Document Type : Research Article

Authors

1 Ferdowsi University of Mashhad

2 Professor Agro meteorology, Department of Water Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad

Abstract

Introduction: Air temperature as an important climatic factor can influence variability and distribution of other climatic parameters. Therefore, tracking the changes in air temperature is a popular procedure in climate change studies.. According to the national academy in the last decade, global temperature has raised 0.4 to 0.8⁰C. Instrumental records show that, with the exception of 1998, the 10 warmest year (during the last 150 years), occurred since 2000, and 2014 was the warmest year. Investigation of maximum and minimum air temperature temporal trend indicates that these two parameters behave differently over time. It has been shown that the minimum air temperature raises noticeably more than the maximum air temperature, which causes a reduction in the difference of maximum and minimum daily air temperature (daily temperature range, DTR). There are several factors that have an influence on reducing DTR such as: Urban development, farms’ irrigation and desertification. It has been shown that DTR reduction occurs mostly during winter and is less frequent during summer, which shows the season’s effect on the temperature trend. Considering the significant effects of the climatological factors on economic and agricultural management issues, the aim of this study is to investigate daily air temperature range for yearly, seasonal and monthly time scales, using available statistical methods.
Materials and Methods: Daily maximum and minimum air temperature records (from 1950 to 2010) were obtained from Mashhad Meteorological Organization. In order to control the quality of daily Tmax and Tmin data, four different types of quality controls were applied. First of all, gross errors were checked. In this step maximum and minimum air temperature data exceeding unlikely air temperature values, were eliminated from data series. Second, data tolerance was checked by searching for periods longer than a certain number of consecutive days with exactly the same temperatures. Third, a revision of internal consistence was done, verifying that daily Tmax always exceeds daily Tmin. Fourth, the temporal coherency was tested by checking if consecutive temperature records differ by more than 8 degrees. The homogeneity of the series was tested by means of the Standard Normal Homogeneity test, the Buishand range and the Pettitt tests, on yearly, seasonal and monthly time scales. Breakpoint can be detected by means of these methods. In addition, Von Neumann ratio test was used to explore the series’ randomness. Having investigated data’s randomness in this study, series’ trend was determined by the Kendal-Tau test. Furthermore, the slope of the series’ trend was calculated using the Sen’s slope method.
Results Discussion: Results indicated a decreasing trend in DTR during last 60 years (1951-2010) in Mashhad climatological station. Moreover, the results revealed that the slope of yearly DTR was decreasing (-0.029 ⁰C per year), which indicates that minimum air temperature values raise more maximum air temperature values. A breakpoint was detected during 1985. During 1951-1985, the average amount of DTR was 14.6⁰C, while this parameter reduced to 12.9⁰C for the period 1985-2010. The Kendall-Tau test was used to obtain the significance of trend during 1951-2010, 1951-1985 and 1985-2010. The results showed that during 1951-2010, DTR significantly reduced at a rate of 0.29oC per decade. However, between 1951 and 1985, DTR trend increased at a rate of 0.61oC per decade, while DTR trend between 1985 and 2010 reduced at a rate of 0.19 ⁰C per decade, which was not significant (P-value=5%). In the seasonal DTR series, the highest trend’s slope was calculated for the summer data (-0.43 ⁰C in a decade), while the lowest one accrued in spring (-0.15⁰C in a decade). From 1951 to 1985, DTR had an increasing trend, due to minimum air temperature’s downward trend. But from the late 1980 to 2010, as it was expected, downward DTR trend was observed, because during this period minimum air temperature increases more than the maximum air temperature, thus the difference between Tmax and Tmin was reduced. Monthly DTR analysis also revealed a decreasing trend from 1951 to 2010, except for March and April, which had a non-significant increasing trend. In monthly DTR series, as it was expected, similar to the yearly and seasonal time series, the breakpoints accrued around 1985 in 8 out of 12 months. During February, March, April and November no significant breakpoint was detected.
Conclusion: DTR decreasing trend indicated that minimum air temperature increase was greater than maximum. This can cause a significant effect on the agricultural sector, hence in an appropriate agricultural management, these points should be considered. For example, changing the sowing time is one of the decisions which a manager can make.

Keywords

1- AziziGh.,Karimiahmadabadi M., andSabokkhiz, Z. 2005. Temprature trend and atmospheric CO2 concentration over Iran in recent decades. Journal of geographical sciences, 4(5): 25-44. (in Persian with English abstract).
2- AziziGh., andRoushani, M. 2008. Using mann-kendall test to recognize of climate change in Caspian Sea southern coasts. Geographical research quarterly,40(64): 13-28. (in Persian with English abstract).
3- Bannayan, M.,Mohamadian, A.,and Alizadeh, A. 2010. On Climate Variability in North-East of Iran. Journal of Water and Soil, 24(1): 118-131.(in Persian with English abstract).
4- Buishand, T.A. 1981. The analysis of homogeneity of long-term rainfall records in the Netherlands. KNMI Scientific Report WR 81-7, De Bilt, Netherlands.
5- Cole, S., and McCarthy, L. 2015. 2014 warmest year in modern record. Available at:http://climate.nasa.gov/news/2221/. (visited 28 Dec 2015).
6- Darren L., Eikeluedeling Y., and Zhang M. 2009. Climate changes sensitivity Assessment of a Highly Agricultural water shed using SWAT. Journal of Hydrology,374: 1- 41.
7- David R.E., Horton, B., Philip D. Jones B.D., Peterson T.C., Karl T.R., Parker D.E., Salinger M.J., Razuvayev V., Plummer N., Jamason P., and Folland C.K. 1997. Maximum and minimum temperature trends for the Globe. Science, 277: 364-367.
8- Grieser J., Tromel S., and Schonwiese C.D. 2002. Statistical time series decomposition into significant components and application to European temperature. Theoretical and Applied Climatology, 71: 171-183.
9- Haan C.T. 1977. Statistical Methods in Hydrology. Iowa State University, Amesterdam.
10- Karl T.R., Jones P.D., Knight R.W., Kukla G., Plummer N., Razuvayev V., Gallo K.P., Lindsay J., Charlson R.J., and Peterson T.C. 1993. Asymmetric trends of daily maximum and minimum temperature. Bulletin of the American Meteorological Society, 74: 1007-1023.
11- Karl T.R., Kukla G., Razuvayev V.N., Changery M.J., Quayle R.G., Heim Jr. R.R., David R., Easterling D.R., and Fu C.B. 1991. Global warming: Evidence for asymmetric diurnal temperature change. Geophysical Research Letters, 18: 2253-2256.
12- Khoshakhlagh F.,Gharibi E., andShafiei Z.2011. The study of the lowest temperature changes in Iran. Geography and environmental planning (University of Isfahan),22(2): 199-216. (in Persian with English abstract).
13- Kumar P.V., Bindi M., Crisci A., and Maracchi G. 2005. Detection of variations in air temperature at different time scales during the period 1889-1998 at Firenze, Italy. Climate Change, 72: 123-150.
14- Marengo J.A., and Camargo C.C. 2008. Surface air Temperature Trends in Southern Brazil for 1960- 2002. International Journal of Climatology, 28: 893- 904.
15- Masudian S.A.,and Kaviyani M.R. 2008. Iran climatology. Isfahan University, Isfahan. (in Persian).
16- National Academy. 2000. National Research Council Reconciling Observations of National Academy, Washington D.C.
17- Noorian, A.M. 1997. Global climate change and global warming. Nivear, 81: 1-3. (in Persianwith English abstract).
18- Omidvar K., and Khosravi Y. 2010. Investigation of Change of Some Climatic Elements in North Coast of Persian Gulf Using Kendal Test. Geography and Environmental Planning, 21(2):33-46. (in Persian with English abstract)
19- Parvin N. 2012. The temperature variability detection of the azerbaijangharbi province in recent decades. Geography,10(33): 195-209. (in Persian with English abstract).
20- Pettitt A.N. 1979. A non-parametric approach to the change-point detection. Applied Statistics, 28: 126–135.
21- Rahimzadeh F., and Asgari A. 2004. A look at the difference between increase rates of minimum and maximum temperature and the decrease rates of diurnal temperature range (DTR) in Iran. Geographical research, 73: 155-171. (in Persian with English abstract).
22- Sabziparvar A., Mirgaloybayat R.,and GhyamiShamami F. 2011. Evaluation of the possible changes in diurnal temperature range (DTR) trend in some arid climates of Iran since last five decades. Iranian Journal of Physics Research, 11(1):27-37. (in Persian with English abstract).
23- Salas J.D. 1999. Analysis and modeling of hydrologic time Series. Chapter 19. In: D.R. Maidment (ed.), Handbook of Hydrology, McGraw Hill Book Company. 200 pp.
24- Salinger M.J. 1995. Southwest Pacific temperatures: Trend in maximum and minimum temperature. Atmospheric Research, 37: 87-99.
25- Salinger M.J. 2005. Climate Variability and Change Past, Present and Future - An Overview. Climate Change, 70: 9-29.
26- Saunders M.A. 1999. Earth’s future climate. Philosophical Transactions of royal society London, 357: 3459-3480.
27- Serra C., Burgueno A., and Lana X. 2001. Analysis of maximum and minimum daily temperatures recorded at fabra observatory (Barcelona, ne Spain) in the period 1917–1998. International Journal of Climatology, 21: 617–636.
28- ShamsSh.,and Mousavi BaygiM. 2014. The Investigation of Mashhad Extremum Temperature in Different Scales. Journal of Water and Soil, 28(1): 46-60. (in Persian with English abstract).
29- Shepard Ch. 2004. Sea surface temperature 1871–2099 in 14 cells around the United Kingdom. Marine Pollution Bulletin, 49:12-16.
30- Takeuchi Z.X., and Ishidiaira H. 2003. Monitoring Trend Step Changes in Precipitation in Japanese Precipitation. Journal of Hydrology, 279: 144-150.
31- Varshavian V., Khalili A., Ghahreman N., and Hajjam S. 2011. Trend analysis of minimum, maximum, and mean daily temperature extremes in several climatic regions of Iran. Journal of the Earth and Space Physics, 37(1): 169-179.(in Persian with English abstract).
32- Wilks D.S. 1995. Statistical method in the atmospheric sciences. Academic Press.
33- Yue S., and Hashino M. 2003. Temperature Trends in Japan: 1900-1996. Theoretical and Applied Climatology, 75: 15-27.
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