عنوان مقاله [English]
Heat waves are one of the most dangerous climate threats associated with global warming, affecting society, economy and environment today, one of the most important concerns from climatic hazards is the occurrence of heat waves, which widely affects human societies. The occurrence and intensity of heat waves have increased throughout the world in recent years. (Ding et al., 2006). An increase in average temperature can lead to hotter days and longer and more frequent heat waves. This, in turn, can cause an increase in heat-related diseases such as heatstroke, heat cramps, heat weakness, and even in advanced cases to die (Haidari et al., 2016). The stagnant atmospheric conditions resulting from heat waves trap pollutants in urban areas, and with the addition of the severe stress of toxic pollutants to the dangerous stress of hot air, it creates a large-scale environmental problem. Also, at night or in winter, the presence of cold air above causes the warmer air layer below it to remain constant along with the dust layer (Almusaed, 2011). Weather and its consequences during the next decades and centuries, the use of coupled atmosphere-ocean models has been considered. These modes are well-known tools for studying the future climate (Xu, 1999). These models are able to model climate variables for a long period using different scenarios (Abbasi et al., 2019).Therefore the purpose of this study is Identification and analysis of heat waves in Tabriz and Ardabil cities and its prediction with CanEsm2 climate model scenarios
In the present study to identify heat waves in Tabriz and Ardabil cites, Maximum daily temperature data of synoptic station of two studied cities, from 2003 to 2018, were obtained from the Meteorological Organization and then SDSM software and CanESM2 model and three RCP scenarios (2.6, 4.5 and 8.5) were used. Then using error measurement indicators maximum temperature was predicted and then the lowest risk scenario was selected for each city and the based on that scenario and using the Fumiaki index and through programming in MATLAB software, Days that had temperatures above +2 standard deviation or above average (NTD) and these conditions lasted for at least two days, were identified and selected as the day with heat waves. The Fumiaki index is obtained by relation 1:
Where T (i, j, n) temperature of day i th from month j th in year n th, the average temperature of day i from month j. To eliminate the noise in the mean, a 9-day moving average filter was performed on these data three times and calculated by the following equation (Fujibi et al., 2007; Ismail Nejad et al. 2014).
Where ∆T= (i, j, n) absolute deviation of temperature from the average on day j th of the month i th, in year n th compared to the average temperature of the same day. In order to the values of temperature deviation of different times and places to be comparable at a certain time and place, it is necessary to standardize these absolute values of temperature deviation by means of temperature diffraction. Like day-to-day changes, diffuse T∆ at 30 days for each day is calculated by the following equation:
The value is the average temperature deviation in 30 days that is calculated by the following equation:
Finally, (NTD) is calculated by the following equation:
Where .Then days with temperatures +2 above average (NTD) and lasting at least two days, were selected as the day with the HW. (Ismail Nejad et al, 2014). Equation 6:
(6 2 ≥ NTD (i+p) NTD (i+p-1) ≥ 2, NTD (i-1), NTD (i+1)… NTD (i),
To evaluate the ability of CanESM2 model scenarios to predict the average maximum temperature for the next 31 years, the outputs of each scenario are averaged by the absolute error values (MAD), mean square error (MSE), root mean square error (RMSE) were compared and the most accurate and least error scenario was selected. Equation 7, 8, 9.
According to the presented results, during the recent decades, with the discussion of climate change, climate events, including the risk of heat waves, occur abundantly. Based on the results of the present research, heat waves during the past 16 years (2003-2018) in both cities of Ardabil and Tabriz were short-term and lasted for a maximum of 4 days, which occurred in December. According to the findings, in the next 30 years, as in the previous period, in both Tabriz and Ardabil, the maximum duration of the heat wave was predicted to be 4 days in Ardabil and 5 days in Tabriz. In terms of seasonal distribution, heat wave showed more frequency in both periods in spring and autumn. By comparing the duration of heat waves in the base period of 16 years with the predicted 30 years, it was concluded that in both periods and in both cities, heat waves with a duration of 2 days were more frequent. According to the results in Ardabil city, the continuation of heat waves is not much different compared to the base period, but it will increase in Tabriz city. Also, the maximum temperature in both stations will increase, and the highest increase will be in Tabriz. Since the maximum temperature also showed an increasing trend in both stations. Therefore, we can say that due to the frequent and continuous occurrence of heat waves and temperature increase, especially in the cold months of the year, early flowering and germination of agricultural and garden crops may occur, which is the result of the occurrence of late spring cold. After a heat wave, if there is no crisis management and insufficient information of farmers and horticulturists, we will see heavy damage to the agricultural economy in the study area. In addition, due to the tropical nature of the studied cities, the increase in temperature will definitely disturb the living comfort of the residents. Therefore, it is necessary to think about the necessary measures to deal with the negative effects caused by the increase in temperature. The findings of the present research, in the sense that heat waves will increase in the coming years and the most frequent heat waves will be two and three day waves and will often be more frequent in the cold seasons of the year. The opinions of most researchers were consistent.