Physical Geography Research
Year:2014 | Volume:46 | Issue:3|Papers Count:8

Introduction: In comparison with fossil fuels which pollute the lower layer of the atmosphere, use of wind energy has many environmental and economic advantages. Wind is a clean and renewable energy resource and use of the energy in the recent decades has been welcomed so much in the world. Energy plays an important role in the development of each society. All different activities including housing, transport, industry and agriculture may be dependent on this source of energy. The use of clean and renewable energy such as wind has environmental advantages compared with fossil fuels. The increase of population and demand for energy has caused that wind energy potential is considered as an alternative source of energy. Wind speed is the most important parameter of the wind energy. This is used in the analyses relating to this energy because wind power has a cubic relation with wind speed. ...

Introduction: Sometimes, the showers of the northern coast of Persian Gulf are very heavy and disastrous and hazardous. They cause heavy damages to the people and the infrastructures of the region. Therefore the economic development of the area is highly dependent upon the identification of the cause and management of these hazardous phenomena. The main factor controlling the surface climate is the pressure patterns of the atmosphere. Therefore, the main objective of this study is to identify the synoptic patterns of these showers. Thus, we can predict their occurrence and mitigate their damages. The successful achievement is dependent on two major factors: (a) the methodology of pattern recognition and (b) identification of actual patterns. Most of the models of pattern analysis are linear while the atmospheric processes are non-linear in nature. Any methodology that neglects the nonlinear nature of atmospheric phenomena would result in inadequate classification of atmospheric circulation. For this reason, this research has used the nonlinear models of classification algorithms to identify the pressure patterns of the heavy rains of the area.

Introduction: The recent developments in computer sciences have considerably affected the application of new methods in climatology. Especially these new technologies have increased the usage of the new methods in climatic classification. The previous classifications were calculated only based on insufficient number of climatic factors. For example, the well-known classification of Koppen was based on precipitation and temperature. In contrary to such threshold-based classifications, the implementation of multivariate statistical techniques has allowed to classify climate without predefined thresholds by grouping individual objects by Jacobeit (2010) methodology. Application of multivariate analysis in climatology is conducted by Yarnal et al (2001).

Introduction: Climate change has played an important role in all aspects of human life. Therefore, climate predictions in atmospheric general circulation models (GCM) will have particular importance. In this study, downscaling by A1B scenarios, IPCM4 and BCM2 of atmosphere general circulation models in LARS-WG model are used for analysis of climate change impacts on maximum and minimum temperature, solar radiation and precipitation. The data have been gathered from 7 Synoptic stations in province of Southern Khorasan. For this purpose, assessment process of simulation and observation data are conducted by three steps, including calibration, validation and modelling. To evaluate the agreement between the observed and simulated data, two indexes were used; Root Mean Square Error (RMSE) and Coefficient of Determination (CD).

Introduction: Surface temperature and cropping intensity maps are the most important components of the water requirements in basin scale and are also the most difficult to measure. Conventional methods are very local, ranging from region to field scales. Estimates of the Surface temperature and crop density over the entire area, especially for irrigated areas, are essential. Today, surface temperature, actual cropped area, crop pattern and cropping intensity under different conditions can be estimated by using satellite data and Remote Sensing (RS) techniques. In order to obtain the surface temperature and cropping intensity, a set of satellite images have been used. Estimated temperatures have been compared with measured values at 5 cm soil depth in meteorological stations.

Introduction: The changes in behaviour of climate and meteorological parameters are closely related to changes in atmospheric circulation. The analysis of historical atmospheric troposphere circulation is critically important to global and regional climate change and extremes with regard to its dynamical features. The circulation changes are manifested by a gradual reduction in high-latitude sea-level pressure, and an increase in mid-latitude sea-level pressure associated with one phase of the Arctic Oscillation (a hemisphere-scale version of the North Atlantic Oscillation. Recent observations have found that the tropical belt running around the equator has grown wider, and has expanded by around 2o to 5o latitude and into the adjacent subtropical regions since 1979. Global greenhouse gas emissions contribute to expansion of the tropics (about 0.05o per decade) in the northern hemisphere tropics.

Introduction: In the modern era of communication, by increasing population the resources would be relatively scarce. Therefore, in order to deal with environmental serious problems and complex humanclimate relationship in all dimensions of spatiotemporal and land use planning and programming practices, the climatic zone map was a sustainable developmental tool in the study area.

Introduction: Planting date plays main role in crop performance. Planting date through correspondence with the climatic elements affect vegetative and reproductive growth and ultimately affect the quality and quantity of crops. Among the climatic elements, temperature and day length are more important under irrigated condition. It is necessary to mention that the majority of crops cultivated in Iran are indifferent to day length. The temperature is the most important element in controlling their growth period. By using long-term weather data and related software such as Arc map we can determine the suitable planting dates for a wide area. Therefore, by eliminating field experiment and avoiding large amount of time and cost, much can be saved. The purpose of this study is to determine the best planting dates for spring safflower in different parts of Esfahan province in order to gain the maximum performance in any climatic zone.