چکیده:
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 to
September 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.
خلاصه ماشینی:
"ir Desert 20-2 (2015) 91-99 A low-level jet in eastern Iran: a possible factor in dust events in the region Sh. Nicholson* Earth, Ocean and Atmospheric Science Department, Florida State University, Tallahassee, FL 32306, USA Received: 25 November 2015; Received in revised form: Accepted by Editor; Accepted: 4 January 2016 Abstract 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.
Keywords: Afghanistan; Iran; Low-level jet; Mineral dust; MODIS 1.
Mean low-level winds (ms-1) for November to March at 925 mb (left) and for May to September at 850 mb (right) Fig. 3.
Vertical cross-section of horizontal wind speed along a transect perpendicular to the jet core (see Fig. 1 for location).
2. Mean for July-August Figure 5 shows cross-sections of mean wind speed along three transects perpendicular to the jet core during July-August.
Vertical cross-section of horizontal wind speeds along transects perpendicular to the jet core, averaged for July and August.
Vertical cross-section of horizontal wind speed along a transect parallel to the jet core, averaged for July and August (see Fig. 1 for location) Fig. 7.
Mean vertical motion (omega, pascals per second) along three transects perpendicular to the jet core at four times per day (see Fig. 1 for location).
This sequence and its relationship to the dust outbreak suggests that the low-level jet plays some role in creating the intensity of this dust source region."