Late Quaternary Permafrost Distribution Downscaled in South America: Examinations of the GCM-based maps with the observations

SAITO, KAZUYUKI ; TROMBOTTO LIAUDAT, DARIO; YOSHIKAWA, K.; MORI, JUNKO ; TOSHIO SONE; MARCHENKO, SERGEY ; ROMANOVSKY, VLADIMIR ; WALSH, JOHN; HENDRICKS, AMY ; BOTTEGAL, ESTEFANÍA

PERMAFROST AND PERIGLACIAL PROCESSES

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2015

1045-6740

Here, we have reconstructed high-resolution maps of the potential frozen ground distribution  in South America for the present-day (0ka), and the Last Glacial Maximum (21ka), examining their validity using fieldwork-based evidence and knowledge. Surface air temperature outputs from global climate models (GCMs) participating in the recent Paleoclimate Model Intercomparison Project (PMIP3) were used for reconstructions, and then downscaled from regional to local scales with help of a one-arc minute digital elevation model (DEM). The downscaled map for the present day successfully reproduced the presence of permafrost in the Andes, at which original coarse-resolution GCM output maps failed, and also showed close coincidence with instrumental observations. Similarly, the downscaled distribution of 21 ka frozen ground showed overall consistency with geomorphological and/or paleoenvironmental reconstructions. The arial coverage of potential permafrost for all of South Ameirca is estimated at 139,000 km2 for today, and 581,000 km2 for 21 ka, located mostly along the Andean mountain ranges. Regional inspections, however, showed divergence from field-observed features partially owing to microclimatic and past permafrost conditions. For southern Patagonia, and especially the eastern lowlands, the diagnosed lower limit for permafrost is about 1000 m a.s.l., whereas field evidence at lower altitudes indicates the presence of either permafrost or deep seasonal frost.