جستجوی مقالات مرتبط با کلیدواژه "کوردکس" در نشریات گروه "جغرافیا"

Climate change is a key factor in most weather-related disasters worldwide. Regarding its distinctive geographical location and diverse climate, Iran has the most variable climate in the world. The present study aims to investigate the effectiveness of the MPI-ESM-LR model from the CMIP5 model series in predicting the monthly temperature of Iran under representative concentration pathway scenarios (RCPs) with the CORDEX-WAS project. In this research, for the historical period of 1980-2005, the daily air temperature data of 49 synoptic stations of the country and the MPI-ESM-LR model under the CORDEX project were used. Likewise, for the future period, from the predicted temperature data of RCP 8.5, RCP 4.5, and RCP 2.6 scenarios of the mentioned model in three periods of the near-future (2021-2050), mid-future (2051-2075) and far-future (2076-2100) was used. Validation of the model was done with three statistical indices: r, RMSE, and MBE. The results revealed that the model has a good performance. The slope of the temperature trend in station data and model data has been increasing in the historical period and the future period in RCP8.5 and RCP4.5 in all months, the temperature trend slope has been observed in every decade. In all months, the maximum anomaly of temperature under the scenarios studied in all three future periods can be seen in the northwest and western highlands. The eastern and southeastern regions of Iran have indicated minimum temperature anomalies, except in RCP 2.6 and RCP 8.5, respectively, the southern coasts and the northeastern heights of the country also show minimum temperature anomalies. In the cold half of the year, the minimum area of temperature anomaly has been extended to the north-western heights and low-altitude interior regions of the country.

The evapotranspiration, as one of the important meteorological variables and the relation between the land surface and the atmosphere, is important to the study of drought and the allocation of water resources. The relationship of this climatic variable with land indices as well as water supply planning reveals its importance. Due to the high relationship between this variable and air temperature, changes in air temperature patterns in global warming and climate change will have a high impact on its behavior and distribution. The relationship and entanglement of this hydro-climatic variable with climate change, especially temperature, has caused that with any fluctuation and change in the behavior of temperature patterns, its value and distribution will also change. Iran as a country located in the arid areas of the planet earth; is currently heavily involved in water stress. This water stress will be exacerbated by climate change, rising temperatures and increased evapotranspiration. Examining the impacts of climate change can be a roadmap for environmental management in this area. The aim of the present study is to reveal the behavior of this climatic parameter in the future period compared to the historical period and its spatial distribution based on the data network.

In the present study, using the output of downscaled dynamic models of the CORDEX-MNA project for North Africa and the Middle -East under (RCP8.5 and RCP4.5) scenarios. For the historical period (1980 – 2005), reference evapotranspiration was estimated by the Penman- Monteith, FAO method. The NOAA-GFDL-GFDL-ESM2M regional climate models (RCMs) as the dynamic model output projection was used for the future to mid century (2025-2050).In this study, RCP4.5 & RCP8.5 representative concentration pathway scenarios were selected, as these two scenarios are used to further investigate climate change vulnerabilities and subsequent climate change responses. The CORDEX-MNA data with 0.22 spatial resolution, RCA4 model for RCM, were used. For the future period, the ETo value is obtained directly from the output of the CORDEX-MNA coordinated project models. In fact, the reference evapotranspiration value is part of the simulation of these models. Statistical criteria are used for the correction of the models to show the similarity between the observed and modeled data in the form of statistical values.

The results showed that in the future period, based on CORDEX-MNA coordinated project simulations for North Africa and the Middle-East, downscaled dynamics models; the amount of reference evapotranspiration as one of the most important components of the hydrological cycle will increase compared to the historical period (1980-2005). In terms of temporal variation, the highest changes will occur in mid-winter to early autumn. Under the RCP scenario, the ETo will increase to 34 mm in the hot months such as August. Under the mid-term scenario, the ETo value will increase compared to the historical period, but this increasing will be less than the upper limit scenario. Spatially, the main foci of high reference evapotranspiration are located in the central areas around Kavir and Lut plains, Jazmourian areas and the southern half of the Iran. The results showed that in the context of climate change and based on the downscaled data of the CORDEX -MNA project; the range of high potential evapotranspiration in the Iran will increase. In fact, high latitudes will experience an increase in the amount of ETo due to changes in air temperature and precipitation patterns and increasing air temperature trends. These conditions will be an alarm for Iran with arid and semi-arid conditions. Any change in the amount of evapotranspiration causes drought in the environment, followed by water needs and irrigation frequency for the agricultural sector as the most important water consuming sector in Iran. Therefore, it is important to pay serious attention to water resources management programs.

 Among the models used, the output of the regional model; NOAA-GFDL-GFDL-ESM2M has more optimal conditions in simulating the effects of climate change in Iran. The ETo spatial pattern is a function of location components throughout the year. These conditions are well evident in the distribution of potential evapotranspiration. The amount of ETo will increase from west to east and from north to south of the country based on the spatial pattern obtained in the historical (1980-2005) and the future period from 2025 until 2050. The southern and central regions of the Iran are the focus of areas with high ETo. The role of altitude and latitude factor in determining this spatial pattern is obvious. Comparison of ETo historical-observational period with the future decads to 2050, shows a significant increasing in the amount of potential evapotranspiration in Iran. Under RCP8.5 from March - September ETo will reach the highest level. In areas with high ETo in Iran, the average amount of ETo will increase by an average of 11 mm from April to June and in the warm months by an average of 17 mm. Under RCP4.5 scenario, these conditions are also observed to be incremental with a lower value. In the cool and cold months, in the high regions, the amount of minor and small changes and in some areas without change is observed. Significant increasing in reference evapotranspiration in August as one of the hottest months of the year in Iran is significant; because at this time of year, the demand for water consumption in all sectors; in particular, the agricultural sector is reaching its highest level, which necessitates attention to water resources management. In general, reference evapotranspiration as one of the hydro-climatic components, with any change in air temperature, will face increasing conditions that result in this increase, imposing more drought on the environment and thus increasing the water demand. Especially in the agricultural sector. These conditions are important for the geography of Iran with its fragile climate. Therefore, the land of Iran is currently facing tensions and instability in the situation of water resources, these conditions will intensify in the coming decades under the conditions of climate change. The need to pay attention to risk management and increase resilience in the face of climate change due to global warming can be considered a roadmap in this area.

South East of Iran will yearly receive part of its water requirements from the summer precipitation, which is mostly due to the monsoon expansion. These precipitations are related to the temperature changes in the Indian Ocean level (Aramash et al., 2016: 2). Producing the accurate climate data is one of the main goals of the forecasting and modeling centers. Among the most important advantages of this data can mention the following: better estimation of the climatic variables in the regions which have no station, possibility to study the climate more appropriately and evaluate the fluctuations and changes of climate elements (Forsythe et al., 2015).

In this research, we used daily precipitation data of 6 synoptic stations and the outputs of various CORDEX models in the South Asia during the statistical period of 30 years (2005-1976) in the studied region.

Evaluation of the accuracy of the global models' output on the basis of the downscaling of the studied regional model on a daily basis during the monsoon period (June, July, August and September) in (1976-2005) indicated that according to the different indicators the CanESM2, CSIRO and NorESM1 models have respectively more accurate estimation of precipitation values at most studied stations than other models. The correlation coefficient of none of the models has a good relationship. The observed and estimated precipitation values of the studied models in the form of the average activity months of the monsoon system showed the accuracy of the investigated models at each station is different but, in general, the three models CanESM2, CSIRO and NorESM1 are more appropriate in the estimation at the most stations than other models. A number of macro criteria must be considered to select the proper model; the 500 HPA Geo-potential height and the sea level pressure have been used in this research for this purpose. In fact, investigating the model's ability to simulate the 500 height as well as the earth is preferable over precipitation and temperature.

The results have suggested that the accuracy of the studied models at a variety of stations is different but, totally and at most of the stations, the three models CanESM2, CSIRO and NorESM1 have respectively better estimation of monsoon precipitation values than the other models. We cannot definitely prefer one model over the others according to the error estimation criteria as well as the comparison of different models with each other. We have shown in this research that the large scale variables such as Geo-potential height and pressure are more predictable than the precipitation and CanESM2, CSIRO-Mk, IPSL-CM2A-MR, MIROC2 and MPI ESM-LR models can be introduced as suitable models to simulate and predict climatic parameters of sea level pressure and 500 HPA Geo-potential in the monsoon system activity governing on the South East of Iran.

Energy, as one of the most important environmental and economic sustainable development indices, is affected by the conditions of climate change. In addition, they are considered as the main factors of increase or decrease of fuel consumption and energy and the changes of cooling and heating degree-days. The quality controlled daily temperatures data of 44 synoptic stations across the country (1976-2005), as well as RCM simulations over the CORDEX were explored to evaluate the potential changes in heating and cooling degree-days due to climate change on Iran. Downscaled output of three RCM models of CNRM¡ EC-Earth and GFDL, with the spatial resolutions of 0.44 degrees under two emissions trajectories (RCPs 4.5 and 8.5), are applied in this regard. The model outputs simulate the increase of cooling demand in the horizons of 2020-2020 and 2040-2050. The highest increase is expected in the regions of the southern shores of the south and especially in the southeastern part of the country and in the central and milder parts of the north coast. It is expected to stabilize and reduce the need for cooling in the Alborz and Zagros ridgetop. In spite of the reduction in heating demand for the country, the horizons are foreseen. The highest decrease is expected in the mountainous regions of the Alborz, Zagros and Azerbaijan, and it is expected to stabilize and increase the need for heating in the southern and southern regions of the country, and it will be localized in the center and north coasts.
Conversely, heating need decreases in RCPs 8.5 at future years GFDL models output more than other models. Totally, the results represent that the need for cooling (increasing min 23% and max 47%) will be increased and heating needs (decreasing min 9% and max 17%) will be decreaseed in the last two cuts the horizons 2020 to 2030 and the 2040 to 2050 in both emissions trajectories RCPs 4.5 and 8.5
Extended Abstract
1-Energy, as one of the most important environmental and economic sustainable development indices, is affected by the conditions of climate change. In addition, they are considered as the main factors of increase or decrease of fuel consumption and energy and the changes of cooling and heating degree-days. Generally, the need for heating and cooling by definition is the sum of difference between mean daily temperatures from a given threshold in certain periods of the year which is expressed in degree-days. Generally, if the average air temperature exceeds 21 degrees Celsius threshold value, the need to cool the environment will be created that day. If the average air temperature is less than 18 degrees Celsius threshold, on that day will need to warm the environment.
2- The quality controlled daily temperatures data of 44 synoptic stations across the country (1976-2005), as well as RCM simulations over the CORDEX were explored to evaluate the potential changes in heating and cooling degree-days due to climate change on Iran. In the study, two types of data, observed and simulated data, (past and future) are examined. The observational data is considered with past data CORDEX database from 1976 to 2005. The reason for the 30-year period has been related to following the principles of parametric data and fact of longevity or base on period of CORDEX data (1951 to 2005). Downscaled output of three GCM model of CNRM¡ EC-Earth and GFDL, with the spatial resolutions of 0.44 degree under two emissions trajectories (RCPs 4.5 and 8.5), was applied in this regard. Post processing error of the model was used To moderate. In general, the mechanism of action of regional circulation model (RCM) is calculated using change factor in this case such as the difference or monthly ratio of simulations of regional circulation model in the future with the last period for heating and cooling degree-days which will be added to the data period last observation stations.
3-The analysis results of the cooling degree-days (CDD) show that generally 65.9 percent of the stations have experienced a significant increase (in 0.95 sig level), 29.6 percent of the condition with no significant process and 4.6 percent with decreasing process. This change started in 1996 in the country, according to studies by the homogeneity test by Petit test. Regarding heating degree-days (HDD), generally, 56.8 percent of the stations observed a significant decrease (in 0.95 sig level) and 29.6 percent with no significant process. The downtrend at average form is calculated with the amount of Sens Slope 7.5 percent in the whole country. This change stated 1997 in the country, according to studies by the homogeneity test by Petit test. . Model outputs show that CDD will be increased in country especially in south, southeast, central and southwest of country in both RCP. The EC-Earth output under the trajectory of 8.5, indicates a further increase in cooling needs for the horizon in 2040 to 2050. Three models output, show that HDD will decrease all over the country, especially in the highlands, Alborz and Zagros Mountainous. Conversely, heating need decreases more, according to the GFDL models outputs. The results represent an increase in the need for cooling and heating needs of the country in the last two cuts of the Horizon from 2020 to 2030 and the 2040 to 2050 in both emissions trajectories RCPs 4.5 and 8.5. Overall, in the extreme condition in the decade of 2040 and 2050, about 13 percent of the area of country (approximately 297 thousand square km) will pass from the mean line. This suggests that reducing the need for heating will be more than of increase cooling needs. Overall, major changes in the temperature status of the country will occur in cold seasons.
4- This study was based on data analysis of observed and simulated extreme values of temperature indicated that heating and cooling degree days of the country is changing. So, the degree-days of heating and heating needs are reduced, and degree-days cooling and the need for cooling is increasing. Of course, the changes in heating needs on the in 2020-2030s and 2040-2050s will be more than changes of cooling need. Leading the constraints and opportunities are created that can be cited to reduce the need for fossil fuels and the need for electrical power in the cold season.