Investigation of temporal and spatial climate variability and aridity of Iran

The aim of this research is to study the spatial and temporal variability of aridity in Iran, through analysis of temperature and precipitation trends during the 48-year period of 1961–2008. In this study, four different aridity criteria have been used to investigate the aridity situation. These aridity indexes included Lang’s index or rain factor, Budyko index or radiational index of dryness, UNEP aridity index, and Thornthwaite moisture index. The results of the analysis indicated that the highest and lowest mean temperatures occurred in July and January respectively in all locations. Among the study locations, Ahvaz with 37.1 °C and Kermanshah with 20.2 °C has the highest and lowest in July. For January, the highest was 12.4 °C for Ahvaz and the lowest was ?4.5 °C for Hamedan and Kermanshah together. The range of monthly mean temperature of study locations indicated that the maximum and minimum difference between day and night temperatures, almost in all study locations, occurred in September and January, respectively, and the highest and lowest fluctuation of temperature was observed in Kerman and Tehran. The temperature anomalies showed that the most significant increasing temperature occurred at the beginning of twenty-first century (2000–2008) in all locations. The long-term mean of monthly rainfall showed that, in most study locations, the maximum and minimum of mean precipitation occurred in winter and summer, respectively. Rasht with 1,355 mm had the highest and Yazd with 55 mm had the lowest of total precipitation compared with other locations. According to precipitation anomalies, all locations experienced dry and wet periods, but generally dry periods occurred more often especially in the beginning of twenty-first century. According to applied different aridity indexes, all the study locations often experienced semi-arid to arid climate, severe water deficit to desert climate, arid to hyperarid climate, and semi-arid climate during the study period.     

Agrometeorological study of crop drought vulnerability and avoidance in northeast of Iran

Drought is one of the crucial environmental factors affecting crop production. Synchronizing crop phenology with expected or predicted seasonal soil moisture supply is an effective approach to avoid drought impact. To assess the potential for drought avoidance, this study investigated the long-term climate data of four locations (Bojnourd, Mashhad, Sabzevar, and Torbat Heydarieh) in Khorasan province, in the northeast of Iran, with respect to the four dominant crops (common bean, lentil, peanut, and potato). Weekly water deficit defined as the difference between weekly precipitation and weekly potential evapotranspiration was calculated. Whenever the weekly water deficit was larger than the critical water demand of a crop, the probability for drought was determined. Results showed that Sabzevar has the highest average maximum temperature (24.6 °C), minimum temperature (11.7 °C), weekly evapotranspiration (32.1 mm), and weekly water deficit (28.3 mm) and has the lowest average weekly precipitation (3.8 mm). However, the lowest mean maximum temperature (19.7 °C), minimum temperature (6.9 °C), weekly evapotranspiration (22.5 mm), and weekly water deficit (17.5 mm) occur in Bojnourd. This location shows the shortest period of water deficit during the growing season for all crops except potato, which also experienced drought at the end of the growing season. Sabzevar and Torbat Heydarieh experienced the highest probability of occurrence and longest duration of drought during the growing season for all crops. The result of this study will be helpful for farmers in order to reduce drought impact and enable them to match crop phenology with periods during the growing season when water supply is more abundant.     

Predictive value of Keetch-Byram Drought Index for cereal yields in a semi-arid environment

The study examines the potential of urban roofs to reduce the urban heat island (UHI) effect by changing their reflectivity and implementing vegetation (green roofs) using the example of the City of Vienna. The urban modelling simulations are performed based on high-resolution orography and land use data, climatological observations, surface albedo values from satellite imagery and registry of the green roof potential in Vienna. The modelling results show that a moderate increase in reflectivity of roofs (up to 0.45) reduces the mean summer temperatures in the densely built-up environment by approximately 0.25 °C. Applying high reflectivity materials (roof albedo up to 0.7) leads to average cooling in densely built-up area of approximately 0.5 °C. The green roofs yield a heat load reduction in similar order of magnitude as the high reflectivity materials. However, only 45 % of roof area in Vienna is suitable for greening and the green roof potential mostly applies to industrial areas in city outskirts and is therefore not sufficient for substantial reduction of the UHI effect, particularly in the city centre which has the highest heat load. The strongest cooling effect can be achieved by combining the green roofs with high reflectivity materials. In this case, using 50 or 100 % of the green roof potential and applying high reflectivity materials on the remaining surfaces have a similar cooling effect.     

Realization of rainfed wheat and barley production environment based on drought patterns in the northeast Iran

Theoretical and Applied Climatology - High spatiotemporal climate variability in the northeast Iran has led to increased production risk for rainfed crops. Hence, to explore potential opportunities...     

Variability of growing season indices in northeast of Iran

Accurate use of precipitation can be considered as one of the best options to decrease the amount of underground water extraction for agriculture in arid and semi-arid areas such as northeast of Iran. For this reason, characteristics of the growing season such as onset, cessation, and length of the growing period should be analyzed. In this paper, we have calculated growing season characteristics of five locations in northeast of Iran using 45?years historical daily weather data and employed four approaches with different calculation methods. As temperature is one of the limiting factors in irrigation-based agriculture, the first approach has been based on this factor. The three remaining approaches were based on joint rainfall and temperature approach, rainfall, evapotranspiration, and temperature approach, and the final approach was based on availability of adequate water in 0.25?m of soil profile. The calculated onset dates using second and third approaches have been based on soil water balance model and relative evapotranspiration rate, and both were evaluated also to find whether the onset is a false start occurrence or not. The results showed that, when temperature was the only limiting factor, Bojnourd station with 197?days showed the longest growing season, however, when precipitation was used along with temperature, longest growing season (124?days) was obtained for Sabzevar station. The third approach which benefits from a water balance model and is similar to rainfed conditions showed the longest growing season with 147?days for Mashhad station. When adequate soil water approach was used, Bojnourd station with 255?days showed the longest growing season. Evaluation of false start of the growing season indicated the lowest probability of false start occurrence for Mashhad compared with other locations.     

Analysis of the climate change effect on wheat production systems and investigate the potential of management strategies

In an emergency, schools are responsible for the safety of students until they can be reunited with their families. This study explored emergencies (i.e. bomb threat, a flood, and an earthquake) in three case study schools in New Zealand. Within each case, a selection of stakeholders (i.e. school leaders, staff, and parents) shared their experiences of responding to emergency events in the school. Lessons from participants’ experiences established factors before, during, and after an emergency that contribute to an effective response. Foremost among those factors was the importance of prior preparation. The study also identified recurring response activities, irrespective of emergency type, which enabled the development of a six-stage model of an effective school-based emergency response. The stages are: (1) Alerts; (2) Safety behaviours; (3) Response actions; (4) Student release/Family reunification; (5) Temporary school closure; and (6) Business as usual. The present study contributes to our understanding of research investigating how schools respond to emergencies and therefore seeks to enhance school safety efforts.     

Time trend analysis of some agroclimatic variables during the last half century over Iran

Theoretical and Applied Climatology - We assessed the trends of precipitation, maximum and minimum temperature (Tmax and Tmin), diurnal temperature range (DTR), water requirement of autumn-planted...     

Sensitivity analysis of monthly reference crop evapotranspiration trends in Iran: a qualitative approach

Theoretical and Applied Climatology - The main objective of this study was to analyze the sensitivity of the monthly reference crop evapotranspiration (ETo) trends to key climatic factors (minimum...