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Dust and the low-level circulation over the Bodele Depression

journal contribution
posted on 2023-06-07, 17:25 authored by Richard Washington, Martin ToddMartin Todd, Sebastian Engelstaedter, Samuel Mbainayel, Fiona Mitchell
Dust plays an important role in climate, recognition of which has led to a concentrated research effort in field campaigns, development and analysis of remotely sensed data, and modeling to better understand dust. There have, however, been very few direct surface-based field measurements from key dust source regions. The Bodélé, Chad, has been shown to be one of the premier sources of dust in the world. This paper reports on the Bodélé Field Experiment (BoDEx 2005) which took place during February and March 2005 and presents the first surface-based measurements of the circulation over the Bodélé. On the basis of Pilot Balloon and AWS data, we confirm the existence of the Bodélé Low Level Jet (LLJ) and show that winds undergo a strong diurnal cycle such that strongest surface winds typically occur in the midmorning when momentum is mixed downward in turbulence induced by radiative heating. In contrast, the core of the LLJ, near 500 m, peaks during the evening and is weakest during the day. The LLJ was present on all days during BoDEx 2005, but winds at the surface reached speeds necessary for large-scale dust entrainment on only a few days. The winds strength during the main dust plume event of BoDEx (10–12 March 2005) was in the bottom third of March plume events of the last 4 years. Pathways of dust transport from the Bodélé using a trajectory model show potential advection of dust over the west African coastline within 5 days.

History

Publication status

  • Published

Journal

Journal of Geophysical Research

ISSN

0148-0227

Publisher

American Geophysical Union

Volume

111

Article number

D03201

Department affiliated with

  • Geography Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

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