The temperature as an indicator of heat intensity is one of the basic elements of knowing weather. The frost is a condition when the air temperature is less than 0 c Due to the geographical possition of Iran, spring is a season that plants resume a new life after leaving a pause in a periode of the growth. At the beginning of such a periode emerge of sudden cold cause loss bloom (in the case of openinig) or delay in a beginning of plant growth periode (Azizi,2002). Recentley with occuring climate chaos, one of the important climatic disasters which treats human and particularly different areas of the country are cold waves and sever frosts that in some years covers large area of the country.
Surface data including minimum daily temperature of the days of 29 to 30 and 25 to 26 of march of 2003 and 2005 in 9 meteorological synoptic stations in the area of north west of Iran in table (1) was collected from meteorology organization then the days of cold waves in the above mentioned time periode, were analyzed. In ordet to analyse the synoptic patterns, using ncep/ncar data, maps of sea level pressure ,combined of geopotential height and vorticity and temperature advection using Grads were drawn and analysed in the levels of 1000 to 500 hpa.
As it mentioned, during the time period, 29 to 30 and 25 to 26 of the march in 2003 and 2005, 2 clod system were located on the area of north west. In oeder to explain and analyze of synoptic patterns of mentioned period time, the absolute minimum temperature below 0 degrees celsius of stations in western Azarbayejan province were selected and maps of sea level pressure, combined of geopotential height and vorticity and temperature advection using Grads were drawed and analysed in the levels of 1000 to 500 HPA.
The results showed that in the time of occuring hazardous cold waves of 29 to 30 of march 2003 and 25 to 26 of march 2005 and analyzing the sea level map in the first day of cold wave with spreading the cold core high pressure from the eastern Europe and its location on north and east north of the black sea and its pentration from north west corner of the country covered most of the areas of the country.
Analyzing the combined maps of geopotential height and vorticity in the levels of 1000 and 850 HPA in the first day of occurrence of cold, generaly faced with huge anticyclonic development . But in the levels of 700 and 500 HPA , the under studied area was in the south trough of the obtained cold core of the low height locating in the cetral Asia. But on the day of cold peak, high pressure core was exactly located on the under the studied area . Also in the upper levels of atmosphere with locating the back of the trough cumulated of cold air of upper width on the sea level high pressure centre while strengthening the lower levels anticyclonic flows, led to intensifying cold and frost in the west Azarbayejan province.
Positive and negative vorticity maximum cells, also conformed the intensity cold circulation flows on the north half of the country in anticyclone and cyclone centers in order. Also analysing the temperature advection in the levels of 1000 to 500 HPA, direction and temperature intensity exactly followed geopotential height maps patterns.
Such that in the levels of 1000 hpA of the both cold wave analysed, the anticyclonic cold temperature adcection and northward is located on the north west of the Iran. In temperature advection maps of 29 and 30 march 2003 in 850 HPA in Azarbayejan province, the anticyclonic circulation is matches with sea level high pressure. But in the 2nd cold wave that’s occured on 25 and 26 march 2005, the north west area is between 2 antycyclonic circulation on Mediterranean and cyclon located on south of Russia that the directions of temperature cold flows is completely north ward in this level.
In the temperature advection maps of 700 and 500 HPA, the Azarbayejan province is in the western edge of central Asia trough or south of Russia.
The results showed that with studying atmospheric motions and synoptic systems which create cold flows, we can prevent of spring late emergence cold wave destructive impact on agricultural products, energy consumption, and road accidentd by forcasting of these atmospheric conditions.
Frost is one of the sources of risk in agriculture which threatens the orchardists' performance and their security of products. The protection of cold-sensitive species of fruits against frost damage is an annual challenge in many growing regions of the world. Frost protection managerial behavior is the the first way to avoid or reduce the effects of frost damage to walnut trees. Application of active and passive methods of frost protection is effective under conditions of strong thermal inversions. However, most of studies on the adoption of managerial behaviors to environmental hazards usually ignore underlying psychological constructs that affect farmers’ decisions and behavior. Sepidan county is one the well-known regions of Fars province which is subjected to frost damage for its climatic nature. The amount of frost damage to walnut orchards of Komehr township, which is located in Northwest of Sepidan county is significantly substantial in recent years. The region is well-known for its walnuts and this product is the most important source of velliagers’ income. This research aims at investigating frost management behavior of walnut orchardists of Sepidan county, Fars province, Iran. The managerial behavior is composed of active and passive methods of protecting walnut trees to frost damage.
This applied study was based on descriptive correlational method. Data collection tools were structured questionnaires. The sample of this survey study was consisted of 90 orchardists of Komehr township. The sample orchardists were selected based on their vulnerability against frost. Structured questionnaires were used to collect information from a random sample of walnut orchardists that were interviewed. Face validity was confirmed by a panel of experts. And the reliability was confirmed by conducting a pilot study in Bardzard region. The calculated Cronbach’s alpha for the measures of the instrument were 0.53-0.82. Statistical package for social science (SPSS) in WINDOWS context was used for analyzing data. Coefficient of variation and cluster analysis was the most important analysis methods applied in this research.
Results revealed that active methods of frost protection includes burning fuel, tires etc., were the most common methods of controlling frost in walnut gardens. While using energy intensive practices (heaters, sprinklers) were shown the lowest rate of interest. However, orchardists' "perceived effectiveness", "perceived ease of use" and "perceived usefulness" of their active and passie controlling behavior was investigated. As it was shown by the results, orchardists' perception of effectiveness of the method of controlling frosts was in a low position. On the other words, they were not belived in the effectiveness of the methods. This was whilst, orchardists belived in ease of using the active and passive measures of controlling frost. They were noted that these methods had the potential of controlling damage to their gardens. Performing frost controlling methods was not easily applicable and garden's context was known as the most important barrier to performing the frost controlling behavior. To better understand orchardists' profile regarding to their frost protection behavior, cluter analysis was used. By means of this method, orchardists were categorized to two clusters: orchardists with convergent behavior with respect of frost protection protocol and divergent ones. Convergent group of orchardists (n=23, 25.5 %) were those who invested more on their gardens, used crop insurance supports, and more importantly they used lower levels of chemical products (poisons, fertilizers, etc.) on their gardens. On the other hand, divergent system of gardening regarding to frost protection pointed to the system of negative orientation towards rational thinking and behavior of gardening protection. These group of orchardist (n=67, 74.5%) were those who were performed eclologically dangerous methods of gardening regarding to use of pesticides, fertilizers and other chemical inputs. Low level of orientation towards crop insurance organizations and investment for the gardens were the most differtation factors for this group. However, results shed light on the difference of these two groups of orchardists regarding to their percievd effectiveness, ease of use and usefulness of frost protection methods. As it was shown by the results, frost protection- conevergent group of crchardists was significantly different from their divergent counterparts regarding their frost protection behavior and perception of ease of use and usefulness of frost protection methods. The aforementioned group of orchardists perceived frost protection methods easy to perform. From their viewpoints, these methods were useful in increasing crop yield, promoting its quality and controlling damge.
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