محمود مولی نژاد

Introduction Climate affects, more than any other factors, the type and form of human life, so that many cities that have made or developed regardless of climatic information are suffering from weather-related problems such as air pollution, water supply and flooding etc. By using the meteorological information in designing new cities as well as developing old cities can reduce the mentioned problems. Human comfort condition, based on the definition, is a thermal condition that is comfortable for at least 80% of people. Regarding the high impact of climate on human comfort, the humankind has been always looking for a suitable usage of the local climate. It was investigated the effective bioclimatic indices over human comfort in Shiraz city and their results showed that Shiraz with having a various bioclimatic condition holds a warm to very cold climatic conditions throughout the year. Attempt was made to study the climatic comfort index in Boushehr city. His findings from THI index indicated that the months of April, May, November, December, January, February and March are appropriate in terms of climate comfort for human. Investigation on the thermal comfort was made in Shahrud-Semnan from military viewpoint. In addition, the effect of climate on the architecture of Qom city was carried out by attempted to classify the climate based on effective parameters on life quality in Markazi province. Therefore, considering the high impact of climate on the human comfort as well as the spread of urbanization, in this research this subject is studied in the megalopolis city of Tehran. Materials & Methods Tehran city, in terms of climatic classification, possesses a warm and dry climate with an annual mean precipitation of approximately 250mm. The figure 1 shows the location under study and indicates climatology stations used. Figure 1 geographical position of Tehran city and the stations under study In the paper, the relations between three elements of temperature, relative humidity and wind speed is identified for 2 periods of 15-years from 1976 to 2005 for the selected stations in Tehran city and these data are studied using neurotic pressure index. This index is aimed to explain the level of comfort using temperature, humidity and wind. The index is stated as follows: Where, is the digital index for comfort; is the effective temperature and humidity index supposing a calm weather; is an index that adds up the effect of the surplus coldness resulting from the air motion and are obtained from the following equations: Where, is temperature in Fahrenheit; is relative humidity in %; is the speed of wind in knots. After obtaining digital index for comfort () from the above relation for finding the heating rate, the table 1 will be used. Table 1 grading index for comfort related to humid in warm climate Fully uncomfortable condition After estimation of the coefficients of the neurotic pressure index, for better indicating the variation of the heating index for comfort in Tehran, the zoning was carried out. With objective in this research, the existing methods including spatial interpolation, spatial analysis for data related to stations and inverse distance weighting (IDW) were used. Similarly in this methodology after defining the coefficients of the neurotic pressure index for two 15 periods including warm and cooling conditions, the index for comfort was extended to surface level and finally by using map of comfort variation and GIS software (Arc Map) the zoning map was developed as follows indicated in figures 2-5. Discussion of Results & Conclusions The coefficients of the neurotic pressure index were evaluated for the selected stations for a 2-period of 15-years in different months of the year. The findings indicated that during the first period the thermal phase in the months of January, February and December was cold and with lack of comfort, so that the North of Tehran station possessed the most condition of the lack of comfort during the cold period of the year. In addition, during the hot period of the year also the months of May, June, July, August and September possessed a thermal phase with a lack of comfort to absolutely lack of comfort. Meanwhile, the months of March and October hold the best comfort condition as well as among the stations, Mehrabad, in comparison with other stations, was recognized as the best station in terms of climate comfort. Generally, the results for the second period also showed that these coefficients had an ascending trend in most of the months. On the other hand, the condition from a cold thermal comfort turned into a hot thermal comfort, which indicates an increase in the local temperature due to the climate change in the study area. The results of interpolation by GIS also indicated that in the cold period, there is strong lack of comfort in the northern areas of Tehran city, meanwhile an appropriate comfort condition was replaced during the hot period. But for the southern areas of the city, there is an appropriate thermal comfort condition during the cold period and a lack of comfort is replaced during the hot period, though.

Frost is one of the most hazardous natural phenomena which it is at times accompanied by abundant damages in the life and properties. Freezing and frost are very important for agricultural products in different stages of the growth. This is because, in case of happening, it results in the reduction of the products. Frost is the stage of water freezing. In such condition, when the air temperature decreases to dew point, ice cover is formed over the surface. Mojarrad Gharehbagh in addition to presenting a new definition of frost, he analyzed and extracted the frost characteristics based on 16 indices systematically. Mirmousavi and Hosseinbabaei studied the temporal-spatial distributions of the frost occurrence probability in Zanjan province. They found that, on average, the first frost events of the region are occurred in autumn season from 19th of September to 15th of November, and generally the frosts events are ended from 9th of April to 20th of May. Montazeri attempted to study the agricultural frosts in NajafAbad city. This results showed that the general frequency of frost days were not decreased, meanwhile the occurrence of the severe frosts have been decreased as well as the frequency of the occurrence of zero-temperature frosts have been highly increased. Jahanbakhsh et al. attempted to analyze the springtime frosts of Tabriz in view of synoptic. Their results indicated that the longest and the severest frosts occurred between 27th March – 1st April 2003 and 5th April 2004, which this is due to the formation of low pressure centers and deepening the related troughs over the north of Caspian Sea. Masoudian and Darand investigated the widespread frosts of Iran and found that 5 patterns of sea level pressures (SLPs) result in severe and widespread frosts in Iran. They also concluded that the severity of the frost events in different regions of Iran is in good agreement with those the path of the anticyclonic systems. Thom and Show proved that the occurrence dates of frosts are random and are based on a normal distribution. For this reason, using mean and standard deviation are considered as valid indices to study the frost events. Tavakoli and Hosseini analyzed the frost indices and its autumn-time occurrence in Ekbatan-Hamedan station and presented a model to predict the autumn-time frosts. Zolfaghari et al. predicted the last date of spring-time frosts in west and northwest of Iran. Their results showed that it was possible to predict the last dates of the spring-time frosts among the stations in the study area using error post-distribution network. The computed error was low in all the stations. The highest error measured in Arak station with %1.1142, while the lowest error computed in Mahabad station with %0.254. Easterling attempted to investigate the recent changes in days with frost and no frost in the USA and he found that during the period 1948-1999 the frequency of frost days declined, but the length of the days without frost increased. Home studied the temporal distribution of seasonal-annual frosts in relation to their trends in the past years. Karl investigated the precipitation and minimum and maximum temperatures, and found that these parameters can be statistically predicted. Bootsma analyzed the minimum temperature and possible occurrence of frost in mountainous regions of Canada. In a research, Behyar studied the cold event of 27th of April, 2003 in Charmahale-e-Bakhtiari province using different meteorological variables to identify the dynamical-synoptic factors responsible for this cold event in the region. Rabani and Karami attempted to study the frequency trend of frost days in Northern Khorasan province. Their results showed that the number of frost’s days during the examined period indicated a descending trend in such a way that it is in good agreement with the increasing trend of annual temperature in the study area. Soltani et al. studied the meteorological aspects of an abnormal cooling event over Iran in April 2009. Their results showed that a polar vortex was responsible for the freezing event over the country extending southward extraordinarily in such a way that its ridge influenced most parts of Iran. This was recognized as an abnormal extension of a polar vortex in the recent years. The sea-level pressure fields indicated that a ridge of large-scale anticyclone centered over Black Sea extended southward and prevailed over most parts of Iran. This resulted in the formation of a severe cold air advection from high latitudes (Polar region) over Iran. Data and In order to investigate the frosts characteristics in synoptic station of Saghez, the frequency of frost days is extracted for the period 1976-2007 and then the minimum temperature data are analyzed on the basis of Jouliosi calendar. The geographic position of the study station is shown in Fig. 1. The homogeneity of the data series verified using Runs Test. After that, the days with a temperature less than 0 ͦC are extracted as a frost day, and the frosts are classified into three categories: weak (ranging from 0 ͦC to -1.1 ͦC); moderate (ranging from -1.1 ͦC to -3.3 ͦC), and severe (less than -3.3 ͦC). Table 1 shows the frequency of occurrence and the beginning/ending date of the frosts with different thresholds during the examined period in Saghez station. In addition, to determine the trend of frost days in Saghez station, a correlation equation was applied between the number of the frost days and length of records (years), which the linear equation is as follows: Which X is the length of records; Y is the total of frost days. It is worthwhile to mention that the above equation is significant at 5%. The knowledge and experience of scientists have presented some solutions over the course of the time, which have been useful in reducing the damages from climatic disasters like frost.. The maps of frost occurrence probability and the first data of autumn-time frosts as well as the last date of spring-time frosts are a simple example, but very significant in studying the frosts for agricultural purposes. Through studying of the temperature data and frosts days in Saghez station during a 32-year period, we found that the minimum temperature over the past two decades had an increasing (positive) trend in such a way that this trend was most severe in the past five years indicating the effect of global warming as a result of a natural process or human activities in the globe. The findings indicate that the severe frosts in Saghez station are mostly occurred in January, February and December months, and the moderate frosts happen in January, February, November, December and March months, and finally the weak frosts usually take place in the months of March, October and April. The trend of frosts days and minimum temperature in Saghez station indicates a vice versa correlation as well as an increasing trend in frost days and decreasing trend in minimum temperature. This trend, which is unusual, is due to the decrease of temperature from 1986 to 1989, which is clear for the number of frost days, as well. The important point in studying the frosts in Saghez station is that, according to the obtained equation, there is a meaningful/significant correlation between the beginning dates of autumn frosts and ending dates of springtime frosts as well as the minimum temperatures of September and April of the same year. So that, the sooner the springtime frosts are ended accompanied by a high minimum temperature of September and April, the later the autumn frosts are started and vice versa. Furthermore, it was determined that the soonest autumn frost occurred on the 2nd day of 2002, and the latest springtime frost took place on the 247th day of the year 2002. Therefore, generally it can be said that through studying and predicting the frost events on time, we will be able to protect the agricultural products against frosts using different methods such as: using heating systems like stove/heater, wind generator machines or helicopters, producing artificial fog etc.

Trade policy is one of the most important segments of a nation-state economic policy. The public policymaking in the segment includes developing long and mid-term plans to direct the decision making process on export، import and foreign investment in a country، by which businesses (either private or public) will be able to perfume more effective in international level and foreign marketplaces. On the other hand، in recent three decades globalization forces of economic، political and cultural scales have great impacts on the societies in different ways. In the paper، a model has been suggested to explain the impacts on trade policymaking process of I. R. Iran. Ministry of Commerce، however، was attained as the research source of data، due to the main role of the ministry on trade policy of Iran. The results indicate that economic، political and cultural forces of globalization have great impacts on trade policymaking process and probably would improve level of participation in planning and enhance trust and commitment of policymakers to the policy network.