This study employed the time series of thirteen extreme temperature indices over the period 1985–2010 to analyze and compare temporal trends at two weather stations in Riyadh city, Saudi Arabia. The trend analysis showed warming of the local air for the city. Significant increasing trends were found in annual average maximum and minimum temperatures, maximum of minimum temperature, warm nights, and warm days for an urban and a rural station. Significant decreasing trends were detected in the number of cool nights and cool days at both stations. Comparison of the trends suggests that, in general, the station closer to the city center warmed at a slower rate than the rural station. Significant differences were found in a lot of the extreme temperature indices, suggesting that urbanization and other factors may have had negative effects on the rate of warming at the urban station. 1. Introduction A better understanding of trends in local extreme temperature has potential benefits to many practical problems. Increasing extremely high temperatures, for example, directly affect energy consumption [1]. In summer 2010, which was the warmest season in Saudi Arabia’s record with temperatures reaching 52°C in Jeddah city, eight power plants throughout Saudi Arabia were forced to shut down, resulting in a loss of power in several cities [2], leaving people exposed and vulnerable to the extreme temperature. If observed trends indicate that such extreme temperatures are becoming more frequent, energy providers may be able to adapt their electricity supply to minimize the likelihood of widespread power outage. Evidence that localized high temperatures are becoming less frequent, on the other hand, along with assessment of possible causes of the cooling, can be used to develop and implement urban planning strategies to mitigate local- and larger-scale warming [3–5]. Multiple recent studies have been dedicated to gaining a better understanding of mean and extreme temperature patterns and trends in Saudi Arabia (e.g., [2, 6–12]). One study [7] reported that annual mean air temperature in Saudi Arabia increased at an average rate of 0.60°C？decade？1 over the period 1978–2009 and another one [8] showed that the increasing trend was robust across the seasons, although the rate of change did vary seasonally. Annual maximum and minimum temperature also increased over the period 1978–2009 [8]. Other extreme temperature indices, such as extremely hot days (maximum temperature >90th percentile), warm spells (6 consecutive days when maximum temperature >90th percentile), and
References
[1]
IPCC, “Climate change 2007: the scientific basis,” in Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, S. Solomon, D. Qin, M. Manning, et al., Eds., Cambridge University Press, New York, NY, USA, 2007.
[2]
Met Office, Climate: Observations, Projections and Impacts Saudi Arabia, Met Office, Devon, UK, 2013.
[3]
T. Susca, S. R. Gaffin, and G. R. Dell'Osso, “Positive effects of vegetation: urban heat island and green roofs,” Environmental Pollution, vol. 159, no. 8-9, pp. 2119–2126, 2011.
[4]
S. Peng, S. Piao, P. Ciais et al., “Surface urban heat island across 419 global big cities,” Environmental Science and Technology, vol. 46, no. 2, pp. 696–703, 2012.
[5]
G.-Y. Qiu, H.-Y. Li, Q.-T. Zhang, W. Chen, X.-J. Liang, and X.-Z. Li, “Effects of evapotranspiration on mitigation of urban temperature by vegetation and urban agriculture,” Journal of Integrative Agriculture, vol. 12, no. 8, pp. 1307–1315, 2013.
[6]
S. Rehman, “Temperature and rainfall variation over Dhahran, Saudi Arabia, (1970–2006),” International Journal of Climatology, vol. 30, no. 3, pp. 445–449, 2010.
[7]
M. Almazroui, M. Nazrul Islam, H. Athar, P. D. Jones, and M. A. Rahman, “Recent climate change in the Arabian Peninsula: annual rainfall and temperature analysis of Saudi Arabia for 1978–2009,” International Journal of Climatology, vol. 32, no. 6, pp. 953–966, 2012.
[8]
M. Almazroui, M. N. Islam, P. D. Jones, H. Athar, and M. A. Rahman, “Recent climate change in the Arabian Peninsula: Seasonal rainfall and temperature climatology of Saudi Arabia for 1979–2009,” Atmospheric Research, vol. 111, pp. 29–45, 2012.
[9]
M. Almazroui, M. N. Islam, R. Dambul, and P. D. Jones, “Trends of temperature extremes in Saudi Arabia,” International Journal of Climatology, vol. 34, no. 3, pp. 808–826, 2014.
[10]
M. Almazroui, M. N. Islam, and P. D. Jones, “Urbanization effects on the air temperature rise in Saudi Arabia,” Climatic Change, vol. 120, no. 1-2, pp. 109–122, 2013.
[11]
S. Rehman and L. M. Al-Hadhrami, “Extreme temperature trends on the west coast of Saudi Arabia,” Atmospheric and Climate Sciences, vol. 2, pp. 351–361, 2012.
[12]
H. Athar, “Trends in observed extreme climate indices in Saudi Arabia during 1979–2008,” International Journal of Climatology, vol. 34, no. 5, pp. 1561–1574, 2014.
[13]
A. T. DeGaetano and R. J. Allen, “Trends in twentieth-century temperature extremes across the United States,” Journal of Climate, vol. 15, no. 22, pp. 3188–3205, 2002.
[14]
R. A. Pielke Sr., T. Stohlgren, L. Schell et al., “Problems in evaluating regional and local trends in temperature: an example from eastern Colorado, USA,” International Journal of Climatology, vol. 22, no. 4, pp. 421–434, 2002.
[15]
R. W. Dixon and T. W. Moore, “Trend detection in Texas temperature and precipitation,” Southwest Geography, vol. 15, pp. 80–103, 2011.
[16]
G. Y. Ren, Y. Q. Zhou, Z. Y. Chu et al., “Urbanization effects on observed surface air temperature trends in north China,” Journal of Climate, vol. 21, no. 6, pp. 1333–1348, 2008.
[17]
Y. Zhou and G. Ren, “Change in extreme temperature event frequency over mainland China, 1961–2008,” Climate Research, vol. 50, no. 2-3, pp. 125–139, 2011.
[18]
T. R. Oke, “The heat island of the urban boundary layer: characteristics, causes and effects,” in Wind Climate in Cities, pp. 81–107, Kluwer Academic Publishers, Dordrecht, The Netherlands, 1995.
[19]
A. Brazel, N. Selover, R. Vose, and G. Heisler, “The tale of two climates-Baltimore and Phoenix urban LTER sites,” Climate Research, vol. 15, no. 2, pp. 123–135, 2000.
[20]
M. A. Pe？a, “Relationships between remotely sensed surface parameters associated with the urban heat sink formation in Santiago, Chile,” International Journal of Remote Sensing, vol. 29, no. 15, pp. 4385–4404, 2008.
[21]
L. Bounoua, A. Safia, J. Masek, C. Peters-Lidard, and M. L. Imhoff, “Impact of urban growth on surface climate: a case study in Oran, Algeria,” Journal of Applied Meteorology and Climatology, vol. 48, no. 2, pp. 217–231, 2009.
[22]
M. L. Imhoff, P. Zhang, R. E. Wolfe, and L. Bounoua, “Remote sensing of the urban heat island effect across biomes in the continental USA,” Remote Sensing of Environment, vol. 114, no. 3, pp. 504–513, 2010.
[23]
M. Lazzarini, P. R. Marpu, and H. Ghedira, “Temperature-land cover interactions: the inversion of urban heat island phenomenon in desert city areas,” Remote Sensing of Environment, vol. 130, pp. 136–152, 2013.
[24]
F. M. Alkolibi, “Possible effects of global warming on agriculture and water resources in Saudi Arabia: impacts and responses,” Climatic Change, vol. 54, no. 1-2, pp. 225–245, 2002.
[25]
R. Municipality, “Riyadh development,” 2014, http://www.alriyadh.gov.sa/en/alriyadh/Pages/development_of_population.aspx.
[26]
M. A. Al-Saleh, “Variability and frequency of daily rainfall in Riyadh, Saudi Arabia,” The Geographical Bulletin, vol. 39, no. 1, pp. 48–57, 1997.
[27]
S. AlSarmi and R. Washington, “Recent observed climate change over the Arabian Peninsula,” Journal of Geophysical Research D: Atmospheres, vol. 116, Article ID D11109, pp. 1984–2012, 2011.
[28]
S. H. Alsarmi and R. Washington, “Changes in climate extremes in the Arabian Peninsula: Analysis of daily data,” International Journal of Climatology, vol. 34, no. 5, pp. 1329–1345, 2014.
[29]
X. Zhang and F. Yang, RClimDex (1.0) User guide. Climate Research Branch Environment Canada, Downsview, Ontario, Canada, 2004.
[30]
G. Choi, D. Collins, G. Ren et al., “Changes in means and extreme events of temperature and precipitation in the Asia-Pacific Network region, 1955–2007,” International Journal of Climatology, vol. 29, no. 13, pp. 1906–1925, 2009.
[31]
A. M. G. Klein Tank, F. W. Zwiers, and X. Zhang, “Guidelines on analysis of extremes in a changing climate in support of informed decisions for adaptation,” WMO-TD 1500, World Meteorological Organization, 2009.
[32]
Q. You, S. Kang, E. Aguilar et al., “Changes in daily climate extremes in China and their connection to the large scale atmospheric circulation during 1961–2003,” Climate Dynamics, vol. 36, no. 11-12, pp. 2399–2417, 2011.
[33]
T. M. L. Wigley, “Appendix A: atatistical issues regarding trends,” in Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences, T. R. Karl, S. J. Hassel, C. D. Miller, and W. L. Murray, Eds., A report by the US Climate Change Science Program and the subcommittee on Global Change Research, Washington, DC, USA, 2006.
[34]
Z. Wu, N. E. Huang, J. M. Wallace, B. V. Smoliak, and X. Chen, “On the time-varying trend in global-mean surface temperature,” Climate Dynamics, vol. 37, no. 3, pp. 759–773, 2011.
[35]
B. ？n？z and M. Bayazit, “The power of statistical tests for trend detection,” Turkish Journal of Engineering & Environmental Sciences, vol. 27, no. 4, pp. 247–251, 2003.
[36]
L. Zhang, G. Y. Ren, Y. Y. Ren, A. Y. Zhang, Z. Y. Chu, and Y. Q. Zhou, “Effect of data homogenization on estimate of temperature trend: a case of Huairou station in Beijing Municipality,” Theoretical and Applied Climatology, vol. 115, no. 3-4, pp. 365–373, 2014.
[37]
M. E. Gregory, “Cooling urban heat islands with sustainable landscapes,” in The Ecological City: Preserving and Restoring Urban Biodiversity, R. A. Rowntree, R. H. Platt, and P. C. Muick, Eds., pp. 151–171, University of Massachusetts Press, Amherst, Mass, USA, 1994.
[38]
H. A. Nasrallah, A. J. Brazel, and R. C. Balling Jr., “Analysis of the Kuwait City urban heat island,” International Journal of Climatology, vol. 10, no. 4, pp. 401–405, 1990.
[39]
R. A. Spronken-Smith and T. R. Oke, “The thermal regime of urban parks in two cities with different summer climates,” International Journal of Remote Sensing, vol. 19, no. 11, pp. 2085–2104, 1998.
[40]
E. Jauregui, “Influence of a large urban park on temperature and convective precipitation in a tropical city,” Energy and Buildings, vol. 15, no. 3-4, pp. 457–463, 1991.
[41]
T. V. Ca, T. Asaeda, and E. M. Abu, “Reductions in air conditioning energy caused by a nearby park,” Energy and Buildings, vol. 29, no. 1, pp. 83–92, 1998.
[42]
N. A. Al Sahhaf, The use of remote sensing and geographic information system technologies to detect, monitor, and model urban change in Riyadh, Saudi Arabia [Dissertation, thesis], Univers ity of California, Santa Barbara, Calif, USA, 2000.
[43]
A. Buyantuyev and J. Wu, “Urban heat islands and landscape heterogeneity: linking spatiotemporal variations in surface temperatures to land-cover and socioeconomic patterns,” Landscape Ecology, vol. 25, no. 1, pp. 17–33, 2010.
[44]
I. D. Stewart and T. R. Oke, “Local climate zones for urban temperature studies,” Bulletin of the American Meteorological Society, vol. 93, no. 12, pp. 1879–1900, 2012.
