A low-level jet in eastern Iran: a possible factor in dust events in the region

One of the world's major mineral dust source regions lies along the border between Iran and Afghanistan. In this study it is hypothesized that a low-level jet may play in role in generating the intensity of this source region. The presence of a low-level jet east of the Seistan mountains is documented here for the first time. The jet exists mainly from May toSeptember and has a core at 850 mb. Maximum speeds are at 18 UTC and 0 UTC and occur in July-August. In the mean the core speed attains 20 ms-1 in those months. The jet attains a maximum at night, a minimum during the day. However, the vertical motions associated with it do not fluctuate greatly over the course of the day. The development of the jet during a dust outbreak in 2002 is also described. It arises a day or so before the outbreak and disappears as the outbreak ends.