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Showing 5 results for khaledi

Zahra Sadat Hoseini, Shahriar Khaledi, Abdolmajid Naderi Bani,
Volume 18, Issue 49 (5-2018)

Paleo-climate reconstructions based on multi-proxy such as sedimentology is current in climatology investigation. In this way, National Institute of Oceanography and Atmospheric Science cored 960cm from Arzhan wetland SW of Iran than we have investigated of sedimentology. Primarily the core was measured on magnetic sensibility per 1cm and secondly was subsampled according to magnetic sensibility and were analyzed include TOC, CaCO3, and Grading laser and etc. Finally four samples of pace of plant were selected and have been dated in carbon 14 dating laboratory of Poznan, Poland, and calibrated trough of core based on Calib rev. 7.1. Dating have determined that core had covered 15000 Cal. BP. According to this investigation, we obtained 5 period of climate conditions during Pleistocene to Holocene in this area. 15000-13000 Cal. BP. Late Pleistocene climate conditions were colder and wetter period that indicate end of the Ace age.  13000-11000 Cal. BP. Climate begin to warmer and dryer. 11000-9000Cal.BP. because of this period shows many fluctuations in all proxies we named this period to the period of transfer from ace age to interglacial period. 9000-7000Cal. BP there have been warm and cold conditions compare to late Holocene. 7000- Present indeed in this period radiantly modern pattern of atmospheric circulation has been performed due to all of proxies in late Holocene begin to fixed on the same pattern. So probably atmospheric circulation from meddle Holocene begin to get harmonic to present. Any way for determinate of paleo-climate in this area we need to use of multi proxy investigation in area.

Hengameh Shiravand, Shahriar Khaledi, Saeed Behzadi, Hojjat Allah Sanjabi,
Volume 20, Issue 57 (6-2020)

   Decline phenomenon is one of the most important reasons for the destruction and mortality of oak trees in Zagros forests due to the wide variety and diversity of the topography of its determination through track and field operations is not readily possible. Changes in an ecosystem are often gradual changes, but sometimes changes occur in an ecosystem in a short time. This change can cause a catastrophe in the ecosystem, which is difficult to identify. A proposed method for identifying a general change in time series is use the BFAST model, which, by analyzing the time series in the process, season, and residual components, identifies the changes in the time series and also repeatedly estimates the time and amount of the changes, and The path and amount of variation in this study, using this model and satellite images to monitor and evaluate the changes in coverage and decline of oak forests in Lorestan province during the statistical period (2000-2017). The results showed that more than 42804 hectares (1.5%) of the oak forests of the province were lost due to the decline phenomenon during the studied period. Also, according to the BFAST method, the trend diagram is a failover and their frequency variations are irregular. Comparison and study of different forest coverings also showed a decrease in NDVI, which indicates that the process of decreasing forest cover is inclusive. The study of autocorrelation and Kendal coefficient showed that there were significant changes and severity of failure (-0.7) in the area Study. The seasonal chart also has uneven and irregular variations due to changes in oak forests in the region. The results of this research can be used to study the changes in the coverage of oak forests in the area and management and the way to think about this phenomenon.

Parisa Ahadi, Shahriar Khaledi, Mahmoud Ahmadi,
Volume 21, Issue 60 (3-2021)

Dust is referred to sediments of less than 100 microns in size which are transmitted as suspended particles. Dust storms are events which naturally occur in arid and semi-arid areas, especially in subtropical latitudes. One of the most known sources of dust is the west of Asia, including Arabian Peninsula, Syria, Iraq, and Iran, especially Khuzestan Province. The purpose of this study is to investigate the frequency and trend of dust phenomena on hourly, monthly, seasonal and annual scale between 1995 and 2015 in Khuzestan Province. The method in this study is based on statistical computation of dust parameters and also the trend analysis of data based on Mann-Kendall test and spatial distribution maps of dust phenomena. The results suggests that 78.57 percent of dust event are occurred between 9.30 am to 15.30 pm local time, concurrent with peak of sun radiation and earth surface warming, dryness of soil and local pressure difference. The hourly trend analysis is increasing and significant in all hours and the highest increase occurred at 9.30 pm to 12.30 pm.49 percent of dusty days occurred in June, July and May and also 73 percent of them are in spring and summer as following from temperature increase and water and soil resources drying in the province. The seasonal and annual spatial distribution of dust indicates that most of dusty days in all seasons are located in west of province which suggests dominance of external sources as the main source of dust and the importance of topography factor in this area.The Z value spatial analysis suggests high increase of dust event in recent 20 years in southeast, south and central areas of the province and also on last hours of day which demonstrator development of internal sources activities in increasing trend of dust event in recent decades.

Anoshiravan Ravand, Shahriar Khaledi, Davod Hasanabadi,
Volume 21, Issue 63 (2-2022)

The purpose of this study is to determine and predict the effects of climate change on architecture using climate models. By clarifying the consequences of the impact of urban architecture on climate change while using the data of surrounding stations with library and field data methods. The climatic parameters of precipitation, temperature and relative humidity of the synoptic station of Miyaneh city during a full period of 32 years (2018-1987) and the possibility of climate change with the models in this city were examined and after obtaining the relevant data Climate change was predicted for the next 84 years through the GCM and SDSM microscale and the AR4 (2007) - HADCM3 (Run 1) - SR-A2 scenarios. In order to evaluate the effects of climate change on the comfort climate of the region, among the bioclimatic models used, the Tarjong model was considered for two periods of 16 and 42 years. In the next 84 years, compared to the last 32 years, the cold months of May, June, July and August will turn into pleasant heat, and in September, the heat will have a great impact on the skin, which indicates a warm climate in the next 84 years. Architectures must be considered.

Mohammad Ahmadvand, Shahriar Khaledi, Parviz Kardavani,
Volume 23, Issue 69 (7-2023)

Climate and the required parameters for agricultural products are the important factors of production. We can determine potential facilities in different areas and consider the maximum tapping through agricultural meteorology. Due to drylands potentials in Hamedan province, we conducted a comprehensive survey based on 20 years (1995-1995) climatic elements of 9 main and supplementary synoptic stations. Thus, according to wheat phenological conditions and matching those with climatic conditions requirements in Hamedan province, we surveyed effective indices in grow crops. Finally, using geographic information systems (GIS) we implemented climatic elements zoning and weighting. Then the appropriate and inappropriate areas of the province for dryland wheat were determined. Results indicated among the climatic elements, annual rainfall and its distribution during the growing season, also the grow degree day (GDD) are important factors in process of dryland wheat. Based on maps extracted from the GIS, about 18 percent of the areas of province which are located in west, south west including Nahavand, Tuiserkan and Asadabad cities, enjoy very potentials and 46percent medium, 34percent good and 2 percent of Ghahavand city of Hamedan city functions lacks the necessary talent. with no potentials.

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