FURTHER CHARACTERIZING OF ANTARCTICA’S MCMURDO DRY VALLEY MICROCLIMATE ZONES AS A FUNCTION OF ELEVATION AND ASPECT

The McMurdo Dry Valleys (MDV) of Antarctica are a hyper-arid, cold polar desert with an environment so unique it may be the closest terrestrial analogue to Mars. Climate in the MDV, a primarily ice-free region in the Transantarctic Mountains, varies with elevation and distance from the coast. The MDV have been subdivided into three microclimate zones based on summertime atmospheric temperature, positive degree-days, and morphological features. The three zones as described by Marchant and Head (2007) include the coastal thaw zone (CTZ), an inland mixed zone (IMZ), and an upland frozen zone (UFZ). Slight variation in climate forcings may significantly influence the spatial distribution of morphologic features and active surface processes. Thus, defining the existing boundaries of the climate zones is important for assessing past and/or future climate change. Here we examine detailed spatial climate variability within the microclimatic zones, warranting further quantifying and sub categorization of climate and landforms into localized nanoclimate zones. The asymmetric shape of many MDV valleys, where south facing slopes are noticeably steeper than opposing northern facing slopes, further suggests that nanoclimate zones may exist within the predefined microclimate zones. Monitoring of alluvial fan activity, snow melt, and adiabatic lapse rates within the coastal zones in the valleys displaying prominent asymmetric shape yields insight into the how the localized climate changes with respect to elevation and aspect. Through examining the differences in adiabatic lapse rate between north and south facing slopes, this research extends and updates the current classification scheme used to describe the processes that control climate within localized zones of the Antarctic Dry Valleys. Increased detailed characterization of these zones has the potential to yield greater understanding of the evolution of past climate, allowing for better downscaling of climate models, insight into the stability of Antarctic valley glaciers, and may also have further implications in explaining Martian landforms.