Permafrost

are placed so that the main cryogenic processes and phenomena had regional character are
depending on permafrost and geomorphologic conditions. (5) Distribution, ice content and
thickness of permafrost on the map are also reflected by combined appreciate numbers and
letters of color and line. There are borehole locations, data on mean annual temperature and
thickness of permafrost, and five boundaries of permafrost on the map.
Key words: permafrost map, ground temperature and mountain permafrost
188
Multiscale, Hierarchical Approach to Validation of Spatial Permafrost
Models
Nikolay I. Shiklomanov 1 , Oleg A. Amisimov 2 , Tingjun Zhang 3 , Vladimir E. Romanovsky 4
(1.Department of Geography, Center for Climatic Research, University of Delaware, Newark, DE 19716,
USA; 2.State Hydrological Institute, St. Petersburg, Russia; 3.National Snow and Ice Data Center, Boulder,
CO, USA; 4.Geophysical Institute, University of Alaska, Fairbanks, Fairbanks, AK, USA)
Abstract: Permafrost is a central element of the cryospheric system. Its importance has become
increasingly recognized in both scientific literature and popular media, especially in the last few
years. The past two decades have seen a dramatic rise in the number of permafrost models used
to evaluate permafrost parameters over geographic space, as well as spatial changes in
permafrost-related phenomena that may follow from global climate change. Despite the
importance of its roles in the geological, ecological, engineering, and climate-change sciences,
modeling of permafrost has, for the most part, remained the domain of individuals and small
groups of scientists, each utilizing its own methodological approach, resulting in a wide range
of results. This situation has made it difficult to incorporate generated data sets and modelling
products into the larger global-change research enterprise. Consequently, there has been little
effort to develop an explicit hierarchy of permafrost models, to evaluate their performance
using standardized validation tools and data sets and to explicitly link results of models
operating at different spatial scales.
At present, spatial permafrost models operating at small geographic scales (circumarctic,
continental) are usually evaluated at sets of point locations. Often, such approaches to
validation do not correspond to the resolution at which models are applied. The high spatial
variability of permafrost parameters requires careful selection of validation points. However,
observation locations rarely correspond well with generalized conditions prescribed for the
model’s grid cells. Correspondence between the scale of observations and modeling resolution
is necessary to compare observed and simulated patterns of permafrost parameters.
We addressed this problem by developing a hierarchical scheme for evaluating spatial
permafrost models. This scheme includes empirical data from point locations and observational
plots provided by current permafrost observation networks, regional characterization of
permafrost conditions, and circumpolar-scale models. This approach was applied to evaluate
results from two models operating at circumpolar scale and representing dynamic and
equilibrium classes of permafrost modeling. The National Snow and Ice Data Center and State
Hydrological Institute/University of Delaware permafrost models were used for analysis. The