Showing 3 results for Interpolation
Professor Ghasem Azizi, , Leyla Sharifi,
Volume 17, Issue 47 (12-2017)
Abstract
Thunderstorms are major climatic events due to the significant effects and catastrophic consequences on humans and the natural environment. The researches have shown that the elevation and latitude factors are two variables that can affect the occurrence of this phenomenon. Therefore, the main aim of this study is to investigate the spatial analysis of the effects of lightning and its effects on the components such as elevation and geographic extent in Iran. Apart from this fact, firstly, the monthly data of thunderstorms occurrence in 118 synoptic stations of Iran, from 1991 to 2010 on a basis from the country's meteorological organization were obtained and GIS software was produced by the annual and seasonal maps of Iran. Then, for the spatial analysis of this climatic phenomenon, the method of landing statistics of the Kriging (Universal) method was to examine its seasonal and annual status. In order to better understand the effect of Thunder hurricanes from altitude and latitude using Curve Expert software, seasonal and annual charts, along with the correlation of each production, were analyzed. The results show that the highest annual thunderstorms occur in the northwest of Iran, and the least amount is consistent with the central and eastern parts of the country. In addition, according to seasonal analysis, although the station has the highest rate at 800 to 1,300 meters, the maximum occurrence of this phenomenon varies from 0 to 2200 meters in different seasons of the stations. The overall result shows that the factor of height is slightly correlated with the occurrence of the Thunder storm phenomenon and the highest correlation is due to the latitude factor.
Sayyed Mohammad Hosseini,
Volume 18, Issue 49 (5-2018)
Abstract
Precipitation is a climatic elements that have temporal - spatial distribution. In this research database of Global Precipitation Climatology Centre (GPCC) with a resolution 0.5×0.5 degree for 50 year is used, that was constituted with dimensions of 12800*600. Temporal data are on the columns and pixels (spatial data) located on the rows. The results show an increasing trend in spring and fall but in summer and winter precipitation trend has been decreased. The most amount of precipitation is located in the northern parts of the Black Sea and Mediterranean Sea, Southeast Asia, southern coast of the Caspian and Central Zagros Mountains. Most of Middle East (about %95) have not trend and only in some parts of Kazakhstan, Afghanistan, Pakistan ,central Iran, and areas in lower-latitude have positive trend and some East and northwest parts of Iran and some parts of Middle East also have decreasing trend of precipitation. The highest percent of area of precipitation trend gradient is 0 to 0.5.
Hamid Salehi, Muhammad Motamedi, Ezatollah Mafi,
Volume 21, Issue 61 (6-2021)
Abstract
The basis of climatic data is measurements taken at a predetermined chronological order at air monitoring stations, so all measured values of climatic elements can only be attributed to the point of measurement. Therefore, different interpolation methods can help a lot in estimating climate data in different places. The study area in this study is northeastern Iran, including the provinces of Khorasan Razavi and North Khorasan, and monthly summer temperature data were used for 21 synoptic and evaporative stations in the northeast belonging to the Meteorological Organization and the Ministry of Energy with appropriate distribution. The statistical period of 21 years (1997-1997) was considered as a common statistical period for all stations. Then, in order to compare the interpolation methods, several different methods, including ordinary kriging, spline, inverse squares and Thyssen were used by ARCGIS software. Comparing the deviations of the estimates from the measured data was evaluated by cross-validation. Then, in order to check the hypothesis of normality of the calculated errors in each interpolation method, the test thigh test was used and finally, to evaluate the best interpolation method, AHP method and Expert Choice software were used. The results showed that based on the root mean square error (RMSE) criterion, Thyssen, Kriging, inverse distance and spline methods were located, respectively. Based on the absolute maximum error criterion (MAE), the kriging method estimates the summer temperature better than other methods. According to the MBE standard, the kriging method is better than other methods and can be used for temperature interpolation. According to the set coefficients, the calculated compatibility rate is 0.03, which indicates the high accuracy of the selection of weights.
