A new approach in temporal-spatial reconstruction and synoptic analysis of cold waves in the northwest of Iran

摘要

The present paper intends to reconstruct temporal-spatial patterns of below -15 degrees C cold waves in the northwest of Iran and carry out a synoptic analysis of the patterns of these cold waves. Carrying out research on this topic can assist researchers and the state authorities in solving problems of different spheres of society, such as agriculture, economics, public health, etc., since cold waves can affect health problems in society and frosts can inflict severe damages to the agricultural crops and thereby lead to serious economic losses. For the purpose of this paper, a data corpus related to a period of 142years from 1871 to 2012 was obtained from the relevant twentieth-century data banks of NOAA. Having sorted out the relevant data, cold waves of -15 degrees C as well as cold waves of below -15 degrees C were identified in the first place. Then, the identified cold wave patterns were classified and synoptically analyzed. The results revealed that, at the sea level, high-pressure waves from Siberia, west and northern regions coupled with the atmospheric blockings and the northern airflow in the upper levels of the atmosphere, led to transition of cold waves from northern latitudes to the northwest regions of Iran, resulting in very intense and long-lasting cold waves.