introduction climate change is an important environmental hazard that has been discussed in recent years. increasing the number or frequency of extreme climatic events such as severe droughts, floods, storms, heat and cold waves and heavy rains are the evidences of climate change. any of these events, due to the severity and persistence and their spread are a natural hazard that adverse effects...

Ahvaz can be regarded as one of the most polluted cities in the world in terms of air pollution. Successive years of drought and weather conditions in recent years have resulted in particulate matter (PM10) concentration in Ahvaz. In this study, using probability distribution techniques, an appropriate threshold to identify the PM10 maximum extreme concentrations (MEC) has been detected. Based ...

At the beginning of the 21st century, the July and August (JA) mean upper-tropospheric temperature over East Asia shows a significant increasing trend, contrary to the decreasing trend in the late 1970 s. The largest warming center is over northern China (between 30°N-45°N and 85°E-120°E) around 300 hPa. Together with the temperature rising, the geo-potential height rises above the warming cent...

Twenty-eight years of NCEP–NCAR reanalysis data are employed in a composite analysis of the structure and evolution of the large-scale circulation associated with rapid, subseasonal, westward retractions of the Northern Hemisphere Pacific jet. Nineteen Pacific jet retractions are identified in the dataset. The salient characteristics of these transitions are presented, emphasizing the structure...