1971) - A telephoto lens view of the prominent feature called Silver Spur in the Hadley Delta region, photographed during the Apollo 15 lunar surface extravehicular activity (EVA) at the Hadley-Apennine landing site. The lower major unit is characterized by thinner bedding and cross bedding.ĪS15-84-11250 (31 July-2 Aug. The upper unit is characterized by massive subunits, each one of which is approximately 200 feet deep. Structural formations in the mountain are clearly visible. The field of view across the bottom is about one mile. The distance from the camera to the spur is about 10 miles. Telephoto lens view of Silver Spur in the Hadley Delta region from Apollo 15Ī telephoto lens view of the prominent feature called Silver Spur in the Hadley Delta region, photographed during the Apollo 15 lunar surface extravehicular activity at the Hadley-Apennine landing site. It is established that the orbital geochemistry data for this region are consistent with the presence of a mixture of ANT suite and Fra Mauro basalt components frequently dominated by a KREEP basalt component toward the west and by a mafic pyroclastic component toward the east. The relationship of the XRF values to Fe, Ti, and Th concentrations, derived from gamma-ray observations, is also considered. The corrected values are than converted to % MgO and % Al2O3, respectively, from theoretical considerations, and as such are compared with similar concentrations for typical lunar rocks and soils of the Apollo 15 landing site. These data are corrected for spurious interorbit variation using a modification of a previously developed method. Orbital XRF Mg/Si and Al/Si intensities are the orbital data that are used primarily. Orbital geochemical data in the Hadley Apennine region are related to typical rock compositions and used in determining the distribution of soils derived from the rock types found in this region. While La Niña also promotes expansion in the American and African sectors during austral winter, these tropical conditions tend to promote contraction in the two sectors during austral summer as a result of compensating convergence over the Americas and Africa sectors: a process driven by variations in the Walker circulation and Rossby wave trains emanating from the tropical Indian Ocean.Ĭompositional variation in the Hadley Apennine region An expanded Hadley circulation in the Southern Hemisphere (both hemispherically and in the Asia-Pacific sector) is associated with La Niña conditions and a poleward expansion of the tropical wet zone in the Asia-Pacific sector. A major finding from this study is that year-to-year variability in the extent of the hemispheric Hadley circulation in the Southern Hemisphere is primarily governed by variations of the extent of the Hadley circulation in the Asia-Pacific sector, especially during austral spring and summer when there is little co-variability with the African sector, and the American sector exhibits an out of phase behavior. These regional circulations are defined by computing a streamfunction from the divergent component of the meridional wind. In order to understand the regional impacts of variations in the extent of the Hadley circulation in the Southern Hemisphere, regional Hadley circulations are defined in three sectors centered on the main tropical heat sources over Africa, Asia-Pacific (Maritime Continent) and the Americas. Variability of the extent of the Hadley circulation in the southern hemisphere: a regional perspective
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