Analysis of flow signals in glaciers smaller than 25 hectares

proposal for a new area threshold for glaciers

Abstract

An analysis was carried out on the signals that denote the present or past movement of “glacieret” (glaciers smaller than 25 ha according to the public glacier inventory IPG2022), in order to determine the frequencies of flow signal features analyzed in ranges every 5 ha and for each glaciological macrozone (North, South, Center and Austral), in order to establish relationships between glacier area and number and frequency of flow signals, in order to propose a new area threshold for the definition of “glacieret”. For this, we worked with the “glacieret” coding present in the public glacier inventory of the year 2022 (IPG2022), which occupies the classification of Cogley et al., (2011), who defines a glacieret as “a very small glacier, less than 0.25 km2 (25 ha) in size, without a marked flow pattern visible on the surface”. In total, 1,573 glaciers were analyzed using Google Earth, Google Engine, and Base Map Arcgis. The results showed that in glacieret with a surface area of less than 15 hectares there is a marked absence of morphologies that may indicate movement, which increase significantly in glacieret larger than 15 ha, exceeding 60% in several flow signals. In view of these results, it is concluded that glacieret larger than 15 hectares may be glaciers with active and present movement conditions, this is because most of them present at least one sign of flow, and all of them have the thickness and tension necessary to deform. Therefore, it is estimated that the definition of “glacieret” should be limited to bodies of ice or patches of perennial snow with areas less than 15 ha.