Abstract
The dynamic of the monsoon and position of its Intertropical Convergence
Zone, as well as global sea level fluctuation are associated and have
controlled the paleoclimate of the Wahiba Sands in Oman (Radies et al.,
2004). Today the climate of the area is considered as hyper-arid but has
also known wetter periods in the past, e.g. Early Holocene, and the
paleodrainage mapped in the highland areas around the desert of Wahiba
Sands by Robinson et al. 2007, using Radarsat-1 C-band SAR images, are
supporting evidences of substantial surficial flows events. However, no
drainage networks were detected under the Wahiba desert itself, which
motivated our study to explore the area with a lower radar frequency to
penetrate deeper into the desiccated dunes. Using ALOS PALSAR L-band
radar SAR images, we observe NW-SE and NE-SW oriented paleochannels,
under meters to few tens of meters of the linear dunes forming the
Wahiba Sands area. The paleochannels are detectable with the loss of
radar backscatter that we attribute to different sedimentary materials
and their permittivity, porosity and scattering properties. To validate
their detection, we perform a 500 MHz ground radar (GPR) survey in the
interdunal area and observe them to be few tens of meters wide and about
1m deep. The scattering observed on the radargrams suggests these
paleochannels to be filled with centimetric size gravels, which we
believe cause the signal attenuation observed on the SAR images. Dunes
are found to be highly favorable for the L-band penetration, with power
loss of 0.2 dB/m derived from dielectric characterizations of field
collected samples. The discovery of these buried paleochannels under the
linear dunes brings new insights to construct the paleoclimatic
evolution of the southern area of the Arabian peninsula and better
understand the indeterminate tropical climate changes during the Late
Pleistocene and Holocene.
Original language | English |
---|---|
Journal | American Geophysical Union, Fall Meeting 2015 |
Volume | 31 |
Publication status | Published - Dec 1 2015 |
Keywords
- 1620 Climate dynamics
- GLOBAL CHANGE
- 4904 Atmospheric transport and circulation
- PALEOCEANOGRAPHY
- 4924 Geochemical tracers
- 4928 Global climate models