Comparison of Persistent Deep Stable Layers over Different Valley Cities of the United States

• 作者: Xu Xiaohui
• 来源期刊: 气象与环境研究：英文版
• 学科: 地球科学
• 关键词: VALLEY PERSISTENT DEEP STABLE LAYERS Climate characteristics MULTIVARIATE ENSO Index
• 年，卷（期）: 2017,（2）
• 页码范围: 5-12
• 页数: 8页
• 分类号: P

摘要

Climate characteristics of persistent deep stable layers (PDSLs) over three valley cities of the United States (Utah's Salt Lake City, Idaho's Boise and Oregon's Medford) were compared. The results reveal that the frequency of PDSLs over Salt Lake City and Boise was very different from that of Medford; there was a good correlation between the frequency of PDSLs over Salt Lake City and MEI（Multivariate ENSO Index), while there was almost no correlation between the frequency of PDSLs over Medford and MEI；the shorter PDSL events occurred much more frequently than longer ones over the three locations； there were slight changes in the frequency and intensity of weak PDSLs with the time, while the frequency of moderate and strong PDSLs reduced obviously with the time； the appearance of PDSLs was usually accompanied by the peak of height at 500 hPa, while the disappearance of PDSLs was often accompanied by the maximum decreasing rate of temperature at 700 hPa； when PDSL events existed over the three cities, wind speed at 700 hPa and on the earth's surface was 1-2m/s smaller than that when PDSL events disappeared , and wind direction had no obvious effect on the formation of PDSL events；over the valleys, with the increase of PDSLs, absolute humidity decreased, and relative humidity dropped greatly； within the valleys, absolute humidity also reduced, while relative humidity rose with the increase of PDSLs.