مجله مدیریت مخاطرات محیطی
سال دوم شماره 4 (زمستان 1394)

The heat waves are the main manifestations of contemporary world climate change, which in terms of the frequency of occurrence and financial and human loss caused by them are of great importance. The aim of this study was to identify, classify and analyze heat waves synoptic occurred in the Northwest of Iran, to verify the effective synoptic system in the occurrence of heat waves. In this study, the heat index introduced by the National Center for the United States weather data (NCDC) was used. For this purpose, long term statistics of 23 years old maximum daily temperature and relative humidity on a daily basis for five hottest months of the year (May to September) of Iran’s Northwest synoptic stations were collected from National Meteorological Organization and the statistical characteristics of heat waves and synoptic and occurrence of heat waves, were evaluated according this the thermal index and classified into five levels of intensity. The analysis of synoptic map showed also that the dominant patterns in the study regions next to a tropical high pressure, Saudi Arabia and Pakistan. The maps of moisture flux also showed a cyclone movement on the Caspian Sea and the Mediterranean Sea, have the most impact on the moisture flux of northwest area of Iran. there is moisture in the event of heat waves on north west area that exacerbate the risks of heat waves, in terms of human risk.

In recent years, the most researches in the field of hazards have been changed their paradigm from losses and damages reduce model to a more comprehensive society resilience model. Accordingly, the views and theories of disaster management and sustainable development are about to make resiliency societies against natural hazards. Resilience is system capacity and their ability to change tolerance, disruption and stability of current relationships between individuals or variables. This study evaluates Damavand's resilience approach in dealing with natural hazards by considering mentioned. The most important of resiliency approaches have been divided into four categories; the first one includes proactive approach, reactive, consistent and wide approach. The second one consist three resiliency approaches as a preparation, performance and Ineffectual resiliency. The third one is divided into two approaches are named specific and general resiliency. Finally, the fourth group includes resilience approaches and global equilibrium and resilience and multiple equilibria. Based on these approaches, this study attempted to examine and analysis resilience approach in case study by survey and questionnaire in study area. The questionnaires were filled randomly and data analyzed by statistical methods. In order to determine the resiliency approach in each group, Data were analyzed separately for each group. The results indicates that resilience approach of this area in the first group is proactive; in the second one is resilience as performance; in third group is specific resiliency and finally fourth one is resiliency approach and global equilibrium.

Agriculture is a major contributor of the greenhouse gases. Therefore, in the agricultural sector, mitigation strategies to reducing the climate change are necessary. Where, mitigating climate change in agriculture is depends to willingness of farmers. Therefore, identify the influencing factors on willingness of farmers is important. The purpose of this study was to investigate of factors influencing on farmers’ willingness in order to mitigation greenhouse gases. This research in terms of purpose is an applied research and in terms of methodology is survey research.The statistical population of this research consisted of 3000 farmers of Bavi Township in khuzestan Province. A sample of 350 persons was selected through random sampling method. The survey instrument was a questionnaire which its validity confirmed by experts. The reliability of the questionnaire using Cronbach's alpha coefficient (α= 0/70-0/90) has been approved. The results showed, the variables of, knowledge about effects, media trust, knowledge about causes of climate change and social trust could predict 28 percent of variations in farmers’ willingness to mitigating climate change. Finally, based on the results of research, policy implications presented.

According to climate changes in recent years due to consequences of economic, social and financial damages associated with uncomfortable events to reduce the risks of many importance. in an effective risk management system, identification and forecast as the main pillar of the system is considered to be so this study aims to mull over the effect of global warming in Iran so cold temperatures during the coming decades to say come in; since the identity of the regions and their zoning is an important step in order to reduce risks arising from it. In order to achieve the prime target of daily temperature data model EH5OM the Max Planck Institute Germany during the period (2015 - 2050 AD) , under the scenario A1B 1 / 75 differentiation degree arched , to the extent of Iran loaded . In the next step releasing data with a separate 0 / 27 * 0 / 27 arched by the model REGCM4 Downscaled. Cold days to identify the standard deviation of index temperature (NTD). Data in terms of rule extended heat index value (NTD< 0) are arranged and then the first 500 days that condition (NTD> -2) estimates that were selected in the sample sentence and an array of size 500 × 2140 was formed. The results indicate that the frost so that Iran could be using cluster analysis methods in neural network SOM divided into nine regions. In the coming decades Extreme cold in the western half and altitude bar (mountains and foothills) more visible areas inside and southern coasts. Minimum event Extreme cold Iran is related to the plain desert and maximum in the northwest.

Air pollution is one of the environmental hazards in metropolitans which made the life very expensive and even hazardous during last decades. The main aim of the present study is to determine the synoptic patterns which lead to formation and intensification of stable atmospheric conditions in cold seasons of year. The present study investigated the thermal and dynamic systems that lead to stable atmospheric conditions in Tehran in the cold season. In this study statistical, synoptic and Thermo-dynamic methods are used to achieve the objectives.The wind characteristics in all geographical directions (16 directions) were examined in a 10-year period in Tehran City. In order to calculate the correlation between CO and wind speed, Pearson Correlation Method and regression analysis were used in SPSS and MS Excell. The results showed a significant correlation between CO emissions and wind speed in all directions, but by separating all 16 wind directions, the highest correlation (significant at 99% confidence level) between the wind speed at the directions of NW ,SSE and W was observed which means that by increasing the wind speed, the density of CO emissions reduced (and vice versa). Another result from wind analysis is that there is a direct correlation between NE and ENE directions and CO pollutant which means that by increasing the wind speed in mentioned directions, the density of CO emissions increased as well. Also results showed that average wind speed in polluted days is 1.3 meter per second which is far less than the average of 2.5 meter per second in the period.
For synoptic analysis, 14 severe polluted days in cold seasons were selected during the period of 2002 to 2012. Maps of MSLP, 700 and 500 hpa and vorticity map in Grads software were drawn using ECMWF reanalysis data.
The results showed that most of the selected polluted days have followed the same synoptic pattern in which high pressure systems dominated and Tehran is located in the ridges axis and due to convergence in upper-air levels, subsidence had occurred near surface levels and the negative vorticity in the region intensified the air pollution. In Thermo-dynamic analysis, by drawing SkewT diagram in Raob software, the type and altitude of inversion, is determined. According to the results, The air pollution severity becomes very hazardous and critical at the times which radiational inversion occurs in altitudes less than 100 meters. Also results showed that in stable atmosphere, wind speed is very low from earth to mid levels of troposphere.

Flash floods caused by short heavy precipitation are one of the most important natural hazards. The main objective of the study is to provide a synoptic and thermodynamic mechanism analysis of the severe rainfall leading to floods on July 28th, 1394, in Alborz province. According to Sijan and Kondor rain-gauge stations as well as Karaj synoptic station, precipitation features and the occurrence of rainfalls in the warm season were determined. Furthermore, anomaly data, geopotential heights, vertical velocity (omega), and vorticity in the days prior to the precipitation at 500 and 850 hpa and sea level were determined and drawn based on GRADS. The instability indexes and the Skew-T thermodynamic graph were analyzed based on Tehran synoptic station. The main synoptic features of the rainfall include the cold weather in the upper atmosphere, creation of quasi-stationary trough, and surface earth low-pressure, injection and continuous supply of moisture from Caspian Sea and northwestern streams. The dominant pattern at sea level before and during the precipitation was thermal low pressure in Pakistan. The vertical velocity (omega) at the time of the rainfall strengthened  and more than 500 hPa and 850 hPa was observed. On the day of the precipitation, the amount of positive vorticity reached +9 due to the movement of the upper atmosphere meridional flows. The rainfall with Showalter Index in severe unstable conditions as well as Precipitation Index enjoyed the necessary water vapor for heavy rainfall in the region. High temperature difference between the upper level in atmosphere and ground surface during warm seasons causes heavy precipitation. Hence, such knowledge could be reliable source for flood warnings before the occurrence of the crisis.