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Archaeological and soil-stratigraphic data define the origin, growth, and collapse of Subir, the third millennium rain-fed agriculture civilization of northern Mesopotamia on the Habur Plains of Syria. At 2200 B. C., a marked increase in aridity and wind circulation, subsequent to a volcanic eruption, induced a considerable degradation of land-use(More)
Land surface properties, such as vegetation cover and soil moisture, influence the partitioning of radiative energy between latent and sensible heat fluxes in daytime hours. During dry periods, soil-water deficit can limit evapotranspiration, leading to warmer and drier conditions in the lower atmosphere. Soil moisture can influence the development of(More)
A set of night time tethered balloon and kite measurements from the central Sahel (15.2 • N, 1.3 • W) in August 2005 were acquired and analyzed. A composite of all nights' data was produced using boundary layer height to normalize measured altitudes. The observations showed some typical characteristics of nocturnal boundary layer development, notably a(More)
African dust emission and transport exhibits variability on diurnal to decadal timescales and is known to influence processes such as Amazon productivity, Atlantic climate modes, regional atmospheric composition and radiative balance and precipitation in the Sahel. To elucidate the role of African dust in the climate system, it is necessary to understand(More)
The Sahelian zone is characterized by low and highly variable rainfall, which strongly affects the hydrology and the climate of the region and creates severe constraints for agriculture and water management. This study provides the first characterization of the rainfall regime in a poorly described region of Central Sahel, Gourma region (14.5° to 17.5° N(More)
The hydrological cycle is expected to intensify under global warming, with studies reporting more frequent extreme rain events in many regions of the world, and predicting increases in future flood frequency. Such early, predominantly mid-latitude observations are essential because of shortcomings within climate models in their depiction of convective(More)
The residence times of the soluble fractions of beryllium and aluminum in seawater are estimated to be 1500 years or more. These residence times are estimated from a comparison of the annual deposition rates of cosmogenic beryllium-10 and aluminum-26 with the concentrations of beryllium-10 and aluminum-26 in seawater estimated from the specific activities(More)