مقالههای B. Bakhtiari
توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.
۱Solar Radiation Estimation from Rainfall and Temperature Data in Arid and Semi–arid Climates of Iran
اطلاعات انتشار: Desert، چهاردهم،شماره۲، ۲۰۰۹، سال ۰
تعداد صفحات: ۱۰
Precipitation and air temperature data, only, are often recorded at meteorological stations, with radiation being measured at very few weather stations, especially in developing countries. Therefore there arises a need for suitable models to estimate solar radiation for a completion of data sets. This paper is about an evaluation of eight models for an estimation of daily solar radiation (Q) from commonly measured variables in six synoptic stations of Iran, namely: Mashhad, Kerman, Tabriz, Esfehan, Hamedan and Zanjan using daily rainfall and temperature data for a duration of three years of 2000, 2001 and 2002. These stations represent several arid and semiarid sub–climates of Iran as based on extended–De Martonne climatic classification (semiarid–cold: Mashhad and Tabriz, arid–cold: Esfehan, Kerman, semiarid–extracold: Hamedan and Zanjan). The STATISTICA (ver. 6.0) software was employed for non–linear multivariate regression. The results indicated that most of the models overestimated in lower values of solar radiation while underestimating in the higher ranges, indicating a systematic error. Performance of the models was evaluated based on the Root Mean Square Errors (RMSE) as well as R2. RMSE ranged from 1.14 to 7.76 Cal cm–2min–1 for the whole data range and in all the six stations. Among the eight models, the Richardson model rendered the best agreement with the measured data in Kerman and Zanjan stations. In case of Hamedan station, Bristow and Campbell model was the most suitable. As for Tabriz station, De Jong and Stewart model using rainfall and range of daily temperature data led to the best performance. In Mashhad station, McCaskill equation can be recommended. Analysis of the data in Esfehan station showed no significant difference among the models. Due to variation in equations'' performances, to come to valid conclusions and to choose the most suitable radiation models, further study would be required from other climatic regions the country.
اطلاعات انتشار: Desert، هجدهم،شماره۲، ۲۰۱۴، سال ۰
تعداد صفحات: ۱۴
Climate is a natural resource that effects decision making for selection of destinations in tourism and ecotourism. The relationship between climate and tourism is a complex one. But application of a climate index provides an ideal approach to understanding this complexity and is a useful tool for the tourism industry. In this study, a modified version of Mieczkowski''s (1985) Tourism Climate Index (TCI) for months was used for Kerman province to determine climate comfort ratings ranging from ideal to unfavorable. Data covering a network of 12 meteorological stations was used to compute a TCI for the study region. Then index evaluations in each city were classified according to one of the six annual TCI distributions presented by Scott and Mcboyle (2001). Results of modeling showed bimodal–shoulder peaks in seven stations namely (Anar, Rafsanjan, Zarand, Sirjan, Shahre–Babak, Bam and Kerman); two stations namely (Baft and Lalehzar) had summer peak, and three cities (Shahdad, Kahnouj and Jiroft) had winter peak. TCI scores for all months in the study stations were transferred into Geographic Information System to determine the most suitable areas and months for tourism activities in Kerman province.
۳Evaluation of Reference Evapotranspiration Models for a Semiarid Environment Using Lysimeter Measurements
اطلاعات انتشار: Journal of Agricultural Science and Technology، سيزدهم،شماره۲، Spring ۲۰۱۱، سال ۰
تعداد صفحات: ۱۶
An accurate determination of evapotranspiration is required for many studies that involve estimation of the water balance. One methodology is the use of lysimeters. Considering the semiarid climate of Kerman Province, in southeastern parts of Iran, the only operating electronic weighing lysimeter in the country was used for calculating daily ETo from April 2004 to March 2005 in three different periods, i.e. the entire year, and high and low evaporative demands periods. The measured error was equal to 1 kg mass, which is equivalent to 0.14 mm of water in the field. An automated weather station was used that provided 10–min recordings of the weather data to be used for predicting daily ETo with models. The lysimeter was installed in proximity of the automated weather station and both were located in a field with grass cover. The lysimeteric data were used for the evaluation of six grass evapotranspiration models, including FAO–56 Penman–Monteith, Penman–Kimberly 1996, FAO–24 Blaney–Criddle, FAO–24 Radiation, Makkink, and Hargreaves–Samani. The root mean square error (RMSE) and index of agreement (d) were used for assessing prediction accuracy of different models. Results indicated that for the entire year period, the FAO–24 Radiation equation was the most precise method for calculating ETo, with a RMSE of 1.63 mm day–1 and a d– index of 0.78. During the high evaporative demand period (April to September 2004) the FAO–24 radiation equation was superior compared to the other methods for calculating ETo with a low RMSE value of 1.86 mm day–1 and a d–index of 0.45. During the low evaporative demand period, again, FAO–24 radiation equation was superior compared to the other methods with RMSE of 1.30 mm day–1 and d–index of 0.46. In all of the three periods, the Makkink method showed poor performance and can not be recommended for the region.
۴Seasonal Sensitivity Analysis for Climatic Variables of ASCE–Penman–Monteith Model in a Semi–arid Climate
اطلاعات انتشار: Journal of Agricultural Science and Technology، سيزدهم،شماره۷، Dec ۲۰۱۱، سال ۰
تعداد صفحات: ۱۲
Seasonal variations of climatic parameters are significant in arid and semi–arid regions and sensitivity of each parameter may differ in different seasons. No work has been done in this regard in Iran. Therefore, in this study, sensitivity analysis of the ASCE–Penman–Monteith grass reference evapotranspiration (ETo) equation was investigated on the basis of variation of mean air temperature (Tmean), vapor pressure deficit (VPD), wind speed at 2 meter height (U2), and short wave solar radiation (Rs) in the semi–arid climate of Kerman, southeast of Iran. The sensitivity coefficients were derived for each variable on a daily basis. The results showed that the computed ETo was sensitive to VPD in all months, to U2 during March to November, and to Rs during the summer months. The change in ETo was linearly related to the change in the climatic variables, with in most cases. The sensitivity coefficient for Rs was higher during the summer months and lower during the winter months. Increase in ETo with respect to the increase in the aforementioned climate variable changed by month. On an annual average, 1 C increase in Tmean, 1 ms–1 increase in U2, and one MJ m–2d–1 increase in Rs resulted in, respectively, 0.11, 0.37, and 0.09 mm d–1increases in ETo. A 0.4 kPa increase in VPD resulted in 0.85 mm d–1 increase in ETo. Generally, various meteorological parameters should be measured with high accuracy in order to use the combination model.
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