A topographic origin for the double-ridge features in visible imagery of ice divides in Antarctica
ABSTRACT. The a ppeara n ce of doubl e-ridge features o n visible image ry of th e ice di vides of Antarctic ice rises has often been noted but, large ly due to a lac k of adeq ua te ground truth, th eir origins have rem a in ed en igma ti c. ' Ve present seve ra l examples of ice rises and oth...
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| Format: | Text |
| Language: | English |
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1995
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.3500 http://www.igsoc.org/journal/41/139/igs_journal_vol41_issue139_pg483-489.pdf |
| Summary: | ABSTRACT. The a ppeara n ce of doubl e-ridge features o n visible image ry of th e ice di vides of Antarctic ice rises has often been noted but, large ly due to a lac k of adeq ua te ground truth, th eir origins have rem a in ed en igma ti c. ' Ve present seve ra l examples of ice rises and oth er iso lated ice-OOl'v ce lllres that a pparentl y show d o ubl e rid ges. vV e investiga te one of th ese in particul a r: Fl etcher Pro montor y, Anta rc ti ca. A di gita l-eleva tion model (DEM) of the summit regio n is der ived fro m surface pro fi les obtained using th e Global Positioning Sys tem (GPS) and thi s is correlated 'with La ndsa t MSS sa tcllite imagery. Prec ise reg istra ti o n is ac hi e\'ed by co rrela ting im age-brightness values with surface slope calcul a ted a long the d irec tion o f the Sun az im uth in th e image. Us ing a simple bi-directional re la tion, th e DEM d a ta a re used to m odel the Landsa t im age. We th erefore d emonstrate that the doub le rid ge is a produ c t o f a subtl e concavity pa ra ll el to the rid ge and is unlikel y to be d epe nd e nt on other factO rs. This concavity is not predi c ted b y stead y-sta te m od els ofi ee di vid es a nd so we sugges t th a t the ridge m ay not be in a steady-sta te but responding to changes in rh e g laciologieal boundary conditions. We spec ul a te that thi s ma v be a n indication o f |
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