排序方式: 共有72条查询结果,搜索用时 115 毫秒
71.
Randolf Rausch Theo Simon Hussain Al Ajmi Heiko Dirks 《Arabian Journal of Geosciences》2014,7(6):2437-2450
In central Saudi Arabia, the combination of rock types and sedimentary bedding created a unique scarp landscape. The escarpments were formed during Late Miocene through Early Quaternary times. At present, cuesta formation and migration are restricted to the actual escarpments as a consequence of negligible sediment removal. The plains between the escarpments are sealed through periodically active fluvial processes and through eolian sedimentation. In this publication, the major escarpments of central Saudi Arabia are described. The interactions between tectonics, climate, and morphogenesis which created this unique landscape are reviewed. 相似文献
72.
The North Atlantic Oscillation as an indicator for greenhouse-gas induced regional climate change 总被引:5,自引:1,他引:4
The time-dependent variability of the North Atlantic Oscillation is examined in an observational data set and several model
data sets with greenhouse-gas-induced external forcings. The index of the North Atlantic Oscillation state is derived from
the time series of mean latitudinal position and central pressure of the Icelandic Low and the Azores High considering the
synchronous meridional shifting of the two pressure systems. While the North Atlantic Oscillation is characterized by intensive
interannual variability, the low-pass filtered index time series shows a decadal component with a time scale of about 50 y
within almost 120 y of observation. Since the late 1960s we observe a positive trend and a transition to a strong positive
phase of the phenomenon indicative of a pre-dominantly zonal circulation over the North Atlantic. This trend occurs equally
in the observations and all examined model data sets with increasing greenhouse-gas-concentration and atmosphere-ocean coupling.
We find statistical evidence that the radiative forcing by increasing CO2 concentration has a significant influence on the simulated variability of the North Atlantic Oscillation on time scales of
60 y and longer, independent of the initial conditions and the model version. The seasonal response is strongest in late summer
and winter. The interannual variability of the North Atlantic Oscillation states on time scales less than 10 y decreases synchronously
with the positive trend of its decadal-mean state implying a stabilization of its present and future zonal state.
Received: 4 January 1999 / Accepted: 16 June 1999 相似文献