نشریه اطلاعات جغرافیایی (سپهر)
پیاپی 87 (پاییز 1392)

Direct influence of precipitation on human life and the role it plays in the development of different countries have resulted in an increase in using methods and algorithms for estimating precipitation. A few decades ago, traditional methods were used for predicting precipitation. Then, the presentation of meteorological satellite revolutionized this field. Considering the high dispersion of weather stations and rain gauges in developing countries like Iran, free access to images taken by sensors like AVHRR and MODIS is an appropriate opportunity to compensate these deficiencies. We can estimate the volume of water vapor ready to be transformed into precipitation using satellite images, water vapor absorption bands and thermal bands in any time, space, and scale. The algorithms used to estimate precipitation in satellite images are classified into three types- infrared, visible, microwave and a combination of the first two types-based on the sensors’ wave length. Methods based on infrared and visible waves have a good spatial and temporal resolution, while microwaves-based methods measure precipitation directly. Yet, these techniques contain many weaknesses, especially in low earth orbits. Combined techniques are used to compensate these weaknesses. Microwave images are not receivable in Iran, thus we cannot take advantage of microwaves and combined methods. As a result, the present article focuses mainly on visible and infrared wave length.

Regarding the level of technological development industrial and postindustrial countries have reached, it is hard to believe that once in this planet human beings could not even satisfy their basic needs, such as building a safe shelter. In the third millennium, access to information has resulted in the development of technology and has changed human life to a large degree. Nowadays, international power is a consequence of countries capabilities in exploiting their geographical environments; the way countries exploit their geopolitical situation creates an opportunity to appear powerfully in international realms. Superior technology is an important factor in securing countries against attacks or threatening other countries in preemptive wars. Superpowers such as USA possesses technologies and developed systems such as HARP. HARP is a research project apparently used for investigating and exploring ionosphere layer and underground mines (using ELF/ULF/VLF radio waves). But in reality, “a project with star war technology” has been launched to complete building a new weapon. The present article takes advantage of a descriptive-analytic method and investigates HARP system using library and internet resources. This article aims to explore HARP system as a superior technology United States of America possesses and can use as a destructive or constructive weapon. Results indicate that the system has not been used for constructive purposes.

Climatic zoning and identifying influential factors and elements in each zone are considered to be the most important factor in environmental planning. Climatic research and climate map can be used in large, medium, small and local scales. Related researches in Kurdistan have been very limited. The present article investigates climatic features of Kurdistan province in a 30 year statistical period using weather stations and Information Technology System software. After qualitative and quantitate control of meteorological data and elimination of statistical deficiencies, two important climatic elements (temperature and precipitation) were investigated across the province. Afterwards, isothermal and isohyetal maps and the correlation between temperature and rainfall with altitude were produced using inverse distance weighting method. Conformity of temperature and rainfall with digital elevation model shows a significant inverse correlation between temperature, rainfall and altitude. So that with an increase in altitude, temperature and rainfall decreases. De Martonne and Embergent methods were used for climatic classification of the province. In De Martonne classification, Kurdistan province was divided into four climates, i.e. arid, Mediterranean, humid and very humid. Embergent method classified the area into four climates, i.e. cold semi-arid, highland climate, cold semi-humid and cold humid. Finally, zoning process was performed in GIS environment and inverse distance weighting method was used for spatial interpolation and spatial data analysis to produce Kurdistan climate map. Resulting zoning maps indicates that semi-arid and Mediterranean climate are dominant and only a small zone in the western parts has humid and semi-humid climate.

Multispectral remote sensing data is an important informational resource used for recognizing surface changes. To the extent that today, remote sensing images can provide the latest information on vegetation and land use. The present study seeks to detect changes in vegetation and land use across Taleqan area in time period between 1988 and 2007 using remote sensing. Taleqan is located in Alborz province (Karaj) and Taleqan basin. Results indicate that area dedicated to gardening has increased to 2.28 percent, while agricultural lands have faced a 15.05 decrease. On the other hand, rangelands have decreased to 16.25 percent and bare lands have increased to 28.08 percent. The most important change happened with the construction of Taleqan storage dam in 1999 which submerged more than 1100 hectares of the most desirable lands in the area. Since bare lands have increased and rangelands have decreased, thus from an ecological viewpoint it is possible to say that vegetation is degrading. Therefore, in order to restore bare lands, performing rangeland plans and avoiding unplanned changes can be suggested.

In order to investigate the dominant patterns in atmosphere during the occurrence of dust storm in Khuzestan province, time and date of occurrence were exploited from 11 synoptic stations during 1997 to 2006. Afterwards, 19 dust storm were exploited which involved at least 6 stations and lasted at least for 2 days, and their related 00, 850, 700 hectopascal pressure level maps were explored. The results identifies 4 dominant patterns during the occurrence of dust storm in Khuzestan province: a) Pakistani low pressure system at ground level, trough at 850 and 700 hectopascal level, b) low pressure system at ground level, trough at 850 and ridge at 700 hectopascal level, c) low pressure system at ground level, ridge at 850 and 700 hectopascal level, d) dynamic Mediterranean low pressure and Siberian high pressure system, trough at 850 and 700 hectopascal level.

With the development of cell phone technology, especially third generation and IP mobile technology (G3), the computational capacity of cell phones has increased and became more powerful. This technology provides us with a new method for solving problems in oil fields, which takes advantage of real time GIS data, and its dynamic capability, while it does not require field operations. The present article studies J2ME platform technologies, SVG (scalable vector graphics), and mobile data transfer technology thoroughly and proposes a framework for GIS mobile services in oil fields and also a plan for key technologies which altogether creates the technical foundation for building oil fields.

Cluster analysis and trend line comparison were used to investigate the trend of circadian changes in tropospheric ozone in Isfahan. First, we categorized similar changing patterns in the statistical period using cluster analysis. In this regard, circadian changes of ozone were divided into four groups (daily maximum, night minimum, daily increase trend, night decrease trend). Validity of these categories was tested using ANOVA. In this way, assigning 646 days (88.3 percent) to the aforementioned category was confirmed in 95 percent confidence level. In Lale station, 94.6 percent of days in each year followed daily increase and night decrease trends. Moreover, investigating mean trend lines and seasonal and annual limits shows that ozone possesses a regular trend in circadian changes. This regularity is more apparent in Lale station.

Availability of spatial information and decision making based on the analyses performed by geographic information system are among the fundamental components of sustainable development. For this purpose, an organization or more is responsible for the production of spatial information in different countries. In recent years and in the era of information technology and public access to internet, creating a platform for providing spatial information in cyberspace is considered to be much more important. As a result, the new generation of spatial information products have the capability of being presented and disseminated in the cyberspace. Some organization have proceeded and not only pioneered for dissemination of spatial information in the Internet, but also have provided users with the possibility of performing some basic spatial analyses. In developed countries, these possibilities are available and spatial information is being provided in cyberspace. In order to take advantage of developed countries knowledge and experience in producing and disseminating spatial information, it is necessary to evaluate the procedure of producing spatial data in these countries. USGS in United States of America and Survey Ordnance in UK are responsible for producing spatial data. Therefore, the present article investigates the procedure of producing spatial information.

The present article aims to review the overall appearance of Chahar Mahal va Bakhtiyari bio climate and the influence of climatic parameters on human comfort using Terjang method. The aforementioned element is applicable in many different fields, such as urban engineering, medical science, architecture, tourism, etc. In order to reach this goal, we prepared bioclimatic zoning maps on a monthly scale using Terjang zoning method and applying parameters of temperature, relative humidity, sunshine and wind hours across 8 synoptic and climatologic stations in a 50 year period (1958-2007). To produce these maps using Terjang method, we applied statistical-graphical software, elevation gradient, and especially buffering soft wares such as Arcgis 9.2, Autocad map. Data analysis in the specified period detected monthly bio climates in Chahar Mahal va Bakhtiyari province. So that in February, just one bio climatic area (k2) is sensible across the province due to external climatic elements’ domination, while in April combined influences of external and local elements creates three bio climatic types (4W, 3M, 2C) and the influence of local elements creates two bio climates in summer (4W, 5H). In December, influential elements change and monthly bio climates return to just one bio climate (2k, very cool with cold nights -2/-3).

Human beings have always been interested in reaching a better understanding of their environment and its phenomena. They have experienced different methods to achieve an understanding of land resources, and in this way they have reached new technologies. Using air and space has always been one of their goals in this regard. With the first controllable flying airplane in about a century ago, the first aerial photo was taken from the ground and remote sensing was born. With the outbreak of First World War and military use of aircrafts, the necessity of applying aerial photos in information collecting and identifying land resources was recognized. The second World War followed by the Cold war on one hand, and technological developments on the other hand resulted in the emergence of exploratory airplanes in aviation and remote sensing realms. The present article investigates and reviews the most important exploratory airplanes and their applications in remote sensing. Despite many satellites that have been launched with different sensors, equipment and resolutions, results indicate that still many geographic studies take advantage of exploratory airplanes.

The importance of climatic effects on architecture necessitates exclusive studies and researches, especially in our country which possesses climatic diversity and diverse architecture. Climate can be defined as an organized collection of vegetation, precipitation, heat, temperature, and sunlight in the area. In order to identify local architectural structures and increase the level of comfort among its inhabitants, we inevitably have to consider local climatic features. If we reach an awareness of climatic elements and direction of buildings in Shiraz, recognition of appropriate materials and choosing appropriate size for windows, we can think of measures so that its inhabitants feel comfortable and can supply the necessary cooling and heating for their house. Information collection was performed in the form of a secondary, documentary and survey research.

With the increasing urbanism in many regions of the world, the insufficiencies and problems of urban life have increased especially in developing countries. Increasing crime and insecurity in cities can be identified as one of these problems. Many sociologists and urban planners agree on the role of urban texture and urban environments in preventing and decreasing crimes and have proposed related designing principles and necessary guidelines. The present article clarifies the role of urban spaces in crime prevention and in creating a secure environment for citizens, using a descriptive-analytic method, secondary resources and different theories proposed by sociologists and urban planners.

Exploring the changing processes of land forms is considered to be one of the key topics in geomorphological studies. Nowadays, geomorphological studies analyzes and clarifies geomorphic forms and processes at ground level. This shows the dominance of a systematic view in this field. In systematic view, geomorphic analyses are performed based on the relation between land form and process. Geomorphologic threshold is one of the key concepts in systematic theory and thus is of significant importance in geomorphology. It indicates borderline situations during the occurrence of changes and shows temporal changes. The present article is based on secondary research and exploits theoretical and applied concepts related to thresholds, seeking to reach a balanced systematic analysis. It tries to study geomorphologic thresholds and classifications using different Persian and English resources. Moreover, we propose a short overview of some geomorphological issues, such as gully erosion, alluvial fan and river systems. Results indicate that geomorphic thresholds separates different situations of a system and are thus distinguishable. In fact, occurrence of a threshold changes the dominant processes in a geomorphologic system. This concept shows the situation in which a process operates to establish a new balance in the system. Siyum classifies geomorphic thresholds into two categories: 1) Internal which is related to the inside of a geomorphic system and 2)external which is under the influence of external variables such as climatic and tectonic changes.