 
variables in baseline period and four scenarios in the future. 
According to figures 3 a) and b), there is a consistent warming 
in both minimum and maximum temperatures with different 
magnitudes for all scenarios during 2080-2099 compared to 
observations in 1986-2005 period. RCP8.5, which is 
representative of the high range of non-climate policy 
scenarios (subsequent radiative forcing of 8.5Wm
-2
 in 2100), 
predicts the highest warming of 3.2 and 3.05C for minimum 
and maximum temperatures, respectively. Similarly, RCP2.6, 
which assumes drastic policy interventions to reduce 
greenhouse gas emissions (subsequent radiative forcing of 2.6 
Wm
-2
 by 2100), predicts the lowest warming of 1.01 and 
0.86C for minimum and maximum temperatures, 
respectively. Warming predicts by two other scenarios varies 
between RCP8.5 and RCP2.6 in similar magnitudes.  
 International Journal of Students Research in Technology & Management 
 Vol 2 (03), May 2014,  ISSN 2321-2543, pg. 109-112 
http://www.giapjournals.org/ijsrtm.html   111 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 2. A scenario file developed to use in the LARS-WG for the MIROC 
global climate model for the RCP4.6 scenario for the time period 2080–2099 
at Muscat. 
 
The differences in the precipitation projections between the 
scenarios are much greater compared to consistent warming 
depicted in temperatures. The results reveal -36.4% and -
36.0% decreases in precipitation for the RCP 2.6 and RCP 4.5 
scenarios, respectively, while, RCP 6.0 and RCP 8.5 scenarios 
predict increase in precipitation in a range from 9.6% to 
12.5%, respectively during 2080-2099 compared to 1986-
2005 period. Figure 3 c) depicts that the RCP8.5 scenario 
predicts the potential of very extreme precipitation events in 
future, which may increase the risk of floods in our study area. 
V. CONCLUSIONS AND RECOMMENDATIONS 
This study was conducted to investigate the potential 
variation of precipitation and temperature in Muscat, the 
capital city of Sultanate of Oman in future. We used the 
MIROC general circulation model output (maximum and 
minimum temperatures and precipitation) from the RCPs 2.6, 
4.5, 6.0 and 8.5 scenarios of the IPCC Fifth Assessment 
Report for assessing changes in climate in the period of 2080-
2099 compared to the baseline period of 1986-2005. LARS-
WG was used for the simulation of weather data under both 
current and future climate conditions. 
 
 
 
 
 
 
 
 
Fig.3 Probability distributions of weather variables in the baseline 
and future time periods 
 
The results obtained for 4 scenarios indicate a significant 
warming in future, which ranges from 0.93
ᴼ
C (minimum 
temperature by 1.1
ᴼ
C and maximum temperature by 0.86
ᴼ
C) for 
the lowest scenario, RCP 2.6, to 3.1
ᴼ
C (minimum temperature 
by 3.2
ᴼ
C and maximum temperature by 3.0
ᴼ
C) for the highest 
one, RCP 8.5, relative to baseline level. 
 
 
 
//   Columns are: 
//   [1] month  
//   [2] relative change in monthly mean rainfall 
//   [3] relative change in duration of wet spell 
//   [4] relative change in duration of dry spell  
//   [5] absolute changes in monthly mean min temperature  
//   [6] absolute changes in monthly mean max temperature 
//   [7] relative changes in daily temperature variability  
//   [8] relative changes in mean monthly radiation 
[VERSION] 
LARS-WG5.5 
[NAME] 
Muscat_RCP46 
[BASELINE] 
1986 
[FUTURE] 
2080 
[GCM PREDICTIONS] 
Jan 0.68    0.94    1.06    1.09    1.09    0.86   1 
Feb 1.40    0.80    0.66    1.09    1.09    0.71   1 
Mar 0.34    0.86    3.99    1.09    1.09    1.04   1 
Apr 1.62    0.84    1.51    1.09    1.10    0.94   1 
May 0.41    1.11    1.39    1.09    1.08    0.86   1 
Jun 0.58    0.74    0.84    1.06    1.05    0.78   1 
Jul 3.69    0.81    1.28    1.04    1.02    0.97   1 
Aug 4.47    1.70    0.52    1.03    1.02    0.77   1 
Sep 1.34    0.76   1.17    1.03     1.02    0.93   1 
Oct 9.27    1.54   1.12    1.05     1.05    1.00   1 
Nov 0.08    0.68   2.06    1.06     1.06    0.80   1 
Dec 0.50    0.78   1.55    1.09     1.09    0.70   1 
[END] 
a) 
b) 
c) 
 International Journal of Students Research in Technology & Management 
 Vol 2 (03), May 2014,  ISSN 2321-2543, pg. 109-112 
http://www.giapjournals.org/ijsrtm.html   112 
TABLE I 
A SUMMARY OF WEATHER VARIABLES CHANGE DURING 2080-2099 COMPARED TO 1986-2005 PERIOD 
 
Data 
Minimum Temperature  Maximum Temperature Rainfall 
Annual 
average value 
(°C) 
Relative change 
(°C) 
Annual 
average value  
(°C) 
Relative change 
(°C) 
Annual total 
(mm) 
Relative change 
(%) 
Observations 23.89   32.99   79.79   
RCP 2.6 24.9 1.01 33.85 0.86 50.75 -36.40 
RCP 4.5 25.57 1.68 34.74 1.75 51.09 -35.97 
RCP 6.0 25.81 1.92 34.83 1.84 89.76 12.50 
RCP 8.5 27.09 3.2 36.04 3.05 87.41 9.55 
 
 
 
The results reveal -36.4% and -36.0% decreases in 
precipitation for the RCP 2.6 and RCP 4.5 scenarios, 
respectively, while, RCP 6.0 and RCP 8.5 scenarios predict 
increase in precipitation in a range from 9.6% to 12.5%, 
respectively during 2080-2099 compared to 1986-2005 period. 
 RCP8.5 scenario alone predicts the probability of very 
extreme precipitation events in future which may have 
implications for planning and decision making for flood 
mitigation infrastructures, land-use regulations and building 
codes. The differences in the precipitation projections between 
the scenarios are much greater compared to consistent 
warming depicted in temperatures. These results need to be 
further improved by adopting more GCMs, which will provide 
potential changes in a consistent range. The results of this 
study can be integrated with hydrological and flood models so 
that risk scenarios can be constructed for future time periods.  
ACKNOWLEDGMENT 
Authors wishes to acknowledge Prof. M. Semenov in 
Rothamsted Research Center for providing LARS-WG model. 
We are also grateful to the National Center for Atmospheric 
Research, Colorado for providing us the NCAR command 
Language (http://dx.doi.org/10.5065/D6WD3XH5).  
REFERENCES 
[1] M. Parry, O. Canziani, J. Palutikof, P. V. Linden and C. Hanson, 
“Climate change 2007: Impacts, Adaptation and Vulnerability. 
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2007. 
[2] K. Eckhardt and U. Ulbrich, “Potential impacts of climate change on 
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mountain range,” Journal of Hydrology, vol. 284, pp. 244-252, 2003. 
[3] S. Brouyere, G. Carabin and A. Dassargues, “Climate change impacts 
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G. Arnold, “Possible impacts of global warming on the hydrology of 
the Ogallala Aquifer region,” Climatic Change, vol. 42, pp. 677–692, 
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[5] M. E. Rafy, and Y. Hafez, “Anomalies in meteorological fields over 
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An Assessment of Temperature and Precipitation Change Projections in Muscat, Oman from Recent Global Climate Model Simulations

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An Assessment of Temperature and Precipitation Change Projections in Muscat, Oman from Recent Global Climate Model Simulations

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