جستجوی مقالات مرتبط با کلیدواژه "global circulation models" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

This study aimed at predicting the effect of climate change on the geographic distribution of Thymus kotschyanus Boiss and Hohen in Mazandaran province. Species presence data were recorded via the Global Positioning System (GPS). The distribution of T. kotschyanus Boiss and Hohen under current and future climatic conditions 2050 and 2070 (1428- 1448 Solar) applying  two scenarios of RCP 4.5 and RCP 8.5 climate change by using the GCM data series of general circulation models BCC-CSM1-1، CCSM4 and MRI-CGCM3  and the five species distribution models such as Generalized Linear Model, Generalized Additive Model, Classification Tree Analyses, Generalized Boosting Model and Random Forest methods was investigated. For this purpose, layers of environmental factors, including six bioclimatic and two physiographic variables, were used as inputs to species distribution models. Among the environmental variables, precipitation seasonality, precipitation in the coldest quarter, and isotherm had the greatest impact on habitat suitability. The assessment of the modelling indicated that the Generalized Additive Model and Generalized Boosting Model had better predictions of climate habitat than the other models. The results also indicate that climate change will change the range size of the T. kotschyanus Boiss and Hohen, and will move toward higher elevations in the future. The results of the present study may be used to plan habitat protection for the medicinal species of T. kotschyanus Boiss and Hohen, as well as its restoration and rehabilitation in the vast regions of the country.

Now a day, long-term prediction of climate variables is necessary for climate change impact studies. Currently Global Circulation Models (GCM) are powerful tools to generate climate scenarios. These models are limited to capture the local climate due to their low spatial resolution. So, they cannot be directly applied for hydrological modeling in a catchment scale. In this research, first the trend of variables such as rainfall, radiation, maximum and minimum temperature were assessed for the base period with nonparametric Man-Kendall test. Second, these variables were downscaled by using the outputs of HADCM model and under three scenarios of A1, A2 and B1 which are accepted by IPCC(1971-2010) under three scenarios and their monthly changes were investigated for three periods of 2011-2030, 2046-2065 and 2080-2099 compared to the base predicted period of (1971-2010). All these scenarios showed almost similar results on precipitation shortage and increasing of solar radiation, minimum and maximum temperature over the future periods. As an example, the results of A2 scenario showed increasing of the annual mean, minimum and maximum temperature by 1.1, 3.2, and 4.6 °C, increasing of solar radiation by 0.07, 0.30 and 0.33 mJ m-2d-1 and decreasing precipitation by 16.4, 17.6 and 31.9 percent for these periods compared to the base period.