جستجوی مقالات مرتبط با کلیدواژه « climatology » در نشریات گروه « جغرافیا »

For this purpose, the data of 13 climatic variables in 14 synoptic stations in a period of 44 years (from 1977 to 2020) used and a 13x14 matrix (rows; climatic elements and columns; number of stations) was created. In order to generalize the station data to the area, a grid with 15x15 km pixel was formed in central Iran and a matrix with dimensions of 446x15 (rows; digital pixel and columns; number of stations) It was found that the basis of the calculations will be factor analysis with varimax rotation and cluster analysis with Ward integration. The results of measuring the relationship between altitude and climatic variables indicate that in Central Iran, there is a direct and significant relationship between these two factors. However, due to the influence of local and macro-scale climatic factors, this relationship is not the same throughout the area and sometimes creates climatic nesting. In addition, the results showed that the 4 main and effective factors that make the climate of central Iran are: precipitation, temperature, humidity and dust storm. These factors explain 86.2 percent of the climatic behavior of this area. So that the rainfall with 35 percent is the most important climatic element in this area, which often dominates in cold mountainous regions and high altitudes. The temperature is 27.3 percent in the central deserts and the sides of Lut desert in Kashan, Khourbiabanak, Lar and Bam. Humidity is effective with 15.3 percent in parts of hot and humid southern areas in Baft, Abadeh and even cold and humid northern areas in Daran, Isfahan. Dust storms with 8.8 percent are the least effective factor in the climate of central Iran, which are scattered in Khourbiabanak, Bafaq, Yazd, and Kashan

Coordinating buildings with climatic conditions and saving energy is one of theimportant goals of climate design. Jolfa city has a relatively cold and dry climate dueto being located in a special geographical location, topographic conditions and climatesystems affecting the region. Is. So that the air temperature in the coldest month of theyear reaches -20 degrees Celsius and in the warmest month of the year sometimesexceeds 44 degrees Celsius. Therefore, bioclimatic conditions have a special status, so it is necessary to study the climatic conditions in relation to design to establish buildings in the cold seasons of the year to reduce the relevant problems. The mainquestion of this article is what effect do the specific climatic elements of Jolfa cityhave on the architecture of this city? The method of this article is a descriptive-analytical one in which an attempt will be made to study and evaluate the humanbioclimate of Oshbin Jolfa using the bioclimatic index of tissue comfort criteria (Pen Warden) and Algi. Using the synoptic meteorological data, the bioclimatic situation ofJolfa city was examined. To do this, meteorological statistics were used over a 27-yearperiod (from 1985 to 2012). The data were analyzed using experimental methods suchas Mahan, Gioni, Pen Warden, Algi and the Climate Need Calendar with the aim ofachieving the correct principles of climate design, the results of which provide solutions based on the study of the lunar climate. The year of the year and the comfortof human beings have been according to these indicators, including the establishmentof buildings in the direction of south, southwest and southeast

The enemy's first goal is to attack and invade a country in its military centers and military installations Passive defense is a set of plans, designs and actions that reduce vulnerability to enemy threats. Therefore, an approach to organizing military centers in a country leads to the establishment of these places in such a way as to provide maximum security and defense capabilities to the country. Locating is an activity in which specific capabilities and abilities of the region are appropriate for the existence of adequate land and its relationship with other urban and rural applications to select the appropriate location for the desired purpose. The purpose of the present research is to find suitable and optimal locations for military garrison locations in East Azarbaijan Province with a climatic approach. To do this, the GIS and the network analysis process were used and nine points were proposed for the military garrison to be located.

Lightning is a sudden electrostatic discharge during an electrical storm between electrically charged regions of a cloud (called intra-cloud lightning), between two clouds (CC lightning), or between a cloud and the ground (CG lightning).This phenomenon is one of the most important featureswhich are associated with extreme storms and seize the life of about 2,000 people in the world each year.The occurrence of lightning is related to the cloud microphysics in the mixed-phase layer becauselightning is frequent in convective clouds that contain many large hydrometeors in the mixed-phase layer.Also, air on the windward side of a mountain is forced to rise; anditoften leads tothecloudand lightning.In fact, lightning activities are highly variable on many spatial and temporal scales, and to some extent depend on the local convective regime.Lightning activities are not registered in the synoptic stations, but the thunder day statistics determined by human observers and compiled by the World Meteorological Organization (WMO) are one of the best sources of proxy information concerning lightning activity worldwide.Lightning day might include more than one hundred events; therefore, it cannot be a good representative for the lightning activitywhilethese stationsdo notshow offa good distribution.Accordingly, using remote sensing technology can be accurately measured lightning activity. Several space borne instruments have measured the global distribution of lightning one of which is Lightning Image Sensor (LIS).In this paper, diurnal, spatial, and temporaldistribution of the lightning phenomenon in Iran werestudied using LIS data.
Study Area: Iran, with an area of 1,648,195 km2 is located in the southern part of the temperate zone of the northern hemisphere.It is situated between 25° and 47°northern latitudes, and 44° to 63° eastern longitudes.This area is generallymountainous and semi-arid.The lowest area is 28 m lower than sea level located on northern Iranand its highest peak is Damavand with an altitude of 5,671 m/ASL.Existence of this diversity in roughness of the ground causes different climatic characteristics in various parts of the country.
Material and Two satellite-based lightning sensors have been successfully used by NASA since April1995. The sensors can detect the total lightning activities (cloud-to-ground flash and intra-cloud flash) on a global scale. One of these sensors is Lightning Image Sensor (LIS) which was launched on November 28, 1997 aboard the Tropical Rainfall Measuring Mission (TRMM). The LIS sensor detects lightning with storm-scale resolution of 3∼6km over a region of 600km×600kmof the earth’s surface. The LIS circles the earth with a velocity of 7km·s−1, and observes a point on theearth or a cloud for about 90s. This short sampling time during the satellite overpass limits the data usage for forecast and requires several years to compute high resolution climatology. Nowadays, LIS has collected lightning measurements for over 16 years making possible the compilation of total lightning climatology maps in high resolution such as 0.250 and 0.100 of horizontal resolution. In this paper, diurnal, spatial and temporal distribution of the lightning phenomenon in Iran werestudied using LIS data. Some geoprocessing functions in ArcGIS were applied tocalculate statistical values and to identify the locations of statistically significant lightning clusters. For generalizing geographic locations of lightning occurrence to an entire area a Kernel Density Interpolation estimator was introduced. Basically, a Kernel density tool calculates the density of point features such as lightning occurrence locations in a radius searcharound all similar features. Conceptually, a smooth, curved surface is fitted over each lightning flash pointincidentin Kernel density procedure regarding all observations. The surface value is highest at the location of the occurrence point and diminishes with increasing distance from the point, reaching zero at the search radius distance from the point. In practice, the density rate at each output raster cell is calculated by adding the values of all the Kernel surfaces where they overlay the raster cell centre, based on a quadratic Kernel function.
The result showed that diurnal cycle of lightning display a local maximum in flash rate in early afternoon (between 12 and 15 local time) and local minimum in flash rate in early morning to late morning (between 01 and 11 local time). Monthly variation of lightning indicated that maximum frequency of lightning occurs in April whereas the minimum happensin January and September. Annual distribution of lightning data indicated that the maximum frequency of lightning coincides with mountain areas. A majority of the lightning activities over the mountain region occurs primarily in southern slopes ofthe mountains. More specifically, this maximum occurs over the south and southeast facing slopes of the mountainous areaslikeZagros, Alborz, Binalud, Barez, etc. Western and south-western slopes of the Zagros Mountains have the highest rate of annual lightning in Iran.Central regions of Iran have the lowest frequency of lightningwhich are generally flat and arid.
The result of Kernel density function showed that distribution of lightning in January, November and December are alike and maximum density of lightning occurs in southwest of Iran (between Khozestan and Lorestan provinces). The maximum density of lightning in February, March and October are also in southwest of Iran but the lightning occurred in a wider area. The peakfrequency oflightningactivityoccurs inApril and Mayanditsspreadismuch more thanother months. In these months, west, southwest and northeast of Iran have maximum frequencies of lightning. In June, July, August and September, the distribution of lightning activities are different from other months and the maximum density of lightning are in southern Kerman, Sistan and Baluchestan and some areas of Hormozgan province.
Although lightning activity occurs in all regions, it appears that some areas havemore favorable conditions for the occurrence of this phenomenon. This study investigated diurnal, spatial and temporal distribution of lightning activity with 16 years (1998–2013) of LIS.The results provide valuable information on the distribution of lightning activity in Iran, sinceno study had been carried outbefore the distribution of this phenomenon in Iran.Results of diurnal cycle indicated that there was a marked daily distribution of lightning frequency during the afternoons peaking between 3PM and 5PM hours. These results nearly match the pervious findings; in such studies it was shown that all maximums in lightning were observed during the afternoons between 3pm and 7pm (EST). The increase in storms during this period is primarily due to the proliferation in energy provided by the sun during the warmer spring and summer months. The monthly distribution of lightning showed a distinct tendency indeed for all lightning to occur during March to May.The increase instorms during this period is primarily due to the increase in energy provided by the sun during the warmer spring. The result of lightning distribution analysis indicated that a majority of the lightning activity over the mountain region occurs primarily over the southern slopes ofthe mountains. Western and south-western slopes of the Zagros Mountains have the highest rate of annual lightning in Iran. Maximum frequency of lightning in January, February, March, October, November and December are also in this region but in warm season (June, July, August and September), south and southeast of Iran have maximum frequency of lightning activity.

The Zagros Mountains present a great potential for paleo-environmental studies for the reconstruction climates of the late-Pleistocene and Holocene. Iranian Zagros Mountains form the northeastern boundary of the Fertile Crescent and Separating the Mesopotamian lowlands from the Iranian Plateau. It is postulated that Near East was a place for the domestication of plants and animals، and the question has been raised as to how far changes in climate and vegetation have stimulated the evolution of food production. So investigation of paleo-environment of the Zagros Mountains as a part of the Near East is very important. There are some major climatic systems over the Zagros Mountains which are very sensitive to the abrupt climate change. Change in the positions and intensities of these systems during the Quaternary could have influenced the paleo-environment of the region. In order to reconstruct these changes، evidence of Quaternary climate change in Zagros is necessary. Previous paleo-environmental researches have revealed general future of the paleo-climate of the Zagros Mountains during the late-Pleistocene and Holocene but yet more researches are needed to reveal details of past climates of Zagros. Hashilan Wetland located in central Zagros، containing 12 m of sediment dating back into Pleniglacial time، is a suitable site for better understanding both paleo-climate and palaeo-environment of the not only Zagros region but also Near East during the last 40000 years. Here we used pollen analysis for reconstructing the past vegetation and paleoclimate of Hashilan Wetland located in Kermanshah province. Study Area: Hashilan Wetland is located in the vast plain of Hashilan in the Kermanshah province، Central Zagros. Formation of this type of wetland in such areas is very notable. The wetland has a special form، so that there are many small islands (approximately 110 islands) on the surface of one side of the plain and strakes of water exist among these islands. Main input of the wetland is Sabzali spring in the north part of the plain. The plain is surrounded in both west and north by Khurrin Mountains (2500 m) and in south by Vais Mountains (1800). The study area is located in steppe region of the Zagros and oak trees do not exist in the catchment of the wetland. Asteraceae، Poaceae and Cyperaceae are the most common plants of the wetland. In the modern climate of the area more precipitation occurs in the cold seasons and summers are dry and hot.

In the spring of the 2012، a 12 meters long sediment core was retrieved from Hashilan Wetland using Russian corer and here we performed pollen analysis on its 5 uppermost. In order to pollen analysis، the core was sub-sampled in 20، 10 and sometimes 5 centimeter intervals. Samples were processed according to Moore et al (1991) with a modification. Lycopodium tablets were added to calculate the pollen concentrations (Stockmarr 1971). The samples were treated with a sequence of 10% KOH (to break up sediment and remove humic acids)، 10% HCl acid (to remove carbonates)، 48% HF acid (to remove silicates: sand، silt، clay)، acetolysis (to remove some organic matter، cleaning and staining the surface of the pollen grains)، and tertiary butanol. Finally the sample were stored in silicon oil and mounted on slides for examination using a light microscope at 400× magnification. Pollen determination was performed using some pollen atlases such as (Moore et al.، 1991; Demske et al.، 2013)، pollen reference slides of palaeo-climatology laboratory of geography faculty of university of Tehran، and pollen and spore websites of Arizona and Australia. More than 300 total land pollen grains were counted for each spectrum except for the spectra of 185، 195، 225، 235 and 245 cm which had exceptionally low pollen concentrations. Pollen of aquatic plants، riparian and pine trees were excluded from the total pollen sum. Pollen percentages were calculated in Polpal Excel and the pollen diagrams were created by Polpal Diagram (PP Diag.) software. Three radiocarbon dates were obtained at the Poznan Radiocarbon Laboratory from 80، 755 and 1193 cm depth of the core which respectively those ages are 2100 ± 25 BP، 31500 ± 300 BP and 39500 ± 700 BP. These three AMS dating showed the core is belonging to the Holocene and Late-Pleistocene.

After the experimental stages and counting the pollen grains، the pollen data was displayed in the form of pollen diagrams. The pollen diagrams were zoned using constrained cluster analysis by sum-of-squares (CONISS) as an option within Polpal software. The pollen diagrams were zoned into 8 pollen assemblage zones (PAZs) and these PAZs were interpreted from viewpoint of palaeo-climatology. H-1 to H-5 PAZs belong to the late Pleistocene and H6 to H8 PAZs belong to the Holocene. Late-Pleistocene represents treeless vegetation and is marked by steppe plants such as Artemisia، Chenopodiaceae، and Poaceae. The Late-Pleistocene has divided into 5 pollen assemblage zone (PAZ) based on changes in frequency of these major steppe plants. With the onset of the Holocene steppe vegetation has changed into pistachio-oak savanna and Poaceae increased abruptly at the expense of Chenopodiaceous and Artemisia. Furthermore، Aquatic plants have increased and riparian plane trees have appeared. Drought tolerant shrubs of Amygdalus have been a component of the vegetation cover in the early Holocene. In this time، the wetland has been desiccated sometimes. In spite of these changes the oak trees could not expand and a limiting factor prevented the expansion of these trees. Gradually، frequency of the oak trees has increased and ultimately in the mid-Holocene open oak woodland has expanded and its frequency remained constant until now.

Hashilan Wetland has a great potential for high-resolution paleonological investigation for the reconstruction of the vegetation and climate change during the Late-Pleistocene and Holocene. A pollen record prepared from the Hashilan Wetland shows some major changes in vegetation and climate. The general patterns of vegetation change are consistent with previous studies from western Iran and southeastern turkey (van Zeist and Bottema 1977; Wick et al.، 2003). The late-Pleistocene Artemisia- Chenopodiaceae steppes imply a cool، dry climate. Based on some minor changes in the frequency of these steppe plants، PAZs of H1، H3 and H5 are drier than H2 and H4. The palynological evidences of vegetation change in the early Holocene such as: (I) development of drought tolerant pistachio trees and Amygdalus shrubs، (II) limitation of oak growth، (III) growth of riparian trees along water bodies، and (IV) desiccation of the wetland imply a long dry season in the warm period of the year which due to significant increase in temperature the precipitation-evaporation ratio (P-E ratio) has became strongly negative during this dry season. So we concluded that in the early Holocene precipitation has been limited to cold season of the year and duration of the hot، dry season has been longer than today. Gradually by development of precipitation duration، the hot، dry season has become shorter. These changes in seasonality led to rise in precipitation-evaporation ratio and climate amelioration. This new condition allowed oak trees to expand and oak woodland increased at the expense of pistachio-oak savanna in the mid-Holocene. As we see in the pollen diagram (figure 2) constant frequency of oak woodland since the mid-Holocene until present indicates that modern climatic regime of the central Zagros has been established from the mid-Holocene. Paleontological evidences reveal that human interferences have affected the environment and vegetation during last millennia. More dating are required to high-resolution analysis of the whole core in order to reveal details of changes in vegetation and climate during both late-Pleistocene and Holocene.

Sunnpest is the main pest of wheat and it is the most important plant medical problems in Iran. In this research, we analyzed the relationship between temperature characteristics (Min, Max, Ave Tem Peratmre, as wall as the number and degree of frost), precipitation and drought-wet years with attacking date in Isfahan during the years 1999-2000 to 2009-2010. The research results showed that the attacking date of sunnpest is depended on the climatic conditions before attacking date of the pest. If the Autumn and Winter temperatures at are higher than the average temperature, and S.P.I. indices are normal, the sunnpest attacking date begins to take place sooner. There is a strong and significant correlation between the yearly and seasonal frost numbers, different frost thresholds, minimum, maximum and average temperature, and the attacking dates of sunnpest at 0.05 and 0.01 significant levels. The R2=97 % shows that 97% of variance depended variable (attacking dates of sunnpest) corresponds with the independed variables (min. and max. temperature, total precipitation during the cold period (Autumn and Winter), and the number of annual frost). This shows that these parameters are important in predicting the attacking date of sunnpest in the regression model.

Today, airports are not complexes like passenger terminals and large railroad stations, with cars and passengers on the one side, and on the other side the planes, but airports have gained a multi-purpose existence.
Nowadays, by increasing the capacity and efficiency of the airports on the one hand, and paying attention to issues such as sustainable development and environmental protection on the other, consideration of geographical factors in the location of airports is deemed very important, as in developed countries It receives a great deal of attention. Among the geographic factors affecting the location of the airport, the climatic and topographic components play a greater role, as they have a great influence on the efficiency and activity of the airport. The main objective of this paper is to assess the strengths and weaknesses of the locating process of the country’s airports based on climatic and topographic factors.
To achieve this goal, secondary and field methods have been used. Based on the findings of this research, insufficient attention to climate and topographic factors in the location of airports in the country has led to a decrease in the safety and health of the flights and, in some cases, severe and fatal accidents. This Situation can be improved by correction of existing deficiencies and the application of geographic factors in future plans.

Today, airports are not complexes like passenger terminals and large railroad stations, with cars and passengers on the one side, and on the other side the planes, but airports have gained a multi-purpose existence.
Nowadays, by increasing the capacity and efficiency of the airports on the one hand, and paying attention to issues such as sustainable development and environmental protection on the other, consideration of geographical factors in the location of airports is deemed very important, as in developed countries It receives a great deal of attention. Among the geographic factors affecting the location of the airport, the climatic and topographic components play a greater role, as they have a great influence on the efficiency and activity of the airport. The main objective of this paper is to assess the strengths and weaknesses of the locating process of the country’s airports based on climatic and topographic factors.
To achieve this goal, secondary and field methods have been used. Based on the findings of this research, insufficient attention to climate and topographic factors in the location of airports in the country has led to a decrease in the safety and health of the flights and, in some cases, severe and fatal accidents. This Situation can be improved by correction of existing deficiencies and the application of geographic factors in future plans.

One of the most important problems in the field of agricultural activities is water scarcity or water resources issues. In this context, only those countries that utilize scientific methods in supplying the water needed for crops have been able to overcome these problems. In this study, we tried to evaluate the application of meteorological studies in estimating the water requirements of the desired crops (wheat and potato) in Tabriz region during different stages of growth. For this purpose, the ETP (plant evapotranspiration potential) was first determined using long-term statistics, and then, using the FAO organization tables, the plant coefficients for each of the crops were extracted. Finally, in order to plan for the supply of water resources, the effective rainfall in the region has been studied, and by subtracting the amount of water required from effective rain, the amount of water deficiency in the region has been identified.